A granular material melt extrusion additive manufacturing device and design method

Abstract

The present invention discloses a granular material melt extrusion additive manufacturing device and design method. The device includes a barrel, a silo temperature control fan, a heating block, an extrusion screw, a coupling, a printing nozzle, a drive motor and a housing; a plurality of mounting sheet metals are provided in the housing, and the barrel, the silo temperature control fan and the drive motor are respectively fixed on the mounting sheet metals; the extrusion screw is arranged in the barrel and connected to the drive motor through a coupling; the printing nozzle is arranged at the discharge hole at the bottom of the barrel, and the heating block is connected to the printing nozzle; a throat-like structure is provided in the barrel. The structural design of the inner and outer barrels in the middle of the barrel of the present invention can simultaneously realize the three functions of heat transfer, heat preservation and heat dissipation, and through the structural design of the inner and outer barrels, the hollow surrounding layer and the airflow channel, the granular materials at different positions of the barrel can reach the corresponding heating state at the same time, effectively ensuring the melting effect.

Description

Technical Field

[0001] The present invention belongs to the field of additive manufacturing technology, and specifically relates to a granular material melt extrusion additive manufacturing device and a design method. Background Art

[0002] Existing screw extrusion 3D printing devices generally consist of an extrusion screw, a feed hopper, a barrel, a printing nozzle, and a heater. The material enters the barrel from the feed hopper and is pushed into the lower section of the barrel by the rotation of the feed screw. The lower section of the barrel is connected to a heating device that can convert the solid material into a molten state by increasing the temperature. Under the pressure of the unmelted material, the molten material is extruded from the printing nozzle. Among them, in order to achieve uniform heating and softening of the granular material inside the barrel, the barrel used often requires a larger volume to gradually soften and extrude the material. The larger barrel structure encroaches on the printing volume of the equipment, limiting the promotion and application of granular material melting additive manufacturing equipment. For compact screw extrusion mechanisms, the barrel temperature is often controlled by the cooperation between the heating block and the hopper fan. When the barrel length is short, it is difficult for the internal granular material to achieve rapid and uniform heating. The material in the lower barrel is prone to carbonization due to excessive heating; the material in the middle barrel struggles to receive sufficient heat, affecting material melting efficiency and hindering printing speed increases; and the pellets in the upper barrel are prone to premature melting, which can easily lead to barrel blockage. Traditional methods of controlling the fan and heating temperature through temperature sensing can address these issues to a certain extent, but they lack design adjustments tailored to the specific conditions of each barrel section and the specific properties of the pellets. They cannot simultaneously achieve heat transfer, insulation, and heat dissipation, resulting in poor pellet melting. Therefore, improvements to the printing mechanism are urgently needed. By rationalizing the temperature field design, problems such as excessive material heating within the compact screw extruder mechanism, which can lead to agglomeration due to improper thermal management, can be addressed. This can improve pellet melting efficiency and performance. Summary of the Invention

[0003] The main purpose of the present invention is to overcome the shortcomings and deficiencies of the prior art and to propose a granular material melt extrusion additive manufacturing device and design method.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] A granular material melt extrusion additive manufacturing device, comprising a barrel, a silo temperature control fan, a heating block, an extrusion screw, a coupling, a printing nozzle, a drive motor and a housing;

[0006] The housing is equipped with multiple sets of mounting sheet metals, on which the barrel, silo temperature control fan and drive motor are fixed respectively; the extrusion screw is set in the barrel and connected to the drive motor through a coupling; the printing nozzle is set at the discharge hole at the bottom of the barrel, and the heating block is connected to the printing nozzle;

[0007] The barrel consists of an upper barrel part, a middle barrel part and a lower barrel part; the middle barrel part consists of an inner barrel and an outer barrel, the outer barrel surrounds the outer periphery of the inner barrel, and the inner barrel is provided with a throat-like structure between the transport section and the metering section. Specifically, the throat-like structure is provided with an annular groove on the outer wall of the inner barrel; the throat-like structure is parameterized according to temperature field simulation, and the overall length of the throat-like structure and the depth of the annular groove are adjusted to control heat transfer.

[0008] Furthermore, the upper part of the barrel is specifically a fence-type silo, which adopts a hollow structure design and is installed flush with the silo temperature control fan;

[0009] The lower part of the barrel includes a discharge hole and a heating block. The heating block is provided with multiple through holes for installing heating rods.

[0010] The inner cylinder wall and the outer cylinder wall are connected at the bottom of the fence-type silo, and a hollow surrounding area and an air flow channel are provided between the inner cylinder wall and the outer cylinder wall.

[0011] Furthermore, it also includes a feeding hopper, which is connected to the fence-type silo and is used for feeding the granular material.

[0012] Furthermore, a discharge channel is provided in the inner barrel, and the discharge channel connects the fence-type silo and the discharge hole; a variable inclination feeding structure is provided between the fence-type silo and the middle of the barrel, which ensures that the material enters the discharge channel smoothly from the fence-type silo by gradually increasing the inclination angle, effectively preventing material retention.

[0013] Furthermore, it also includes temperature sensors. There are two temperature sensors, one of which is set at the bottom of the fence-type silo to measure the internal temperature of the fence-type silo, and cooperates with the silo temperature control fan to form a closed-loop control of the silo temperature. The other is set in the through hole of the heating block at the lower part of the barrel to measure the material temperature of the discharge hole, and cooperates with the heating rod to form a closed-loop control of the heating block temperature.

[0014] Furthermore, it also includes a control main board, which is respectively connected to the temperature sensor, the silo temperature control fan, the heating block and the drive motor. The control main board is used to control the operation of the silo temperature control fan, set the heating temperature of the heating block and control the operation of the drive motor according to the temperature data collected by the temperature sensor.

[0015] Furthermore, according to requirements, the number of throat-like structures can be one or more.

[0016] The present invention also includes a design method for a granular material melt extrusion additive manufacturing device based on the provided method, the method comprising the following steps:

[0017] S1. Obtain the diameter of the required printing granular material and design a fence-type silo hollow structure according to the diameter of the granular material;

[0018] S2. Obtain the melting temperature of the required printing particle material, and determine the theoretical threshold of the material melting temperature and the maximum value of the corresponding storage temperature based on the melting temperature;

[0019] S3. Combined with temperature field simulation, design the inner tube wall thickness, overall length of the throat-like structure, and annular groove depth;

[0020] S4. Combined with temperature field simulation, design the outer cylinder shape, length and cylinder wall thickness;

[0021] S5. Combined with temperature field simulation, design the length and width of the hollow enclosure;

[0022] S6. Combined with temperature field simulation, design the airflow channel width;

[0023] S7. Manufacture and assemble the components of the device to obtain a granular material melt extrusion additive manufacturing device.

[0024] Furthermore, the fence-type silo hollow structure is designed according to the diameter of the granular material, including the design of the shape, size, and density of the hollow structure;

[0025] The design of the inner cylinder, outer cylinder, hollow surrounding area and airflow channel is adjusted according to the theoretical threshold of the melting temperature of the printed granular material and the maximum temperature of the storage material, and the digital design of the cylinder is completed through 3D design software.

[0026] Furthermore, the method also includes using a mechanical processing method to manufacture an internal discharge channel, manufacturing a barrel by an additive manufacturing method, and assembling the discharge channel and the inner barrel of the barrel after the manufacturing is completed.

[0027] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0028] 1. The structural design of the inner and outer barrels in the middle of the barrel of the present invention can simultaneously realize the three functions of heat transfer, heat preservation and heat dissipation, reduce the heating power of the hot end and reduce the probability of silo agglomeration. The structural design of the heating block makes it compatible with the large-volume and low-priced heating elements on the market. The heat is conducted upward from the heating block, and the granular material in the discharge channel is gradually melted by the heat. The heat is then conducted outward from the lower part of the variable-angle feed structure through the outer barrel wall, thereby achieving the heat dissipation of the silo and the heat preservation of the compression section and metering section of the inner barrel; there is a hollow surrounding area between the inner and outer barrels, which can effectively isolate the outward loss of the temperature of the inner barrel through air, and the design of the airflow channel can also effectively control the heat preservation and heat dissipation effects; through the multiple structural designs of the inner and outer barrels, the hollow surrounding layer and the airflow channel, the granular materials at different positions of the barrel can reach the corresponding heating state at the same time, effectively ensuring the melting effect.

[0029] 2. A throat-like structure is designed in the inner barrel to achieve effective management of the barrel temperature field. Existing compact screw extruder mechanisms all achieve temperature management of the transport section and the silo by combining a single heating end with a multi-stage cooling fan. However, this will lead to uneven barrel temperature and a significant increase in the heating power of the hot end. The present invention designs a throat-like structure in the barrel and combines it with three-dimensional digital design and temperature field simulation. During the design phase, by changing the length, thickness, distribution position and other parameters of the throat-like structure, the heat transfer of the barrel can be controlled, thereby achieving efficient management of the entire barrel temperature field. The throat-like structure is further used to increase the temperature difference between the barrel in the compression section and the silo, thereby achieving rapid softening of the material and improving the forming efficiency of the compact screw extruder.

[0030] 3. Realize precise temperature detection and real-time regulation: Temperature sensors are respectively provided at the bottom of the fence-type silo and the lower part of the barrel. The temperature sensor at the bottom of the fence-type silo detects the silo temperature in real time and transmits it to the control main board. The control main board controls the opening and closing of the silo temperature control fan, effectively ensuring that the temperature in the silo is always kept below the melting temperature, the solid granular material will not melt prematurely, and the problem of granular material denaturation caused by excessive heating time is avoided to the greatest extent; the temperature sensor at the bottom of the barrel detects the temperature of the molten material in real time and transmits it to the control main board. The control main board adjusts the temperature of the heating block to avoid the problem that excessive temperature affects the material properties and excessive temperature makes the material unable to fully melt and clog the printing nozzle; the dual closed-loop temperature control system constructed by two temperature sensors, the control main board and the controlled elements will realize precise temperature detection and real-time regulation, and effectively control the printing temperature within a reasonable range.

[0031] 4. The barrel structure can be designed using three-dimensional software with a high degree of freedom. The dimensional parameters of the fence-type silo, inner barrel, outer barrel, hollow enclosure, and airflow channel structure can be adjusted according to the specific parameters of the actual granular material. On the basis of the existing barrel structure, only the corresponding parameters need to be changed to obtain a barrel with the expected temperature, making the design of the printing device more reasonable. At the same time, the assembly position of the temperature sensor is also designed, making the temperature detection and control more in line with reality, and having a wider range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a schematic diagram of the device of the present invention;

[0033] Figure 2 is a schematic diagram of the interior of the device of the present invention;

[0034] Figure 3 It is a schematic diagram of the barrel of the present invention;

[0035] Figure 4is a flow chart of the method of the present invention;

[0036] Figure 5a These are the temperature field simulation results for different throat structure lengths;

[0037] Figure 5b is the temperature difference between the two ends of the transport section for different lengths of pipe structures;

[0038] Figure 6a This is the temperature field simulation result of the inner wall thickness of different throat structures;

[0039] Figure 6b is the temperature difference between the two ends of the transport section with different inner wall thickness of the throat structure;

[0040] Explanation of the accompanying numbers: 1-driving motor; 2-housing; 3-feed hopper; 4-silo temperature control fan; 5-coupling; 6-barrel; 7-extrusion screw; 8-feed end temperature sensor; 9-mounting sheet metal; 10-heating end temperature sensor; 11-heating block; 12-printing nozzle; 13-heating rod; 14-fence type silo; 15-variable inclination feeding structure; 16-outer cylinder wall; 17-inner cylinder wall; 18-hollow surrounding area; 19-throat-like structure. DETAILED DESCRIPTION

[0041] The present invention will be described in further detail below with reference to the embodiments and drawings, but the embodiments of the present invention are not limited thereto.

[0042] Example

[0043] like Figure 1 、 Figure 2 as well as Figure 3 As shown, the present invention is a granular material melt extrusion additive manufacturing device, comprising a barrel 6, a silo temperature control fan 4, a heating block, an extrusion screw 7, a coupling 5, a printing nozzle 12, a drive motor 1, a temperature sensor, a control mainboard and a housing 2;

[0044] Multiple sets of mounting sheet metals 9 are provided in the outer shell, and the barrel, silo temperature control fan and drive motor are respectively fixed on the mounting sheet metals; the extrusion screw is arranged in the barrel and connected to the drive motor through a coupling; the printing nozzle is arranged at the discharge hole at the bottom of the barrel, and the heating block is connected to the printing nozzle.

[0045] In this embodiment, the barrel is specifically composed of an upper barrel portion, a middle barrel portion, and a lower barrel portion;

[0046] The upper part of the barrel is specifically a fence-type silo 14. The fence-type silo adopts a hollow structure design and is installed flush with the silo temperature control fan. The hollow design can effectively achieve rapid heat dissipation of the material in the silo, avoiding premature melting of the material.

[0047] The middle part of the barrel is composed of an inner barrel and an outer barrel. The inner barrel is provided with a throat-like structure 19 between the transport section and the metering section. The throat-like structure is specifically an annular groove on the outer wall of the inner barrel, which is used to change the heat conduction area of ​​different parts of the barrel. Parameter design is carried out according to temperature field simulation, and the position, length and depth of the throat-like structure can be adjusted to control heat transfer. The outer barrel surrounds the outer periphery of the inner barrel. A discharge channel is provided in the inner barrel, and the discharge channel connects the fence-type silo and the discharge hole. A variable inclination feeding structure 15 is provided between the fence-type silo and the middle part of the barrel. By gradually increasing the inclination angle, the material is ensured to smoothly enter the discharge channel from the fence-type silo, effectively preventing material retention. The design of the variable inclination feeding structure effectively increases the transportation time of the granular material, and the gradually shrinking pipeline avoids material blockage caused by sudden tightening of the channel, thereby ensuring smooth printing.

[0048] The lower part of the barrel includes a barrel discharge hole and a heating block 11. The heating block has three through holes, two of which are used to install heating rods 13.

[0049] The inner cylinder wall 17 and the outer cylinder wall 16 are connected at the bottom of the fence-type silo, and a hollow surrounding area 18 and an air flow channel are provided between the inner cylinder wall and the outer cylinder wall.

[0050] In this embodiment, the barrel can simultaneously realize the three functions of heat transfer, heat preservation and heat dissipation from the silo; the inner barrel ensures the low roughness of the discharge channel by setting an embedded discharge channel, so that the granular material can move downward smoothly; the heat is transferred upward from the heating block to the discharge channel inside the inner barrel, ensuring that the solid granular material inside the embedded discharge channel is fully heated; when the heat is further conducted upward, the heat transfer cross-sectional area at the throat-like structure is reduced, which hinders the upward conduction of heat, thereby achieving insulation of the barrel compression section and the metering section and reducing the silo temperature; the inner barrel wall and the outer barrel wall are connected at the bottom of the silo, and the outside of the barrel conducts excess heat to the external air, avoiding the solid material in the middle of the barrel from melting prematurely in the silo or transportation section, resulting in blockage of the discharge channel.

[0051] In this embodiment, a feed hopper 3 is further included, which is connected to the fence-type silo and is used for feeding the granular material.

[0052] In this embodiment, there are two temperature sensors, one of which is arranged at the bottom of the fence-type silo, used to measure the internal temperature of the fence-type silo, namely, the feed end temperature sensor 8, which cooperates with the silo temperature control fan to form a closed-loop control of the silo temperature; the other temperature sensor is arranged in the through hole of the heating block at the lower part of the barrel, used to measure the material temperature of the discharge hole, and cooperates with the heating rod to form a closed-loop control of the heating block temperature, namely, the heating end temperature sensor 10.

[0053] In this embodiment, the control main board is arranged in an external printer control cabinet. The control main board is respectively connected to the temperature sensor, the silo temperature control fan, the heating block and the drive motor. The control main board is used to control the operation of the silo temperature control fan, set the heating temperature of the heating block and control the operation of the drive motor according to the temperature data collected by the temperature sensor.

[0054] Based on this embodiment, the number of throat-like structures can be designed to be one or more according to needs.

[0055] During the printing process, heat is conducted upward from the heating block along the inner barrel, fully melting the granular material in the discharge channel. Driven by the drive motor, the extrusion screw begins to rotate, pushing the solid granular material toward the interior of the barrel, allowing the molten material to be extruded at the print nozzle. After this upward conduction, the heat is then conducted outward through the outer barrel wall. The hollow area between the inner and outer barrel walls effectively controls the loss of temperature within the inner barrel, while the airflow channel effectively controls the rate of heat exchange between the inner barrel and the exterior, achieving three functions: heat transfer, heat preservation, and heat dissipation. During printing, a temperature sensor at the bottom of the barrier-type silo measures the internal silo temperature in real time and transmits this information to the control board. When the temperature exceeds the theoretical threshold for the material's melting temperature, the control board activates the silo's temperature-controlled fan until the temperature drops below this threshold. A temperature sensor at the bottom of the barrel measures the material temperature at the discharge port in real time and transmits this information to the control board. When the temperature exceeds the theoretical threshold for the material's melting temperature, the control board lowers the heating block's heating temperature; when the temperature falls below the theoretical threshold, the control board increases the heating block's heating temperature.

[0056] In another embodiment, a design method for a granular material melt extrusion additive manufacturing device based on the above embodiment is also provided, such as Figure 4 As shown, the method includes the following steps:

[0057] S1. Obtain the diameter of the required printing granular material and design a fence-type silo hollow structure according to the diameter of the granular material. Specifically, the fence-type silo hollow structure is designed according to the diameter of the granular material, including the design of the shape, size, and density of the hollow structure, so that the fence-type silo is more suitable for the storage of the corresponding solid material and can achieve the best heat dissipation effect, thereby avoiding premature melting of the material and failure and clogging of the barrel.

[0058] When designing the fence-type silo hollow structure, the heat dissipation effect must be optimized, and the material must not fall out of the silo. In this embodiment, the diameter of the printed granular material is 3 mm, so the aperture of the fence-type silo hollow structure is designed to be between 1 mm and 2 mm.

[0059] S2. Obtain the melting temperature of the required printing particle material, and determine the theoretical threshold of the material melting temperature and the maximum value of the corresponding storage temperature based on the melting temperature;

[0060] Specifically, the minimum material melting temperature should be the temperature at which the pellets are completely melted; the maximum material melting temperature should be the highest temperature at which the melted pellets retain their optimal properties. Using these two temperatures as thresholds for regulating the heating block temperature ensures both complete and complete melting of the material and guaranteed material properties. The maximum storage temperature should be the highest temperature at which the material remains solid. Using this value as the temperature at which the silo temperature control fan turns on and off prevents the material from melting inside the silo. Premature melting can cause uneven results and easily clog the barrel, affecting printing quality. In this embodiment, the melting temperature of the printed pellets is 168°C, and the material melting temperature is determined to be between 195°C and 210°C. The maximum storage temperature is 145°C.

[0061] S3. Combined with temperature field simulation, design the inner tube wall thickness, overall length of the throat-like structure, and annular groove depth;

[0062] S4. Combined with temperature field simulation, design the outer cylinder shape, length and cylinder wall thickness;

[0063] S5. Combined with temperature field simulation, design the length and width of the hollow enclosure;

[0064] S6. Combined with temperature field simulation, design the airflow channel width;

[0065] For steps S3 to S6, the relevant designs of the inner cylinder, outer cylinder, hollow enclosure and airflow channel are adjusted according to the theoretical threshold of the melting temperature of the printed granular material and the maximum value of the storage temperature, and the digital design of the cylinder is completed through three-dimensional design software (Solidworks in this embodiment).

[0066] The shape (fin structure can be used for better heat dissipation) and length of the outer cylinder have an impact on the heat dissipation effect; the hollow surrounding area has a heat preservation effect, and its length and width will affect the effect of the inner cylinder to transfer temperature upward; the width of the air flow channel will control the speed of air circulation between the hollow surrounding area and the outside air, and its width will affect the heat preservation and heat dissipation effect of the barrel; by reducing the thickness of the inner and outer cylinder walls, the air gap between the inner and outer cylinders is expanded, thereby slowing down the heat transfer speed and achieving the heat preservation effect; the air flow channel can achieve width changes by adjusting the thickness of the inner and outer cylinder walls, thereby adjusting the heat preservation effect of the barrel.

[0067] In steps S3 to S6, the dimensions of the lower barrel structure are designed based on the size, shape, and properties of the pellets. By changing the dimensions of the inner barrel outer wall, the barrel heat transfer effect can be adjusted.

[0068] like Figure 5a 、 Figure 5b 、 Figure 6a as well as Figure 6b Figure 2 shows the temperature field simulation results for different throat pipe lengths and inner wall thicknesses. Designing a throat pipe with an 18mm length and a 2mm thickness reduces the feed temperature to 144.8°C, and the temperature difference between the front and rear sections of the conveyor section can reach 31.1°C. The barrel offers a high degree of design freedom, and the barrel designed using this method is perfectly suited for printing pellets, ensuring maximum performance.

[0069] S7. Manufacture and assemble the components of the device to obtain a granular material melt extrusion additive manufacturing device.

[0070] In this embodiment, the discharge channel is manufactured by machining, and the barrel is manufactured by additive manufacturing. After the production is completed, the discharge channel is assembled with the inner barrel. The embedded channel effectively reduces the roughness of the discharge channel, ensuring smooth forward movement of the pellets.

[0071] In this embodiment, the manufactured barrel is assembled with the extrusion screw, heating block, printing nozzle, silo temperature control fan, drive motor, control main board, temperature sensor and other components to finally obtain a granular material melt extrusion additive manufacturing device.

[0072] It should also be noted that, in this specification, terms such as "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article or apparatus comprising the element.

[0073] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A granular material melt extrusion additive manufacturing device, characterized in that: Including barrel, silo temperature control fan, heating block, extrusion screw, coupling, printing nozzle, drive motor and housing; The housing is equipped with multiple sets of mounting sheet metals, on which the barrel, silo temperature control fan and drive motor are fixed respectively; the extrusion screw is set in the barrel and connected to the drive motor through a coupling; the printing nozzle is set at the discharge hole at the bottom of the barrel, and the heating block is connected to the printing nozzle; The barrel consists of an upper barrel section, a middle barrel section, and a lower barrel section. The middle barrel section consists of an inner barrel and an outer barrel section. The outer barrel section surrounds the inner barrel section, and the inner barrel section is provided with a throat-like structure between the transport section and the metering section. The throat-like structure consists of an annular groove on the outer wall of the inner barrel. The throat-like structure is parameterized based on temperature field simulation. The overall length of the throat-like structure and the depth of the annular groove are adjusted to control heat transfer. The reduction in heat transfer cross-sectional area at the throat-like structure hinders upward heat conduction, thereby achieving thermal insulation in the compression and metering sections of the barrel and reducing the silo temperature. The upper part of the barrel is a fence-type silo, which adopts a hollow structure design and is installed flush with the silo temperature control fan; The lower part of the barrel includes a discharge hole and a heating block. The heating block is provided with multiple through holes for installing heating rods. The inner cylinder wall and the outer cylinder wall are connected at the bottom of the fence-type silo, and a hollow surrounding area and an air flow channel are provided between the inner cylinder wall and the outer cylinder wall; A discharge channel is provided in the inner barrel, which connects the fence-type silo and the discharge hole. A variable inclination feeding structure is provided between the fence-type silo and the middle of the barrel. By gradually increasing the inclination angle, the material is ensured to smoothly enter the discharge channel from the fence-type silo, effectively preventing material retention.

2. The device for additive manufacturing by melt extrusion of pellets according to claim 1, characterized in that: The utility model also comprises a feeding hopper which is connected with the fence type silo and is used for feeding the granular material.

3. The device for additive manufacturing by melt extrusion of pellets according to claim 1, characterized in that: It also includes temperature sensors. There are two temperature sensors, one of which is set at the bottom of the fence-type silo to measure the internal temperature of the fence-type silo, and cooperates with the silo temperature control fan to form a closed-loop control of the silo temperature. The other is set in the through hole of the heating block at the lower part of the barrel to measure the material temperature of the discharge hole, and cooperates with the heating rod to form a closed-loop control of the heating block temperature.

4. The device for additive manufacturing by melt extrusion of pellets according to claim 3, characterized in that: It also includes a control main board, which is respectively connected to the temperature sensor, the silo temperature control fan, the heating block and the drive motor. The control main board is used to control the operation of the silo temperature control fan, set the heating temperature of the heating block and control the operation of the drive motor according to the temperature data collected by the temperature sensor.

5. The device for additive manufacturing by melt extrusion of granular materials according to claim 1, characterized in that: The number of the throat-like structures can be one or more according to requirements.

6. A method for designing a device for additive manufacturing by melt extrusion of granular materials according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1. Obtain the diameter of the required printing granular material and design a fence-type silo hollow structure according to the diameter of the granular material; S2. Obtain the melting temperature of the required printing particle material, and determine the theoretical threshold of the material melting temperature and the maximum value of the corresponding storage temperature based on the melting temperature; S3. Combined with temperature field simulation, design the inner tube wall thickness, overall length of the throat-like structure, and annular groove depth; S4. Combined with temperature field simulation, design the outer cylinder shape, length and cylinder wall thickness; S5. Combined with temperature field simulation, design the length and width of the hollow enclosure; S6. Combined with temperature field simulation, design the airflow channel width; S7. Manufacture and assemble the components of the device to obtain a granular material melt extrusion additive manufacturing device.

7. The design method according to claim 6, characterized in that: Design the fence-type silo hollow structure according to the diameter of the granular material, including the design of the shape, size and density of the hollow structure; The design of the inner cylinder, outer cylinder, hollow surrounding area and airflow channel is adjusted according to the theoretical threshold of the melting temperature of the printed granular material and the maximum temperature of the storage material, and the digital design of the cylinder is completed through 3D design software.

8. The design method according to claim 7, characterized in that: The method also includes using a mechanical processing method to manufacture an internal discharge channel, using an additive manufacturing method to manufacture a barrel, and after the manufacturing is completed, assembling the discharge channel and the inner barrel of the barrel.

Images