Granule melt extrusion additive manufacturing device and design method

Abstract

The invention discloses a granule melt extrusion additive manufacturing device and a design method. The device comprises a machine barrel, a stock bin temperature control fan, a heating block, an extrusion screw, a coupler, a printing nozzle, a driving motor and a shell. A plurality of groups of mounting metal plates are arranged in the shell; the machine barrel, the stock bin temperature control fan and the driving motor are fixedly arranged on the mounting metal plates respectively; the extrusion screw rod is arranged in the machine barrel and is connected with the driving motor through a coupler; the printing nozzle is arranged at a discharging hole in the bottom of the machine barrel; the heating block is connected with the printing nozzle; and a throat-pipe-like structure is arranged in the machine barrel. The structural design of the inner barrel and the outer barrel in the middle of the machine barrel can simultaneously realize three functions of heat transfer, heat preservation and heat dissipation, and through the structural design of the inner barrel, the outer barrel, the hollow surrounding layer and the air flow channel, granules at different positions of the machine barrel can simultaneously reach corresponding heating states, so that the melting effect is effectively ensured.

Description

Technical Field

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

[0002] Existing screw extrusion 3D printing devices are generally composed 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 the material will be pushed into the lower section of the barrel under the rotation of the feed screw. The lower section of the barrel is connected to a heating device, which can convert the solid material into a molten state by heating. Under the extrusion 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 and limits 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 silo fan. When the barrel length is short, it is difficult for the internal granular material to be heated quickly and evenly. The material in the lower part of the barrel is prone to carbonization due to excessive heat; the material in the middle of the barrel is difficult to be fully heated, the material melting efficiency is affected, and the printing speed is difficult to increase; and the granular material in the upper part of the barrel is prone to premature melting due to heat, which is very likely to cause barrel clogging. The traditional method of controlling the fan and heating temperature through temperature detection can solve the above problems to a certain extent, but it cannot be designed and adjusted according to the specific conditions of each section of the barrel and the specific properties of the granular material, and it is impossible to achieve the three functions of heat transfer, heat preservation, and heat dissipation at the same time, and the melting effect of the granular material is not good. Therefore, there is an urgent need to improve the printing device. Through the rational design of the temperature field, the problems such as excessive heating of the internal material of the compact screw extruder mechanism and improper thermal management and agglomeration can be solved. Improve the melting effect and efficiency of the granular material. 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 provide a granular material melt extrusion additive manufacturing device and a 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 driving motor and a housing;

[0006] Multiple sets of mounting sheet metals are arranged in the shell, and the barrel, the silo temperature control fan and the driving motor are fixed on the mounting sheet metals respectively; the extrusion screw is arranged in the barrel and connected to the driving 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;

[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 parameter-designed according to the temperature field simulation, and the overall length of the throat-like structure and the depth of the annular groove are adjusted to control the 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 at the same level as the silo temperature control fan;

[0009] The lower part of the barrel includes a discharge hole and a heating block, and the heating block is provided with a plurality of through holes for installing a heating rod;

[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 arranged between the inner cylinder wall and the outer cylinder wall.

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

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

[0013] Furthermore, it also includes a temperature sensor. There are two temperature sensors, one of which is arranged 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 arranged 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 the requirements, the number of the throat-like structures is one or more.

[0016] The present invention also includes a design method for a particle 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 printed granular material, and design a fence-type silo hollow structure according to the diameter of the granular material;

[0018] S2, obtaining the required melting temperature of the printing particle material, and determining the theoretical threshold of the material melting temperature and the maximum value of the corresponding storage material temperature according to the melting temperature;

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

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

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

[0022] S6. Combined with temperature field simulation, design the air flow 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 related designs of the inner cylinder, outer cylinder, hollow surrounding area 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 3D design software.

[0026] Furthermore, the method also includes manufacturing the internal discharge channel by mechanical processing, manufacturing the barrel by additive manufacturing, 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 realizing 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 the air, and at the same time, 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 material 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, and the effective management of the barrel temperature field is achieved through the throat-like structure; the existing compact screw extruder mechanism realizes the temperature management of the transport section and the silo through the combination of a single heating end and a multi-stage cooling fan, but this will lead to uneven barrel temperature and a substantial increase in the heating power of the hot end; the present invention designs a throat-like structure in the barrel, and combines three-dimensional digital design with temperature field simulation. In the design stage, the heat transfer of the barrel inner barrel is controlled by changing the length, thickness, distribution position and other parameters of the throat-like structure, 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, so as to achieve rapid softening of the material and improve the forming efficiency of the compact screw extruder.

[0030] 3. Realize precise detection and real-time regulation of temperature: 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, which effectively ensures that the temperature in the silo is always kept below the melting temperature, and the solid granular material will not melt in advance, thus avoiding the problem of denaturation of granular material caused by too long heating time to the greatest extent; the temperature sensor at the lower part 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 too high temperature affects the material properties and too low temperature makes the material unable to fully melt and clog the printing nozzle; the double closed-loop temperature control system constructed by two temperature sensors, the control main board and the controlled elements will realize precise detection and real-time regulation of temperature, 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 relevant 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 practical 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 simulation results of temperature fields for different throat structure lengths;

[0037] Figure 5b is the temperature difference between the two ends of the transport section of different throat structure lengths;

[0038] Figure 6a These are the simulation results of the temperature field 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 is further described in detail below in conjunction with 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] A plurality of mounting sheet metals 9 are arranged in the outer shell, and the barrel, the silo temperature control fan and the driving motor are respectively fixed on the mounting sheet metals; the extrusion screw is arranged in the barrel and connected to the driving 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, which adopts a hollow structure design and is installed at the same level as 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 that the outer wall of the inner barrel is provided with an annular groove, which is used to change the different local heat conduction areas of the barrel. Parameter design is carried out according to temperature field simulation, and the position, length and depth of the annular groove 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 arranged in the inner barrel, and the discharge channel connects the fence-type silo and the discharge hole. A variable inclination feeding structure 15 is arranged between the fence-type silo and the middle part of the barrel. By gradually increasing the inclination angle, it is ensured that the material can 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 is provided with three through holes, two of which are used to install the heating rod 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 heat preservation of the compression section and the metering section of the barrel and reducing the temperature of the silo; 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 outside air, avoiding the premature melting of the solid material in the middle of the barrel in the silo or transportation section, which leads to blockage of the discharge channel.

[0051] In this embodiment, a feed hopper 3 is also 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, and is used to measure the internal temperature of the fence-type silo, that is, the feed end temperature sensor 8, which cooperates with the silo temperature control fan to form a silo temperature closed-loop control; the other temperature sensor is arranged in the through hole of the heating block at the lower part of the barrel, and is used to measure the material temperature of the discharge hole, and cooperates with the heating rod to form a heating block temperature closed-loop control, that is, 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 requirements.

[0055] During the printing process of the device of this embodiment, the heat is conducted upward along the inner barrel by the heating block, so that the granular material in the discharge channel is fully melted, and the extrusion screw starts to rotate under the drive of the driving motor, and pushes the solid granular material to move into the barrel, so that the molten material is extruded at the printing nozzle. Among them, after the heat is conducted upward, it is conducted outward from the outer barrel wall. The hollow surrounding area between the inner and outer barrel walls will effectively control the loss of the temperature of the inner barrel. At the same time, the air flow channel will effectively control the speed of heat exchange between the inner barrel and the outside, and the three functions of heat transfer, heat preservation and heat dissipation are realized at the same time. During the printing process, the temperature sensor at the bottom of the fence-type silo measures the internal temperature of the silo in real time and transmits the information to the control main board. When the temperature is higher than the theoretical threshold of the material melting temperature, the control main board controls the silo temperature control fan to start working until the temperature in the silo drops below the theoretical threshold; the temperature sensor at the bottom of the barrel measures the material temperature at the discharge hole in real time and transmits the information to the control main board. When the temperature is higher than the theoretical threshold of the material melting temperature, the control main board sets the heating temperature of the heating block to be lowered; when the temperature is lower than the theoretical threshold, the heating temperature of the heating block will be set to be increased.

[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 comprises the following steps:

[0057] S1. Obtain the diameter of the required printing granular material, and design the fence-type silo hollow structure according to the diameter of the granular material; specifically, 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, so that the fence-type silo is more suitable for the storage of the corresponding solid material, and at the same time can achieve the best heat dissipation effect, 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, obtaining the required melting temperature of the printing particle material, and determining the theoretical threshold of the material melting temperature and the maximum value of the corresponding storage material temperature according to the melting temperature;

[0060] Specifically, the minimum value of the material melting temperature should be the temperature corresponding to when the granular material is completely melted; the maximum value of the material melting temperature should be the highest temperature corresponding to the best performance of the molten granular material. Using the above two temperatures as the threshold for regulating the temperature of the heating block can not only ensure that the material is fully melted, but also ensure the material performance; the maximum value of the storage temperature should be the highest temperature corresponding to the material being able to remain in a solid state. Using this value as the temperature to control the opening and closing of the silo temperature control fan will prevent the material from melting inside the silo. The uneven effect of premature melting can easily cause the barrel to become blocked, affecting the printing effect. In this embodiment, the melting temperature of the printed granular material is 168°C, the material melting temperature is determined to be between 195°C and 210°C, and the maximum value of the storage temperature is 145°C.

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

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

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

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

[0065] For steps S3 to S6, the related designs of the inner cylinder, outer cylinder, hollow surrounding area 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 transferring 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 speed of heat transfer and achieving the heat preservation effect; the air flow channel can change its width 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 relevant structures at the bottom of the barrel are designed according to the size, shape and performance of the pellets. The heat transfer effect of the barrel can be adjusted by changing the dimensions of the outer wall of the inner barrel.

[0068] like Figure 5a , Figure 5b , Figure 6a as well as Figure 6b The figure shows the simulation results of the temperature field for different throat structure lengths and inner wall thicknesses. The throat structure length of 18 mm and thickness of 2 mm can reduce the feed temperature to 144.8 ° C, and the temperature difference before and after the transport section can reach 31.1 ° C. The barrel has a very high degree of design freedom. The barrel designed by this method will be fully suitable for the printing of the corresponding granular materials, and the performance of the printed materials is guaranteed to the greatest extent.

[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 mechanical processing, the barrel is manufactured by additive manufacturing, and after the manufacturing is completed, the discharge channel is assembled with the inner barrel of the barrel. The embedded channel effectively reduces the roughness of the discharge channel, so that the granules are smoothly pushed forward.

[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 device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of more restrictions, an element defined by the sentence "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0073] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be 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 will not be limited to the embodiments shown herein, but rather 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; Multiple sets of mounting sheet metals are arranged in the shell, and the barrel, the silo temperature control fan and the driving motor are fixed on the mounting sheet metals respectively; the extrusion screw is arranged in the barrel and connected to the driving 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; 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 parameter-designed according to the temperature field simulation, and the overall length of the throat-like structure and the depth of the annular groove are adjusted to control the heat transfer.

2. The particle material melt extrusion additive manufacturing device according to claim 1, characterized in that: 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, and the heating block is provided with a plurality of through holes for installing a heating rod; 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 arranged between the inner cylinder wall and the outer cylinder wall.

3. The particle material melt extrusion additive manufacturing device according to claim 2, 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.

4. The particle material melt extrusion additive manufacturing device according to claim 2, characterized in that: A discharge channel is arranged in the inner barrel, and the discharge channel connects the fence-type silo and the discharge hole; a variable inclination feeding structure is arranged between the fence-type silo and the middle part of the barrel, which ensures that the material smoothly enters the discharge channel from the fence-type silo by gradually increasing the inclination angle, thereby effectively preventing material retention.

5. The particle material melt extrusion additive manufacturing device according to claim 2, characterized in that: It also includes temperature sensors. There are two temperature sensors. One of them 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.

6. The particle material melt extrusion additive manufacturing device according to claim 5, 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.

7. The particle material melt extrusion additive manufacturing device according to claim 1, characterized in that: The number of the throat-like structures is one or more according to the requirements.

8. A design method for a particle material melt extrusion additive manufacturing device based on any one of claims 1 to 7, characterized in that: The following steps are involved: S1. Obtain the diameter of the required printed granular material, and design a fence-type silo hollow structure according to the diameter of the granular material; S2, obtaining the required melting temperature of the printing particle material, and determining the theoretical threshold of the material melting temperature and the maximum value of the corresponding storage material temperature according to the melting temperature; S3. Combined with the temperature field simulation, the inner tube wall thickness, the overall length of the throat-like structure and the depth of the annular groove are designed; S4. Combined with temperature field simulation, design the shape, length and wall thickness of the outer cylinder; S5. Combined with temperature field simulation, design the length and width of the hollow enclosure area; S6. Combined with temperature field simulation, design the air flow channel width; S7. Manufacture and assemble the components of the device to obtain a granular material melt extrusion additive manufacturing device.

9. The design method according to claim 8, 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 related designs of the inner cylinder, outer cylinder, hollow surrounding area 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 3D design software.

10. The design method according to claim 9, characterized in that: The method also includes using a mechanical processing method to manufacture an internal discharge channel, and using an additive manufacturing method to manufacture a barrel. After the manufacturing is completed, the discharge channel is assembled with the inner barrel of the barrel.

Images