Additive manufacturing apparatus and method for filament forming

Abstract

This invention provides an additive manufacturing apparatus and method for filament forming. The additive manufacturing apparatus includes a filament pressing mechanism, a filament feeding mechanism, a moving mechanism, and a control device. The filament pressing mechanism has at least one heating filament pressing head, enabling real-time heating and pressing of the filament. The filament feeding mechanism is mounted on the filament pressing mechanism via a connector and is used to obliquely and downwardly feed the filament to the lower surface of the filament pressing head, ensuring continuous feeding of the filament into the forming area. The moving mechanism drives the filament pressing mechanism to move, and the control device coordinates the control of the forming path, filament pressing head temperature, and filament feeding. This invention performs filament melting and pressing simultaneously, realizing additive manufacturing of filaments. The apparatus has a compact structure, is easy to operate, and can meet the needs of additive manufacturing of large and complex shaped parts under microgravity extreme conditions.

Description

Technical Field

[0001] This invention relates to the field of additive manufacturing, to a forming technology using filament as raw material, and particularly to an additive manufacturing apparatus and method for forming filament. Background Technology

[0002] Additive manufacturing (AM) is a technology that uses CAD design path data and adds materials layer by layer to create three-dimensional solid objects. Compared with traditional manufacturing technologies, AM technology can quickly and precisely manufacture complex-shaped parts on a single machine, featuring simple processing steps, short processing cycles, and a high degree of automation. Thermoplastic materials and fiber-reinforced composite materials are widely used in additive manufacturing due to their good plasticity, low requirements for molding conditions, and good performance of molded products.

[0003] Fused Deposition Modeling (FDM) technology primarily uses filaments made from thermoplastic materials and fiber-reinforced composites. Traditional FDM additive manufacturing involves heating and melting the filament inside the processing head, then extruding it through a nozzle for printing. In this FDM printing method, the temperature of the molten thermoplastic material decreases within the nozzle channel during the forming process, making it prone to forming clumps at the bottom of the tiny nozzle and clogging it, resulting in decreased forming accuracy or even failure to form. Patent CN113787712A discloses a split-type FDM 3D printer nozzle system that uses a threaded structure to clean residual material clogging the extrusion orifice; however, its structure is complex, production costs are high, and it is difficult to process precisely. Furthermore, when the filament is a composite material or a material with uneven properties, insufficient melting can still cause nozzle clogging, leading to unstable performance of the formed parts. Meanwhile, due to the lack of a hot-pressing process for the material, FDM technology still faces prominent problems such as low interfacial bonding strength and high porosity of the molded parts, resulting in poorer interlayer mechanical properties of the molded parts compared to those prepared by traditional processes. This will severely limit the effective application of filaments made of thermoplastic materials or fiber-reinforced composite materials in the field of additive manufacturing. Summary of the Invention

[0004] This invention provides an additive manufacturing apparatus and method for filament forming, enabling simultaneous melting and compaction of thermoplastic filaments or fiber-reinforced composite filaments during the additive manufacturing process. The apparatus is compact and simple, resulting in improved strength, surface quality, and interfacial bonding of the formed thermoplastic or fiber-reinforced composite material. The use of a bypass filament feeding system improves feeding accuracy and simplifies the forming path when manufacturing complex parts.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] The present invention provides an additive manufacturing apparatus for forming filaments, wherein the filaments are thermoplastic filaments or fiber-reinforced composite filaments, and includes a filament melting and pressing mechanism, a filament feeding mechanism, a moving mechanism and a control device;

[0007] The fuse clamping mechanism is mounted on the moving mechanism via a connector, and the fuse clamping mechanism has at least one fuse clamping head that can be heated.

[0008] The wire feeding mechanism is mounted on the wire clamping mechanism via a connector and is used to feed the wire at an angle downwards to the area below the wire clamping head;

[0009] The moving mechanism is used to drive the fuse clamping mechanism to move in three-dimensional space, thereby realizing the moving processing process in space;

[0010] The control device is used to control the movement of the moving mechanism, the heating of the fuse clamping head, and the wire feeding of the wire feeding mechanism.

[0011] The control device controls the moving mechanism to drive the fused wire clamping head to move along the set path, and presses the wire fed to the fused wire clamping head below the template or core mold surface while heating and melting. When the fused wire clamping head moves to the next clamping point, the molten wire at the previous clamping point cools and solidifies, thereby performing additive manufacturing on the template or core mold.

[0012] Furthermore, the moving mechanism is a three-dimensional moving mechanism or a multi-axis robotic arm.

[0013] Furthermore, the fuse clamping head includes a heat-conducting metal head and a heating device for heating it. The lower part of the heat-conducting metal head is a conical structure that increases pressure, and the end of the conical structure is a smooth clamping head.

[0014] Furthermore, the heating device is an electric heating device fitted onto a heat-conducting metal head.

[0015] Furthermore, a guide groove for supporting and guiding the wire is provided between the wire outlet of the wire feeding mechanism and the lower end of the wire pressing head.

[0016] Furthermore, the wire feeding mechanism is connected to the connecting member via a rotating joint that can lock the angle, so that the wire feeding angle can be adjusted.

[0017] Furthermore, the fiber-reinforced composite filament is prepared by coating fibers with polymer materials.

[0018] Furthermore, the fiber is a chopped fiber or a continuous fiber, and is one or a mixture of carbon fiber, glass fiber, and other fibers.

[0019] Furthermore, the wire feeding mechanism includes a housing base and a pair of wire feeding rollers disposed within the housing base. The housing base is mounted on a connector, and the guide groove is installed at the wire outlet end of the housing base.

[0020] The present invention also provides an additive manufacturing method for filament forming, employing the additive manufacturing apparatus described in any one of the above-mentioned methods, comprising the following steps:

[0021] Step 1: Assemble the additive manufacturing device. The filament clamping mechanism of the additive manufacturing device is installed on the moving mechanism. Adjust the tilt angle and filament feeding speed of the filament feeding mechanism according to the additive manufacturing object and filament type.

[0022] Step 2: Using the control device, drive the filament clamping head to move to the vicinity above the template or core mold surface via the moving mechanism, and start the wire feeding mechanism to send the front end of the filament to the area below the filament clamping head;

[0023] Step 3: Drive the filament clamping head and the filament below it to the template or core mold surface and clamp them by moving the moving mechanism;

[0024] Step 4: Simultaneously activate the heating functions of the moving mechanism, wire feeding mechanism, and fused wire clamping head. The wire feeding mechanism continuously feeds wire to the area below the fused wire clamping head. The moving mechanism drives the fused wire clamping head to move continuously along a set path while maintaining pressure on the wire below. The wire comes into external contact with the fused wire clamping head and is heated and melted. At the same time, the wire is compacted during the clamping process, ensuring a tight bond between the molten layer and the deposited layer. When the fused wire clamping head moves to the next point, the wire at the previous point cools and solidifies, forming the desired workpiece material, completing the wire forming additive manufacturing process.

[0025] The beneficial technical effects of this invention are as follows:

[0026] 1. This invention integrates the melting and compaction processes of thermoplastic filaments or fiber-reinforced composite filaments, simplifying the mechanical structure. While melting the polymer material, the electrothermal processing head also applies pressure to compact the filament, thereby improving the strength, surface quality, and interfacial bonding of the formed product.

[0027] 2. In traditional nozzle extrusion filament production, the filament melts inside the heating chamber, and the extrusion of the composite material easily clogs the nozzle, leading to discontinuous manufacturing. In this invention, the filament is heated primarily through heat conduction outside the processing head, eliminating the need for nozzle extrusion and preventing nozzle clogging, thus making the additive manufacturing process more continuous and reliable.

[0028] 3. This invention utilizes a bypass wire feeding method, improving wire feeding accuracy and simplifying the path when printing complex parts. It can be used with multi-axis machine tools and multi-axis robotic processing equipment, making it widely applicable. Furthermore, compared to other bypass wire feeding devices that use lasers as a heat source for non-contact heating, this invention eliminates the need for a laser, resulting in lower costs and more controllable wire clamping, enabling precise manufacturing of large curvature geometric features.

[0029] 4. In this invention, the wire feeding mechanism and the wire clamping mechanism remain relatively fixed. During wire feeding, there is no need to separately adjust the angle and movement path of the wire feeding mechanism itself; only the movement path and contact pressure with the wire of the wire clamping mechanism need to be controlled. This simplifies control and results in high processing quality. Forming relies primarily on contact pressure, rather than the gravity of the wire, resulting in better spreadability of the deposited layer, meeting the needs of additive manufacturing in extreme environments such as microgravity and space. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the additive manufacturing apparatus for filament forming in an embodiment of the present invention.

[0031] Figure 2 This is a schematic diagram of an additive manufacturing apparatus for filament forming in an embodiment of the present invention.

[0032] Figure 3 This is a schematic diagram of the surface structure of a workpiece prepared using the additive manufacturing method in this embodiment of the invention.

[0033] Legend: 100-Fuse clamping mechanism, 110-Fuse clamping head, 111-Heat-conducting metal head, 112-Electric heating device, 113-Conical structure, 114-Clamping head, 120-Flange; 200-Wire feeding mechanism, 210-Guide groove, 300-Three-dimensional moving mechanism, 301-Base, 302-Gantry frame, 303-X-direction slide, 304-Y-direction slide, 305-Z-direction slide, 400-Base plate, 500-Connector, 501-Crossbar, 502-Clamping clamp, 503-Fasting bolt, 600-Control device, 700-Wire. Detailed Implementation

[0034] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and should not be construed as limiting the scope of the invention.

[0035] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described below in conjunction with the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0036] Numerous specific details are set forth in the following description to provide a thorough understanding of the invention; however, the invention may also be practiced in other ways than those described herein. Therefore, the invention is not limited to the specific embodiments disclosed in the following specification.

[0037] Example 1, as Figure 1 As shown, an additive manufacturing apparatus for forming filaments, wherein the filaments are thermoplastic filaments or fiber-reinforced thermoplastic composite filaments, includes a filament melting and pressing mechanism 100, a filament feeding mechanism 200, a moving mechanism, and a control device.

[0038] The fuse clamping mechanism 100 is mounted on the moving mechanism via a connector, and the fuse clamping mechanism 100 has at least one fuse clamping head 110 that can be heated.

[0039] The wire feeding mechanism 200 is mounted on the wire pressing mechanism 100 via a connector 500, and is used to feed the wire 700 inclined downward to the area below the wire pressing head 110.

[0040] The moving mechanism is used to drive the fuse clamping mechanism 100 to move in three-dimensional space, so as to realize the moving processing process in space;

[0041] The control device is used to control the movement of the moving mechanism, the heating of the fuse clamping head 110, and the wire feeding of the wire feeding mechanism 200.

[0042] The control device controls the moving mechanism to drive the fused wire clamping head 110 to move along the set path, and presses the fused wire below the fused wire clamping head 110 onto the surface of the template or core mold while heating and melting it. When the fused wire clamping head moves to the next clamping point, the molten fused wire at the previous clamping point cools and solidifies, thereby performing additive manufacturing on the template or core mold.

[0043] The moving mechanism is a three-dimensional moving mechanism 300 or a multi-axis robotic arm, the specific form of which is not limited, such as a six-axis robotic arm.

[0044] The present invention also provides a three-dimensional moving mechanism 300, which has the ability to move in three directions: X, Y, and Z. Specifically, it includes a base 301, a portal frame 302 mounted on the base 301, a Y-axis slide 304 mounted between two vertical beams of the portal frame 302, and a Z-axis slide 305 mounted on the Y-axis slide 304. The fuse clamping mechanism 100 is fixed to the Z-axis slide 305 by a flange. In this embodiment, the template is a base plate 400. The base plate 400 is mounted on the base 301 by the X-axis slide 303, thereby forming the three-dimensional moving mechanism 300, so that the fuse clamping mechanism 100 can move arbitrarily in a certain range of three-dimensional space relative to the base plate 400.

[0045] In a preferred embodiment, the fuse clamping head 110 includes a heat-conducting metal head 111 and a heating device for heating it. The lower part of the heat-conducting metal head 111 is a conical structure 113 that increases pressure, and the end of the conical structure 113 is a smooth clamping head 114. The top of the heat-conducting metal head 111 is provided with a flange for connection.

[0046] In a preferred embodiment, the heating device is an electric heating device 112 sleeved on the heat-conducting metal head 111. Specifically, it can be a resistance wire heating sleeve sleeved on the upper end of the heat-conducting metal head 111. After heating, the heat-conducting metal head 111 heats the pressing head 114 through heat conduction, thereby achieving heating of the wire.

[0047] In a preferred embodiment, the fiber-reinforced composite filament is a filament made by coating a thermoplastic polymer material with fibers; the fibers are chopped fibers or continuous fibers, and are one or a mixture of carbon fiber, glass fiber, and other fibers.

[0048] In a preferred embodiment, the temperature of the heat-conducting metal head 111 is set to 5-100°C above the melting point of the resin contained in the fiber-reinforced composite material; the contact pressure of the heat-conducting metal head 111 on the fiber-reinforced composite material is 0.5-10 MPa.

[0049] As a preferred embodiment, a force sensor can be provided between the fuse clamping head 110 and the moving mechanism to control the pressure of the fuse clamping head 110 on the wire.

[0050] It should be noted that the specific form and structure of the wire feeding mechanism 200 are not limited, and existing technology can be used. For example, this embodiment provides a structure in which the wire feeding mechanism 200 includes a housing base 301 and a pair of wire feeding rollers (not shown in the figure) disposed in the housing base 301. The housing base 301 is mounted on the connector 500, and the guide groove 210 is installed at the wire outlet end of the housing base 301.

[0051] In a preferred embodiment, a guide groove 210 for guiding the wire is provided between the wire outlet of the wire feeding mechanism 200 and the lower end of the wire pressing head 110, so that the wire feeding mechanism 200 has sufficient adjustment angle space and the wire 700 can smoothly reach the lower surface of the wire pressing head 110.

[0052] Further improvements can be made by setting the guide groove 210 as a telescopic guide groove that can extend and retract. After adjusting the tilt angle of the wire feeding mechanism 200, it can still be ensured that the guide groove 210 and the lower surface of the fused wire clamping head 110 are seamlessly connected.

[0053] In a preferred embodiment, the wire feeding mechanism 200 is connected to the connector 500 via a rotating joint that can lock the angle, so that the wire feeding angle can be adjusted. Specifically, the connector 500 is a crossbar 501, one end of which is fixed to the upper end of the wire clamping head 110 by a clamp 502, and the other end is provided with a screw hole, in which the wire feeding mechanism 200 is fixed by a fastening bolt 503.

[0054] The following uses carbon fiber as an example to illustrate the additive manufacturing method based on the above-mentioned additive manufacturing apparatus, including the following steps:

[0055] Step 1: Assemble the additive manufacturing device. The filament clamping mechanism 100 of the additive manufacturing device is installed on the moving mechanism. The fiber-reinforced composite material is installed on the filament feeding mechanism 200, and the front end of the fiber-reinforced composite material is sent to the filament clamping head 110 through the filament feeding mechanism 200. Adjust the tilt angle and filament feeding speed of the filament feeding mechanism 200 according to the additive manufacturing object and the type of fiber-reinforced composite material. The filament 700 used is a continuous fiber-reinforced composite material with ABS coated carbon fiber. The diameter of the filament 700 is 1.75 mm, and the additive speed is 10 mm / s.

[0056] Step 2: Drive the fused wire clamping head 110 via the moving mechanism to move the fiber-reinforced composite material below it to the template or mandrel surface and clamp it;

[0057] Step 3: Simultaneously activate the heating functions of the moving mechanism, the wire feeding mechanism 200, and the fused wire clamping head 110. The wire feeding mechanism 200 continuously feeds the fiber-reinforced composite material to the area below the fused wire clamping head 110. The moving mechanism drives the fused wire clamping head 110 to move continuously along a set path while maintaining a clamping force on the fiber-reinforced composite material below it. The fused wire clamping head 110 heats up during the clamping process, melting and compacting the fiber-reinforced composite material. When the fused wire clamping head 110 moves to the next point, the fiber-reinforced composite material at the previous point cools and solidifies, forming the desired workpiece material, thus completing the additive manufacturing of the fiber-reinforced composite material. In this embodiment, the temperature is controlled at 400°C, and multiple layers of additive deposition are performed to obtain a plate-shaped workpiece.

[0058] In a preferred embodiment, the control device is an industrial computer or a PLC controller, used to coordinate the movement of the moving mechanism, the heating of the electric heating device 112, and the wire feeding of the wire feeding mechanism 200.

[0059] The overall working principle is as follows: In the additive manufacturing process using continuous fiber reinforced composite materials, the filament clamping mechanism 100 and the filament feeding mechanism 200 are first connected and fixed to the machine tool with bolts via flanges. The filament 700 is pressed by the clamping head 114 on the filament clamping mechanism 100 through the filament feeding mechanism 200, compressing the carbon fiber filament. The filament clamping mechanism 100 is then energized by the control device and preheated for a certain period until the temperature stabilizes. Afterward, the drive motor of the filament feeding mechanism 200 is switched on, and the processing path, processing temperature, filament feeding, and other functions are controlled by the control device. The carbon fiber reinforced composite material undergoes melting, compaction, and movement processes to achieve product molding. In this example, the filament 700 used is a continuous fiber reinforced composite material with ABS coated carbon fiber, the diameter of the filament 700 is 1.75 mm, and the additive speed is 10 mm / s. Figure 3 As shown, when the temperature is controlled at 400°C, this method is applied to achieve more than 700 multilayer additive deposition results for this type of filament.

[0060] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments that can be applied to other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. An additive manufacturing apparatus for forming filaments, wherein the filaments are thermoplastic filaments or fiber-reinforced composite filaments, characterized in that, It includes a fuse clamping mechanism, a wire feeding mechanism, a moving mechanism, and a control device; The fuse clamping mechanism is mounted on the moving mechanism via a connector, and the fuse clamping mechanism has at least one fuse clamping head that can be heated. The wire feeding mechanism is mounted on the wire clamping mechanism via a connector and is used to feed the wire at an angle downwards to the area below the wire clamping head; The moving mechanism is used to drive the fuse clamping mechanism to move in three-dimensional space, thereby realizing the moving processing process in space; The control device is used to control the movement of the moving mechanism, the heating of the fuse clamping head, and the wire feeding of the wire feeding mechanism. The control device controls the moving mechanism to drive the fused wire clamping head to move along the set path, and presses the wire fed to the fused wire clamping head below the fused wire clamping head onto the template surface while heating and melting it. When the fused wire clamping head moves to the next clamping point, the molten wire at the previous clamping point cools and solidifies, thereby performing additive manufacturing on the template. The fuse clamping head includes a heat-conducting metal head and a heating device for heating it. The lower part of the heat-conducting metal head is a conical structure that increases pressure, and the end of the conical structure is a smooth clamping head. The heating device is an electric heating device sleeved on the heat-conducting metal head. The wire feeding mechanism has a guide groove between its outlet and the lower end of the wire pressing head to support and guide the wire. The wire feeding mechanism is connected to the connector via a rotating joint that can lock the angle, so that the wire feeding angle can be adjusted. The connector is a horizontal bar, one end of which is fixed to the upper end of the wire pressing head by a clamp, and the other end is provided with a screw hole. The wire feeding mechanism is fixed in the screw hole by a fastening bolt. The guide groove is set as a telescopic guide groove, so that after adjusting the tilt angle of the wire feeding mechanism, the guide groove can still be seamlessly connected with the lower surface of the wire pressing head.

2. The additive manufacturing apparatus according to claim 1, characterized in that: The moving mechanism is a three-dimensional moving mechanism or a multi-axis robotic arm.

3. The additive manufacturing apparatus according to claim 1, characterized in that: The fiber-reinforced composite filament is a filament made by coating fibers with polymer materials.

4. The additive manufacturing apparatus according to claim 3, characterized in that: The fiber is either chopped fiber or continuous fiber, and is one or a mixture of carbon fiber, glass fiber, or a blend of fibers.

5. The additive manufacturing apparatus according to claim 1, characterized in that: The wire feeding mechanism includes a housing base and a pair of wire feeding rollers disposed within the housing base. The housing base is mounted on a connector, and the guide groove is installed at the wire outlet end of the housing base.

6. An additive manufacturing method for filament forming, employing the additive manufacturing apparatus according to any one of claims 1-5, characterized in that, Includes the following steps: Step 1: Assemble the additive manufacturing device. The filament clamping mechanism of the additive manufacturing device is installed on the moving mechanism. Adjust the tilt angle and filament feeding speed of the filament feeding mechanism according to the additive manufacturing object and filament type. Step 2: Using the control device, the moving mechanism drives the fuse clamping head to move to the vicinity above the template surface, and the wire feeding mechanism is started to send the front end of the wire to the bottom of the fuse clamping head; Step 3: Drive the filament clamping head and the filament below it to the template surface and clamp them by moving the moving mechanism; Step 4: Simultaneously activate the heating functions of the moving mechanism, wire feeding mechanism, and wire clamping head; the wire feeding mechanism continuously feeds the wire to the area below the wire clamping head; the moving mechanism drives the wire clamping head to move continuously along the set path and maintains the clamping force on the wire below it. The wire comes into contact with the wire clamping head externally and is heated and melted. At the same time, the wire is compacted during the clamping process, so that the molten layer and the deposited layer are tightly bonded; when the wire clamping head moves to the next point, the wire at the previous point cools and solidifies to form the required workpiece material, completing the wire forming additive manufacturing.

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