Material changing hub, material changing system and material changing method

Abstract

The present invention relates to the field of 3D printing. Disclosed is a material changing system. The material changing system at least comprises a material changing hub; the material changing hub comprises a plurality of feeding ports and a plurality of discharging ports; the feeding ports are respectively correspondingly provided with switching mechanisms; inlet ends of the switching mechanisms are connected to the feeding ports; and each switching mechanism has a plurality of outlet ends which are respectively adaptively connected to the discharging ports, so that by changing the states of the switching mechanisms, the feeding ports can all be communicated with any discharging ports.

Description

A material changing hub, a material changing system, and a material changing method Technical Field

[0001] This invention relates to the field of 3D printing technology, and in particular to a material changing hub, a material changing system, and a material changing method. Background Technology

[0002] 3D printing is a process that uses digital model files as a basis to construct objects by printing layer by layer. The fused extrusion molding process, also known as FFF (Fused Filament Fabrication) or FDM (Fused Deposition Modeling), involves extruding heated, molten resin printing material through nozzles that move along the printing path onto a printing platform. After one layer is printed, the print head and the printing platform move away from each other by a certain distance, and then a new layer is printed. This process is repeated layer by layer until a three-dimensional model is formed.

[0003] 3D printing may require printing models using multiple materials, such as different colors or support structures, necessitating material changes. One existing approach is multi-nozzle printing, but the number of nozzles on the print head is limited, typically to dual nozzles, making it difficult to print more materials. Another approach is to change the print head to achieve multi-material printing. While this expands the range of printable materials to some extent, the higher cost and larger space required by multiple print heads still restrict the printing of a wider variety of materials. Alternatively, multiple materials can be fused together sequentially to a preset length before being conveyed to the print head, but these methods often impact printing speed.

[0004] Therefore, it is necessary to propose new technical solutions to improve the current situation. Summary of the Invention

[0005] Existing 3D printer structures have room for improvement. For example, the method of changing printheads places higher demands on the repeatability and accuracy of the replacement process. The complex structure of the printhead makes it difficult to maintain consistent nozzle position accuracy when changing different printheads, often leading to poor bonding between the printed parts of the model. Techniques such as retracting the printing material from the feed tube and then feeding another piece of material into it to the printhead for multi-material printing, or fusing multiple pieces of material sequentially to a preset length before feeding them to the printhead, significantly impact printing speed due to the processes of retracting and refeeding the material, as well as the fusing of multiple material segments. While connecting multiple feed tubes to the printhead can increase the speed of material changes, the number of different types of material is limited by the number of feed tubes connected to the printhead. Furthermore, too many feed tubes increase the complexity of the printhead structure, increasing the drag force exerted by the feed tubes during printhead movement and further hindering printing speed improvements.

[0006] To overcome the shortcomings of existing technologies, this application proposes a new technical solution.

[0007] The present invention provides a material changing system, which includes at least one material changing hub. The material changing hub includes several inlet ports and several outlet ports. Each inlet port is provided with a switching mechanism. The inlet end of the switching mechanism is connected to the inlet port, and the outlet end of the switching mechanism has several outlets, which are adapted and connected to each of the outlet ports, so that by changing the state of the switching mechanism, each inlet port can be connected to any of the outlet ports.

[0008] In some preferred embodiments, each of the switching mechanisms is equipped with a feeding structure, which includes a plurality of feeding manifolds or a plurality of feeding channels; the feed end of the feeding structure for receiving printing material is connected to the outlet end of each of the switching mechanisms, and the discharge end of the feeding structure for discharging printing material is connected to each of the discharge ports; or,

[0009] The feeding structure adopts a channel structure with each of the discharge ports. The channel structure is conical. The port in the channel structure used to receive the printing material is the larger end and faces the outlet end of the switching mechanism. The projection of the outlet end of each switching mechanism along the printing material conveying direction falls on the port in the channel structure used to receive the printing material. Alternatively, the outlet end of the switching mechanism is connected to the channel structure through a feeding pipeline. The port in each of the channel structures used to discharge the printing material forms the discharge port or is connected to the discharge port.

[0010] In some preferred embodiments, the switching mechanism is one or a combination of the following:

[0011] The switching mechanism includes a rotating body and a rotating support for supporting the rotating body to rotate about its own axis; the rotating body has a feeding channel, and in the direction of printing material feeding, the projection of the port of the feeding channel for receiving printing material always at least partially overlaps with the projection of the feeding port; the port of the feeding channel for discharging printing material is spaced apart from the axis of the rotating body; the outlet end of the switching mechanism is circumferentially spaced at positions corresponding to the rotating path of the port of the feeding channel for discharging printing material; or,

[0012] The switching mechanism includes a rotating body and a rotating support for supporting the rotating body to rotate around its own axis. The rotating body has a feeding channel, with both the port for receiving printing material and the port for discharging printing material located on the outer circumferential surface of the rotating body. The feeding channel has several ports for receiving printing material, all of which communicate with a common port for discharging printing material. The outlet end of the switching mechanism is circumferentially spaced at corresponding positions on the rotation path of the common port for discharging printing material. When the rotating body moves to multiple positions where the ports for receiving printing material in the feeding channel are opposite to the inlet end of the switching mechanism, the common port for discharging printing material in the feeding channel is then opposite to the outlet end of the switching mechanism. Alternatively,

[0013] The switching mechanism includes a rotating body and a rotating support for supporting the rotating body to rotate around its own axis. A feeding channel is provided in the rotating body. Both the port for receiving printing material and the port for discharging printing material are located on the outer circumferential surface of the rotating body. The outlet end of the switching mechanism is circumferentially spaced at corresponding positions on the rotating path of the outlet of the feeding channel. The port for receiving printing material is conical, with the larger end facing the inlet port. When the rotating body moves to multiple positions where the port for discharging printing material in the feeding channel is opposite the outlet end of the switching mechanism, the projection of the inlet end of the switching mechanism along the direction of printing material feeding always falls within the port for receiving printing material in the feeding channel; or...

[0014] The switching mechanism includes a sliding body and a sliding support for supporting the sliding of the sliding body; the outlet end of the switching mechanism is arranged at intervals along the movement trajectory of the sliding body; the sliding body has a plurality of material feeding channels; when the sliding body moves to multiple positions such that the port in each of the material feeding channels for receiving the printing material is opposite to the inlet end of the switching mechanism, the port in each of the material feeding channels for discharging the printing material is respectively opposite to each outlet end of the switching mechanism; or,

[0015] The switching mechanism includes a sliding body and a sliding support for supporting the sliding of the sliding body; the outlet ends of the switching mechanism are arranged at intervals along the movement trajectory of the sliding body; the sliding body has a material feeding channel with several ports for receiving printing material, all of which are connected to a common port for discharging printing material. When the sliding body moves to multiple positions where the ports for receiving printing material in the material feeding channel are opposite to the inlet end of the switching mechanism, the common port for discharging printing material in the material feeding channel is then opposite to each outlet end of the switching mechanism; or,

[0016] The switching mechanism includes a sliding body and a sliding support for supporting the sliding of the sliding body; the outlet ends of the switching mechanism are arranged at intervals along the movement trajectory of the sliding body; a feeding channel is provided on the sliding body, the feeding channel is conical, and the port in the feeding channel for receiving the printing material is the larger end and faces the inlet end of the switching mechanism. When the sliding body moves to multiple positions where the port in the feeding channel for discharging the printing material is opposite to the outlet ends of the switching mechanism, the projection of the inlet end of the switching mechanism along the printing material feeding direction always falls on the port in the feeding channel for receiving the printing material; or,

[0017] The switching mechanism includes a movable body and a movable support for supporting the movement of the movable body; the outlet ends of the switching mechanism are arranged at intervals along the movement trajectory of the movable body; wherein, the inlet end of the switching mechanism is connected to the movable body through a feed pipe (material conveying channel); or,

[0018] The switching mechanism includes a flipping body and a flipping support for supporting the flipping body to rotate around its flipping axis. The flipping support has a feeding channel, which includes an infeed section for receiving printing material and two outlet sections for discharging printing material. The infeed section intersects with both outlet sections. The flipping body is pivotally connected between the two outlet sections, or pivotally connected between the infeed section and the two outlet sections, or pivotally connected within the feeding channel, and / or the flipping body can rotate around an axis perpendicular to the axis of the infeed section and / or the axis of the outlet sections. The port of the infeed section for printing material entry forms the inlet end of the switching mechanism, and the ports of the outlet sections for printing material discharge form the outlet ends of the switching mechanism; or...

[0019] The switching mechanism includes a rotating body and a rotating support for supporting the rotating body to rotate around its axis of rotation. The rotating support has a material conveying channel, which includes an inlet section for receiving printing material and multiple outlet sections for discharging printing material. The inlet section intersects with multiple outlet sections. When the rotating body rotates to its corresponding position, it blocks the inlets of all outlet sections except the one corresponding to that position. The port of the inlet section for receiving printing material forms the inlet end of the switching mechanism, and the ports of each outlet section for discharging printing material form the outlet end of the switching mechanism. Alternatively,

[0020] The switching mechanism includes a rotating body and a rotating support for supporting the rotating body to rotate about its own axis. The rotating body has a feeding channel; the port for receiving printing material is located on the first end face of the feeding channel, and the port for discharging printing material is located on the second end face of the rotating body. The feeding channel has several ports for receiving printing material, all of which are connected to a common port for discharging printing material. The outlet end of the switching mechanism is circumferentially spaced at corresponding positions on the rotation path of the common port for discharging printing material. When the rotating body moves to multiple positions where the ports for receiving printing material in the feeding channel are opposite to the inlet end of the switching mechanism, the common port for discharging printing material in the feeding channel is then opposite to the outlet end of the switching mechanism. Alternatively...

[0021] The switching mechanism includes a rotating body and a rotating support for supporting the rotating body to rotate about its own axis; the rotating body has multiple feeding channels, with the port for receiving printing material in each feeding channel located on a first end face of the rotating body, and the port for discharging printing material in each feeding channel located on a second end face of the rotating body; when the rotating body moves to multiple positions such that the ports in each feeding channel for receiving printing material are opposite to the inlet end of the switching mechanism, the ports in each feeding channel for discharging printing material are respectively opposite to the outlet ends of the switching mechanism; or,

[0022] The switching mechanism includes a rotating body and a rotating support for supporting the rotating body to rotate around its own axis. The rotating body has a feeding channel; the port for receiving printing material is located on the first end face of the feeding channel, and the port for discharging printing material is located on the second end face of the rotating body. The outlet end of the switching mechanism is circumferentially spaced at corresponding positions on the rotating path of the outlet of the feeding channel for discharging printing material. The port for receiving printing material in the feeding channel is conical, with the larger end facing the inlet port. When the rotating body moves to multiple positions where the port for discharging printing material in the feeding channel is opposite to the outlet end of the switching mechanism, the projection of the inlet end of the switching mechanism along the direction of printing material feeding always falls on the port for receiving printing material in the feeding channel.

[0023] In some preferred embodiments, at least one of the feed ports is configured with two or more of the switching mechanisms, the switching mechanisms being divided into at least two levels along the conveying direction of the printing material, each level including one or more of the switching mechanisms;

[0024] When the switching mechanism is divided into two levels along the conveying direction of the printing material, the inlet end of the switching mechanism in the uppermost level is connected to the feeding port, and the inlet end of the switching mechanism in the lowermost level is connected to the outlet end of the switching mechanism in the uppermost level. The port in the material conveying structure used to receive the printing material is connected to the idle outlet end of each switching mechanism.

[0025] When the switching mechanism is divided into three or more levels along the conveying direction of the printing material, the inlet end of the switching mechanism in the uppermost level is connected to the feeding port, the inlet end of the switching mechanism in the middle level is connected to the outlet end of the switching mechanism in the level above, and the outlet end of the switching mechanism in the middle level is connected to the inlet end of the switching mechanism in the level below. The port in the material conveying structure used to receive the printing material is connected to the idle outlet end of each switching mechanism.

[0026] In some preferred embodiments, the material changing center is said to have s inlet ports and m outlet ports; wherein,

[0027] When the switching mechanisms are arranged in a single layer along the conveying direction of the printing material, the switching mechanism realizes the switching of the connection line used to convey the printing material from the inlet port to the outlet port. The material changing hub can include *s* switching mechanisms, each switching mechanism including one inlet end and *m* outlet ends. The inlet end of each switching mechanism is connected to the inlet port of the material changing hub, or the inlet end of each switching mechanism forms the inlet port of the material changing hub, and the outlet end of each switching mechanism is connected to the outlet port of the material changing hub; or...

[0028] When the switching mechanism is arranged in multiple levels along the conveying direction of the printing material, one outlet end of the upper-level switching mechanism is connected to the inlet end of the corresponding lower-level switching mechanism to form a cascaded switching mechanism. The switching of the connection line used to convey the printing material from the feed port to the discharge port is realized through the cascaded switching mechanism. Then, s cascaded switching mechanisms are used, and each cascaded switching mechanism has m idle outlet ends. The inlet end of each switching mechanism in the uppermost level is connected to the feed port of the material changing center, or the inlet end of each switching mechanism in the uppermost level forms the feed port of the material changing center. The discharge port is connected to the idle outlet end of each cascaded switching mechanism. Here, s and m are positive integers greater than or equal to 2.

[0029] In some preferred embodiments, the present invention provides a material changing system, including a material changing hub, a print head, and a plurality of material sources as described above; each of the material sources is connected to a respective feed port of the material changing hub; wherein,

[0030] The printhead has one outlet port connected to the material changing center via a feed pipe; or...

[0031] The printhead has two or more parts, and each printhead is connected to at least one discharge port of the material changing center via a feed pipe; or,

[0032] The print head includes multiple hot ends, each of which is connected to at least one of the discharge ports of the material changing hub via a feeding pipe.

[0033] In some preferred embodiments, a material detection sensor and a wire feeder are also included; wherein,

[0034] The filament feeders are respectively installed on the printing material conveying path between each of the aforementioned material sources and the corresponding feeding port; and / or...

[0035] The wire feeder is installed at the discharge port of the switching mechanism; and / or,

[0036] The filament feeder is configured on the printing material transport path of the print head; and / or,

[0037] Each of the aforementioned feed ports or the inlet end of the aforementioned switching mechanism is respectively equipped with a detection sensor; and / or,

[0038] The material detection sensor is respectively installed at each discharge port of the material changing hub or at the outlet end of the switching mechanism; and / or,

[0039] The feeding pipeline is equipped with the material detection sensor at the end near the print head; and / or,

[0040] The feed inlet of the print head is equipped with the detection sensor; or,

[0041] The printhead inlet is equipped with a two-inlet-one-outlet connecting pipe, and the material detection sensor is respectively installed at the two inlet ends of the connecting pipe, or at the outlet end of the connecting pipe; or,

[0042] The material detection sensor is provided at the feed and / or discharge points of the wire feeder.

[0043] In some preferred embodiments, the inlet of the printhead is provided with a multi-inlet-one-outlet connecting pipe, the outlet end of which is connected to the inlet of the printhead, and the inlet ends of which are respectively connected to the outlet ports of the material changing hub through the feeding pipeline; or,

[0044] The feeding pipeline includes a feeding pipe, with the inlet of the print head connected to one end of the feeding pipe, and the other end of the feeding pipe connected to the outlet end of a multi-inlet-one-outlet connecting pipe. The inlet ends of the multi-inlet-one-outlet connecting pipe are respectively connected to the outlet ports of the material changing hub through the feeding pipeline. The multi-inlet-one-outlet connecting pipe can be a two-inlet-one-outlet connecting pipe.

[0045] In some preferred embodiments, there are two or more material changing centers, and each material changing center is equipped with a plurality of material sources, wherein,

[0046] The print head is connected to at least one discharge port of each of the material changing centers via a feeding pipeline; or...

[0047] Each of the aforementioned material changing centers forms a combined material changing center. The combined material changing center further includes several multi-inlet, one-outlet connecting pipes. The outlet ends of these pipes respectively form the outlet ports of the combined material changing center, or are respectively connected to the outlet ports of the combined material changing center. The inlet ends of these pipes are respectively connected to the outlet ports of each of the material changing centers. The inlet ports of each material changing center respectively form the inlet ports of the combined material changing center, or are respectively connected to the inlet ports of the combined material changing center. By changing the state of the switching mechanism, each inlet port of the combined material changing center can be connected to any outlet port of the combined material changing center. The outlet ports of the combined material changing center are then connected to the printhead via feeding pipes; or...

[0048] Each of the aforementioned material changing centers forms a combined material changing center. This combined material changing center also includes several multi-inlet / one-outlet connecting pipes. These multi-inlet / one-outlet connecting pipes are divided into two levels along the material conveying direction. The outlet ends of the multi-inlet / one-outlet connecting pipes at the lowest level respectively form the outlet ports of the combined material changing center or are respectively connected to the outlet ports of the combined material changing center. The outlet ends of the multi-inlet / one-outlet connecting pipes at the highest level are respectively connected to one inlet end of a different multi-inlet / one-outlet connecting pipe at the lowest level. The discharge ports of the material changing hubs are respectively connected to the idle inlet ends of each multi-inlet-one-outlet connecting pipe. The inlet ports of each material changing hub form the inlet ports of the combined material changing hub or are respectively connected to the inlet ports of the combined material changing hub. By changing the state of the switching mechanism, each inlet port of the combined material changing hub can be connected to any outlet port of the combined material changing hub. The outlet ports of the combined material changing hub are respectively connected to the print head through feeding pipes; or...

[0049] Each of the aforementioned material changing centers forms a combined material changing center. This combined material changing center also includes several multi-inlet / one-outlet connecting pipes. These multi-inlet / one-outlet connecting pipes are divided into three or more levels along the material conveying direction. The outlet ends of the multi-inlet / one-outlet connecting pipes at the lowest level form the outlet ports of the combined material changing center, or are connected to the outlet ports of the combined material changing center. The outlet ends of the multi-inlet / one-outlet connecting pipes in the middle levels are connected to the inlet ends of different multi-inlet / one-outlet connecting pipes in the next lower level. The inlet ends of the multi-inlet / one-outlet connecting pipes in the middle levels are connected to the upper... The outlet ends of the multi-inlet-one-outlet connecting pipes within a single level are connected. The outlet port of the material changing hub is connected to the corresponding empty inlet in each of the multi-inlet-one-outlet connecting pipes. The inlet ports of each material changing hub form the inlet ports of the combined material changing hub or are connected to the inlet ports of the combined material changing hub. By changing the state of the switching mechanism, each inlet port of the combined material changing hub can be connected to any outlet port of the combined material changing hub. The outlet ports of the combined material changing hub are then connected to the print head through feeding pipes; or...

[0050] The aforementioned material changing centers form a combined material changing center. Each combined material changing center further includes several multi-inlet / one-outlet connecting pipes. These multi-inlet / one-outlet connecting pipes are arranged in a single layer along the material conveying direction. The number of inlets of the multi-inlet / one-outlet connecting pipes is equal to or greater than the number of material changing centers. This combined material changing center includes n material changing centers, each with m outlet ports and using m multi-inlet / one-outlet connecting pipes. The corresponding outlet port of each material changing center is connected to the inlet end of each multi-inlet / one-outlet connecting pipe, and the outlet end of each multi-inlet / one-outlet connecting pipe is connected to the outlet end of the combined material changing center. The material ports are connected one-to-one or the outlet ends of multiple inlet and outlet connecting pipes respectively form the outlet ports of the combined material changing hub. The inlet ports of each of the material changing hubs respectively form the inlet ports of the combined material changing hub or are respectively connected to the inlet ports of the combined material changing hub. By changing the state of the switching mechanism, each inlet port of the combined material changing hub can be connected to any outlet port of the combined material changing hub. The outlet ports of the combined material changing hub are respectively connected to the print head through feeding pipes; where m and n are both positive integers greater than or equal to 2; or,

[0051] The aforementioned material changing centers form a combined material changing center. This combined material changing center also includes several multi-inlet / one-outlet connecting pipes. These multi-inlet / one-outlet connecting pipes are arranged in multiple levels along the material conveying direction. The outlet end of the multi-inlet / one-outlet connecting pipe of the upper level is connected to one inlet end of the multi-inlet / one-outlet connecting pipe of the lower level, forming a cascaded multi-inlet / one-outlet connecting pipe. This combined material changing center includes n material changing centers, each with m outlet ports. Therefore, m cascaded multi-inlet / one-outlet connecting pipes can be used. Each cascaded multi-inlet / one-outlet connecting pipe has n or more idle inlet ports. The corresponding outlet port of each material changing center is connected to the idle inlet port of the cascaded multi-inlet / one-outlet connecting pipe. At the inlet end, the outlet end of the lowest-level multi-inlet-one-outlet connecting pipe is connected to the outlet port of the combined material changing center, or the outlet end of the lowest-level multi-inlet-one-outlet connecting pipe forms the outlet port of the combined material changing center. The inlet ports of each of the material changing centers form the inlet ports of the combined material changing center, or are connected to the inlet ports of the combined material changing center. By changing the state of the switching mechanism, each inlet port of the combined material changing center can be connected to any outlet port of the combined material changing center. The outlet ports of the combined material changing center are connected to the print head through feeding pipes. Where m and n are positive integers greater than or equal to 2.

[0052] In some preferred embodiments, the feeding pipeline includes multiple inlet and one outlet connecting pipes; wherein,

[0053] A portion of the discharge port of the material changing hub is connected to the inlet end of the multi-inlet-one-outlet connecting pipe, and the outlet end of the multi-inlet-one-outlet connecting pipe is connected to the print head via a feeding pipe; or,

[0054] Several multi-inlet / one-outlet connecting pipes are divided into two levels along the printing material conveying direction. The outlet end of the multi-inlet / one-outlet connecting pipe at the bottom level is used to connect to the print head. The outlet end of the multi-inlet / one-outlet connecting pipe at the top level is connected to an inlet end of a different multi-inlet / one-outlet connecting pipe at the bottom level. The discharge port of each material changing hub is connected to an idle inlet end of each multi-inlet / one-outlet connecting pipe; or...

[0055] The plurality of multi-inlet / one-outlet connecting pipes are divided into three or more levels along the material conveying direction. The outlet end of the multi-inlet / one-outlet connecting pipe in the lowest level is used to connect to the print head. The outlet ends of the multi-inlet / one-outlet connecting pipes in the middle levels are respectively connected to the inlet ends of different multi-inlet / one-outlet connecting pipes in the next level. The inlet ends of the multi-inlet / one-outlet connecting pipes in the middle levels are connected to the outlet ends of the multi-inlet / one-outlet connecting pipes in the previous level. The discharge port of each material changing hub is respectively connected to the idle inlet of each multi-inlet / one-outlet connecting pipe; or,

[0056] Several multi-inlet / one-outlet connecting pipes are arranged in a single layer along the conveying direction of the printing material. The number of inlet ends of the multi-inlet / one-outlet connecting pipes is equal to or greater than the number of material changing centers. The number of material changing centers is n, and each material changing center has m outlet ports. Each material changing center uses m multi-inlet / one-outlet connecting pipes, with each outlet port of the material changing center connected to the inlet end of one of the multi-inlet / one-outlet connecting pipes. The outlet ends of the multi-inlet / one-outlet connecting pipes are connected one-to-one with the outlet ports of the combined material changing center, or the outlet ends of the multi-inlet / one-outlet connecting pipes form the outlet ports of the combined material changing center. Here, m is a positive integer greater than or equal to 2, and n is a positive integer greater than or equal to 1; or...

[0057] Several multi-inlet / one-outlet connecting pipes are divided into multiple levels along the conveying direction of the printing material. The outlet end of the multi-inlet / one-outlet connecting pipe of the upper level is connected to one inlet end of the multi-inlet / one-outlet connecting pipe of the lower level to form a cascaded multi-inlet / one-outlet connecting pipe. The combined material changing center includes n material changing centers, each material changing center has m outlet ports, so m cascaded multi-inlet / one-outlet connecting pipes can be used. Each cascaded multi-inlet / one-outlet connecting pipe has n or more idle inlet ends. The corresponding outlet port of each material changing center is connected to the idle inlet end of the cascaded multi-inlet / one-outlet connecting pipe. The outlet end of the multi-inlet / one-outlet connecting pipe of the lowest level is connected to the outlet port of the combined material changing center, or the outlet end of the multi-inlet / one-outlet connecting pipe of the lowest level forms the outlet port of the combined material changing center, where m is a positive integer greater than or equal to 2 and n is a positive integer greater than or equal to 1.

[0058] In some preferred embodiments, the device includes a plurality of material changing hubs, which are divided into multiple levels along the material conveying direction. The discharge port of the material changing hub in the upper level is connected to the feed port of the material changing hub in the next level. The feed port of the material changing hub in the uppermost level is connected to the material source. The discharge port of the material changing hub in the lowermost level is connected to the print head through a feeding pipeline.

[0059] In some preferred embodiments, the present invention provides a material changing method or process applied to the material changing system described above, wherein the printhead has one output port connected to at least two output ports of the material changing hub via a feeding pipe, and the material changing process or method includes the following steps:

[0060] The first printing material to be used in the current step and its corresponding first material source are determined. Under the conveying of the filament feeder equipped with the first material source, the first printing material is conveyed to the corresponding first feeding port of the material changing center or to the inlet end of the corresponding first switching mechanism of the material changing center. The corresponding first switching mechanism is controlled to connect the first feeding port with the first discharge port in the material changing center that is connected to the print head, so that the first printing material is conveyed to the first discharge port. Under the action of the filament feeder equipped with the first material source, the first printing material is conveyed to the print head through the first discharge port along the first feeding path in the feeding pipeline, and the print head performs printing.

[0061] During the printing process of the first printing material, the second printing material to be used in the next step and its corresponding second material source are determined. Under the action of the filament feeder equipped with the second material source, the second printing material is transported to the corresponding second feeding port of the material changing center or to the inlet end of the corresponding second switching mechanism of the material changing center. The corresponding second switching mechanism is controlled to connect the second feeding port with the second discharge port in the material changing center that is connected to the print head, and the second printing material is transported to the second discharge port. Under the action of the filament feeder equipped with the second material source, the second printing material is transported through the second discharge port along the second feeding path in the feeding pipeline to a position near the intersection of the second feeding path and the first feeding path, ready for use.

[0062] After the printing process of the first printing material in the current step is completed, the first printing material is cut off at a position downstream of the printing material conveying direction at the intersection of the second feeding path and the first feeding path, and the first printing material is pulled back to the position where the first feeding path and the second feeding path intersect in the feeding pipeline to prevent the first printing material from obstructing the second printing material.

[0063] Under the action of the filament feeder equipped with the second material source, the second printing material is conveyed to the print head, and the print head prints the second printing material.

[0064] In some preferred embodiments, the printing process of the first printing material further includes the following steps:

[0065] Determine the third printing material to be used in the next step and its corresponding third material source;

[0066] When two outlet ports of the material changing center are available, the third printing material is transported to the corresponding third inlet port of the material changing center or to the inlet of the corresponding third switching mechanism of the material changing center under the action of the filament feeder equipped with the third material source. The third switching mechanism is controlled to connect the third inlet port with the first outlet port. After the first printing material is pulled back to the first inlet port or the inlet of the first switching mechanism or has passed the first outlet port to avoid obstruction to the third printing material, the third printing material is transported to the first outlet port through the filament feeder equipped with the third material source. The third printing material is then transported along the first feeding path in the feeding pipeline to a position near the intersection of the first feeding path and the second feeding path, ready for use.

[0067] When three or more outlet ports of the material changing center are available, the third printing material is conveyed to the corresponding third inlet port of the material changing center or to the inlet of the corresponding third switching mechanism of the material changing center by the filament feeder equipped with the third material source. The corresponding third switching mechanism is controlled to connect the third inlet port with the third outlet port of the material changing center that is connected to the print head. Then, the third printing material is conveyed to the third outlet port by the filament feeder equipped with the third material source. Under the action of the filament feeder equipped with the third material source, the third printing material is conveyed along the third feeding path in the feeding pipeline to a position near the intersection of the third feeding path and the second feeding path, ready for use.

[0068] After the printing process of the second printing material is completed, the second printing material is cut off at a position downstream of the intersection position along the printing material conveying direction. The second printing material is then pulled back to the position where the second feeding path and the third feeding path intersect in the feeding pipeline through the second filament feeder, so as to prevent the second printing material from obstructing the third printing material.

[0069] The third printing material is fed into the print head by the filament feeder of the third material source, and the print head prints the third printing material.

[0070] In some preferred embodiments, the present invention provides a material changing method or process applied to the material changing system described above, wherein there are two or more printheads, each printhead being connected to at least one discharge port of the material changing hub via a feeding pipe, and the method or process includes the following steps: during the material changing process,

[0071] The first print head, the first printing material, and its corresponding first material source are determined for the current step. Under the action of the filament feeder equipped with the first material source, the first printing material is transported to the corresponding first feed port of the material changing center or to the inlet end of the corresponding first switching mechanism of the material changing center. The corresponding first switching mechanism is controlled to connect the first feed port with the first discharge port of the material changing center that is connected to the first print head. Then, under the action of the filament feeder equipped with the first material source, the first printing material is transported to the first print head through the first discharge port and along the first feeding path in the feeding pipeline. The first print head then performs printing.

[0072] During the printing process of the first printing material, the second print head, the second printing material, and its corresponding second material source to be used in the next step are determined. Then, under the action of the filament feeder equipped with the second material source, the second printing material is transported to the corresponding second feeding port of the material changing center or to the inlet end of the corresponding second switching mechanism of the material changing center. The corresponding second switching mechanism is controlled to connect the second feeding port with the second discharge port in the material changing center that is connected to the second print head. Under the action of the filament feeder equipped with the second material source, the second printing material is transported to the second print head through the second discharge port and along the second feeding path of the feeding pipeline, ready for use.

[0073] After the first printing process is completed, the first print head is moved out of the printing area, and then the second print head is moved into the printing area to print the second printing material.

[0074] In some preferred embodiments, when a third printhead needs to be printed using the first printhead in a subsequent step, the method or process further includes the following steps:

[0075] When the first printhead is connected to a discharge port on the material changing hub via the feeding pipeline, the first printhead is cut off during the printing of the second printhead. After the first printhead is pulled back to the first feed port of the material changing hub or the inlet of the first switching mechanism, or after passing the first discharge port, it avoids obstruction to the third printhead. Then, the third printhead is transported to the first discharge port of the material changing hub through the filament feeder equipped with the third printhead, and the third printhead continues to be transported to the first printhead along the first feeding path in the feeding pipeline, ready for use.

[0076] After the second printing process is completed, the second print head is moved out of the printing area, and then the first print head is moved into the printing area to print the third printing material.

[0077] or,

[0078] When the first print head is connected to multiple outlet ports on the material changing hub through the feeding pipeline, during the process of the first print head printing the first print material or the process of the second print head printing the second print material, under the action of the filament feeder equipped with the third material source, the third print material is transported to the third outlet port of the material changing hub and transported along the third feeding path of the feeding pipeline to the position where it intersects with the first feeding path, ready for use;

[0079] After the first printing material is printed, the first printing material is cut off at a position downstream of the intersection position along the printing material conveying direction. The first printing material is then pulled back to the position where the first feeding path and the third feeding path intersect in the feeding pipeline (or pulled back to a position that no longer obstructs the other feeding path) to prevent the first printing material from obstructing the third printing material.

[0080] Then, under the action of the filament feeder equipped with the third printing material, the third printing material is transported to the first print head. After the second print head finishes printing and moves out of the printing area, the first print head connected to the third printing material is moved back into the printing area to facilitate the printing of the third printing material.

[0081] In some preferred embodiments, when performing a printing material switching operation on the printhead, the hot end of the printhead is replaced accordingly, and the newly replaced hot end does not contain printing material or contains printing material residue that is the same as the printing material to be received.

[0082] In some preferred embodiments, the print head is provided with two hot ends, each of which is connected to at least one discharge port of the material changing hub through a feeding pipe; or, the print head has two or more, and at least two of the print heads are fixedly connected to each other and merged into one print head.

[0083] By adopting the above technical solution, the beneficial effects of the present invention are at least one of the following:

[0084] 1. Regardless of the number of types or quantities of printing media, as long as at least two outlet ports of the media changing hub are connected to a single printhead, free and rapid switching between any printing media can be achieved. For example, the media changing hub can have two outlet ports, each connected to the same printhead via flexible feeding lines to supply media to the hot end of that printhead. Alternatively, a two-in-one-out connecting pipe can be used. This greatly simplifies and lightens the printhead's structure, allowing for free switching between various printing media and improving printing speed and accuracy. Furthermore, the media switching process is rapid, achieved through the media changing hub... The hub enables the conversion of various printing materials into two or more output channels. The material switching hub allows each feed port to be simultaneously connected to any output port. It allows all printing materials connected to the feed ports to be transmitted in any combination with the output ports. One channel can be used for printing by the 3D print head, while the other channel can be used for standby. For example, the printing material to be used in the next step can be selected in advance from a large number of printing materials and switched to another channel in advance, realizing a faster printing material switching process. In addition, the two or more output ports are shared and symmetrical with all feed ports, and the switching process is free and flexible.

[0085] 2. The feed ports of the feed changer can be connected to different printheads, enabling different printheads to share all feed sources and to deliver various combinations of feed materials to multiple printheads. Furthermore, it allows for free and rapid switching of any number of feed materials with only two printheads. It also allows one printhead to print while the other switches feed materials simultaneously, further improving printing speed or reducing printing time spent on feed switching. For example, the feed changer has two feed ports, each connected to a separate printhead. By having the two printheads print alternately, with one printhead in printing mode and the other in feed switching / standby mode, free and rapid switching of any number of feed materials and printing of any feed material can be achieved. Additionally, it can supply feed materials to printheads belonging to different printers, allowing different printers to share feed materials connected to the feed changer. This facilitates centralized feed material management, reduces feed material reuse when printing with multiple printers, and lowers costs.

[0086] 3. It is easier to expand the types or quantities of printing materials. Since the printing materials to be switched have been pre-switched by the material switching center and delivered to the pipeline near the print head, such as the inlet of the two-in-one-out connecting pipe on the print head, the distance between the material source (such as the material tray) and the print head has almost no impact on the material switching speed. Therefore, it is easier to place the material source as needed. For example, it can be placed in a space farther away from the print head, so more material sources can be set up. Multiple material switching centers can also be connected in parallel to achieve the connection and switching of more material sources.

[0087] 4. The printing material switching process is easily automated and highly reliable. For example, the switching mechanism does not need to move the feeding pipeline during printing material switching. The switching mechanism body is simply moved (sliding) or rotated (turning) relative to the support body at the corresponding outlet positions via a power device (such as a motor, servo motor, or solenoid valve) to switch the printing material delivery line. The printing material switching process is fast, stable, and reliable. Furthermore, it facilitates modular design of each switching mechanism or material changing center, simplifying design and development as well as maintenance and replacement. Attached Figure Description

[0088] Figure 1a is a schematic diagram of a material changing system with a material changing center.

[0089] Figure 1b is a schematic diagram of a material changing center using a switching mechanism.

[0090] Figure 2 is a schematic diagram of a method for conveying printing materials from multiple material sources to a single printhead via a material changing hub.

[0091] Figure 3 is a schematic diagram of a method for conveying printing materials from multiple material sources to two printheads via a material changing hub.

[0092] Figure 4 is a schematic diagram of another type of multi-input multi-output material changing center.

[0093] Figure 5 is a schematic diagram of a cascaded switching mechanism layout that enables a material changing center to connect more discharge ports.

[0094] Figure 6a is a schematic diagram of a switching mechanism and a material changing system in which two printheads are each connected to two feed tubes.

[0095] Figure 6b is a schematic diagram of a rotary switching mechanism and a schematic diagram of a material changing system in which two printheads are each connected to two feed pipes and one feed pipe.

[0096] Figure 7a is a schematic diagram of a sliding multi-inlet single-outlet switching mechanism and a schematic diagram of a material changing hub with four discharge ports formed by a cascaded switching mechanism layout.

[0097] Figure 7b is a schematic diagram of a rotary multi-inlet single-outlet switching mechanism and a schematic diagram of a material changing hub with four discharge ports formed by a cascaded switching mechanism layout.

[0098] Figure 7c is a schematic diagram of another rotary multi-inlet single-outlet switching mechanism and a schematic diagram of a material changing hub with four discharge ports formed by a cascaded switching mechanism layout.

[0099] Figure 7d is a schematic diagram of the material changing center with a channel structure at the discharge port.

[0100] Figure 8a is a schematic diagram of a combination of multiple material changing hubs that transport printing materials from multiple material sources to a single printhead.

[0101] Figure 8b is a schematic diagram of a material changing system that connects four material changing hubs through a four-inlet-one-outlet pipe connection structure.

[0102] Figure 8c is a schematic diagram of a material changing system that connects four material changing centers through a cascaded two-inlet-one-outlet pipe connection structure.

[0103] Figure 8d is a schematic diagram of a material changing system in which multiple material changing hubs with four discharge ports are connected in parallel.

[0104] Figure 8e is a schematic diagram of a material changing system that connects three material changing centers through a cascaded multi-inlet-one-outlet pipe connection structure.

[0105] Figure 8f is a schematic diagram of a material changing system in which multiple discharge ports of a material changing hub are connected by a cascade of multi-inlet and one-outlet connecting pipes.

[0106] Figure 8g is a schematic diagram of another material changing system in which multiple discharge ports of a material changing hub are connected by cascading multi-inlet-one-outlet connecting pipes.

[0107] Figure 8h is a schematic diagram of a combination of multiple material changing hubs that transport printing materials from multiple material sources to two printheads.

[0108] Figure 9a is a schematic diagram of a cascaded material changing system with a central material changing hub.

[0109] Figure 9b is a schematic diagram of another material changing system with a cascaded material changing hub.

[0110] Figures 10a to 10e are schematic diagrams of the printing material switching process, in which printing materials from multiple sources are transported to a single printhead via a material switching hub.

[0111] Figures 11a to 11c are schematic diagrams of the process of switching printing materials by transporting printing materials from multiple sources to two printheads through a material switching hub.

[0112] Figures 12a and 12b are schematic diagrams of a material exchange system including a heat exchange end mechanism. Figure 12a shows the state of the heat exchange end, and Figure 12b shows the state of the heat exchange end installed on the print head. Detailed Implementation

[0113] The following is a further description of specific embodiments of the present invention in conjunction with the accompanying drawings. It should be noted that the description of these embodiments is intended to facilitate understanding of the present invention and does not constitute a limitation of the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0114] Example 1

[0115] As shown in Figures 1b, 3, 4 and 6b, an embodiment of the present invention provides a material changing hub 10, which includes a feeding end group and a discharging end group. The feeding end group includes at least two feeding ports, for example, as shown in the figure, it includes six feeding ports, namely feeding ports 11, 12, 13, 14, 15 and 16. The discharging end group includes at least two discharging ports, for example, as shown in the figure, it includes two discharging ports 91 and 92.

[0116] A switching mechanism exists between the feed port group and the discharge port group. Operation of this mechanism allows for selective connection between any feed port and any discharge port, and simultaneously, selective connection between any other feed port and any other discharge port, enabling any feed port to be connected to any discharge port. For example, when feed port 12 is connected to discharge port 91, the remaining feed ports 11, 13, 14, 15, or 16 can also be connected to discharge port 92. For instance, feed port 14 can be connected to discharge port 92. This allows the printing material input through feed port 12 to be transported to discharge port 91, and simultaneously allows the printing material input through feed port 14 to be transported to discharge port 92. Ideally, the number of feed ports is greater than or equal to the number of discharge ports.

[0117] Each feeding port is equipped with a corresponding switching mechanism. The switching mechanism has an inlet end and several outlet ends. The inlet end is connected to the feeding port of the material changing hub, or the inlet end can coincide with the feeding port. The outlet ends are connected to the discharge ports of the material changing hub to transfer the printing material from the switching mechanism to the discharge ports of the material changing hub. The switching mechanism also includes a body (such as a rotating body or a sliding body) and a support body (such as a rotating support body or a sliding support body). The body has a material conveying channel and can move relative to the support body (such as sliding or rotating). The body can switch between multiple positions corresponding to each outlet end by moving relative to the support body. The port of the material conveying channel that receives the incoming printing material is connected to the inlet end of the switching mechanism, and the port of the material conveying channel that discharges the printing material is connected to each outlet end of the switching mechanism. Here, the inlet end of the switching mechanism refers to the port used to receive the incoming printing material, and the outlet end of the switching mechanism refers to the port used to discharge the printing material.

[0118] As shown in Figure 1b, the material changing hub 10 has six feed ports, namely feed ports 11, 12, 13, 14, 15, and 16. The material changing hub also includes two discharge ports 91 and 92. A switching mechanism is provided downstream of each feed port (in the direction of the printing material being conveyed towards the discharge port). The switching mechanisms are all identical in structure. Each feed port is connected to multiple material conveying manifolds through the corresponding switching mechanism. Each material conveying manifold is connected to the discharge port. The feed end of each material conveying manifold is connected to the outlet end of the switching mechanism, or the feed end of each material conveying manifold coincides with the outlet end of the switching mechanism. As shown in 1b, each switching mechanism is connected to two material conveying manifolds. One material conveying manifold is connected to the discharge port 91, and the other material conveying manifold is connected to the discharge port 92. The connection between the inlet port and the discharge port can be achieved by switching the switching mechanism. For example, a multi-inlet-one-outlet connecting pipe channel structure 991 is set at the discharge port 91, and a multi-inlet-one-outlet connecting pipe channel structure 992 is set at the discharge port 92. Each inlet end of the multi-inlet-one-outlet connecting pipe channel structure 991 is connected to one outlet end of each switching mechanism 31, 32, 33, 34, 35, and 36, respectively. Each inlet end of the multi-inlet-one-outlet connecting pipe channel structure 992 is connected to the other outlet end of each switching mechanism 31, 32, 33, 34, 35, and 36, respectively. For example, in Figure 1b, the feed port 11 is connected to the inlet end of the switching mechanism 31. The body 310 of the switching mechanism 31 is provided with a feeding channel 313. The port of the feeding channel 313 for receiving the printing material is connected to the inlet end of the switching mechanism 31. The inlet end of the switching mechanism 31 is connected to the feed port 11. The port of the feeding channel 313 for discharging the printing material is set towards the outlet end of the switching mechanism 31. By rotating the body 310 relative to the support 320, the port of the feeding channel 313 for discharging the printing material can be aligned with each outlet end of the switching mechanism 31. The outlet end of the switching mechanism 31 and the feed port 11 are connected to the inlet end of the switching mechanism 31. The inlet end can be fixedly connected to the support body 320. The outlet end of the switching mechanism is respectively connected to the feed ends of the feed manifold 211 and the feed manifold 212, or they are overlapping. In this way, the feed port 11 is connected to the feed manifold 211 and the feed manifold 212 through the switching mechanism 31. The feed manifold 211 is connected to the discharge port 91, and the feed manifold 212 is connected to the discharge port 92. The switching mechanism 31 can realize the connection between the feed port 11 and one of the feed manifold 211 or the feed manifold 212 by rotating around its own axis 300, thereby realizing the controllable connection between the feed port 11 and one of the discharge ports 91 and 92.Similarly, the feed port 12 can be connected to one of the conveying manifolds 221 and 222 by switching control via the switching mechanism 32, thereby achieving controllable connection between the feed port 12 and one of the discharge ports 91 and 92; the feed port 13 can be connected to one of the conveying manifolds 231 and 232 by switching control via the switching mechanism 33, thereby achieving controllable connection between the feed port 13 and one of the discharge ports 91 and 92; the feed port 14 can be connected to one of the conveying manifolds 241 and 242 by switching control via the switching mechanism 34. One of the inlet ports 14 and 91 or 92 can be connected, thus achieving controllable connection between the inlet port 14 and one of the outlet ports 91 or 92. The inlet port 15 can be connected to one of the conveying manifolds 251 or 252 through the switching mechanism 35, thus achieving controllable connection between the inlet port 15 and one of the outlet ports 91 or 92. The inlet port 16 can be connected to one of the conveying manifolds 261 or 262 through the switching mechanism 36, thus achieving controllable connection between the inlet port 16 and one of the outlet ports 91 or 92. The switching mechanism is equivalent to a one-inlet-multiple-outlet pipeline connection switching device, that is, the switching mechanism can achieve selective connection between the inlet end and any outlet end. The switching mechanism includes a body (such as a rotating body, a tilting body, a moving body, or a sliding body) and a support body (such as a rotating support body, a tilting support body, a moving support body, or a sliding support body). The switching mechanism can achieve connection between the inlet end and any outlet end by changing the state (relative movement between the body and the support body). A material conveying channel can be set within the main body or the support body. The switching mechanism includes one inlet end and multiple outlet ends. The relative movement between the main body and the support body allows the material conveying channel to connect the inlet end to any outlet end. Material conveying manifolds 211, 221, 231, 241, 251, and 261 are all connected to outlet port 91, and material conveying manifolds 212, 222, 232, 242, 252, and 262 are all connected to outlet port 92. The material conveying manifolds and outlet ports can be connected by a multi-inlet, one-outlet connecting pipe (pipe connection structure). Upstream of each switching mechanism (where the printing material is conveyed from the upstream position to the corresponding switching mechanism) and close to the switching mechanism, a material detection sensor can also be set. For example, a material detection sensor can be set at the feeding port or on the printing material conveying line between the feeding port and the corresponding switching mechanism to detect whether the end of the printing material is located upstream of the corresponding switching mechanism. For example, material detection sensors 51, 52, 53, 54, 55 and 56 are respectively set upstream of the printing material conveying lines corresponding to the switching mechanisms 31, 32, 33, 34, 35 and 36.

[0119] As shown in Figure 4, the material changing hub 10 has three inlet ports and three outlet ports, namely inlet ports 11, 12, and 13, and outlet ports 91, 92, and 93. Inlet ports 11, 12, and 13 correspond to switching mechanisms 31, 32, and 33, respectively. Each switching mechanism is connected to three material conveying manifolds, which are connected to the three outlet ports. For example, inlet port 11 is connected to the three inlet ends of switching mechanism 31. One end (inlet end) of the three material conveying manifolds 211, 212, and 213 is connected to the outlet end of switching mechanism 31, and the other end (outlet end) of the three material conveying manifolds 211, 212, and 213 is connected to outlet ports 91, 92, and 93, respectively. For example, as shown in Figure 4, the three feed manifolds connected to each switching mechanism are respectively connected to one inlet end of the multi-inlet-one-outlet connecting pipe channel structure 991, 992, and 993, thereby connecting to the discharge ports 91, 92, and 93 respectively. The body 310 of the switching mechanism 31 in Figure 4 can rotate around its own axis so that the port of the feed channel in the body 310 used to discharge the printing material is opposite to the corresponding outlet end of the switching mechanism, thereby selectively connecting (communicating) with one of the three feed manifolds, thus selectively connecting the feed port 11 with one of the three discharge ports. Similarly, the feed port 12 is connected to the inlet end of the switching mechanism 32. One end of each of the three feed manifolds 221, 222, and 223 is connected to the outlet end of the switching mechanism 32, and the other ends are connected to the discharge ports 91, 92, and 93, respectively. The switching mechanism 32 can selectively connect to one of the three feed manifolds by rotating around its own axis, thus allowing the feed port 12 to selectively connect to one of the three discharge ports. Similarly, the feed port 13 is connected to the inlet end of the switching mechanism 33. One end of each of the three feed manifolds 231, 232, and 233 is connected to the outlet end of the switching mechanism 32, and the other ends are connected to the discharge ports 91, 92, and 93, respectively. The switching mechanism 32 can selectively connect to one of the three feed manifolds by rotating around its own axis, thus allowing the feed port 12 to selectively connect to one of the three discharge ports. Of course, the material changing center can also have other numbers of inlet and outlet ports, as long as there are at least two inlet and outlet ports each.

[0120] Figures 4 and 5 illustrate the material switching hub with three output ports. These three output ports can also be connected to the print head via three feed pipes. For example, the three feed pipes can be connected to the three inlets of the three-in-one-out connector on the print head. This allows one feed pipe to deliver the currently printing material, while the other two are used to deliver the material needed for the next and subsequent steps. For instance, the material needed for the next and subsequent steps can be delivered to the other two inlets of the three-in-one-out connector as a backup. When a material switching is needed, the currently printed material is cut off and extracted. After the printhead, the next piece of printing material is fed into it. If the material just fed into the printhead needs to be switched to the next material after a very short printing time, and there are only two feed tubes (i.e., the material changing hub has only two outlet ports), the material extracted in the previous step may not have enough time to be replaced with the next material. However, if there are three feed tubes (i.e., the material changing hub has three outlet ports), the next material already switched in the third feed tube has been switched in advance, allowing for rapid material switching. In other words, when the material changing hub has three outlet ports, it can further shorten the material switching time in applications that require frequent switching between different materials in a short period. Of course, the material changing hub can have three, four, or more outlet ports. These outlet ports can also be used to connect different printheads, allowing more printheads to share the material source connected to the material changing hub (or a combined material changing hub). Enabling multiple printheads or printers to share a material source makes material source management more convenient for 3D printing applications, helps reduce the amount of printing material needed, and helps lower printing costs.

[0121] Figure 6b also illustrates the material changing hub with three output ports. The first output port 91 and the second output port 92 are connected to one of the printheads via feed pipes 27 and 28, respectively, to supply printing material to the hot end 810 of that printhead. A two-in-one-out connecting pipe 209 is provided on the printhead, with feed pipes 27 and 28 connected to the two inlet ends of the connecting pipe 209, and the outlet end of the connecting pipe connected to the printhead, thus supplying printing material to the hot end 810 of that printhead. The third output port 93 is connected to a secondary printhead via feed pipe 29, to supply printing material to the secondary hot end 810a of the secondary printhead, for example. The printhead and the secondary printhead can be printheads on the same printer or printheads on different printers. This allows for more flexible supply of printing material to multiple printheads. As shown in Figures 1b, 3, 4, and 6b, in this embodiment of the invention, the switching mechanism is configured as a rotary shaft type (rotary type). For example, the switching mechanism 31 includes a rotary support 320, a rotary body 310 rotatably mounted in the rotary support, and a material conveying channel 313 formed in the rotary body 310. The port of the material conveying channel 313 for receiving the printing material is arranged along the axial direction of the rotary body 310, so as to correspond with the inlet end 321 of the switching mechanism. The inlet end 321 of the switching mechanism is correspondingly connected to the feeding port, and when the rotary body 310 rotates around its own axis, the inlet end 321 of the switching mechanism is always connected to the port of the material conveying channel 313 for receiving the printing material, thereby ensuring that the printing material can enter the material conveying channel 313 from the feeding port. The inlet end of the switching mechanism can be the feeding port of the material changing hub. As shown in Figure 6b, one end (feed end) of the three feed manifolds 211, 212, and 213 is connected to the outlet ends 322, 323, and 324 of the switching mechanism 31, respectively, and the other end (discharge end) of the three feed manifolds 211, 212, and 213 is connected to the discharge ports 91, 92, and 93, respectively. Preferably, the projection of the inlet end of the switching mechanism along the direction of printing material feeding always falls in the port of the feed channel 313 used to receive the printing material. For example, as shown in Figure 1b or Figure 6b, the port of the feed channel 313 used to receive the printing material can be set as a cone with the larger end facing the inlet end of the switching mechanism. Ideally, the axis of the inlet end of the switching mechanism coincides with the rotation axis of the rotating body 310, and the axis of the port of the feed channel 313 used to receive the printing material coincides with the rotation axis of the rotating body 310.In Figures 3 and 4, the ports of the feeding channels 313 used for discharging printing material are all located on the radial sidewall of the rotating body 310. In Figures 1b and 6b, the ports of the feeding channels 313 used for discharging printing material are located on the end face of the rotating body 310 away from its inlet. This allows the feeding manifolds to be closer together, making the structure of the switching mechanism and the feeding manifold more compact. It also allows for a smaller angle of inclination of the feeding channel 313 or its port used for discharging printing material relative to the rotation axis of the rotating body 310, which is more conducive to smoother material delivery. The rotation axis of the rotating body 310 shown in Figure 4 is perpendicular to the plane of the drawing, while the rotation axis of the rotating body 310 shown in Figures 1b, 3, and 6b is parallel to the plane of the drawing. When a feeding port needs to be switched to connect with a discharging port, the switching mechanism rotates around its own axis, so that the port of the feeding channel 313 used for discharging printing material connects with the corresponding feeding manifold. For example, in Figure 1b, feed ports 11 and 14 are connected to discharge port 91, and feed ports 12, 13, 15, and 16 are connected to discharge port 92. In Figure 3, feed ports 11, 14, and 16 are connected to discharge port 91, and feed ports 12, 13, and 15 are connected to discharge port 92. In Figure 4, feed port 11 is connected to discharge port 93, feed port 12 is connected to discharge port 92, and feed port 13 is connected to discharge port 92. By switching the corresponding feed port, for example, by rotating the body 310 around its own axis, the port of the feed channel 313 used to discharge printing material can be connected to the corresponding feed manifold. For example, in Figure 1b, if the switching mechanism 31 switches by rotating (clockwise), the port of the feed channel 313 used to discharge printing material can be aligned with the feed end of the feed manifold 212 or the inlet end of the switching mechanism connected to that feed end, thus connecting the feed port 11 to the discharge port 92. In short, by switching the different states of the material switching center, the connection between any feed port and any discharge port can be achieved. The inlet and outlet ends of the switching mechanism can be fixedly connected to a support body (such as a sliding support body, a moving support body, or a rotating support body).

[0122] As shown in Figure 4, a rotary support body 320 is also sleeved on the outside of the rotary body 310. A hole is provided on the rotary support body 320. This hole can be used to form the outlet end of the switching mechanism or the feed end of the material conveying manifold. The hole is used to connect the material conveying channel 313 and the material conveying manifold. A hole can also be provided on the rotary support body 320 opposite to the port of the rotary body 310 where the material conveying channel is used to receive the printing material, which can form the inlet end of the switching mechanism. Similarly, in Figures 1b, 3 and 6b, a rotary support 320 can be fitted on the outside of the rotary body 310. A hole can be provided on the rotary support 320 at a position opposite to the port of the material conveying channel used to discharge printing material when the rotary body 310 rotates to different switching positions, to form an outlet end. The hole is used to connect the material conveying channel 313 and the material conveying manifold. Based on the scheme shown in Figure 1b, Figure 6b also illustrates an embodiment where the switching mechanism 31 has three outlet ends. The three outlet ends are respectively connected to the material conveying manifolds 211, 212 and 213. The control states of the switching mechanisms 31 and 33 make the inlet ports 11 and 13 connected to the outlet port 91. The control state of the switching mechanism 32 makes the inlet port 12 connected to the outlet port 92. The control state of the switching mechanism 34 makes the inlet port 14 connected to the outlet port 93. In summary, the switching mechanism only needs to control the rotary body 310 to rotate to the position where the port of the feeding channel 313 used to discharge the printing material is opposite to the corresponding hole or outlet end on the rotary support 320, so as to realize the connection and switching between the corresponding feeding port and the corresponding discharging port.

[0123] Overall, the material changing hub includes several inlet ports and several outlet ports. Each inlet port is equipped with a corresponding switching mechanism. The inlet end of the switching mechanism is connected to the inlet port, and the outlet end of the switching mechanism has several connections, each adapted to and connected to a different outlet port. This allows each inlet port to be connected to any outlet port by changing the state of the switching mechanism. The connection of the outlet end of the switching mechanism to each outlet port means that when each inlet port is equipped with only one switching mechanism (as shown in Figures 1b, 2, 3, 4, 6a, 6b, or 12b), the outlet end of the switching mechanism can be connected to each outlet port of the material changing hub. When multiple switching mechanisms are provided for each inlet port... When switching mechanisms are arranged in layers along the material conveying direction (as shown in Figure 5, Figure 7a, or Figure 7b), the inlet end of the top-level switching mechanism is connected to the corresponding feed port, the outlet end of the upper-level switching mechanism is connected to the inlet end of the lower-level switching mechanism or to the corresponding outlet port, and the outlet end of the bottom-level switching mechanism is connected to the corresponding outlet port. Thus, the outlet end of the top-level switching mechanism can be connected to different outlet ports through the switching of the lower-level switching mechanisms. In short, the outlet ends of the switching mechanisms are adapted and connected to each outlet port. By controlling the action or state of the switching mechanisms, each feed port can be connected to any outlet port. Ideally, no two outlet ends of the several outlet ends of each switching mechanism should be connected to the same outlet port; that is, the several outlet ends of each switching mechanism should be connected to different outlet ports of the material switching hub. Suppose the material changing hub has s inlet ports and m outlet ports. When the switching mechanism is arranged in a single layer along the conveying direction of the printing material (as shown in Figure 1b, Figure 2, Figure 3, Figure 4, Figure 6a, Figure 6b or Figure 12b), the switching mechanism realizes the switching of the connection line used to convey the printing material from the inlet port to the outlet port. The outlet end of the switching mechanism is adapted and connected to each outlet port respectively. It can also be represented as follows: Suppose the material changing hub may include s switching mechanisms. Each switching mechanism includes an inlet end and m outlet ends. The inlet end of each switching mechanism is connected to the inlet port of the material changing hub in a one-to-one correspondence, or the inlet end of each switching mechanism forms the inlet port of the material changing hub. The outlet end of each switching mechanism is connected to the outlet port of the material changing hub in a one-to-one correspondence.Each discharge port of the material changing hub can also use a multi-inlet-one-outlet connecting pipe. This multi-inlet-one-outlet connecting pipe includes s inlet ends, each inlet end being connected to one outlet end of each switching mechanism. s and m are positive integers greater than or equal to 2; for example, when m = 2, two discharge ports are set. When the switching mechanisms are arranged in multiple levels along the conveying direction of the printing material, one outlet end of the upper-level switching mechanism is connected to the inlet end of the corresponding lower-level switching mechanism to form a cascaded switching mechanism. The cascaded switching mechanism is used to switch the connection line used to convey the printing material from the inlet port to the outlet port, as shown in Figure 5. Figure 7a or Figure 7b shows a two-level arrangement; the material changing hub can use s cascaded switching mechanisms, each cascaded switching mechanism has m idle outlets (e.g., outlets not connected to the inlet of the lower level or other switching mechanisms), the inlet of each switching mechanism in the uppermost level is connected one-to-one with the feed port of the material changing hub, or the inlet of each switching mechanism in the uppermost level forms the feed port of the material changing hub, and the discharge port is connected to the idle outlet of each cascaded switching mechanism; by changing the state of the cascaded switching mechanism, each feed port can be connected to any discharge port.

[0124] It should be noted that the outlet end of the switching mechanism or the inlet of the material conveying manifold can be arranged around the rotation axis of the corresponding rotary body, or at any interval. Figures 1b and 3 illustrate that the switching mechanism rotates 180 degrees during switching; this is for illustrative purposes only, and in reality, such an angle is not necessary; any other angle is acceptable. In fact, the closer the inlets of the material conveying manifold are arranged around the rotation axis of the corresponding rotary body, the more beneficial it is to reduce the rotation angle of the switching mechanism and speed up the switching process. The rotary body can be driven by a motor or servo motor, or by a gear pair or synchronous belt drive.

[0125] It should be noted that a solid material conveying component can also be configured, with a corresponding number of material conveying channels inside, thus replacing the function of the material conveying manifold. The material conveying manifold can be a flexible feeding pipe, for example, with a multi-inlet-one-outlet pipe connection structure set at the discharge port, so that one end of each flexible feeding pipe is connected to the outlet end of the switching mechanism, and the other end is connected to one inlet of the multi-inlet-one-outlet pipe connection structure at the discharge port. Of course, each material conveying manifold can also be a rigid pipe, such as a one-piece molded plastic part with a corresponding number of material conveying channels formed inside, which are connected to the outlet end of the switching mechanism and the discharge port of the material changing hub, or the material conveying manifold and the discharge port can be one-piece molded, or the support body of the switching mechanism (such as the rotary support body 320), the material conveying manifold and the discharge port can be one-piece molded.

[0126] Each of the switching mechanisms in the material changing hub of each embodiment may also be equipped with a material conveying structure (such as a material conveying manifold or material conveying channel). The material conveying structure is used to connect the switching mechanism with the discharge port. The inlet end of the material conveying structure for receiving printing material is connected to the outlet end of the switching mechanism, and the outlet end of the material conveying structure for discharging printing material is connected to each discharge port, so that each outlet end of each switching mechanism is connected (connected) or adapted to each discharge port. The material conveying structure may also include multiple inlet and outlet connecting pipes (a multiple inlet and outlet connecting pipe channel structure is set for each outlet port), as shown in Figures 1b and 2, Figures 4 and 5, Figures 6a, 7a, 7b and 7c, and Figures 7c, and the material conveying structure in the material changing center can also be referred to in other attached figures. The various inlets of this multiple inlet and outlet connecting pipe channel structure... Each end of the multi-inlet-one-outlet connecting pipe is connected to one outlet end of the corresponding switching mechanism. Each outlet end of the multi-inlet-one-outlet connecting pipe is connected to or forms a corresponding discharge port. Alternatively, the material conveying structure may include multi-level multi-inlet-one-outlet connecting pipes. For example, the inlet of the multi-inlet-one-outlet connecting pipe in the uppermost level is connected to the outlet end of the switching mechanism; the outlet of the multi-inlet-one-outlet connecting pipe in the upper level is connected to one inlet of the corresponding multi-inlet-one-outlet connecting pipe in the next level; and the outlet of the multi-inlet-one-outlet connecting pipe in the lowest level is connected to the corresponding discharge port. This ensures that each outlet end of each switching mechanism is connected to a corresponding outlet port. Do not connect to each discharge port. Alternatively, if the material changing hub includes multiple switching mechanisms, each inlet end of the multi-inlet-one-outlet connecting pipe channel structure is connected to one outlet end of the corresponding switching mechanism closest to the discharge port. This allows each inlet end of the multi-inlet-one-outlet connecting pipe channel structure to be connected to the switching mechanism closest to the feed port (such as the switching mechanism corresponding to the feed port), as shown in Figures 5, 7a, 7b, and 7c. For example, in the figures, discharge ports 91 and 92 are respectively connected to the switching mechanism corresponding to feed port 11 through switching mechanism 31a. One outlet end of the switching mechanism 31 (on the left in the figure) is adapted and connected. The other outlet end of the switching mechanism 31 in Figure 5 (on the right in the figure) is connected to the discharge port 93. The discharge ports 93 and 94 in Figures 7a, 7b and 7c are respectively adapted and connected to the other outlet end (on the right in the figure) of the switching mechanism 31 corresponding to the feed port 11 through the switching mechanism 31b. The inlet ends of the multi-inlet and one-outlet connecting pipe channel structures 991 and 992 in Figures 7a and 7b are respectively connected to the outlet ends of the lower layer (closer to the discharge port) switching mechanisms 31a, 32a, 33a and 34a.The inlet ends of the multi-inlet-one-outlet connecting pipe channel structures 993 and 994 are respectively connected to the outlet ends of the lower-level (near the discharge port) switching mechanisms 31b, 32b, 33b, and 34b, and then adapted to the outlet ends of the upper-level (near the feed port) switching mechanism. Figure 7c shows that some inlet ends (left side) of the multi-inlet-one-outlet connecting pipe channel structures 991 and 992 are respectively connected to the outlet ends of the lower-level (near the discharge port) switching mechanisms 31a and 32a, thus achieving connection to the outlet ends of the upper-level (near the feed port) switching mechanism. Some inlet ends are directly connected to other outlet ends of the upper-level (near the feed port) switching mechanism. It can be seen that this adaptation connection is generally used when the number of outlet ends of the switching mechanism is less than the number of discharge ports, or when the switching mechanism is arranged in multiple levels. A multi-inlet-one-outlet connecting pipe channel structure or a funnel-shaped (conical) channel structure can also be set at each discharge port. The material conveying structure can also adopt or include a funnel-shaped (conical) channel structure for the discharge port. For example, the discharge port can be made into a funnel-shaped channel structure, with the large end facing each switching mechanism (along the transmission path of the printing material), and the small end forming the corresponding discharge port. Each outlet end of each switching mechanism corresponds to the large end opening of each funnel-shaped discharge port, allowing the printing material to directly enter the corresponding discharge port from the outlet end of the switching mechanism. As shown in Figure 7d, suppose the material changing hub has 3 inlet ports and 3 outlet ports, and suppose the material changing hub has 3 switching mechanisms, namely switching mechanisms 31, 32, and 33. The inlet end of each switching mechanism is connected to the corresponding inlet port, and each switching mechanism has 3 outlet ends, namely outlet ends 322, 323, and 324. Each discharge port of the material changing hub has a channel structure, which is conical. The port in the channel structure used to receive the printing material is the large end and faces the outlet end of the switching mechanism. Ideally, the projection of the outlet end of each switching mechanism along the material conveying direction falls into the port in the channel structure used to receive the material. Alternatively, the outlet end of each switching mechanism can be connected to a material delivery manifold, which in turn connects to the corresponding channel structure. The ports in each channel structure used to discharge the material form discharge ports. For example, outlet ends 322, 323, and 324 of the switching mechanism correspond to channel structures 911 (discharge port 91), 921 (discharge port 92), and 931 (discharge port 93), respectively. That is, after being drawn out from outlet ends 322, 323, or 324, the material can directly enter channel structures 911 (discharge port 91), 921 (discharge port 92), or 93 (discharge port 93), and is finally discharged from discharge ports 91, 92, or 93.

[0127] Example 2

[0128] This embodiment provides a switching mechanism with an alternative structural form.

[0129] As shown in Figure 2, the switching mechanisms 31, 32, 33, and 34 are of a swivel-type structure, including a rotating body 312 and a rotating support for supporting the rotating body to rotate around its rotating axis. The rotating body 312 is fixedly mounted on the rotating shaft 311, allowing it to be rotatably connected to the rotating support. The rotating support has a material conveying channel, which includes an infeed section for receiving printing material and two outlet sections for discharging printing material. One end of the infeed section forms the inlet end of the switching mechanism, and the other end intersects with the two outlet sections. The other end of the outlet sections, away from the intersection, forms the two outlet ends of the switching mechanism. The infeed section intersects with the two outlet sections simultaneously. The rotating body 312 can be pivotally connected to this intersection via the rotating shaft 311, which is located between the two outlet sections. Ideally, the axis of the rotating shaft 311 is perpendicular to the axis of the infeed section, with a deviation of no more than ±40°. For example, as shown in Figure 2, the rotating shaft 311 is perpendicular to the plane of the drawing. The outlet end of the switching mechanism can be connected to two discharge ports respectively via a material conveying manifold. The switching mechanisms 35 and 36 in Figures 2, 11a, 11b, or 11c are rotary structures, including a rotary body 362 and a rotary support for supporting the rotary body to rotate around its rotation axis. The rotary body 362 is fixedly mounted on the rotary shaft 361, allowing the rotary body 362 to be rotatably connected to the rotary support. The rotary support body is equipped with a material conveying channel, which includes an infeed section for receiving printing material and multiple (e.g., two or more) outlet sections for discharging printing material. One end of the infeed section forms the inlet of the switching mechanism, and the other end intersects with multiple outlet sections. The other end of the outlet sections, away from the intersection, forms the outlet of the switching mechanism. The infeed section intersects with multiple outlet sections simultaneously. The rotary body 362 can be pivotally connected to this intersection via a rotary shaft 361. The rotary shaft 361 can be located between multiple outlet sections. Ideally, the axis of the rotary shaft 361 is parallel to the axis of the infeed section, with a deviation of no more than ±40°. For example, as shown in Figure 2, the rotary shaft 361 is parallel to the drawing plane and is in a vertical state. The outlet of the switching mechanism can be connected to multiple outlet ports respectively via material conveying manifolds.

[0130] By rotating the flipping body 312 or the rotary body 362, one discharge section or conveying manifold can be selectively opened while another discharge section or conveying manifold is blocked. As shown in Figure 2, the switching mechanisms 31 and 32 have the same structure. Taking the switching mechanism 31 as an example, the flipping body 312 of the switching mechanism 31 blocks the discharge section corresponding to the conveying manifold 212, allowing the inlet port 11 to connect with the conveying manifold 211, thereby connecting the inlet port 11 with the discharge port 91. When the flipping body 312 rotates counterclockwise, it blocks the conveying manifold 211, allowing the inlet port 11 to connect with the discharge port 92. Alternatively, referring to the state shown by the switching mechanism 33 in Figure 2, the flipping body 312 blocks the discharge section corresponding to the conveying manifold 231, allowing the inlet port 13 to connect with the discharge port 92. Ideally, after the flip body 312 rotates and switches to its position, the inner hole at the end of the feed section projects onto the flip body 312 along the feed direction. This projection does not extend beyond the outer side of the flip body 312 away from the rotating shaft 311, so that when the filamentous printing material (filament) is conveyed to the switching mechanism, the end of the filamentous printing material will not get stuck at the end of the flip body 312 away from the flip shaft 311. Ideally, the thickness of the flip body 312 increases from the end away from the flip shaft 311 towards the flip shaft 311, so that the flip shaft 311 is not exposed externally, and the end of the filamentous printing material will not be stuck by the flip shaft during its sliding along the flip body 312 towards the flip shaft 311. Ideally, as shown in Figure 2, the flip shaft 311 is located at the inner junction of the two feed manifolds.The switching mechanisms 33 and 34 in Figure 2 have the same structure. Taking switching mechanism 3 as an example, the switching mechanism includes a flipping body 332 and a flipping axis 331 supporting the flipping body 332. The switching mechanism is provided with a material conveying channel, which includes a feeding section for receiving the printing material and two discharging sections for discharging the printing material. The feeding section intersects with the two discharging sections. The flipping body 332 of the switching mechanisms 91a and 92b extends and pivotally connects between the feeding section and the two discharging sections or pivotally connects in the material conveying channel in two opposite directions perpendicular to its axis of rotation. Optimally, the flipping axis 331 passes through the middle region of the flipping body 332, and the part near the inlet end is concave, while the part near the outlet end is convex. The flipping body 33... When the switch rotates to the corresponding position, the inlets of the other discharge sections, except for the inlet of the discharge section corresponding to that position, are blocked. This facilitates the passage of printing material. The port of the feeding section used for the printing material to enter forms the inlet end of the switching mechanism, and the ports of the discharge sections used for the printing material to exit form the outlet end of the switching mechanism. In this case, as shown in Figure 2, the flipping body 332 of the switching mechanisms 33 and 34 can rotate clockwise or counterclockwise along the rotation axis 331 perpendicular to the plane of the figure. When the flipping body of the switching mechanism 33 flips to the first state position, the feeding port 13 is connected to the conveying manifold 232 and then to the discharge port 92. When the flipping body of the switching mechanism 34 flips to the second state position, the feeding port 14 is connected to the conveying manifold 241 and then to the discharge port 91. The switching mechanisms 35 and 36 in Figure 2 have the same structure, both having two discharge sections. Of course, switching mechanisms 35 or 36 can also have more discharge sections. Taking switching mechanism 36 as an example, the rotating body 362 of switching mechanism 31 blocks the discharge section corresponding to the conveying manifold 262, allowing the inlet port 16 to connect with the conveying manifold 261, thereby connecting the inlet port 16 with the outlet port 91. The rotation of the rotating body 362 can switch the state of the switching mechanism. Here, the switching mechanism is described with two discharge sections as an example. By rotating the rotating body 362, the switching mechanism 36 can form the state shown in switching mechanism 35. The rotating body 362 blocks the conveying manifold 261, allowing the inlet port 16 to connect with the outlet port 92. When there are more than two discharge sections, when the rotary body 362 is in each rotation position, it blocks the inlet of the discharge section other than the inlet of the discharge section corresponding to that position, and opens the inlet of the discharge section corresponding to that position. Ideally, after the rotary body 362 is rotated and switched into position, the inner hole at the end of the feed section is projected onto the rotary body 362 along the feed direction. This projection does not extend beyond the outer side of the rotary body 362 away from the rotation axis 361, so that when the filament printing material is conveyed to the switching mechanism, the end of the filament printing material will not get stuck at the end of the rotary body 362 away from the rotation axis 361.The tilting body 312 or the rotating body 362 can be driven to rotate by the output shaft of a motor or servo motor, or by a gear pair or a synchronous belt drive pair.

[0131] Example 3

[0132] This embodiment provides another type of switching mechanism, as shown in Figure 5. The switching mechanism shown in Figure 5 adopts a slider-based switching mechanism, which includes a sliding body 310 and a sliding support 320 for supporting the sliding body 310 to slide.

[0133] For example, taking the switching mechanism 31 as an example, the others are similar. The slider-type sliding body 310 moves in a straight line, for example, along the axis direction perpendicular to the feed port. Two feeding channels 313 and 314 are provided inside the sliding body 310. The ports of the two feeding channels 313 and 314 for receiving the printing material are both facing the inlet end or feed port 11 of the switching mechanism. For example, the feed port 11 is located above the sliding body 310. The outlet end of the switching mechanism or the feed end of the feeding manifold can be located below or to the side of the sliding body 310. When the slider-type sliding body 310 moves in a straight line, the port of one of the feeding channels for receiving the printing material is opposite to or opposite to the inlet end of the switching mechanism. When port 11 is connected, the port of the feeding channel for discharging printing material is connected to the outlet end of the switching mechanism or the inlet end of a corresponding feeding manifold. For example, in Figure 5, when the slider-type sliding body 310 of the switching mechanism 31 moves to the right, the port of the feeding channel 313 for receiving printing material is connected to the inlet port 11, and the port of the feeding channel 313 for discharging printing material is connected to the manifold connected to the switching mechanism 31a. When the slider-type sliding body 310 moves to the left, when the port of the feeding channel 314 for receiving printing material is connected to the inlet port 11, the port of the feeding channel 314 for discharging printing material will be connected to the feeding manifold 213. The sliding body 310 can be driven by a lead screw nut, electromagnetic actuator, linear motor, cylinder, hydraulic cylinder, gear rack pair, etc.

[0134] As shown in Figure 5, the switching mechanism 31 is switched to a state in which the feed port 11 is connected to the inlet end of the switching mechanism 31a, and the switching mechanism 31a is switched to a state in which it is connected to the conveying manifold 212. The conveying manifold 212 is connected to the discharge port 92, thus connecting the discharge port 11 and the discharge port 92. If the switching mechanism 31a is moved to the right, the feed port 11 can be connected to the discharge port 91. If the switching mechanism 31a is moved to the left, the feed port 11 can be connected to the discharge port 93.

[0135] In this embodiment, the connection between the feed port and any discharge port can be achieved by switching and combining the upper and lower switching mechanisms in the cascade. In Figure 5, one outlet end of switching mechanism 31 is connected to the inlet end of switching mechanism 31a. Switching mechanism 31 and switching mechanism 31a are combined to form a cascaded switching mechanism, switching mechanism 32 and switching mechanism 32a are combined to form a cascaded switching mechanism, and switching mechanism 33 and switching mechanism 33a are combined to form a cascaded switching mechanism. The cascaded switching mechanism can be regarded as a special switching mechanism. For example, the cascaded switching mechanism formed by the combination of switching mechanism 31 and switching mechanism 31a is equivalent to a switching mechanism that can switch three feed pipelines. Similarly, the cascaded switching mechanism formed by the combination of switching mechanism 32 and switching mechanism 32a, and the cascaded switching mechanism formed by the combination of switching mechanism 33 and switching mechanism 33a can also be regarded as switching mechanisms that can switch three pipelines, thus forming a material switching hub for three discharge ports. By changing the state of the cascaded switching mechanism, each feed port can be connected to any discharge port.

[0136] In general, the switching mechanism between the inlet and outlet ports can be divided into two or more levels, with each level including one or more switching mechanisms. The corresponding switching mechanisms on multiple levels along the connection direction from the inlet to the outlet port are connected in series to form a cascaded switching mechanism. When the switching mechanism is divided into two levels along the material conveying direction, the inlet end of the switching mechanism in the uppermost level is connected to the corresponding inlet port, and the inlet end of the switching mechanism in the lowermost level is connected to the corresponding outlet end of the switching mechanism in the uppermost level. The outlet port of the material switching hub is connected to the corresponding idle outlet end in each cascaded switching mechanism, or the inlet end in the material conveying structure (such as a material conveying manifold or material conveying channel) used to receive the incoming material is connected to the idle outlet end in each switching mechanism. When the switching mechanism is divided into two levels along the material conveying direction... When there are three or more levels, the inlet end of the switching mechanism in the top level is connected to the corresponding feed port. The inlet end of the corresponding switching mechanism in the middle level is connected to the corresponding outlet end of the switching mechanism in the previous level. The outlet end of the switching mechanism in the middle level is connected to the inlet end of the corresponding switching mechanism in the next level. The outlet port of the material switching hub is connected to the corresponding idle outlet end in each cascaded switching mechanism. Alternatively, the feed end in the material conveying structure used to receive the printing material is connected to the corresponding idle outlet end in each switching mechanism. Ideally, the number of switching mechanisms in the next level corresponding to each upper-level switching mechanism is the same, and each outlet port is connected to an idle outlet end in each cascaded switching mechanism. For example, in Figures 7a and 7b, the idle outlet ends are the outlet ends of the lowest-level switching mechanism. Figure 5 shows that the idle outlet ends include the outlet ends of the lowest-level switching mechanism as well as the outlet ends of the upper-level (or top-level) switching mechanisms.

[0137] It is readily understood that the switching mechanisms disclosed in other embodiments of the present invention can also be combined hierarchically to form a cascaded switching mechanism, such as the swashplate switching mechanism shown in Figure 1b, Figure 2 or Figure 3; and the switching mechanisms disclosed in different embodiments can also be combined to form a cascaded switching mechanism.

[0138] Example 4

[0139] This embodiment provides a switching mechanism with another structural form for the material changing hub 10.

[0140] As shown in Figure 6a, the switching mechanism adopts a transposition structure, that is, the switching mechanism includes a body 310 and a support body (not shown in the figure) for supporting the body 310.

[0141] The main body 310 can switch between corresponding outlet ends or feed manifolds. For example, the main body 310 of the switching mechanism 31 can switch between the feed manifolds 211, 212, 213, and 214, which are used to receive the printing material (each feed end can coincide with the corresponding outlet end of the switching mechanism 31). The feed manifolds 211, 212, 213, and 214 are connected to the outlet ports 91, 92, 93, and 94, respectively. A connecting pipe 301 is provided between the main body 310 of the switching mechanism 31 and the feed port 11, so that the printing material (filament printing material) can be conveyed from the feed port 11 (which can coincide with the inlet end of the switching mechanism 31) to the switching mechanism 31. The switching mechanism 31 switches between the feed ends of the feed manifolds 211, 212, 213, and 214 to achieve the switching of the connection between the feed port 11 and the outlet ports 91, 92, 93, and 94. The main body 310 can be driven to move by a motor, servo, or servo motor. The movement path of the main body 310 can be a straight line or an arc. When the movement path is a straight line, the connecting pipe 301 is configured as a flexible pipe. When the movement path is a circle (for example, the main body 310 can rotate around the vertical axis in the drawing to switch), the connecting pipe 301 can be configured as a rigid pipe. The feeding ends of the material feeding manifolds 211, 212, 213, and 214, which are used to receive the printing material (filament printing material), are set at the corresponding positions on the movement path.

[0142] Similarly, switching mechanisms 32, 33, and 34 can switch the connection between inlet ports 12, 13, and 14 and outlet ports 91, 92, 93, and 94, respectively. Figure 6a shows another perspective of material sources 61, 62, 63, and 64. Material sources 61, 62, 63, and 64 can be material trays, each with filamentous printing material wound on it, for example, printing materials 601, 602, 603, and 604 wound on them, respectively. Ideally, the diameter of the port for discharging printing material in the feed channel of each switching mechanism is smaller than the diameter of the corresponding outlet end of the switching mechanism or the feed end of the corresponding feed manifold. This facilitates the introduction of filamentous printing material from the switching mechanism to the corresponding feed manifold.

[0143] Example 5

[0144] This embodiment provides a switching mechanism with another structural form for the material changing hub 10. As shown in Figures 7a, 7b, 12b and 7c, Figure 7a illustrates a sliding multi-inlet single-outlet switching mechanism and another material changing hub based on a cascaded switching mechanism to realize 4 outlet ports. Figures 7b and 12b illustrate a rotary multi-inlet single-outlet switching mechanism and a cascaded switching mechanism. Figure 7c illustrates another rotary multi-inlet single-outlet switching mechanism and a cascaded switching mechanism.

[0145] The sliding multi-inlet single-outlet switching mechanism shown in Figure 7a is illustrated using switching mechanism 31 as an example. Switching mechanism 31 includes a slider-type sliding body 310 and a sliding support (not shown in the figure) for supporting the sliding body 310. The sliding body 310 can move in the left-right direction shown in the figure. The sliding body 310 is provided with two material conveying channels, namely material conveying channel 313 and material conveying channel 314. The ports for discharging printing material in material conveying channels 313 and 314 are combined and face the outlet end of switching mechanism 31 or the inlet of the material conveying manifold connected to the corresponding outlet port, or the inlet of the next-level switching mechanism or the inlet of the material conveying manifold connected to the inlet (feed end). The ports of the material conveying channels 313 and 314 for receiving the printing material are spaced apart from each other. Ideally, the center-to-center distance between the ports of the material conveying channels 313 and 314 for receiving the printing material is equal to the center-to-center distance between the two outlet ends of the switching mechanism 31 (or the feed ends of the manifolds 318 and 319). Taking the switching mechanism 31 as an example, when the sliding body 310 moves to the right so that the port of the feeding channel 313 used to receive the printing material is opposite to the inlet end of the switching mechanism 31 or connected to the feeding port 11, the common port of the feeding channel 313 and the feeding channel 314 used to discharge the printing material is connected to the inlet of the feeding manifold 319 or opposite to the outlet end of the switching mechanism corresponding to the inlet of the feeding manifold 319. When the sliding body 310 moves to the left so that the port of the feeding channel 314 used to receive the printing material is opposite to the inlet end of the switching mechanism 31 or connected to the feeding port 11, the common port of the feeding channel 313 and the feeding channel 314 used to discharge the printing material is connected to the inlet of the feeding manifold 318 or opposite to the outlet end of the switching mechanism corresponding to the inlet of the feeding manifold 318. The material conveying manifolds 318 and 319 can be connected to different discharge ports, such as discharge ports 91 and 92 respectively. In this way, the switching connection from the feed port 11 to the discharge ports 91 and 92 can be achieved by controlling the switching mechanism 31.

[0146] The switching mechanisms 31, 32, 33, and 34 in Figure 7b or Figure 12b illustrate rotary multi-inlet single-outlet switching mechanisms. Taking switching mechanism 31 as an example, switching mechanism 31 includes a rotary body 310 and a rotary support body 320 for supporting the rotation of the rotary body 310. The rotary body 310 can rotate along a rotation axis that passes through the center of the crosshair in the figure and is perpendicular to the plane of the figure. The rotating body 310 is provided with two material conveying channels 313 and 314. The ports for receiving printing material and the ports for discharging printing material in the material conveying channels 313 and 314 are located on the radial sidewall of the rotating body 310. Ideally, the extension direction of the material conveying channels 313 and 314 is perpendicular to the rotation axis of the rotating body 310, with a deviation of no more than ±40°. The ports for discharging printing material in the material conveying channels 313 and 314 are combined and face the outlet end of the switching mechanism or the inlet of the material conveying manifold connected to the corresponding discharge port, or the inlet of the next-level switching mechanism or the inlet of the material conveying manifold connected to that inlet (feed end). The outlet end (e.g., outlet ends 322 and 323) and the inlet end 321 of the switching mechanism can be holes provided on the sidewall of the rotating support body 320. The ports of material conveying channels 313 and 314 for receiving printing material are spaced apart from each other. Ideally, in the view shown in Figure 7b, the angle between the line connecting the center of the port of material conveying channel 313 and 314 for receiving printing material to the axis of rotation of the rotating body is equal to the angle between the line connecting the center of the two outlet ends of the switching mechanism (or the feed end of the material conveying manifold 318 and the feed end of the material conveying manifold 319) to the axis of rotation of the rotating body 310. Taking switching mechanism 31 as an example, switching mechanisms 32, 33, and 34 have the same structure as switching mechanism 31. When the rotating body 310 rotates clockwise so that the port of the feeding channel 313 used to receive the printing material is opposite to the inlet end of the switching mechanism 31 or connected to the feeding port 11, the common port of the feeding channel 313 and the feeding channel 314 used to discharge the printing material is connected to the inlet of the feeding manifold 318 or opposite to the outlet end of the switching mechanism 31 corresponding to the inlet of the feeding manifold 318. When the sliding body 310 rotates to the left so that the port of the feeding channel 314 used to receive the printing material is opposite to the inlet end of the switching mechanism 31 or connected to the feeding port 11, the common port of the feeding channel 313 and the feeding channel 314 used to discharge the printing material is connected to the inlet of the feeding manifold 319 or opposite to the outlet end of the switching mechanism 31 corresponding to the inlet of the feeding manifold 319.Material feed manifolds 318 and 319 can be connected to different discharge ports, such as discharge ports 91 and 92 (as shown in Figure 12b). In this way, the switching from feed port 11 to discharge ports 91 and 92 can be achieved by controlling the different states of the switching mechanism 31. Figure 12b also shows that the material source 63 transmits the printing material 603 to the print head or one inlet of the two-in-one-out connecting pipe 209 on the print head via the switching mechanism 33, material feed manifold 231 and feed pipe 27. For example, it can be transmitted to the inlet of the filament feeder 49 on the print head. The filament feeder 49 on the print head can further drive the printing material to the hot end 810. The printing material 604 from the material source 64 is transmitted to the other inlet of the two-in-one-out connecting pipe 209 on the print head via the switching mechanism 34, material feed manifold 242 and feed pipe 28, ready for use. The switching mechanisms 31a, 32a, 33a, 34a, 31b, 32b, 33b and 34b in Figure 7b can also be combined into one conveying channel based on the schemes shown for switching mechanisms 31, 32, 33 and 34. The conveying channel provided in the rotating body 310 is funnel-shaped, with the large end of the funnel-shaped conveying channel facing the inlet end of the switching mechanism or the corresponding feed port, and the small end of the funnel-shaped conveying channel facing the outlet end of the switching mechanism or the inlet of the conveying manifold connected to the corresponding discharge port or the inlet of the next-level switching mechanism or the inlet of the manifold connected to the inlet. Thus, regardless of whether the rotating body 310 rotates counterclockwise or clockwise, the large end of the funnel-shaped material conveying channel remains connected to the inlet or feed port of the switching mechanism. For example, in the figure, the large end of the material conveying channel of the switching mechanism 31a is always connected to the inlet of the switching mechanism or to the material conveying manifold 318. The small end of the material conveying channel of the switching mechanism 31a is connected to different discharge ports by rotating counterclockwise and clockwise. For example, in the figure, when the switching mechanism 31a is currently rotating clockwise, the small end of the material conveying channel is connected to the inlet of the material conveying manifold 211. When the switching mechanism 31a rotates counterclockwise, the small end of the material conveying channel will be connected to the inlet of the material conveying manifold 212. By rotating the rotating body 310 of the switching mechanism 31, the connection state between the feed port 11 and the discharge ports 91 and 92 can be switched.

[0147] Figure 7c illustrates another type of rotary multi-inlet single-outlet switching mechanism, with switching mechanisms 31, 32, and 33. It includes a rotary body 310 and a rotary support (not shown) for supporting the rotary body's rotation around its own axis. The rotary body 310 has feeding channels 313 and 314. The ports for receiving printing material in the feeding channels 313 and 314 are located on the first end face of the rotary body 310 (e.g., the upper end face), and the ports for discharging printing material are located on the second end face of the rotary body (e.g., the lower end face). Both the ports for receiving printing material and the ports for discharging printing material are arranged around the axis of the rotary body. The feeding channel has several ports for receiving printing material, all of which are connected to a common port for discharging printing material. The outlet ends of the switching mechanism (such as outlet end 322 and outlet end 323) are arranged circumferentially at intervals on corresponding positions on the rotation path of the common port for discharging printing material in the feeding channel. When the rotating body moves to multiple positions that make each port in the feeding channel for receiving printing material opposite to the inlet end 321 of the switching mechanism, the common port in the feeding channel for discharging printing material is opposite to the outlet end of the switching mechanism. Alternatively, consider the switching mechanisms 31a and 32a shown in Figure 7c. Taking switching mechanism 31a as an example, the switching mechanism includes a rotating body 310 and a rotating support (not shown in the figure) for supporting the rotating body 310 to rotate around its own axis. The rotating body 310 has material conveying channels 313a and 314a. The ports of the material conveying channels 913a and 314a for receiving the printing material are located on the first end face of the rotating body 310, and the ports of the material conveying channels 913a and 314a for discharging the printing material are located on the rotating body 310. On the second end face; when the rotating body 310 moves to multiple positions where the ports in each feeding channel 913a and 314a used to receive the printing material are opposite to the inlet end of the switching mechanism, the ports in each feeding channel 913a and 314a used to discharge the printing material are respectively opposite to the outlet ends of the switching mechanism. It should be noted that the rotating body 310 is not limited to a ring or cylinder shape, as long as the ports in the feeding channels used to receive the printing material and the ports used to discharge the printing material are arranged around the axis of the rotating body itself. The axis of rotation of the rotating body 310 can be parallel to the axis of the feeding port or perpendicular to the first end face, or the axis of the ring-shaped rotating body shown in Figure 7c can be used as the axis of rotation. The switching mechanisms 31, 32, 31a, and 32a are shown to have 2 outlet ends, and the switching mechanism 33 is shown to have 4 outlet ends.Alternatively, based on the schemes shown in switching mechanisms 31, 32, 33, 31a, and 32a, material conveying channels 313 and 314 can be merged into one material conveying channel, as shown in switching mechanisms 34, 31b, and 32b in Figure 7c. This makes the material conveying channel inside the rotating body 310 funnel-shaped. Ideally, the large end of the funnel-shaped material conveying channel is a funnel-shaped arc around the rotation axis of the rotating body. The large end of the funnel-shaped material conveying channel faces the inlet end of the switching mechanism or the corresponding feed port, and the small end of the funnel-shaped material conveying channel faces the outlet end of the switching mechanism or the inlet of the material conveying manifold connected to the corresponding discharge port or the inlet of the next-level switching mechanism or the inlet of the manifold connected to the inlet. Thus, regardless of whether the rotating body 310 rotates counterclockwise or clockwise, the large end of the funnel-shaped material conveying channel can remain connected to the inlet or feed port of the switching mechanism. Switching and communication 31b and 32b indicate that there are 2 outlet ends, and the switching mechanism 34 indicates that there are 4 outlet ends.

[0148] Furthermore, based on the switching mechanism shown in Figure 7a, the material conveying channels 313 and 314 of the switching mechanism 31 in Figure 7a can be merged into one material conveying channel, and the material conveying channel provided in the sliding body 310 can be funnel-shaped. The large end of the funnel-shaped material conveying channel faces the inlet end of the switching mechanism or the corresponding feed port, and the small end of the funnel-shaped material conveying channel faces the outlet end of the switching mechanism or the inlet of the material conveying manifold connected to the corresponding discharge port or the inlet of the next-level switching mechanism or the inlet end of the material conveying manifold connected to the inlet. Thus, regardless of whether the sliding body 310 moves to the left or right, the large end of the funnel-shaped material conveying channel can remain connected to the inlet or feed port of the switching mechanism. For example, in the figure, the large end of the material conveying channel of the switching mechanism 31 is always connected to the feed port 11. The small end of the material conveying channel of the switching mechanism 31 is connected to different discharge ports by moving to the left and right respectively. For example, in Figure 7a, when the inlet of the switching mechanism 31 is currently moved to the right, the small end of the material conveying channel is connected to the inlet of the material conveying manifold 318. When the inlet of the switching mechanism 31 moves to the left, the small end of the material conveying channel will be connected to the inlet of the material conveying manifold 319. If the material conveying manifolds 318 and 319 are connected to two discharge ports such as 91 and 92 respectively, the connection state between the feed port 11 and the discharge ports 91 and 92 can be switched by moving the sliding body 310 of the switching mechanism 31.

[0149] Furthermore, Figures 7a, 7b, and 7c illustrate that a cascaded switching mechanism with more switching capabilities can also be formed by cascading the switching mechanisms. In Figures 7a, 7b, and 7c, the two outlet ends 322 and 323 of the switching mechanism 31 are connected to the material conveying manifolds 318 and 319, respectively. The material conveying manifold 318 is connected to the inlet end of the next-level switching mechanism 31a, and the material conveying manifold 319 is connected to the inlet end of the next-level switching mechanism 31b. The outlet ends of the switching mechanisms 31a and 31b form the outlet ends of the cascaded switching mechanism. Two of the outlet ends of the cascaded switching mechanism (the outlet ends of the switching mechanism 31a) correspond to the inlets of the material conveying manifolds 211 and 212, respectively, or two of the outlet ends of the cascaded switching mechanism coincide with the inlets of the material conveying manifolds 211 and 212, respectively. The outlet end of the switching mechanism 31b is connected to the inlets of the material conveying manifolds 213 and 214, respectively. Material conveying manifolds 211, 212, 213, and 214 are connected to discharge ports 91, 92, 93, and 94, respectively. Thus, switching mechanisms 31, 31a, and 31b form a two-stage, cascaded switching mechanism, enabling the switching of the printing material conveying lines from inlet port 11 to the four discharge ports. The cascaded switching mechanism can be viewed as a novel type of switching mechanism formed by self-nesting and serial combination. The idle outlet end is the outlet end of the cascaded switching mechanism, referring to the outlet end not used to connect to the inlet end of the lower-level switching mechanism. The inlet end of the top-level switching mechanism is the inlet end of the cascaded switching mechanism. Furthermore, as shown in Figure 7c, switching mechanisms 33 and 34 already have four outlet ends, so a cascaded switching mechanism is unnecessary; the four outlet ends of switching mechanisms 33 and 34 can be directly connected to the four discharge ports 91, 92, 93, and 94, respectively.

[0150] Figure 7b further illustrates another arrangement of the switching mechanisms, where the top-level switching mechanisms 31-34 can be combined to form a module, such as a switching mechanism module with 4 switching mechanisms, or a switching module with 6 or other numbers of switching mechanisms. This switching mechanism module can be applied to the top-level switching mechanism module 30a, and also to the next-level switching mechanism modules 30b and 30c. That is, switching mechanisms of the same level that can correspond to switching mechanisms of different levels can be combined to form a switching mechanism module, such as switching mechanism module 30a. In addition, switching mechanisms in the next level that are connected to different switching mechanisms in the previous level can form a switching mechanism module. For example, switching mechanisms 31a, 32a, 33a, and 34a can form switching mechanism module 30b, and switching mechanisms 31b, 32b, 33b, and 34b can form switching mechanism module 30c. Of course, the switching mechanisms in switching mechanism modules 30a, 30b, and 30c can all use the same structure. For example, switching mechanism modules 30a and 30b can both use the same multi-inlet single-outlet switching mechanism as switching mechanism 31. This allows switching mechanism modules 30a, 30b, and 30c to be reused as the same switching mechanism module at different levels or when connected to different manifolds. Such modularity facilitates design and development, product installation, and manifold layout.

[0151] In Figures 7a and 7b, similarly, switching mechanism 32 corresponds to feed port 12. The outlet end of switching mechanism 32 is connected to the inlet ends of switching mechanisms 32a and 32b respectively through a feed manifold. Switching mechanism 32a is connected to two outlet ports through a feed manifold, and switching mechanism 32b is connected to two other outlet ports through two other feed manifolds, realizing the switching of the printing material conveying line from feed port 12 to the four outlet ports. Similarly, switching mechanisms 33, 33a, and 33b also form a two-stage cascaded layout, realizing the switching of feed port 13 to the four outlet ports. Similarly, switching mechanisms 34, 34a, and 34b also form a two-stage cascaded layout, realizing the switching of the printing material conveying line from feed port 14 to the four outlet ports.

[0152] In Figures 7a, 7b, and 7c, it is easy to understand that if there are two discharge ports, it is not necessary to adopt a cascaded layout of switching mechanisms. For example, if discharge ports 93 and 94 are canceled and only discharge ports 91 and 92 are retained, then the switching mechanisms 31a, 31b, 32a, 32b, 33a, 33b, 34a, and 34b located in the second stage can be canceled. Correspondingly, material conveying manifolds 318 and 319, as well as material conveying manifolds 213 and 214, can also be canceled. The outlet ends 322 and 323 of switching mechanism 31 (as shown in Figure 7b) can be directly connected to the corresponding material conveying manifolds 211 and 212 connected to the discharge ports 91 and 92. The outlet of switching mechanism 32 is directly connected to the other two material conveying manifolds connected to the discharge ports 91 and 92. The outlet end of switching mechanism 33 is directly connected to the other two material conveying manifolds connected to the discharge ports 91 and 92. The outlet of switching mechanism 34 is directly connected to the other two material conveying manifolds connected to the discharge ports 91 and 92. Through the action of the switching mechanism, the corresponding feed port can be connected to the desired discharge port. The inlet and outlet ends of the switching mechanism can be fixedly connected to a support body (such as a sliding support body, a moving support body, or a rotating support body).

[0153] In various embodiments, preferably, the switching mechanism stops switching when the printing material passes through the feeding channel of the switching mechanism (e.g., the feeding channel within the body or support); the switching mechanism can switch when the printing material is outside the feeding channel of the switching mechanism (e.g., the feeding channel within the body or support). Each switching mechanism in the material changing hub can operate independently without interference, or multiple feeding ports can be connected to any feeding port independently without interference. Multiple feeding ports can be connected simultaneously to the same feeding port or connected to different feeding ports. Each switching mechanism can be modularly developed and can be connected as an independent model to the corresponding material source, greatly facilitating the expansion of the number of material sources. Each switching mechanism in the switching hub can easily be enclosed into an independent device, connected to the material source and feeding structure through the inlet and outlet ends, resulting in better operational reliability and stability.

[0154] Example 6

[0155] As shown in Figures 1a and 2, an embodiment of the present invention provides a material changing system, which includes the material changing hub 10 disclosed in the above embodiments. The material changing system also includes multiple material sources, such as material sources 61, 62, 63, 64, 65, and 66 shown in the figures. Each material source can be connected to the feeding ports 11, 12, 13, 14, 15, and 16 through feeding pipes 21, 22, 23, 24, 25, and 26, respectively. Wire feeders 41, 42, 43, 44, 45, and 46 can also be respectively installed on the feeding pipes 21, 22, 23, 24, 25, and 26. Each wire feeder is used to drive and feed its corresponding printing material (filamentous printing material) along its respective printing material axis. Alternatively, instead of setting up separate feed lines 21, 22, 23, 24, 25, and 26, each wire feeder 41, 42, 43, 44, 45, and 46 can be directly installed at feed ports 11, 12, 13, 14, 15, and 16. Alternatively, material detection sensors 71, 72, 73, 74, 75, and 76 can be installed on the printing material conveying line between the material source 61 (and 62, 63, 64, 65, and 66) and the filament feeder 41 (and 41, 42, 43, 44, 45, and 46). That is, material detection sensors 71, 72, 73, 74, 75, and 76 are installed upstream of the filament feeders 41, 42, 43, 44, 45, and 46, respectively. Each material detection sensor is used to detect whether the end of the printing material has been conveyed to the upstream position of each filament feeder, or to detect whether there is printing material at the corresponding position in each feed pipe 21, 22, 23, 24, 25, and 26. For example, when printing material is inserted into a certain feed pipe or printing material conveying line, the corresponding material detection sensor will be triggered, and then the corresponding filament feeder can be started to drive the printing material to feed along its axial direction. The filament feeder in the diagram is for illustrative purposes only; any mechanism or solution capable of driving the printing material along its axial direction is acceptable. When the printing material is fed to the inlet of each switching mechanism or the corresponding feed port in the material changing hub 10, a detection sensor, such as sensors 51, 52, 53, 54, 55, and 56 in Figure 1b or Figure 2, can detect whether the end of the printing material is located upstream of the corresponding switching mechanism, at the inlet of the corresponding switching mechanism, or at the corresponding feed port. A detection sensor can also be installed at the discharge port 91 or 92, etc. When the end of the retracted printing material has passed this point, printing material from another feed port can begin to be conveyed to this discharge port. This detection sensor can also be used to detect the conveying length of the printing material. Detection sensors can also be installed at the inlet of the multi-inlet-one-outlet tube structure at the discharge port to determine that the end of the retracted printing material reaching this point means that the printing material has passed the position of the discharge port.Additionally, feeders can be installed at outlet ports 91 and 92, with each feeder having a stronger feeding thrust, making it easier for the filament (filamentous printing material) to be conveyed to the print head through the long feed tube. Each material source can provide filamentary printing materials, such as thermoplastic resins like PLA (polylactic acid), PP (polypropylen), PE (polyethylene), ABS (Acrylonitrile Butadiene Styrene), PA (Polyamide) (nylon), PC (Polycarbonate), PS (Polystyrene), PEI (Polyetherimide), PET (Poly(Ethylene Terephthalare)), PEEK (Polyetheretherketone), TPU (Thermoplastic polyurethanes), etc.; or materials of different colors, or elastic materials, such as thermoplastic elastomers (TPE), styrene-butadiene rubber (SBR), and styrene-butadiene rubber (SBS), etc.; or thermoplastic polyurethane (TPU) or thermoplastic vulcanizate (TPV); of course, it can also be thermosetting resins or photopolymerizable resins; or other flowable extruded materials. The filamentous material can also be continuous fiber printing material (or continuous fiber filament), fiber material, metal wire material (such as copper wire), optical fiber material, or other continuous linear material. It can also be resin-preimpregnated continuous fiber material, such as carbon fiber, glass fiber, polyester, aramid, ceramic fiber, boron fiber, or basalt fiber. For example, each material source can be a reel with filamentous printing material wound on it. When the filamentous printing material is fed out, the reel rotates synchronously. When the filamentous printing material is retracted, the reel can rotate in the opposite direction synchronously to rewind the retracted printing material onto the reel. The material source can also be in other forms, as long as it can provide printing material. Material sources 61, 62, 63, 64, 65, and 66 can simultaneously transport the printing material to the corresponding (near) outlet port 91 or 92 (not shown in the figure) through the corresponding switching mechanism, which can further reduce the transmission time when switching printing materials.

[0156] The discharge ports 91 and 92 are connected to the print head via a feeding pipeline. The feeding pipeline, as shown in the diagram, includes two feeding pipes and a two-in-one-out connecting pipe 209. Discharge ports 91 and 92 are connected to feeding pipes 27 and 28, respectively. Feed pipes 27 and 28 are connected to the two inlets of the two-in-one-out connecting pipe 209, and the outlet of the two-in-one-out connecting pipe 209 is connected to the feed input end of the print head. The two-in-one-out connecting pipe 209 can be fixedly mounted on the print head, thus becoming part of the print head. The outlet of the two-in-one-out connecting pipe 209 communicates with the nozzle (extrusion port) of the print head. The print head may include a hot end 810, which includes a nozzle (extrusion port) 89 for extruding printing material. The hot end 810 also includes a feed pipe section, which includes a heating section, a throat section, and a heat dissipation section. The nozzle 89 is connected to the heating section. The printing material fed into the printhead is conveyed through the feed tube to the nozzle 89 and then extruded, for example, according to a preset printing path onto the printing platform. After one layer is printed, the distance between the printhead and the platform increases by a preset distance (such as layer thickness) before printing the next layer, and so on, layer by layer, to form a three-dimensional model. Feed sensors 77 and 78 can also be installed at the ends of the feed tubes 27 and 28 near the printhead, respectively. These sensors detect whether the printing material in the feed tubes 27 and 28 has been delivered to that location, for example, whether it has been delivered to the inlet of the two-in-one-out connecting tube 209. The feed tubes 27 and 28 can be made of plastics such as polytetrafluoroethylene or other materials with elasticity or flexibility. The multi-in-one-out connecting tube (such as the two-in-one-out connecting tube 209) can be installed on the printhead, on the printer frame, or connected to a guide rail that constrains the sliding of the printhead.

[0157] The material changing system can employ the aforementioned material changing hubs, and also includes a print head and several material sources. Each material source is connected to a feed port of the material changing hub, and the print head is connected to at least two discharge ports of the material changing hub via a feeding pipeline. The print head may also include at least one hot end or nozzle for extruding printing material, and the material source is used to supply printing material. Alternatively, two hot ends or nozzles can be provided on the same print head, and a corresponding feeding pipeline can be provided for each hot end or nozzle. Each feeding pipeline can also include two feeding pipes connected to the print head, supplying printing material to the two hot ends respectively. For example, hot ends 810 and 810a in Figures 3, 6a, 6b, 8d, or 8e can be installed on the same print head. For the material changing system's feeding and changing of hot ends 810 and 810a, refer to Embodiments 8 and 9.

[0158] As shown in Figure 2, both the output port 91 and the output port 92 are connected to the same printhead. For example, output ports 91 and 92 are connected to feed pipes 27 and 28, respectively. Feed pipes 27 and 28 are connected to the two inlets of a two-in-one-out connecting pipe 209, which is located on the printhead. The outlet of the two-in-one-out connecting pipe 209 faces the hot end 810 on the printhead and communicates with the nozzle 89 on the printhead. As shown in Figure 2, a filament feeder 49 can also be provided between the two-in-one-out connecting pipe 209 and the hot end 810. For example, the filament feeder 49 is located upstream of the hot end 810 relative to the printing material conveying line. The outlet of the aforementioned two-in-one-out connecting pipe 209 communicates with the inlet of the filament feeder 49. The filament feeder 49 is used to enhance the driving force or speed of the printing material towards the hot end 810 or the nozzle 89, and can be used to more accurately deliver the printing material to the hot end 810. A gap (slit or notch) can also be provided between the filament feeder 49 and the hot end 810, which can be used by the cutter 85 (such as a cutting blade) to cut the printing material according to instructions. The two-in-one-out connecting pipe 209 may not necessarily be located on the print head. As shown in Figures 6a, 6b, or 8b, the outlet end of the two-in-one-out connecting pipe 209 is connected to one end of the feed pipe 290, and the other end of the feed pipe 290 is connected to the feed port (corresponding hot end) of the print head. That is, the two-in-one-out connecting pipe 209 is connected to the print head through the feed pipe 290. The two-in-one-out connecting pipe 209 can be fixed along with the wires connected to the print head, or fixed to the frame of the print head or the guide rail for print head movement. This helps to reduce the weight of the print head and simplify its structure. The filament feeder 49 can be fixed to the print head or to the outlet end of the two-in-one-out connecting pipe 209.

[0159] Additionally, a filament feeder can be installed at the discharge port of the switching mechanism, as shown in Figures 10a and 11a. For example, a filament feeder 47 can be installed at discharge port 91 and a filament feeder 48 can be installed at discharge port 92. Fiber feeders 47 and 48 can be referred to as intermediate filament feeders. The filament feeder at the discharge port can serve as a common filament feeder for the printing material fed into each feed port of the switching mechanism. This filament feeder can be a filament feeder with a stronger driving force, which is beneficial for conveying the printing material to a greater distance or at a faster feed speed. This allows the filament feeder corresponding to each feed port of the material changing center to have a compact structure or a less powerful driving force, thus saving the overall cost of the material changing center or the material changing system or reducing the overall size of the material changing center or the material changing system. For stiffer or continuous fiber-type printing materials, a filament feeder may not be necessary on the print head. Other filament feeders on the printing material delivery line, such as feed tubes 27 or 28, or feeders located at the ends of auxiliary feed tubes 27a or 28a furthest from the print head, can be used to drive the filamentous printing material axially toward the corresponding hot end, as shown by feeders 47 and 48 in Figures 6a, 8b, 8e, 8g, 10a, or 11a. A filament feeder 49 can also be installed at the outlet end of the two-in-one-out connecting tube (multi-in-one-out connecting tube) 209, as shown in Figure 6b. This eliminates the need for a filament feeder on the print head, reducing its weight and size.

[0160] Example 7

[0161] As shown in Figures 8a-8c, based on Embodiment 6, the material changing system in this embodiment can be configured with two or more material changing centers, thereby forming a material changing system with more feeding ports and thus enabling the connection of more material sources. For example, each material changing center can be configured with several material sources, that is, each feeding port of each material changing center can be configured with a corresponding material source. These material sources can provide the filament printing material to the corresponding feeding ports of the material changing center. The corresponding discharge ports of each material changing center are connected to the same pipeline through pipelines to form a new discharge port of the combined material changing center, realizing the parallel connection of multiple material changing centers and increasing and expanding the number of material sources.

[0162] For example, Figure 8a includes a material changing center 10 and a secondary material changing center 10a, which can have the same structure as the material changing center 10. The discharge port 91 of the material changing center 10 and the discharge port 91a of the secondary material changing center 10a correspond and are respectively connected to the two inlet ends of the multi-inlet-one-outlet connecting pipe 201, and the outlet end 901 of the multi-inlet-one-outlet connecting pipe 201 is connected to the feeding pipe 27. The discharge port 92 of the material changing center 10 and the discharge port 92a of the secondary material changing center 10a correspond and are respectively connected to the two inlets of the multi-inlet-one-outlet connecting pipe 202, and the outlet end 902 of the multi-inlet-one-outlet connecting pipe 202 is connected to the feeding pipe 28. The outlet ends of the multi-inlet-one-outlet connecting pipe 201 and 202 form or connect to new outlet ports 901 and 902 of the combined material changing hub 100. Feed pipes 27 and 28 are connected to the print head, for example, to the two inlet ends of a two-inlet-one-outlet connecting pipe 209 mounted on the print head. The outlet of the two-inlet-one-outlet connecting pipe 209 faces the hot end 810. A near-end extruder (filament feeder) 49 can also be installed between the outlet end of the two-inlet-one-outlet connecting pipe 209 and the hot end 810. This expands the amount of printing material. If each material changing hub has six feed ports, it can connect to six material sources. The parallel connection of two material changing hubs can switch the transmission lines of 12 material sources, realizing a material changing system for 12 material sources.

[0163] While one feed tube of feed tubes 27 and 28 supplies the printhead with the ink being printed, the other feed tube can switch to the spare printhead to be used in the next step, preparing for the next printhead to be used.

[0164] Figure 8a illustrates two feed change centers arranged in parallel, with multi-inlet-one-outlet connecting pipes 201 and 202 being two-inlet-one-outlet connecting pipes respectively. If more feed change centers are arranged in parallel, multi-inlet-one-outlet connecting pipes with more inlets can be used. For example, Figures 8b and 8c show that the number of feed change centers can be further expanded, such as having four feed change centers connected in parallel. This allows for the switching of 24 filament printing material delivery lines, forming a feed change system with 24 material sources. However, the number of feed pipes connected to the print head can remain unchanged; for example, a minimum of two feed pipes are sufficient.

[0165] Figure 8b illustrates the parallel connection of four material changing centers using two multi-inlet-one-outlet connecting pipes with four inlet ends, i.e., using two four-inlet-one-outlet connecting pipes. For example, the outlet ports 91 of material changing center 10, 91a, 91b, and 91c of material changing center 10a, 10b, and 10c are respectively connected to the four inlet ends of multi-inlet-one-outlet connecting pipe 201. Similarly, the outlet ports 92, 92a, 92b, and 92c of material changing center 10a, 10b, and 10c are respectively connected to the four inlet ends of multi-inlet-one-outlet connecting pipe 202. The outlet 901 of 01 and the outlet 902 of the multi-inlet-one-outlet connecting pipe 202 respectively form new discharge ports of the combined material changing hub 100. The new discharge ports 901 and 902 are connected to the feeding pipes 27 and 28 respectively. The feeding pipes 27 and 28 are connected to the print head, for example, to the two inlet ends of the two-inlet-one-outlet connecting pipe 209 on the print head, so as to simultaneously deliver two paths of filament printing material to the hot end 810 of the print head. One path of printing material can be used for printing, and the other path of printing material is delivered to the inlet end of the two-inlet-one-outlet connecting pipe 209 for backup.

[0166] For cases where multiple material changing centers are combined in parallel using a single-level multi-inlet-one-outlet connecting pipe along the conveying direction of the printing material, as shown in Figures 8a, 8b, or 8d, the number of inlet ends of each multi-inlet-one-outlet connecting pipe can be equal to or greater than the number of material changing centers. For example, if there are n material changing centers, each with m outlet ports, then m multi-inlet-one-outlet connecting pipes can be used. Each multi-inlet-one-outlet connecting pipe has n inlet ends, and the corresponding outlet port of each material changing center is connected to the inlet end of the multi-inlet-one-outlet connecting pipe. The outlet end of the multi-inlet-one-outlet connecting pipe is connected one-to-one with the outlet port of the combined material changing center 100, or the outlet ends of the multi-inlet-one-outlet connecting pipes form the outlet ports of the combined material changing center 100, where m and n are both positive integers greater than or equal to 2.

[0167] For cases where multiple material changing centers are combined in parallel and new discharge ports are led out using multi-level multi-inlet-one-outlet connecting pipes along the material conveying direction, as shown in Figure 8c or Figure 8e, for example, with n material changing centers, each with m discharge ports, m cascaded multi-inlet-one-outlet connecting pipes can be used. Each cascaded multi-inlet-one-outlet connecting pipe has n unused inlet ends. The corresponding discharge port of each material changing center is connected to the unused inlet end of the cascaded multi-inlet-one-outlet connecting pipe. The outlet end of the lowest level multi-inlet-one-outlet connecting pipe is connected to the discharge port of the combined material changing center 100 or the lowest level... The outlet end of the multi-inlet-one-outlet connecting pipe of the stage forms the outlet port of the combined material changing hub 100, where m is a positive integer greater than or equal to 2 and n is a positive integer greater than or equal to 2. Refer to Figure 8c or Figure 8e. When n equals 2, there may be a remaining inlet end. That is, after the outlet port of each material changing hub is connected to the idle inlet end of each cascaded multi-inlet-one-outlet connecting pipe, there is still a remaining idle inlet end. This inlet end can also be used to connect the material source. For example, a material tray with printing material wound on it can be connected to the remaining inlet end. A filament feeder can also be set on the printing material conveying line between the material tray and the remaining inlet end.

[0168] Multiple multi-inlet / one-outlet connecting pipes can also be cascaded to form a cascaded multi-inlet / one-outlet connecting pipe system. This system is divided into at least two levels along the material conveying direction, with the number of connecting pipes in each level decreasing sequentially along the material conveying direction. When the multi-inlet / one-outlet connecting pipe system is divided into two levels along the material conveying direction, the inlet ends of each connecting pipe in the uppermost level are connected to the corresponding outlet ports of different material changing centers, the inlet ends of each connecting pipe in the lowermost level are connected to the outlet ends of each connecting pipe in the uppermost level, and the outlet end of each connecting pipe in the lowermost level is connected to the print head. When the connecting pipe is divided into three or more levels along the conveying direction of the printing material, the inlet end of each multi-inlet-one-outlet connecting pipe in the uppermost level is connected to the corresponding outlet port of each different material changing center. The inlet end of each multi-inlet-one-outlet connecting pipe in the lowermost level is connected to the outlet end of each multi-inlet-one-outlet connecting pipe in the upper level connected to different material changing centers. The outlet end of the multi-inlet-one-outlet connecting pipe in the lowermost level is connected to the print head. The inlet end of each multi-inlet-one-outlet connecting pipe in the middle level is connected to the outlet end of each multi-inlet-one-outlet connecting pipe in the upper level. The outlet end of each multi-inlet-one-outlet connecting pipe in the middle level is connected to the inlet end of each multi-inlet-one-outlet connecting pipe in the lower level. Figure 8c illustrates the use of cascaded two-in-one-out connecting pipes to achieve parallel connection of multiple material changing centers. Ultimately, this can achieve a combined material changing center with the same number of material changing centers and the same new discharge port as shown in Figure 8b. The outlet ends of the upper-level multi-in-one-out connecting pipes 201 and 202 are respectively connected to the inlet end of the lower-level multi-in-one-out connecting pipe 205, forming a cascaded multi-in-one-out connecting pipe. The outlet ends of the upper-level multi-in-one-out connecting pipes 203 and 204 are respectively connected to the inlet end of the lower-level multi-in-one-out connecting pipe 206, forming another cascaded multi-in-one-out connecting pipe. As shown in Figure 8c, the discharge port 91 of the material changing hub 10 and the discharge port 91a of the material changing hub 10a are respectively connected to the two inlet ends of the multi-inlet-one-outlet connecting pipe 201; the discharge port 92 of the material changing hub 10 and the discharge port 92a of the material changing hub 10a are respectively connected to the two inlet ends of the multi-inlet-one-outlet connecting pipe 202; the discharge port 91b of the material changing hub 10b and the discharge port 91c of the material changing hub 10c are respectively connected to the two inlets of the multi-inlet-one-outlet connecting pipe 203; and the discharge port 92b of the material changing hub 10b and the discharge port 92c of the material changing hub 10c are respectively connected to the two inlet ends of the multi-inlet-one-outlet connecting pipe 204.The outlet ends of the multi-inlet-one-outlet connecting pipe 201 and 203 are respectively connected to the two inlet ends of the multi-inlet-one-outlet connecting pipe 205. The outlet ends of the multi-inlet-one-outlet connecting pipe 202 and 204 are respectively connected to the two inlet ends of the multi-inlet-one-outlet connecting pipe 206. The outlet ends 901 and 902 of the two-inlet-one-outlet connecting pipe 205 and 206 respectively form new discharge ports of the combined material changing center 100 after the combination of multiple material changing centers. The new discharge ports 901 and 902 of the combined material changing center 100 are respectively connected to the feeding pipes 27 and 28. The feeding pipes 27 and 28 are connected to the print head, for example, to the two inlet ends of the two-inlet-one-outlet connecting pipe 209 installed on the print head.

[0169] In Figure 8c, the multi-inlet / one-outlet connecting pipes 201, 202, 203, 204, 205, and 206 are all two-inlet / one-outlet connecting pipes. The material changing center 10, auxiliary material changing center 10a, material changing center 10b, and 10c in Figures 8a-8c can be any of the aforementioned material changing centers. The number of material changing centers in Figure 8a can also be increased, for example, to three. In this case, due to the increased number of outlet ports, the two-inlet / one-outlet connecting pipes are replaced with three-inlet / one-outlet connecting pipes. When the number of material changing centers increases to four, the embodiment shown in Figure 8b is obtained.

[0170] Furthermore, the combination of multiple material changing centers in Figures 8a, 8b, and 8c can form a combined material changing center 100. Discharge ports 901 and 902 can serve as discharge ports of this combined material changing center 100. Discharge ports 901 and 902 of this combined material changing center are connected to the print head via feed pipes. Thus, at least two feed pipes are still needed to achieve the transfer and rapid switching of any number of printing material sources to the print head. That is, the combined material changing center can have the same number of discharge ports as each of its constituent material changing centers, and each discharge port of the combined material changing center is connected to one discharge port of each of the constituent material changing centers. For example, the discharge ports 901 and 902 of the combined material changing hub 100 can have the same application method or connection method with the discharge ports 91 and 92 of the material changing hub 10, except that more filamentary printing material feeding lines are switched, or more material sources are connected. By combining multiple material changing hubs, a combined material changing hub or material changing system with any number of feeding ports or material sources can be realized, but the number of discharge ports of each combined material changing hub can still be kept the same as the number of discharge ports of the original single material changing hub. For example, two feeding pipes 27 and 28 can always be connected to the print head. The process of increasing the number of material sources does not require changing the feeding pipes connected to the print head, nor does it require modifying the print head.

[0171] Material detection sensors can also be installed at each inlet of the discharge port of the combined material changing hub 100 (or at the inlet of the multi-inlet-one-outlet connecting pipe 201 or 202) (as shown in Figure 8a), or at the discharge port of the combined material changing hub 100 (or at the outlet of the multi-inlet-one-outlet connecting pipe 201 or 202) (as shown in Figure 8b) to detect whether the printing material has been conveyed to that location. This allows the printing material needed for the next step or the next step after that to be conveyed in advance to the vicinity of the discharge port of the combined material changing hub 100 (or at the inlet or outlet of the multi-inlet-one-outlet connecting pipe 201 or 202 in Figure 8a or 8b, or at the inlet or outlet of the multi-inlet-one-outlet connecting pipe 205 or 206 in Figure 8c). When changing the printing material, this reduces the distance the printing material travels to the print head or to the two-inlet-one-outlet connecting pipe on the print head, thus improving the speed of printing material changing.

[0172] It should be noted that the upper ports of the feed pipes 27 and 28 in each diagram are connected to the discharge ports 91 or 92 of the material changing center, or the outlet ends 901 and 902 of the multi-inlet-one-outlet connecting pipe 205 and 206. In practical applications, the discharge ports 91 or 92 of the material changing center can be as close as possible to each other, and the outlet ends 901 and 902 of the multi-inlet-one-outlet connecting pipe 205 and 206 can be as close as possible to each other, so that the feed pipes 27 and 28 can be as close as possible to each other, facilitating connection to the print head. Each multi-inlet-one-outlet connecting pipe has multiple inlet ends (inlets) and one outlet end (outlet), for example, the number of inlets is 2, 3, 4, or 6, and each inlet is connected to the outlet. For example, all inlets are connected to the outlet through their respective corresponding pipes, so that printing material fed in by any inlet can be discharged by the outlet. Multiple multi-inlet-one-outlet connecting pipes can also be mechanically combined.

[0173] Example 8

[0174] The material changing system provided in this embodiment may include two printheads (each printhead has a hot end). These two printheads can move relative to each other or be fixedly connected together. When the two printheads are fixedly connected together, it is equivalent to having two hot ends on one printhead, as shown in Figure 3. In this embodiment, the discharge port 91 and discharge port 92 can also be connected to different printheads respectively. For example, the discharge port 91 and discharge port 92 are connected to the feed pipes 27 and 28 respectively. The feed pipes 27 and 28 are connected to different printheads respectively. For example, the feed pipes 27 and 28 are connected to the hot end 810 and the auxiliary hot end 810a respectively. The hot end 810 and the auxiliary hot end 810a are respectively set on two printheads. Each of the two printheads may also be equipped with a filament feeder 49 and a secondary filament feeder 49a. For example, the filament feeder 49 may be located upstream of the hot end 810. The filament feeder 49 is used to enhance the driving force or speed of the printing material towards the hot end 810 or the nozzle 89. The secondary filament feeder 49a may be located upstream of the secondary hot end 810a. The secondary filament feeder 49a is used to enhance the driving force or speed of the printing material towards the secondary hot end 810a or the secondary nozzle 89a. A material detection sensor 77 may also be located upstream of the filament feeder 49 to detect whether the end of the printing material has reached the inlet of the filament feeder 49. A material detection sensor 78 may be located upstream of the secondary filament feeder 49a to detect whether the end of the printing material has reached the inlet of the secondary filament feeder 49a. Gap (slit or notch) is provided between the filament feeder 49 and the hot end 810, and between the auxiliary filament feeder 49a and the auxiliary hot end 810a. These gaps can be used by a cutter to cut the printing material. These two print heads can belong to the same 3D printer or different 3D printers. Alternatively, the hot end 810 and the auxiliary hot end 810a can be located on the same print head, with feed tube 27 feeding the printing material to the hot end 810 and another feed tube 28 feeding the printing material to the auxiliary print head 810a. The filament feeder 49 and the auxiliary filament feeder 49a can also both be located on the same print head.

[0175] In addition, based on the scheme shown in Figure 3, multiple material changing hubs can be set up to expand the number of material sources. For example, there are two or more printheads and two or more material changing hubs. One printhead is connected to at least one discharge port of one of the material changing hubs through a feeding pipe, and is also connected to at least one discharge port of another of the material changing hubs through a feeding pipe. The other printhead is connected to at least one discharge port of one of the material changing hubs through a feeding pipe, and is also connected to at least one discharge port of another of the material changing hubs through a feeding pipe. As shown in Figure 8h, each of the two feed centers is equipped with six feed ports and two discharge ports. Discharge ports 91 and 91a are connected to the two inlets of one of the two-in-one-out connecting pipes 209, and discharge ports 92 and 92a are connected to the two inlets of the other two-in-one-out connecting pipe 209a. The outlets of the two two-in-one-out connecting pipes are connected to different printheads. For example, the outlet of the two-in-one-out connecting pipe 209 is connected to the hot end 810 of one printhead to provide printing material, and the outlet of the two-in-one-out connecting pipe 209a is connected to the hot end 810a of another printhead to provide printing material. This expands the amount of material supplied to multiple printheads. Of course, the hot end 810 and the subheater 810a can also be located on the same printhead. Theoretically, the amount of printing material or material source can be expanded indefinitely. Regardless of the number of types of printing material, only two feed pipes need to be connected to the printheads to achieve a rapid printing material replacement process. For example, based on the scheme shown in Figure 3 or Figure 8h, when three material changing centers are arranged in parallel, the multi-inlet-one-outlet connecting pipe connected to the print head should be replaced with a three-inlet-one-outlet connecting pipe, with each of the three inlets of the three-inlet-one-outlet connecting pipe connected to one outlet port of each material changing center. When n material changing centers are arranged in parallel, the multi-inlet-one-outlet connecting pipe connected to the print head is an n-inlet-one-outlet connecting pipe, with each inlet of the n-inlet-one-outlet connecting pipe connected to one outlet port of each of the n material changing centers, where n is a positive integer greater than or equal to 2.

[0176] Additionally, as shown in Figure 6a, the schematic material changing system discloses a material changing hub 10 with four discharge ports. This material changing hub can adopt a switching mechanism, with the four discharge ports connected to two printheads, each printhead connected to two discharge ports, or the four discharge ports connected to two hot ends, each hot end connected to two discharge ports. These two hot ends can be set on the same printhead, or the two printheads can be merged into one printhead.

[0177] Figure 6a shows a material changing hub 10 with four feed ports 11, 12, 13, and 14, though other numbers, such as six, are also possible. The material changing hub 10 has four discharge ports 91, 92, 93, and 94, though other numbers are also possible. These four discharge ports connect to two 3D print heads (or hot ends), allowing each print head (or hot end) to be allocated two discharge ports. For example, discharge ports 91 and 92 are connected to one of the print heads via feed pipes 27 and 28, respectively. The print head includes a hot end 810 and a base 820 for mounting the hot end 810. Feed pipes 27 and 28 are connected to the two inlets of a two-in-one-out connecting pipe 209, whose outlet communicates with the hot end 810. The print head may also include a filament feeder (extruder) 49 for feeding filamentous printing material to the hot end 810. For example, discharge ports 93 and 94 are connected to another print head via feed pipes 27a and 28a, respectively. The print head includes a hot end 810a and a base 820a for mounting the hot end 810a. Feed pipes 27a and 28a are connected to the two inlets of a two-in-one-out connecting pipe 209a, respectively. The outlet of the two-in-one-out connecting pipe 209a is connected to the hot end 810a. The print head may also include a filament feeder (extruder) 49a for feeding printing material to the hot end 810a.

[0178] Since any one of the discharge ports of the material changing hub 10 can be connected to any one of the feed ports through the switching mechanism, the two discharge ports connected to the print head (or hot end) can be any two of the four discharge ports. Taking one printhead as an example, when the feed tube 27 delivers printing material to the printhead for printing, another feed tube, such as the feed tube 28, can switch the next printing material to be printed through the material changing center 10 and deliver it to the vicinity of the printhead, for example, at the inlet of the multi-inlet-one-outlet (two-inlet-one-outlet in Figure 6a) connecting tube 209 connected to the printhead for backup. When a switch is required, simply cut off the currently printed printing material at the gap above the hot end 810, and then the printing material is pulled back by the feed tube 27. When the end of the printing material is pulled back into the feed tube 27 (that is, equivalent to being pulled back to the inlet of the two-inlet-one-outlet connecting tube 209 on the printhead), the printing material in the feed tube 28 can be delivered to the printhead for printing the next type of printing material. Then, the printing material in the feed tube 27 can be switched to the next printing material or prepared in advance through the material changing center 10.

[0179] The other printhead works similarly; while printing with one type of ink via feed tubes 27a and 28a, preparation and switching of the next ink can also be performed. This allows the two printheads to share all the ink connected to the ink change hub 10, and the ink switching process can be carried out in parallel with the printing process of that printhead via the two feed tubes connected to each printhead, further accelerating the ink switching process of that printhead.

[0180] Figure 6b illustrates a connection method when the number of output ports is odd, such as three output ports. One method is to connect all three output ports to the same printhead. For example, each port can be connected to the inlet of a three-in-one-out connector via a feed pipe, with the outlet of the three-in-one-out connector connected to the printhead. This allows one output port to print while the other two are kept in reserve. Alternatively, as shown in Figure 6b, two output ports, such as output ports 91 and 92, can be connected to a printhead via feed pipes 27 and 28, respectively, to supply printing material to the hot end 810 of that printhead, allowing one output port to print while the other is kept in reserve. Another output port 93 can be connected to a secondary printhead via feed pipe 29 to supply printing material to the secondary hot end 810a of the secondary printhead. This allows multiple printheads to share the various types of printing material provided by the material exchange system. Of course, the hot ends 810 and 810a can also be located on the same printhead, or the two printheads can be combined into one.

[0181] Example 9

[0182] As shown in Figures 8d and 8e, based on the material changing system shown in Figures 6a and 8a to 8c, multiple material changing hubs are further combined to form more material sources and allow multiple printheads (or multiple hot ends) to share each material source. Each printhead can have two feed tubes, so that one feed tube can deliver printing material for printing, while the other feed tube can simultaneously switch and prepare the printing material to be used in the next step.

[0183] For example, three material changing hubs can be combined. Material changing hubs 10, 10a, and 10b can adopt all the aforementioned embodiments of material changing hubs. Here, it is assumed that the material changing hub has four discharge ports. Then, each of the aforementioned embodiments of material changing hubs can form a material changing hub with four discharge ports. For example, the embodiments with four discharge ports shown in Figures 6a, 7a, and 7b can be implemented. Other material changing hubs shown can also implement an implementation scheme with four discharge ports.

[0184] Because three material changing centers are used, Figure 8d illustrates the use of a three-inlet-one-outlet connecting pipe. That is, if the pipeline is not connected by cascading multiple-inlet-one-outlet connecting pipes, the number of inlets of each multiple-inlet-one-outlet connecting pipe is equal to the number of material changing centers. Each inlet of each multiple-inlet-one-outlet connecting pipe is connected to one outlet port of each of the material changing centers. The outlet of each multiple-inlet-one-outlet connecting pipe can serve as the outlet port of a combined material changing center formed by the various material changing centers, or it can be connected to each outlet port of a combined material changing center formed by multiple material changing centers. For example, the discharge ports 91, 91a, and 91b of the material changing hub 10, 10a, and 10b are respectively connected to the three inlets of the three-in-one-out connecting pipe 201; the discharge ports 92, 92a, and 92b of the material changing hub 10, 10a, and 10b are respectively connected to the three inlets of the three-in-one-out connecting pipe 202; the discharge ports 93, 93a, and 93b of the material changing hub 10, 10a, and 10b are respectively connected to the three inlets of the three-in-one-out connecting pipe 203; and the discharge ports 94, 94a, and 94b of the material changing hub 10, 10a, and 10b are respectively connected to the three inlets of the three-in-one-out connecting pipe 204. The outlets of the three inlet and one outlet connecting pipes 201, 202, 203 and 204 form the discharge ports 901, 902, 903 and 904 of the combined material changing hub 100.

[0185] For example, outlet 901 of three-in-one-out connecting pipe 201 and outlet 902 of three-in-one-out connecting pipe 202 are respectively connected to feed pipes 27 and 28; outlet 903 of three-in-one-out connecting pipe 203 and outlet 904 of three-in-one-out connecting pipe 204 are respectively connected to feed pipes 27a and 28a; feed pipes 27 and 28 are respectively connected to the first print head (or hot end 810) or the two inlets of two-in-one-out connecting pipe 209 on the first print head (or connected to the hot end 810), with the outlet of the two-in-one-out connecting pipe 209 facing the hot end 810 of the first print head; feed pipes 27a and 28a are respectively connected to the second print head (or hot end 810a) or the two inlets of two-in-one-out connecting pipe 209a on the second print head (or connected to the hot end 810a), with the outlet of the two-in-one-out connecting pipe 209a facing the hot end 810a of the second print head. Hot end 810 and hot end 810a can also be mounted on the same printhead.

[0186] Figure 8e illustrates a combined material changing hub formed by cascading multiple inlet / outlet connecting pipes based on the scheme shown in Figure 8d. The outlet of the two-inlet / one-outlet connecting pipe 205 is connected to one inlet of the two-inlet / one-outlet connecting pipe 201. The two-inlet / one-outlet connecting pipes 201 and 205 form a cascaded multiple-inlet / one-outlet connecting pipe, equivalent to the three-inlet / one-outlet connecting pipe 201 in Figure 8d. Similarly, the outlet of the two-inlet / one-outlet connecting pipe 206 is connected to one inlet of the two-inlet / one-outlet connecting pipe 202, the outlet of the two-inlet / one-outlet connecting pipe 207 is connected to one inlet of the two-inlet / one-outlet connecting pipe 203, and the outlet of the two-inlet / one-outlet connecting pipe 208 is connected to one inlet of the two-inlet / one-outlet connecting pipe 204. Thus, the two-inlet / one-outlet connecting pipes 202 and 206, 203 and 207, and 204 and 208 respectively form cascaded multiple-inlet / one-outlet connecting pipes. The discharge ports 91, 92, 93, and 94 of the switching mechanism 10 are connected to one inlet (inlet end) of the two-inlet-one-outlet connecting pipes 201, 202, 203, and 204, respectively. The discharge ports 91a, 92a, 93a, and 94a of the switching mechanism 10a are connected to one inlet of the two-inlet-one-outlet connecting pipes 205, 206, 207, and 208, respectively. The discharge ports 91b, 92b, 93b, and 94b of the switching mechanism 10b are connected to the other inlet of the two-inlet-one-outlet connecting pipes 205, 206, 207, and 208, respectively. The outlets (outlet ends) of the two-inlet-one-outlet connecting pipes 201, 202, 203, and 204 form the discharge ports 901, 902, 903, and 904 of the combined material changing hub 100, respectively.

[0187] Ideally, the combined material changing hub can have the same number of discharge ports as each of its constituent material changing hubs. Each discharge port of the combined material changing hub is connected to one discharge port of each of the constituent material changing hubs. The multi-inlet-one-outlet connecting pipes between the discharge ports of individual material changing hubs and the discharge ports of the combined material changing hub can be hierarchically arranged. Different levels of multi-inlet-one-outlet connecting pipes are connected in series along the printing material conveying direction, forming a cascaded multi-inlet-one-outlet connecting pipe system.

[0188] When the multi-inlet-one-outlet connecting pipe is divided into two levels along the conveying direction of the printing material, the outlet of the multi-inlet-one-outlet connecting pipe at the bottom level forms the discharge port of the combined material changing center or is connected to the discharge port of the combined material changing center. The outlet of the multi-inlet-one-outlet connecting pipe at the top level is connected to one inlet of a different multi-inlet-one-outlet connecting pipe at the bottom level. The discharge port of each material changing center is connected to the idle inlet of each cascaded multi-inlet-one-outlet connecting pipe.

[0189] When the multi-inlet / one-outlet connecting pipe is divided into three or more levels along the printing material conveying direction, the outlets of the multi-inlet / one-outlet connecting pipes in the lowest level form the discharge ports of the combined material changing hub or are connected to the discharge ports of the combined material changing hub. The outlets of the multi-inlet / one-outlet connecting pipes in the middle levels are connected to the inlets of the multi-inlet / one-outlet connecting pipes in the next level, and the inlets of the multi-inlet / one-outlet connecting pipes in the middle levels are connected to the outlets of the multi-inlet / one-outlet connecting pipes in the previous level. The discharge ports of the material changing hubs are connected to the available inlets of each cascaded multi-inlet / one-outlet connecting pipe. Ideally, the number of multi-inlet / one-outlet connecting pipes in each lower level is the same as the number of multi-inlet / one-outlet connecting pipes in the previous level, and the discharge port of each material changing hub is connected to an available inlet of each cascaded multi-inlet / one-outlet connecting pipe. For example, in Figure 8c, the idle inlets are all the inlets of the top-level multi-inlet-one-outlet connecting pipe. Figure 8e shows that the idle inlets include not only the inlets of the top-level multi-inlet-one-outlet connecting pipe but also the inlets of the next level (or the lowest level) multi-inlet-one-outlet connecting pipe. With this structure, the two printheads can share more printing media formed by the combination of three media changing hubs. They can also perform printing and media switching in parallel through their respective connected two feed pipes, improving the media selection range and switching speed. A base 820 can also be provided on the first printhead, and a base 820a can be provided on the second printhead. The structure of the hot end 810a can be the same as that of the hot end 810a, and the structure of the base 820a can be the same as that of the base 820. The base 820 and base 820a can also be located on the same printhead. Multiple material changing centers 10, 10a, and 10b form a combined material changing center 100. The combined material changing center 100 still has four discharge ports. In Figure 8d, the outlets 901, 902, 903, and 904 of the three-in-one-out connecting pipe 201, 202, 203, and 204 respectively form the four discharge ports of the combined material changing center 100. In Figure 8e, the outlet 901 of the two-in-one-out connecting pipe 201... The outlets 902 of the two-in-one-out connecting pipe 202, 903 of the two-in-one-out connecting pipe 203, and 904 of the two-in-one-out connecting pipe 204 form the four discharge ports of the combined material changing hub 100. The discharge ports 901, 902, 903, and 904 of the combined material changing hub 100 can be used and connected to the feeding pipes 27, 28, 27a, and 28a in a manner similar to the four discharge ports 91, 92, 93, and 94 of a single material changing hub 10 shown in Figure 6a.

[0190] Example 10

[0191] Figures 8f and 8g illustrate that a material changing system can also be implemented by connecting multiple outlet ports of a material changing hub using multi-inlet-one-outlet connecting pipes. The material changing hub 10 can be the material changing hub described in the aforementioned embodiments. Figure 8f shows that the material changing hub 10 has 6 inlet ports and 3 outlet ports. Outlet ports 91 and 92 can be connected to the two inlet ends of the two-inlet-one-outlet connecting pipe 201 via feed pipes. For example, outlet ports 91 and 92 can be connected to the two inlet ends of the two-inlet-one-outlet connecting pipe 201 via flexible feed pipes 271 and 272, respectively. The outlet end of the two-inlet-one-outlet connecting pipe 201 is connected to the two-inlet-one-outlet connecting pipe 209 via feed pipe 27. Outlet port 93 can be directly connected to the other inlet end of the two-inlet-one-outlet connecting pipe 209 via feed pipe 28. The outlet end of the two-inlet-one-outlet connecting pipe 209 is connected to the print head, supplying printing material to the hot end 810 of the print head. Figure 8g shows that the material changing hub 10 has four discharge ports. Discharge ports 91 and 92 can be connected to the two inlet ends of the two-inlet-one-outlet connecting pipe 201 through feeding pipes. For example, discharge ports 91 and 92 can be connected to the two inlet ends of the two-inlet-one-outlet connecting pipe 201 through flexible feeding pipes 271 and 272, respectively. Discharge ports 93 and 94 can be connected to the two inlet ends of the two-inlet-one-outlet connecting pipe 202 through feeding pipes. For example, discharge ports 93 and 94 can be connected to the two inlet ends of the two-inlet-one-outlet connecting pipe 202 through flexible feeding pipes 281 and 282, respectively. The outlet end of the two-inlet-one-outlet connecting pipe 201 is connected to one inlet end of the two-inlet-one-outlet connecting pipe 209 via the feeding pipe 27. The outlet end of the two-inlet-one-outlet connecting pipe 202 is connected to the other inlet end of the two-inlet-one-outlet connecting pipe 209 via the feeding pipe 28. The outlet end of the two-inlet-one-outlet connecting pipe 209 is connected to the print head and is used to feed printing material to the hot end 810.

[0192] In this embodiment, the material changing center can also be a combined material changing center as described in the aforementioned embodiments (e.g., Embodiment 14, 9, and Embodiment 7). The discharge ports 91, 92, and 93 can be the discharge ports 901, 902, and 903 of the combined material changing center, and the discharge port 94 can be the discharge port 904 of the combined material changing center. Of course, this embodiment can be combined with Embodiment 9 or Embodiment 7, allowing some discharge ports of a certain material changing center to be connected to the inlet end of a multi-inlet-one-outlet connecting pipe. Furthermore, other discharge ports of the material changing center, or the outlet end of the multi-inlet-one-outlet connecting pipe, can be connected to the inlet ends of other multi-inlet-one-outlet connecting pipes, respectively. In this combination or embodiment, even when a single material changing hub has more than two discharge ports, it can ultimately be connected to the print head via only two (or a small number) feed tubes. Simultaneously, the ability to feed printing material in parallel from multiple discharge ports allows for the pre-delivery of printing material needed for subsequent steps to the inlet end of the multi-inlet / one-outlet connecting pipe 201 or 202. For example, the multi-inlet / one-outlet connecting pipe 201 or 202 can be fixed to the 3D printer or its frame, allowing the print head to move relative to it. This improves material changing speed. Similarly, in Embodiments 7 and 9, the multi-inlet-one-outlet connecting pipes adjacent to the discharge port of the combined material changing hub 100, such as multi-inlet-one-outlet connecting pipes 201 or 202, can also be fixedly connected to the 3D printer or the frame of the 3D printer. The print head of the 3D printer can move relative to the multi-inlet-one-outlet connecting pipe, so that the printing material to be used in the next step, the next step after that, or the step after that can be delivered to the inlet end of the multi-inlet-one-outlet connecting pipe 201 or 202 in advance. When the material source is far away from the 3D printer, this solution can significantly improve the material changing speed.

[0193] Example 11

[0194] Figures 9a and 9b illustrate that the material changing system can also be implemented using a cascaded material changing hub configuration. That is, along the material conveying direction, multiple material changing hubs are divided into multiple levels. The discharge port of the material changing hub in the upper level is connected to the feed port of the material changing hub in the lower level. If there are three or more levels, the feed port of the material changing hub in the middle level is matched and connected to the discharge port of the material changing hub in the upper level, and the discharge port of the material changing hub in the middle level is matched and connected to the feed port of the material changing hub in the lower level. The feed port of the material changing hub in the uppermost level is connected to the material source, and the discharge port of the material changing hub in the lowermost level can be connected to the print head through a feeding pipeline.

[0195] Figure 9a illustrates the upper level, which includes a material changing center 10 and a material changing hub 10a. The feed ports 11, 12, 13, 14, 15, and 16 of the material changing hub 10 can be connected to material sources, respectively. The feed ports 11a, 12a, 13a, 14a, 15a, and 16a of the material changing hub 10 can also be connected to material sources, respectively. The discharge ports 91, 92, 93, and 94 of the material changing hub 10 are respectively connected to the feed ports 11b, 12b, 13a, and 14a of the lower-level material changing hub 10b. The discharge ports 91a, 92a, 93a, and 94a of the material changing center 10a can also be connected to the inlet ports 11b, 12b, 13b, and 14b of the lower-level material changing center 10b, respectively. Two-in-one-out connecting pipes can be installed at the inlet ports 11b, 12b, 13b, and 14b of the material changing center 10b, respectively. The inlet end of each two-in-one-out connecting pipe is connected to the corresponding discharge port of the material changing center 10 and the discharge port of the material changing center 10a. Figure 9b illustrates that if the number of discharge ports of a certain material changing center in the upper level is less than the number of discharge ports of the material changing center in the lower level, or if the discharge port of a certain material changing center in the upper level does not need to be connected to the inlet port of the material changing center in the lower level, then a certain inlet port of the material changing center in the lower level can be connected to only one discharge port of the upper-level material changing center. For example, the feed port 14b in the lower-level feed exchange center 10c is only connected to the discharge port 94 of the upper-level feed exchange center 10. Preferably, each discharge port of the upper-level feed exchange center is connected to a different feed port of the lower-level feed exchange center. Ideally, the connection between the discharge port of the upper-level feed exchange center and the feed port of the lower-level feed exchange center uses a flexible, elastic feed tube, such as a polytetrafluoroethylene (PTFE) plastic tube. The discharge ports of the lowest-level feed exchange center 10b are connected to the feed inlet of the print head through feed tubes 27 and 28, respectively, for example, to the two inlet ends of the two-in-one-out connecting pipe 209 on the print head, with the outlet end of the two-in-one-out connecting pipe 209 supplying printing material to the hot end 810.

[0196] Of course, this embodiment can be combined with Embodiment 10, Embodiment 9 or Embodiment 7, so that some of the multiple discharge ports of a certain material changing center are respectively connected to the inlet end of a multi-inlet-one-outlet connecting pipe. Other discharge ports of the material changing center or the outlet end of the multi-inlet-one-outlet connecting pipe and the discharge ports of other material changing centers can be respectively connected to the inlet end of other multi-inlet-one-outlet connecting pipes. Alternatively, multiple discharge ports of the same material changing center can be respectively connected to the inlet end of a multi-inlet-one-outlet connecting pipe, and then connected to the inlet port of the next-level material changing center through the outlet end of the multi-inlet-one-outlet connecting pipe. In this combination, or in this embodiment where a single material changing hub has more than two discharge ports, it can ultimately be connected to the print head via only two feed tubes (or a small number of feed tubes). Simultaneously, the ability to feed printing material in parallel from multiple discharge ports allows for the pre-delivery of printing material needed for the next, subsequent, or even further steps to the lowest-level material changing hub, such as to its inlet port or near its outlet port. For example, the lowest-level material changing hub 10b can be fixed to the 3D printer or its frame, and the print head of the 3D printer can move relative to this material changing hub 10b. This improves material changing speed, especially when the material source is far from the 3D printer.

[0197] Example 12

[0198] The aforementioned material changing system may also include a fast heat exchange end structure (i.e., a heat exchange end mechanism). See Figures 1a, 2, 6a, 6b, 8a, 8b, 8c, 8d, 8e, 8h, 12a, and 12b for reference. The heat exchange end mechanism includes a hot end 810, which includes a nozzle (extrusion port) 89 for extruding printing material and a feeding passage for conveying printing material. The feeding passage sequentially includes a heating section 812, a throat section 813, and a heat dissipation section 814. The heating section 812 is used to heat the printing material, and the heat dissipation section 814 is used to dissipate heat from the feeding pipeline. The throat section 813 is used to connect the heating section and the heat dissipation section, and can also be used to reduce the conduction of heat from the heating section 812 to the heat dissipation section 814. The nozzle is connected to the heating section 812. A heating block 815 can be provided on the heating section 812. The printing material is conveyed from the heat dissipation section 814 to the heating section 812 and then to the nozzle 89.

[0199] It also includes a base 820, which can be used to mount the hot end 810. The base may include a heating assembly 821, heat dissipation fins 822, and a lower clamping mechanism 830 for fixing the heating section 812 to the heating assembly 821 and / or an upper clamping mechanism 840 for fixing the heat dissipation section 814 to the heat dissipation fins 822. For example, the heating component 821 can be fixed to the heat dissipation fin 822 via a small structure such as heat insulation material or a thin-walled steel pipe, or the heating component 821 can be fixed to the body structure of the 3D printing head. The heat dissipation fin 822 can also be fixedly connected, elastically connected, or movably connected to the body structure of the 3D printing head; or the heat dissipation fin 822 can be the body structure of the 3D printing head itself. The heat dissipation fin 822 dissipates heat by contacting a fluid, such as wind or liquid. The hot end 810 is detachably connected to the base 820. The heating section 812 is installed in contact with the heating component 821, either directly or with thermal grease, a thermal pad, or other thermally conductive medium in between. The heat dissipation section 814 is installed in contact with the heat dissipation fin 822, either directly or with thermal grease, a thermal pad, or other thermally conductive medium in between.

[0200] The hot end 810 can be composed of a heating block 815 and a section of metal tube. The metal tube is inserted into the heating block at the upper end of the heating block 815, and a nozzle (extrusion port) is provided at the lower end of the heating block, as shown in the cross-sectional views of the hot end 810 in Figures 1a, 2, 8a, 8d, 8g, and 9a; or a nozzle section can be installed at the lower end of the heating block 815, with the nozzle located at the lower end of the nozzle section. Ideally, the metal tube and the nozzle are coaxially arranged, as shown in the cross-sectional views of the hot end 810 in Figures 3, 6a, 6b, and 8f.

[0201] Preferably, the side of the heat dissipation fin 822 (perpendicular to the axis of the feed pipe) has an open heat dissipation surface 8221 for the heat dissipation section 814 to be inserted and contacted; or the side of the heat dissipation fin 822 has a notch for the heat dissipation section 814 to be inserted; or the heat dissipation fin 822 is provided with a semi-inner tubular heat dissipation surface that matches the cylindrical heat dissipation section 814; or the heat dissipation fin 822 is provided with a planar heat dissipation surface; or an upper pressure cover is provided on the base for pressing the heat dissipation section 814 against the heat dissipation fin 822; or a semi-inner tubular upper contact surface or a planar upper contact surface is provided on the upper pressure cover to press the heat dissipation section 814 onto the heat dissipation fin 822. The heating assembly 821 has an open heating surface 8211 for contacting the heating section 812 or the heating block 815 on the heating section. The clamping mechanism for the hot end is not limited to that shown in Figures 12a and 12b. For example, a positioning structure can be provided between the heating section 812 and the heating assembly 821 to accurately position the hot end as it is mounted on the base. For instance, a groove or side groove structure can be provided on the heating block 815 and a corresponding boss or shaft can be provided on the heating assembly 821, a boss can be provided on the heating block 812 and a corresponding side or groove structure can be provided on the heating assembly 821, or screws can be used to clamp the hot end. A cooling fan (not shown in the figures) can also be provided on the base or printhead to blow air to cool the heat dissipation fins 822, or a coolant circulation pipeline (not shown in the figures) can be provided to cool the heat dissipation fins 822.

[0202] In this embodiment, the heating block 815 does not require a heater or temperature sensor. The heater (such as a ceramic heating element or heating rod) can be mounted on the heating assembly 821 on the base. The heating block 815 is heated by heat conduction after being mounted on the base and in contact with the heating surface of the heating assembly 821. The heat dissipation section 814 can also dissipate heat by heat conduction after being mounted on the base and in contact with the heat dissipation fins 822 (heat dissipation surface).

[0203] In Figure 12a, the lower clamping mechanism 830 and the upper clamping mechanism 840 are in the open state, allowing the hot end to be installed on the base or removed from the base. The clamping mechanisms shown in the figure are illustrative; other lower and upper clamping mechanisms can also be used, as long as they can clamp the hot end onto the base and allow the hot end to be removed from the base after opening the clamping mechanism. For example, in Figure 12a, the hot end 810 can be replaced, and the printed material 604 can also be replaced simultaneously. For instance, the printed material 604 can be retracted, and the printed material 603 can be conveyed to the hot end. After replacement, it is shown in Figure 12b. This facilitates quick replacement of the hot end. For example, the lower clamping mechanism 830 may include a lower pressure cover rotatably mounted on the base, and a rocker arm assembly for fastening and fixing the lower pressure cover to the heating assembly, or a rocker arm or cam structure including one or more rotating shafts mounted on the base to fasten the heating section onto the heating assembly. For example, the upper clamping mechanism 840 includes an upper pressure cover rotatably mounted on the base, and a rocker arm assembly for fastening and fixing the upper pressure cover to the base; or it includes a rocker arm or cam structure with one or more rotating shafts mounted on the base to fasten the heat dissipation section to the heat dissipation fins.

[0204] A gap can also be set above the hot end or between the hot end and the filament feeder, allowing the filamentous printing material to be exposed. The printing material can be cut at the gap using a cutter 85 (such as a cutting blade) to facilitate hot end replacement.

[0205] In the heat exchanger mechanism, the heat dissipation fins 822 can also be set in the heat dissipation section 814 of the hot end, as shown in Figure 6b or Figure 8h, with the secondary hot end 810a and the secondary base 820a. In this case, the heat dissipation fins (such as heat dissipation fins 822 or secondary heat dissipation fins 822a) do not need to be set on the base, but the secondary heating component 821a is still set. The upper clamping mechanism 840 does not need to be set on the secondary base 820a, or the upper clamping mechanism 840 can use a magnetic pair to connect the heat dissipation fins 822a and the secondary base 820a. The hot end can be fixed to the base by the lower clamping mechanism. In the heat exchanger mechanism, the heating component 821 can also be set in the heating section 812 of the hot end, and an electrical connection structure (such as elastic contacts or plug sockets) can be set between the hot end and the base. When the hot end is installed on the base, this electrical connection structure allows the circuit on the base to be connected to the heating component on the hot end to heat the heating section of the hot end. The hot-end switching mechanism can be any mechanism that achieves hot-end switching, such as a robotic gripper mechanism for removing and installing the hot end, or a mechanism for removing or installing the hot end via magnetic adsorption, etc. It can also be a mechanism for replacing the entire printhead, replacing the entire printhead to change the hot end. Alternatively, the printhead can be moved to a fixed position on the printer frame, and the hot end on the printhead or the entire printhead can be switched or replaced via a toggle or positioning mechanism located on the printer frame.

[0206] Preferably, when performing a printhead material switching operation, the hot end of the printhead is replaced accordingly, and the newly replaced hot end of the printhead does not contain printhead material or contains printhead material residue that is the same as the printhead material to be received by the hot end.

[0207] The print head and print platform 87 can move relative to each other for printing. For example, the base can move the hot end relative to the print platform 87, or the print head base can move along the guide rail 86. Alternatively, the print platform can move relative to the hot end. The hot end 810 moves relative to the print platform 87. The hot end extrudes printing material onto the print platform according to the layer printing instructions. After printing one layer, the distance between the hot end and the print platform is increased (e.g., layer thickness) to print the next layer, stacking layers to form a three-dimensional model.

[0208] Example 13

[0209] The present invention also provides a material changing method or process, as shown in Figures 10a-10e. This material changing process or method is performed on the same printhead and includes the following steps:

[0210] The first printing material to be used in the current step and its corresponding first material source are determined. Under the conveying of the filament feeder equipped with the first material source, the first printing material is input to the material changing center along the corresponding first feeding port. For example, the first printing material is conveyed to the corresponding first feeding port of the material changing center or to the inlet end of the corresponding first switching mechanism of the material changing center. The corresponding first switching mechanism is controlled to connect (connect) the first feeding port with the first discharge port connected to the print head in the material changing center, so that the first printing material is conveyed to the port connected to the print head in the material changing center. At the first discharge port, the first printing material, under the action of the filament feeder equipped with the first material source (such as a filament feeder located at the first inlet port or the first discharge port), is conveyed to the print head along the first feeding path in the feeding pipeline. The print head then performs printing, that is, the print head extrudes the printing material along the printing path. During the printing process of the first printing material, the second printing material to be used in the next step and its corresponding second material source are determined. Under the action of the filament feeder equipped with the second material source, the second printing material is conveyed to the corresponding second inlet port of the material changing center. The material is fed to the inlet of the corresponding second switching mechanism in the material changing center; the corresponding second switching mechanism is controlled to connect the second feed port with the second discharge port in the material changing center that is connected to the print head, and the second printing material is fed to the second discharge port. Under the action of the filament feeder equipped with the second material source (such as the filament feeder set at the second feed port or the second discharge port), the second printing material continues to be fed through the second discharge port along the second feeding path in the feeding pipeline to a position close to the intersection with the first feeding path, ready for use; while the current step is proceeding... After the printing process of the first printing material is completed, the first printing material is cut off at a downstream position along the printing material conveying direction relative to the intersection position, and the first printing material is pulled back to the position where the first feeding path and the second feeding path intersect in the feeding pipeline to prevent the first printing material from obstructing the second printing material; under the action of the filament feeder equipped with the second material source (such as a filament feeder set at the second inlet port or the second outlet port, or a filament feeder set on the print head), the second printing material is conveyed into the print head, and the print head prints the second printing material. The following steps may also be included:

[0211] Further, determine the third printing material and its corresponding third material source to be used in the next step; when the material changing center has two or more outlet ports, under the action of the filament feeder equipped with the third material source, the third printing material is transported to the corresponding third inlet port of the material changing center or to the inlet end of the corresponding third switching mechanism of the material changing center, and the third switching mechanism is controlled to connect the third inlet port with the first outlet port; after the first printing material is pulled back to the first inlet port or the inlet end of the first switching mechanism, or after being pulled back past the first outlet port to avoid obstructing the third printing material, the third printing material is transported to the first outlet port by the filament feeder equipped with the third material source, and the third printing material continues to be transported along the first feeding path in the feeding pipeline to a location close to the second feeding port by the filament feeder equipped with the third material source. At the intersection of the material paths, it is ready for use; when there are three or more outlet ports of the material changing center, under the action of the filament feeder equipped with the third material source, the third printing material corresponding to the third material source is transported to the corresponding third inlet port of the material changing center or to the inlet end of the corresponding third switching mechanism of the material changing center. The corresponding third switching mechanism is controlled to connect the third inlet port with the third outlet port connected to the print head in the material changing center. Then, the third printing material is transported to the third outlet port connected to the print head through the filament feeder equipped with the third material source. Under the action of the filament feeder equipped with the third material source, the third printing material is transported along the third feeding path in the feeding pipeline to the position near the intersection of the third feeding path and the first feeding path and / or the intersection of the third feeding path and the second feeding path, ready for use;

[0212] After the printing process of the second printing material in the current step is completed, the second printing material is cut off at a position downstream of the intersection position along the printing material conveying direction, and the second printing material is pulled back to the position where the second feeding path intersects with the first feeding path and / or the third feeding path in the feeding pipeline, so as to prevent the second printing material from obstructing the third printing material.

[0213] The third printing material is fed into the print head by the filament feeder (such as a filament feeder set at the third feed port or the third discharge port, or a filament feeder set on the print head), and the print head prints the third printing material.

[0214] It should be noted that when there is no printing material inside the corresponding switching mechanism, the switching action of each filament feeder driving the corresponding printing material conveying and the corresponding switching mechanism can be performed simultaneously, or the switching action of the switching mechanism can be performed before the filament feeder drives the corresponding printing material conveying. The retraction of printing material can be completed by the corresponding filament feeder or by the corresponding material source (such as a material tray). The filament feeder equipped with the first material source can be a filament feeder set on the printing material conveying line between the first material source and the first feed port of the material changing center, or the filament feeder can be switchable and equipped with the first material source to drive the printing material of the first material source to convey to the material changing center or the print head. The filament feeder equipped with the first material source can also be a filament feeder set at the discharge port of the material changing center. This filament feeder can be shared by the printing materials connected to the various feed ports of the material changing center. The filament feeder equipped with the first material source can also be a filament feeder on the print head. The wire feeder 49, the first material source, can also be a wire feeder located at the outlet end of a multi-inlet-one-outlet connecting pipe (e.g., a multi-inlet-one-outlet connecting pipe adjacent to the outlet port of the combined material changing hub 100), or a wire feeder located at the end of the feeding pipe 27 or feeding pipe 28 that is far from the print head, or a wire feeder 49 located at the outlet end of a two-inlet-one-outlet connecting pipe 209 (as shown in Figure 6b). These wire feeders can work partially simultaneously, alternately, or only one can work for a period of time. The same applies to the wire feeders of other material sources, and will not be described further.

[0215] For example, as shown in Figure 10a, the material source 61 (such as a material tray) delivers printing material 601 to the hot end 810 of the print head via the switching mechanism 31, the material supply manifold 211, and the discharge port 91. The hot end 810 extrudes the printing material to form a model. At the same time, the printing material 605 on the material source 65 is delivered to the inlet of the two-in-one-out connecting pipe on the print head via the switching mechanism 35, the material supply manifold 252, the discharge port 92, and the feeding pipe 28, and is ready for use, for example, by detection by the material detection sensor 78.

[0216] Figure 10b illustrates the start of printing material switching. The cutter (e.g., a cutting blade) 85 cuts the printing material 601 at the gap above the hot end 810. Alternatively, before the cutter cuts the printing material 601, the printing material 601 is first retracted by a preset length to draw back as much printing material as possible from the hot end 810, preventing molten printing material from dripping or reducing printing material residue in the hot end. Then, the cutter cuts the printing material 601 at the gap above the hot end, and the printing material 601 is then drawn back to the inlet of the two-in-one-out connecting tube on the print head. Alternatively, ideally, after the printing material 601 is cut, it is first fed downwards to push the portion of the cut printing material exposed above the hot end 810 into the hot end, and then the printing material 601 is drawn back. Whether the printing material 601 has been drawn back to the inlet of the two-in-one-out connecting tube can be detected and determined by the material detection sensor 77. This also indicates that the printing material 601 no longer obstructs the feeding of the printing material 605.

[0217] Additionally, after cutting the printing material 601 at the gap above the hot end 810, the hot end can be replaced. For example, the hot end 810 can be replaced with a hot end that matches the printing material to be used next (an empty hot end or one with the same residual printing material as the next printing material). This avoids the problem of having to squeeze out the original residual printing material in the hot end before printing the newly replaced printing material. For example, if the printing material 601 being printed is a red filamentous material, and the next printing material 605 to be used is blue, then when replacing the printing material with 605, the hot end can also be replaced with an empty hot end or one with the same blue printing material as printing material 605. In this way, the newly replaced printing material does not need to have the printing material in the hot end pushed out before printing, and can be printed directly, resulting in faster overall printing speed and greater material conservation.

[0218] As shown in Figure 10c, after the printing material 601 is cut off and retracted to a position in the two-in-one-out connecting pipe that does not obstruct the other feed path, such as the inlet of the two-in-one-out connecting pipe (which can be detected and determined by the material detection sensor 77), the printing material 605 to be used next can be fed into the print head. It can be seen that during the process of switching printing materials, the retraction of the printing material 601 that is being printed and the feeding of the printing material 605 to be used are both completed at the two-in-one-out connecting pipe. That is, the final switching only needs to be done at the print head. The switching process between the two printing materials only requires a very short retraction and feeding process, thereby achieving rapid printing material switching.

[0219] If the next step requires printing material 601, then printing material 601 can remain unchanged. If the next step requires printing material from material source 63, then the printing material in the feed tube 27 needs to be replaced. This process can be carried out simultaneously with the print head printing printing material 605.

[0220] As shown in Figure 10d, the printing material 601 is retracted and can be rewound onto the reel 61. When the end of the printing material 601 reaches the inlet of the switching mechanism 31, the material sensor 71 detects and determines whether to stop the retraction of the printing material 601. The retraction of the printing material 601 can be driven by the filament feeder 41 or by the reverse rotation of the first material source 61 using the reel. In addition, after the printing material 601 is retracted to the outlet port 91, it avoids obstructing the next printing material to be used, and the next printing material to be used (e.g., printing material 603) can begin to be conveyed towards the outlet port 91.

[0221] As shown in Figure 10e, the switching mechanism 33 connects the feed port 13 and the discharge port 91. The printing material 603 from the material source 63 is conveyed through the feed port 13, the switching mechanism 33, the material conveying manifold 231, the discharge port 91 and the feeding pipe 27 to the inlet of the two-in-one-out connecting pipe on the print head, ready for use, for example, it can be detected and judged by the material detection sensor 77.

[0222] In this way, the printing material switching process is completed. The two feed tubes 27 and 28 connected to the print head, one of which supplies printing material to the print head that is currently printing, and the other feed tube can simultaneously switch to the printing material to be used in the next step. This can greatly reduce the time occupied by the printing material switching process, and the printing material transmission distance in the final stage of switching from the printing material currently in use to the printing material to be used in the next step is very short, and the switching speed is fast.

[0223] Example 14

[0224] The material changing process is shown in Figures 11a-11c, and can be based on the material switching process or method of the material changing system disclosed in Embodiment 8 or Embodiment 9. The material changing process or method is performed for two or more printheads and includes the following steps:

[0225] The first printhead, first printing material, and their corresponding first material source are determined for the current step. Under the action of the filament feeder equipped with the first material source, the first printing material is transported to the corresponding first feed port of the material changing center or to the inlet end of the corresponding first switching mechanism of the material changing center. The corresponding first switching mechanism is controlled to connect the first feed port with the first discharge port connected to the first printhead in the material changing center, allowing the first printing material to be input into the material changing center along the corresponding first feed port. The corresponding first switching mechanism is then controlled to transport the first printing material to the first discharge port connected to the first printhead. Under the action of the filament feeder equipped with the first material source, the first printing material is transported to the first printhead via the first discharge port and along the first feeding path in the feeding pipeline. The first printhead then performs printing. During the printing process of the first printing material, the second print head, the second printing material, and its corresponding second material source to be used in the next step are determined. Then, under the action of the filament feeder equipped with the second material source, the second printing material is conveyed to the corresponding second feeding port of the material changing center or to the inlet end of the corresponding second switching mechanism of the material changing center. The corresponding second switching mechanism is controlled to connect the second feeding port with the second discharge port in the material changing center connected to the second print head. Under the action of the filament feeder equipped with the second material source, the second printing material is conveyed to the second print head via the second discharge port and along the second feeding path of the feeding pipeline, ready for use. After the printing process of the first printing material is completed, the first print head is moved out of the printing area, and then the second print head is moved into the printing area to print the second printing material. Multiple print heads can move relative to each other or be fixedly connected to form a print head with multiple hot ends.

[0226] If a subsequent step requires printing a third printhead using the first printhead, the process or method further includes the following steps:

[0227] When the first printhead is connected to an outlet port on the material changing hub via the feeding pipeline, the first printhead is cut off during the printing of the second printhead. The first printhead is then pulled back to the first inlet port of the material changing hub or the inlet of the first switching mechanism, or after passing the first outlet port, avoiding obstruction to the third printhead. The third printhead is then transported to the first outlet port of the material changing hub via the filament feeder equipped with the third material source. The third printhead continues to be transported to the first printhead along the first feeding path in the feeding pipeline via the filament feeder equipped with the third material source, ready for use. After the printing process of the second printhead is completed, the second printhead is moved out of the printing area, and then the first printhead is moved into the printing area to print the third printhead.

[0228] or,

[0229] When the first printhead is connected to multiple outlet ports on the material changing hub via a feeding pipeline, during the printing of the first printhead or the printing of the second printhead, the third printhead is fed to the third outlet port of the material changing hub by the filament feeder of the third material source. The third printhead is then fed along the third feeding path of the feeding pipeline to a position where it intersects with the first feeding path, ready for use. After the printing of the first printhead is completed, the third printhead is fed along the third feeding path relative to the intersecting position. Downstream of the ink delivery direction, the first printing material is cut off and pulled back to the position where the first and third feeding paths intersect in the feeding pipeline (or pulled back to a position that no longer obstructs the other feeding path) to prevent the first printing material from obstructing the third printing material. Under the action of the filament feeder equipped with the third material source, the third printing material is delivered to the first print head. After the second print head finishes printing and moves out of the printing area, the first print head connected to the third printing material is moved back into the printing area to facilitate the printing of the third printing material.

[0230] For example, as shown in Figure 11a, the printing material 604 from the material source 64 is conveyed to the first print head through the feed port 14, switching mechanism 34, material conveying manifold 241, discharge port 91 and feeding pipe 27. The hot end 810 of the first print head extrudes the printing material to form a printing process. The printing material 602 from the material source 62 is conveyed to the second print head through the feed port 12, switching mechanism 32, material conveying manifold 222, discharge port 92 and feeding pipe 28.

[0231] As shown in Figure 11a, if the first print head and the second print head belong to two different printers, or if the first print head and the second print head belong to the same printer but can print independently, the printing material 604 can be extruded through the hot end 810 of the first print head for the printing process, and the printing material 602 can be extruded through the auxiliary hot end 810a of the second print head for the printing process.

[0232] If the first and second printheads belong to the same printer and need to print alternately, the second printhead can be in standby mode. The standby second printhead can be located outside the printing area. When the next printing step requires the use of printing material 602, the first printhead is moved out of the printing area, and the second printhead can enter the printing area to print. This can achieve a faster material change printing speed.

[0233] If the next printing material to be used is still printing material 604, the first print head does not need to change the printing material. If the next printing material to be used is not printing material 604, for example, printing material 606 from the second material tray 66, the cutting tool 85 can be used to cut the printing material 604 at the gap above the hot end 810. Then, the upper part of the printing material is pulled back to the inlet end of the switching mechanism 34 or the outlet port 91, so as not to obstruct other printing materials, as shown in Figure 11b. As shown in Figure 11c, the switching mechanism 36 connects the inlet port 16 and the outlet port 91. The filamentous printing material 606 on the material source 66 is conveyed to the first print head through the inlet port 16, the switching mechanism 36, the feed manifold 261, the outlet port 91, and the feed pipe 27. In this way, the switching of the next printing material can be completed in advance. When the second print head finishes printing and needs to switch printing materials, the first print head can simply go directly to the printing area to print.

[0234] Based on the relevant embodiments of the above-mentioned material replacement method or process, a step of replacing the hot end may be further included. When performing the printing material switching operation on the print head, the hot end of the print head is replaced accordingly. The newly replaced hot end on the print head does not contain printing material or contains printing material residue that is the same as the printing material to be received by the print head or the hot end.

[0235] In this text, "perpendicular," "parallel," "coaxial," "coplanar," or "equal" refers to terms that are theoretically precise but have inherent errors in actual manufacturing or installation. For example, the error may be less than ±45 degrees, or less than ±30 degrees, or less than ±15 degrees, or less than ±10 mm, or less than ±5 mm, or less than ±3 mm, or no greater than ±50%, ±40%, ±30%, ±20%, or ±10%.

[0236] It should be noted that in the description of this invention, the terms "upper," "lower," "left," "right," "front," and "rear," etc., indicate the orientation or positional relationship based on the accompanying drawings, and are only for the convenience of describing the invention. They do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. The terms "connection," "linking," "associated," "connected to," or "interconnected" in the text refer to the formation of a passage or pipeline or material conveying structure on the printing material conveying line, or the connection between a switching mechanism, a multi-inlet / one-outlet connecting pipe, a material changing hub, a print head, or other devices and a pipeline capable of conveying printing material. Of course, there may be gaps between them, and different pipelines may not need to be in contact, as long as the printing material can be conveyed.

[0237] In this technical solution, the terms "first" and "second" are merely designations for corresponding structures that are identical or similar, or that perform similar functions. They do not represent an arrangement of the importance of these structures, nor do they imply any ranking, comparison, or other meaning. The embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and these variations still fall within the protection scope of the present invention.

Claims

1. A material changing center, characterized in that: It includes several infeed ports and several discharge ports. Each infeed port is provided with a corresponding switching mechanism. The inlet end of the switching mechanism is connected to the infeed port, and the outlet end of the switching mechanism has several outlets, which are adapted and connected to each of the discharge ports, so that each infeed port can be connected to any of the discharge ports by changing the state of the switching mechanism.

2. The material changing hub according to claim 1, characterized in that: Each of the switching mechanisms is equipped with a feeding structure, which includes a plurality of feeding manifolds or a plurality of feeding channels; the feed end of the feeding structure for receiving printing material is connected to the outlet end of each switching mechanism, and the discharge end of the feeding structure for discharging printing material is connected to each of the discharge ports; or, Each of the aforementioned discharge ports is provided with a channel structure, the channel structure being conical. The port in the channel structure used to receive the printing material is the larger end and faces the outlet end of the switching mechanism. The projection of the outlet end of the switching mechanism along the printing material conveying direction falls on the port in the channel structure used to receive the printing material, or the outlet end of the switching mechanism is connected to the channel structure through a material conveying pipeline. The port in each of the aforementioned channel structures used to discharge the printing material forms the discharge port or is connected to the discharge port.

3. The material changing center according to claim 1, characterized in that: The switching mechanism is one or more of the following combinations. The switching mechanism includes a rotating body and a rotating support for supporting the rotating body to rotate about its own axis; the rotating body has a material feeding channel, and in the direction of material feeding, the projection of the port of the material feeding channel for receiving the material always at least partially overlaps with the projection of the inlet end. The port of the feeding channel for discharging printing material is spaced apart from the axis of the rotating body; the outlet end of the switching mechanism is circumferentially spaced at corresponding positions on the rotation path of the port of the feeding channel for discharging printing material; or, The switching mechanism includes a rotating body and a rotating support for supporting the rotating body to rotate around its own axis. The rotating body has a feeding channel, with both the port for receiving printing material and the port for discharging printing material located on the outer circumferential surface of the rotating body. The feeding channel has several ports for receiving printing material, all of which communicate with a common port for discharging printing material. The outlet end of the switching mechanism is circumferentially spaced at corresponding positions on the rotation path of the common port for discharging printing material. When the rotating body moves to multiple positions where the ports for receiving printing material in the feeding channel are opposite to the inlet end of the switching mechanism, the common port for discharging printing material in the feeding channel is then opposite to the outlet end of the switching mechanism. Alternatively, The switching mechanism includes a rotating body and a rotating support for supporting the rotating body to rotate around its own axis. A feeding channel is provided in the rotating body. Both the port for receiving printing material and the port for discharging printing material are located on the outer circumferential surface of the rotating body. The outlet end of the switching mechanism is circumferentially spaced at corresponding positions on the rotating path of the outlet of the feeding channel for discharging printing material. The port for receiving printing material in the feeding channel is conical, with the larger end facing the inlet end. When the rotating body moves to multiple positions where the port for discharging printing material in the feeding channel is opposite the outlet end of the switching mechanism, the projection of the inlet end of the switching mechanism along the direction of printing material feeding always falls within the port for receiving printing material in the feeding channel; or... The switching mechanism includes a sliding body and a sliding support for supporting the sliding of the sliding body; the outlet end of the switching mechanism is arranged at intervals along the movement trajectory of the sliding body; the sliding body has a plurality of material feeding channels, and when the sliding body moves to multiple positions such that the port in each of the material feeding channels for receiving printing material is opposite to the inlet end of the switching mechanism, the port in each of the material feeding channels for discharging printing material is respectively opposite to each outlet end of the switching mechanism; or, The switching mechanism includes a sliding body and a sliding support for supporting the sliding of the sliding body; the outlet ends of the switching mechanism are arranged at intervals along the movement trajectory of the sliding body; the sliding body has a material feeding channel with several ports for receiving printing material, all of which are connected to a common port for discharging printing material. When the sliding body moves to multiple positions where the ports for receiving printing material in the material feeding channel are opposite to the inlet end of the switching mechanism, the common port for discharging printing material in the material feeding channel is then opposite to each outlet end of the switching mechanism; or, The switching mechanism includes a sliding body and a sliding support for supporting the sliding of the sliding body; the outlet ends of the switching mechanism are arranged at intervals along the movement trajectory of the sliding body; a feeding channel is provided on the sliding body, the feeding channel is conical, and the port in the feeding channel for receiving the printing material is the larger end and faces the inlet end of the switching mechanism. When the sliding body moves to multiple positions where the port in the feeding channel for discharging the printing material is opposite to the outlet ends of the switching mechanism, the projection of the inlet end of the switching mechanism along the printing material feeding direction always falls on the port in the feeding channel for receiving the printing material; or, The switching mechanism includes a movable body and a movable support for supporting the movement of the movable body; the outlet ends of the switching mechanism are arranged at intervals along the movement trajectory of the movable body, wherein the inlet end of the switching mechanism is connected to the movable body through a feed pipe; or, The switching mechanism includes a flipping body and a flipping support for supporting the flipping body to rotate around its flipping axis. The flipping support has a feeding channel, which includes an infeed section for receiving printing material and two outlet sections for discharging printing material. The infeed section intersects with both outlet sections. The flipping body is pivotally connected between the two outlet sections, or pivotally connected between the infeed section and the two outlet sections, or pivotally connected within the feeding channel, and / or the flipping body can rotate around an axis perpendicular to the axis of the infeed section and / or the axis of the outlet sections. The port of the infeed section for printing material entry forms the inlet end of the switching mechanism, and the ports of the outlet sections for printing material discharge form the outlet ends of the switching mechanism; or... The switching mechanism includes a rotating body and a rotating support for supporting the rotating body to rotate around its axis of rotation. The rotating support has a material conveying channel, which includes an inlet section for receiving printing material and multiple outlet sections for discharging printing material. The inlet section intersects with multiple outlet sections. When the rotating body rotates to its corresponding position, it blocks the inlets of all outlet sections except the one corresponding to that position. The port of the inlet section for receiving printing material forms the inlet end of the switching mechanism, and the ports of each outlet section for discharging printing material form the outlet end of the switching mechanism. Alternatively, The switching mechanism includes a rotating body and a rotating support for supporting the rotating body to rotate about its own axis. The rotating body has a feeding channel; the port for receiving printing material is located on the first end face of the feeding channel, and the port for discharging printing material is located on the second end face of the rotating body. The feeding channel has several ports for receiving printing material, all of which are connected to a common port for discharging printing material. The outlet end of the switching mechanism is circumferentially spaced at corresponding positions on the rotation path of the common port for discharging printing material. When the rotating body moves to multiple positions where the ports for receiving printing material in the feeding channel are opposite to the inlet end of the switching mechanism, the common port for discharging printing material in the feeding channel is then opposite to the outlet end of the switching mechanism. Alternatively... The switching mechanism includes a rotating body and a rotating support for supporting the rotating body to rotate about its own axis; the rotating body has multiple feeding channels, with the port for receiving printing material in each feeding channel located on a first end face of the rotating body, and the port for discharging printing material in each feeding channel located on a second end face of the rotating body; when the rotating body moves to multiple positions such that the ports in each feeding channel for receiving printing material are opposite to the inlet end of the switching mechanism, the ports in each feeding channel for discharging printing material are respectively opposite to the outlet ends of the switching mechanism; or, The switching mechanism includes a rotating body and a rotating support for supporting the rotating body to rotate around its own axis. The rotating body has a feeding channel; the port for receiving printing material is located on the first end face of the feeding channel, and the port for discharging printing material is located on the second end face of the rotating body. The outlet end of the switching mechanism is circumferentially spaced at corresponding positions on the rotating path of the outlet of the feeding channel for discharging printing material. The port for receiving printing material in the feeding channel is conical, with the larger end facing the inlet end. When the rotating body moves to multiple positions where the port for discharging printing material in the feeding channel is opposite to the outlet end of the switching mechanism, the projection of the inlet end of the switching mechanism along the direction of printing material feeding always falls on the port for receiving printing material in the feeding channel.

4. The material changing center according to claim 1, characterized in that: At least one of the feed ports is configured with two or more of the switching mechanisms, the switching mechanisms being divided into at least two levels along the conveying direction of the printing material, each level including one or more of the switching mechanisms; When the switching mechanism is divided into two levels along the conveying direction of the printing material, the inlet end of the switching mechanism in the uppermost level is connected to the feeding port, and the inlet end of the switching mechanism in the lowermost level is connected to the outlet end of the switching mechanism in the uppermost level. The port in the material conveying structure used to receive the printing material is connected to the idle outlet end of each switching mechanism. When the switching mechanism is divided into three or more levels along the conveying direction of the printing material, the inlet end of the switching mechanism in the uppermost level is connected to the feeding port, the inlet end of the switching mechanism in the middle level is connected to the outlet end of the switching mechanism in the level above, and the outlet end of the switching mechanism in the middle level is connected to the inlet end of the switching mechanism in the level below. The port in the material conveying structure used to receive the printing material is connected to the idle outlet end of each switching mechanism.

5. The material changing center according to any one of claims 1-3, characterized in that: Suppose that the material changing center has s inlet ports and m outlet ports; where, When the switching mechanisms are arranged in a single layer along the conveying direction of the printing material, the switching mechanism realizes the switching of the connection line used to convey the printing material from the inlet port to the outlet port. The material changing hub can include *s* switching mechanisms, each switching mechanism including one inlet end and *m* outlet ends. The inlet end of each switching mechanism is connected to the inlet port of the material changing hub, or the inlet end of each switching mechanism forms the inlet port of the material changing hub, and the outlet end of each switching mechanism is connected to the outlet port of the material changing hub; or... When the switching mechanism is arranged in multiple levels along the conveying direction of the printing material, one outlet end of the upper-level switching mechanism is connected to the inlet end of the corresponding lower-level switching mechanism to form a cascaded switching mechanism. The switching of the connection line used to convey the printing material from the feed port to the discharge port is realized through the cascaded switching mechanism. Then, s cascaded switching mechanisms are used, and each cascaded switching mechanism has m idle outlet ends. The inlet end of each switching mechanism in the uppermost level is connected to the feed port of the material switching hub, or the inlet end of each switching mechanism in the uppermost level forms the feed port of the material switching hub. The discharge port is connected to the idle outlet end of each cascaded switching mechanism. Here, s and m are positive integers greater than or equal to 2.

6. A material changing system, characterized in that: It includes a material changing center, a print head, and a plurality of material sources as described in any one of claims 1-5; each of the material sources is connected to a respective feed port of the material changing center; wherein, The printhead has one outlet port connected to the material changing center via a feed pipe; or... The printhead has two or more parts, and each printhead is connected to at least one discharge port of the material changing center through a feeding pipe. The printhead includes multiple hot ends, and each hot end is connected to at least one discharge port of the material changing center through a feeding pipe.

7. The material changing system according to claim 6, characterized in that: It also includes a material detection sensor and a wire feeder; among which, The filament feeders are respectively installed on the printing material conveying path between each of the aforementioned material sources and the corresponding feeding port; and / or... The wire feeder is installed at the discharge port of the switching mechanism; and / or, The filament feeder is configured on the printing material transport path of the print head; and / or, Each of the aforementioned feed ports or the inlet end of the aforementioned switching mechanism is respectively equipped with a detection sensor; and / or, The material detection sensor is respectively installed at each discharge port of the material changing hub or at the outlet end of the switching mechanism; and / or, The feeding pipeline is equipped with the material detection sensor at the end near the print head; and / or, The feed inlet of the print head is equipped with the detection sensor; or, The printhead inlet is equipped with a two-inlet-one-outlet connecting pipe, and the material detection sensor is respectively installed at the two inlet ends of the connecting pipe, or at the outlet end of the connecting pipe; or, The material detection sensor is provided at the feed and / or discharge points of the wire feeder.

8. The material changing system according to claim 6, characterized in that: The printhead has a multi-inlet, one-outlet connecting pipe at its feed inlet. The outlet end of the multi-inlet, one-outlet connecting pipe is connected to the feed inlet of the printhead, and the inlet ends of the multi-inlet, one-outlet connecting pipe are respectively connected to the outlet ports of the material changing hub through the feeding pipeline; or, The feeding pipeline includes a feeding pipe, the inlet of the print head is connected to one end of the feeding pipe, the other end of the feeding pipe is connected to the outlet end of the multi-inlet-one-outlet connecting pipe, and the inlet end of the multi-inlet-one-outlet connecting pipe is connected to the outlet port of the material changing hub through the feeding pipeline.

9. The material changing system according to claim 6, characterized in that: There are two or more material changing centers, and each material changing center is equipped with a plurality of material sources, wherein... The print head is connected to at least one discharge port of each of the material changing centers via a feeding pipeline; or... Each of the aforementioned material changing centers forms a combined material changing center. The combined material changing center further includes several multi-inlet, one-outlet connecting pipes. The outlet ends of these pipes respectively form the outlet ports of the combined material changing center, or are respectively connected to the outlet ports of the combined material changing center. The inlet ends of these pipes are respectively connected to the outlet ports of each of the material changing centers. The inlet ports of each material changing center respectively form the inlet ports of the combined material changing center, or are respectively connected to the inlet ports of the combined material changing center. By changing the state of the switching mechanism, each inlet port of the combined material changing center can be connected to any outlet port of the combined material changing center. The outlet ports of the combined material changing center are then connected to the printhead via feeding pipes; or... Each of the aforementioned material changing centers forms a combined material changing center. This combined material changing center also includes several multi-inlet / one-outlet connecting pipes. These multi-inlet / one-outlet connecting pipes are divided into two levels along the material conveying direction. The outlet ends of the multi-inlet / one-outlet connecting pipes at the lowest level respectively form the outlet ports of the combined material changing center or are respectively connected to the outlet ports of the combined material changing center. The outlet ends of the multi-inlet / one-outlet connecting pipes at the highest level are respectively connected to one inlet end of a different multi-inlet / one-outlet connecting pipe at the lowest level. The discharge ports of the material changing hubs are respectively connected to the idle inlet ends of each multi-inlet-one-outlet connecting pipe. The inlet ports of each material changing hub form the inlet ports of the combined material changing hub or are respectively connected to the inlet ports of the combined material changing hub. By changing the state of the switching mechanism, each inlet port of the combined material changing hub can be connected to any outlet port of the combined material changing hub. The outlet ports of the combined material changing hub are respectively connected to the print head through feeding pipes; or... Each of the aforementioned material changing centers forms a combined material changing center. This combined material changing center also includes several multi-inlet / one-outlet connecting pipes. These multi-inlet / one-outlet connecting pipes are divided into three or more levels along the material conveying direction. The outlet ends of the multi-inlet / one-outlet connecting pipes at the lowest level form the outlet ports of the combined material changing center, or are connected to the outlet ports of the combined material changing center. The outlet ends of the multi-inlet / one-outlet connecting pipes in the middle levels are connected to the inlet ends of different multi-inlet / one-outlet connecting pipes in the next lower level. The inlet ends of the multi-inlet / one-outlet connecting pipes in the middle levels are connected to the upper... The outlet ends of the multi-inlet-one-outlet connecting pipes within a single level are connected. The outlet port of the material changing hub is connected to the corresponding empty inlet in each of the multi-inlet-one-outlet connecting pipes. The inlet ports of each material changing hub form the inlet ports of the combined material changing hub or are connected to the inlet ports of the combined material changing hub. By changing the state of the switching mechanism, each inlet port of the combined material changing hub can be connected to any outlet port of the combined material changing hub. The outlet ports of the combined material changing hub are then connected to the print head through feeding pipes; or... The aforementioned material changing centers form a combined material changing center. Each combined material changing center further includes several multi-inlet / one-outlet connecting pipes. These multi-inlet / one-outlet connecting pipes are arranged in a single layer along the material conveying direction. The number of inlets of the multi-inlet / one-outlet connecting pipes is equal to or greater than the number of material changing centers. This combined material changing center includes n material changing centers, each with m outlet ports and using m multi-inlet / one-outlet connecting pipes. The corresponding outlet port of each material changing center is connected to the inlet end of each multi-inlet / one-outlet connecting pipe, and the outlet end of each multi-inlet / one-outlet connecting pipe is connected to the outlet end of the combined material changing center. The material ports are connected one-to-one or the outlet ends of multiple inlet and outlet connecting pipes respectively form the outlet ports of the combined material changing hub. The inlet ports of each of the material changing hubs respectively form the inlet ports of the combined material changing hub or are respectively connected to the inlet ports of the combined material changing hub. By changing the state of the switching mechanism, each inlet port of the combined material changing hub can be connected to any outlet port of the combined material changing hub. The outlet ports of the combined material changing hub are respectively connected to the print head through feeding pipes; where m and n are both positive integers greater than or equal to 2; or, The aforementioned material changing centers form a combined material changing center. This combined material changing center also includes several multi-inlet / one-outlet connecting pipes. These multi-inlet / one-outlet connecting pipes are arranged in multiple levels along the material conveying direction. The outlet end of the multi-inlet / one-outlet connecting pipe of the upper level is connected to one inlet end of the multi-inlet / one-outlet connecting pipe of the lower level, forming a cascaded multi-inlet / one-outlet connecting pipe. This combined material changing center includes n material changing centers, each with m outlet ports. Therefore, m cascaded multi-inlet / one-outlet connecting pipes can be used. Each cascaded multi-inlet / one-outlet connecting pipe has n or more idle inlet ports. The corresponding outlet port of each material changing center is connected to the idle inlet port of the cascaded multi-inlet / one-outlet connecting pipe. At the inlet end, the outlet end of the lowest-level multi-inlet-one-outlet connecting pipe is connected to the outlet port of the combined material changing center, or the outlet end of the lowest-level multi-inlet-one-outlet connecting pipe forms the outlet port of the combined material changing center. The inlet ports of each of the material changing centers form the inlet ports of the combined material changing center, or are connected to the inlet ports of the combined material changing center. By changing the state of the switching mechanism, each inlet port of the combined material changing center can be connected to any outlet port of the combined material changing center. The outlet ports of the combined material changing center are connected to the print head through feeding pipes. Where m and n are positive integers greater than or equal to 2.

10. The material changing system according to any one of claims 6-9, characterized in that: The feeding pipeline includes multiple inlet and one outlet connecting pipes; wherein... A portion of the discharge port of the material changing hub is connected to the inlet end of the multi-inlet-one-outlet connecting pipe, and the outlet end of the multi-inlet-one-outlet connecting pipe is connected to the print head via a feeding pipe; or, Several multi-inlet / one-outlet connecting pipes are divided into two levels along the printing material conveying direction. The outlet end of the multi-inlet / one-outlet connecting pipe at the bottom level is used to connect to the print head. The outlet end of the multi-inlet / one-outlet connecting pipe at the top level is connected to an inlet end of a different multi-inlet / one-outlet connecting pipe at the bottom level. The discharge port of each material changing hub is connected to an idle inlet end of each multi-inlet / one-outlet connecting pipe; or... The plurality of multi-inlet / one-outlet connecting pipes are divided into three or more levels along the material conveying direction. The outlet end of the multi-inlet / one-outlet connecting pipe in the lowest level is used to connect to the print head. The outlet ends of the multi-inlet / one-outlet connecting pipes in the middle levels are respectively connected to the inlet ends of different multi-inlet / one-outlet connecting pipes in the next level. The inlet ends of the multi-inlet / one-outlet connecting pipes in the middle levels are connected to the outlet ends of the multi-inlet / one-outlet connecting pipes in the previous level. The discharge port of each material changing hub is respectively connected to the idle inlet of each multi-inlet / one-outlet connecting pipe; or, Several multi-inlet / one-outlet connecting pipes are arranged in a single layer along the conveying direction of the printing material. The number of inlet ends of the multi-inlet / one-outlet connecting pipes is equal to or greater than the number of material changing centers. The number of material changing centers is n, and each material changing center has m outlet ports. Each material changing center uses m multi-inlet / one-outlet connecting pipes, with each outlet port of the material changing center connected to the inlet end of one of the multi-inlet / one-outlet connecting pipes. The outlet ends of the multi-inlet / one-outlet connecting pipes are connected one-to-one with the outlet ports of the combined material changing center, or the outlet ends of the multi-inlet / one-outlet connecting pipes form the outlet ports of the combined material changing center. Here, m is a positive integer greater than or equal to 2, and n is a positive integer greater than or equal to 1; or... Several multi-inlet / one-outlet connecting pipes are divided into multiple levels along the conveying direction of the printing material. The outlet end of the multi-inlet / one-outlet connecting pipe of the upper level is connected to one inlet end of the multi-inlet / one-outlet connecting pipe of the lower level to form a cascaded multi-inlet / one-outlet connecting pipe. The combined material changing center includes n material changing centers, each material changing center has m outlet ports, so m cascaded multi-inlet / one-outlet connecting pipes can be used. Each cascaded multi-inlet / one-outlet connecting pipe has n or more idle inlet ends. The corresponding outlet port of each material changing center is connected to the idle inlet end of the cascaded multi-inlet / one-outlet connecting pipe. The outlet end of the multi-inlet / one-outlet connecting pipe of the lowest level is connected to the outlet port of the combined material changing center, or the outlet end of the multi-inlet / one-outlet connecting pipe of the lowest level forms the outlet port of the combined material changing center, where m is a positive integer greater than or equal to 2 and n is a positive integer greater than or equal to 1.

11. The material changing system according to claim 6, characterized in that: The device includes multiple material changing centers, which are divided into multiple levels along the material conveying direction. The discharge port of the material changing center in the upper level is connected to the feed port of the material changing center in the next level. The feed port of the material changing center in the uppermost level is connected to the material source. The discharge port of the material changing center in the lowermost level is connected to the print head through a feeding pipeline.

12. A material changing method, characterized in that: The method is applied to the material changing system as described in any one of claims 6-11, wherein the printhead has one output port connected to at least two output ports of the material changing hub via a feeding pipe, and the method includes the following steps: The first printing material to be used in the current step and its corresponding first material source are determined. Under the conveying of the filament feeder equipped with the first material source, the first printing material is conveyed to the corresponding first feeding port of the material changing center or to the inlet end of the corresponding first switching mechanism of the material changing center. The corresponding first switching mechanism is controlled to connect the first feeding port with the first discharge port in the material changing center that is connected to the print head, so that the first printing material is conveyed to the first discharge port. Under the action of the filament feeder equipped with the first material source, the first printing material is conveyed to the print head through the first discharge port along the first feeding path in the feeding pipeline, and the print head performs printing. During the printing process of the first printing material, the second printing material to be used in the next step and its corresponding second material source are determined. Under the action of the filament feeder equipped with the second material source, the second printing material is transported to the corresponding second feeding port of the material changing center or to the inlet end of the corresponding second switching mechanism of the material changing center. The corresponding second switching mechanism is controlled to connect the second feeding port with the second discharge port in the material changing center that is connected to the print head, and the second printing material is transported to the second discharge port. Under the action of the filament feeder equipped with the second material source, the second printing material is transported through the second discharge port along the second feeding path in the feeding pipeline to a position near the intersection of the second feeding path and the first feeding path, ready for use. After the printing process of the first printing material in the current step is completed, the first printing material is cut off at a position downstream of the printing material conveying direction at the intersection of the second feeding path and the first feeding path. The first printing material is then pulled back to the position where the first feeding path and the second feeding path intersect in the feeding pipeline or pulled back to a position that no longer obstructs the other feeding path, so as to prevent the first printing material from obstructing the second printing material. Under the action of the filament feeder equipped with the second material source, the second printing material is conveyed to the print head, and the print head prints the second printing material.

13. The method according to claim 12, characterized in that: The printing process for the first printout also includes the following steps: Determine the third printing material to be used in the next step and its corresponding third material source; When two outlet ports of the material changing center are available, the third printing material is transported to the corresponding third inlet port of the material changing center or to the inlet of the corresponding third switching mechanism of the material changing center under the action of the filament feeder equipped with the third material source. The third switching mechanism is controlled to connect the third inlet port with the first outlet port. After the first printing material is pulled back to the first inlet port or the inlet of the first switching mechanism or has passed the first outlet port to avoid obstruction to the third printing material, the third printing material is transported to the first outlet port through the filament feeder equipped with the third material source. The third printing material is then transported along the first feeding path in the feeding pipeline to a position near the intersection of the first feeding path and the second feeding path, ready for use. When three or more outlet ports of the material changing center are available, the third printing material is conveyed to the corresponding third inlet port of the material changing center or to the inlet of the corresponding third switching mechanism of the material changing center by the filament feeder equipped with the third material source. The corresponding third switching mechanism is controlled to connect the third inlet port with the third outlet port of the material changing center that is connected to the print head. Then, the third printing material is conveyed to the third outlet port by the filament feeder equipped with the third material source. Under the action of the filament feeder equipped with the third material source, the third printing material is conveyed along the third feeding path in the feeding pipeline to a position near the intersection of the third feeding path and the second feeding path, ready for use. After the printing process of the second printing material is completed, the second printing material is cut off at a position downstream of the intersection position along the printing material conveying direction. The second printing material is then pulled back to the position where the second feeding path and the third feeding path intersect in the feeding pipeline or pulled back to a position that no longer obstructs the other feeding path, so as to prevent the second printing material from obstructing the third printing material. The third printing material is fed into the print head by the filament feeder of the third material source, and the print head prints the third printing material.

14. A material changing method, characterized in that: The method is applied to the material changing system as described in any one of claims 6-11, wherein there are two or more printheads, and each printhead is connected to at least one discharge port of the material changing hub via a feeding pipeline. The method includes the following steps: The first print head, the first printing material, and its corresponding first material source are determined for the current step. Under the action of the filament feeder equipped with the first material source, the first printing material is transported to the corresponding first feed port of the material changing center or to the inlet end of the corresponding first switching mechanism of the material changing center. The corresponding first switching mechanism is controlled to connect the first feed port with the first discharge port of the material changing center that is connected to the first print head. Then, under the action of the filament feeder equipped with the first material source, the first printing material is transported to the first print head through the first discharge port and along the first feeding path in the feeding pipeline. The first print head then performs printing. During the printing process of the first printing material, the second print head, the second printing material, and its corresponding second material source to be used in the next step are determined. Then, under the action of the filament feeder equipped with the second material source, the second printing material is transported to the corresponding second feeding port of the material changing center or to the inlet end of the corresponding second switching mechanism of the material changing center. The corresponding second switching mechanism is controlled to connect the second feeding port with the second discharge port in the material changing center that is connected to the second print head. Under the action of the filament feeder equipped with the second material source, the second printing material is transported to the second print head through the second discharge port and along the second feeding path of the feeding pipeline, ready for use. After the first printing process is completed, the first print head is moved out of the printing area, and then the second print head is moved into the printing area to print the second printing material.

15. The method according to claim 14, characterized in that: When a subsequent step requires printing a third printhead using the first printhead, the method further includes the following steps: When the first printhead is connected to a discharge port on the material changing hub via the feeding pipeline, the first printhead is cut off during the printing of the second printhead. After the first printhead is pulled back to the first feed port of the material changing hub or the inlet of the first switching mechanism, or after passing the first discharge port, it avoids obstruction to the third printhead. Then, the third printhead is transported to the first discharge port of the material changing hub through the filament feeder equipped with the third printhead, and the third printhead continues to be transported to the first printhead along the first feeding path in the feeding pipeline, ready for use. After the second printing process is completed, the second print head is moved out of the printing area, and then the first print head is moved into the printing area to print the third printing material. or, When the first print head is connected to multiple outlet ports on the material changing hub through the feeding pipeline, during the process of the first print head printing the first print material or the process of the second print head printing the second print material, under the action of the filament feeder equipped with the third material source, the third print material is transported to the third outlet port of the material changing hub and transported along the third feeding path of the feeding pipeline to the position where it intersects with the first feeding path, ready for use; After the printing of the first printing material is completed, the first printing material is cut off at a position downstream of the intersection position along the printing material conveying direction. The first printing material is then pulled back to the position where the first feeding path and the third feeding path intersect in the feeding pipeline, or pulled back to a position that no longer obstructs the other feeding path, so as to prevent the first printing material from obstructing the third printing material. Then, under the action of the filament feeder equipped with the third printing material, the third printing material is transported to the first print head. After the second print head finishes printing and moves out of the printing area, the first print head connected to the third printing material is moved back into the printing area to facilitate the printing of the third printing material.

16. The method according to any one of claims 12-15, characterized in that: When switching the printing material of the printhead, the hot end of the printhead is replaced accordingly. The newly replaced hot end does not contain printing material or contains printing material residue that is the same as the printing material to be received.

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