A preheating aid for additive manufacturing and method

Abstract

This invention discloses a preheating auxiliary device and method for additive manufacturing, belonging to the field of additive manufacturing preheating technology. It includes: a support frame with a preheating device vertically fixed to one side; a conveying pipe horizontally connected to the outer wall of the preheating device, with a powder outlet seat sealed below the preheating device; a heat-insulating cylinder disposed below the preheating device and connected to the powder outlet seat; and a classifying disc fixed to the support frame and located on one side of the preheating device, with a powder feeding pipe vertically connected to the middle of the upper surface of the classifying disc, and the other end of the powder feeding pipe connected to the heat-insulating cylinder. In this invention, the powder used for additive manufacturing can enter the preheating device for sufficient preheating and then be transferred to the classifying disc. Drying gas enters the classifying disc from a gas storage tank, contacts and mixes with the powder to complete online drying separation and atmosphere protection, achieving the removal of fine powder and agglomerates from the powder, thereby improving the density and consistency of the cladding layer.

Description

Technical Field

[0001] This invention belongs to the field of preheating technology in additive manufacturing, specifically a preheating auxiliary device and method for additive manufacturing. Background Technology

[0002] Additive manufacturing uses software and CNC systems to deposit specialized metallic, non-metallic, and medical biomaterials layer by layer through methods such as extrusion, sintering, melting, photocuring, and spraying to create physical objects. In traditional technologies, before additive manufacturing, powder needs to be loaded into a stainless steel can or tray and heated in a resistance heating oven or rotating tank. After reaching the set temperature, it is kept at that temperature for a period of time before being removed and transferred to a powder feeder or powder cylinder. For example, the invention patent with publication number CN114523126B uses a combination of heating tubes, rolling mechanisms, heating mechanisms, translation mechanisms, and tilting mechanisms to automatically and uniformly heat the powder to achieve the purpose of preheating. However, this simple preheating method requires each batch of powder to undergo the entire process of loading, preheating, tilting, and transferring, which cannot provide continuous online powder supply. Moreover, the hot powder is exposed to room temperature air after being poured out of the drum. Especially during the preheating process, the powder accumulation thickness inside the drum is large. Although rolling and tumbling are more effective than static preheating, there is still a large surface temperature difference in the center of the powder accumulation, which cannot guarantee the uniformity of powder temperature.

[0003] Therefore, it is necessary to provide a preheating auxiliary device and method for additive manufacturing to solve the problems mentioned in the background art. Summary of the Invention

[0004] To achieve the above objectives, the present invention provides the following technical solution: a preheating auxiliary device for additive manufacturing, comprising:

[0005] The support frame has a preheating device vertically fixed on one side;

[0006] A conveying pipe is horizontally connected to the outer wall of the preheating device, and a powder outlet seat is sealed and installed below the preheating device.

[0007] An insulation cylinder is located below the preheating device and is connected to the powder outlet seat;

[0008] A grading disc is fixed on the support frame and located on one side of the preheating device. A powder feeding pipe is vertically connected to the middle of the upper end face of the grading disc, and the other end of the powder feeding pipe is connected to the heat preservation cylinder.

[0009] A gas storage tank is located on the side of the support frame away from the preheating device, and an airflow pipe is connected between the gas storage tank and the distribution plate;

[0010] The desorption tank is located inside the support frame below the grading disc, and a fixing pipe connects the desorption tank and the grading disc.

[0011] Furthermore, as a preferred embodiment, the gas storage tank stores dry gas; and a powder supply pipe is connected to one side of the lower end face of the grading disc.

[0012] Furthermore, preferably, the preheating device includes:

[0013] An insulated tank has a powder hopper fixed inside and above, and the side wall of the powder hopper has an opening that is sealed and connected to the conveying pipe.

[0014] A screen plate is horizontally fixed inside the powder hopper, and the lower end face of the powder hopper is provided with a powder discharge port;

[0015] A lever is disposed inside the powder hopper and above the screen plate. A rotating shaft is rotatably connected to the center of the powder hopper, and the lever is fixed coaxially with the rotating shaft.

[0016] The vibrators are multiple and arranged in a circle, and each vibrator is installed on the lower end face of the screen plate;

[0017] A preheating chamber is provided inside the heat insulation tank and located below the powder silo. The preheating chamber is provided with multiple preheating pipe units.

[0018] The discharge seat is fixed below the heat insulation tank.

[0019] Furthermore, as a preferred embodiment, an upper partition and a lower partition are horizontally arranged at the top and bottom of the preheating chamber, respectively, and multiple preheating tube units are equidistantly distributed and vertically fixed on the upper partition and the lower partition.

[0020] Multiple heaters are vertically fixed on the lower partition plate, and each heater is spaced apart from the preheating tube unit.

[0021] A heat-conducting medium is filled between the upper and lower partitions; a support plate is fixed parallel to the lower partition, and the lower end of each preheating pipe unit is fixed through the support plate.

[0022] Furthermore, preferably, the preheating pipe unit includes:

[0023] The heat pipe has a powder inlet sleeve fixed inside at the top.

[0024] A connecting plate is axially arranged inside the heat pipe, and multiple connecting holes are opened on the inner circumference of the connecting plate;

[0025] The air passage is coaxially and vertically installed inside the heat pipe;

[0026] The airbag columns are multiple airbag columns arranged axially, with each airbag column and the connecting plate spaced apart and sleeved and fixed outside the air passage tube;

[0027] Side air vents are provided on the side wall of the air passage and are arranged one-to-one with the airbag columns.

[0028] Furthermore, as a preferred embodiment, a flow-stopping plate is rotatably installed below each of the connecting plates, and the flow-stopping plate has a through hole corresponding to the connecting hole;

[0029] The outer wall of the heat insulation tank is fixed with a mounting bracket, and an air pump is fixed on the mounting bracket. The air pump has multiple exhaust ports distributed on it, and each exhaust port is horizontally connected to a branch pipe. A solenoid valve is installed on the branch pipe.

[0030] Each of the branch pipes is provided with a plurality of vertically distributed connecting pipes, and a section pipe is slidably provided below the connecting pipe, and is connected to each of the air passage pipes through the section pipe.

[0031] Furthermore, as a preferred embodiment, the interior of the heat insulation tank is provided with a plurality of drive shafts distributed parallel to the branch pipes, and each air pipe is vertically rotatably connected to a linkage shaft at its lower end, the upper end of the linkage shaft being connected to the air pipe.

[0032] The upper end of the air pipe is rotatably and sealed to the joint pipe. The lower end of the linkage shaft is fixed with a transmission gear, and the transmission shaft is distributed with multiple bevel gears corresponding to the linkage shaft. The bevel gears mesh with the transmission gears. An external motor is fixed outside the heat insulation tank, and the output end of the external motor is fixed to the transmission shaft.

[0033] Furthermore, as a preferred embodiment, the linkage shaft is composed of two upper shafts and a support shaft that slide vertically. A support spring is provided between the upper shafts and the support shaft. A toothed ring is fixed inside the heat-conducting pipe below the air passage pipe, and a convex toothed ring is fixed outside the upper shaft below the toothed ring. The convex toothed ring and the toothed ring abut against each other.

[0034] Furthermore, as a preferred embodiment, a secondary cavity is provided below the air passage, and a shaft plug is slidably disposed in the secondary cavity. The lower part of the shaft plug slides through the upper shaft and is fixed to the support shaft.

[0035] A preheating auxiliary method for additive manufacturing includes the following steps:

[0036] S1. The additive manufacturing powder to be preheated is fed into the preheating device through the conveying pipe, the preheating device is started, and the powder is heated according to the preset preheating temperature curve;

[0037] S2. The powder to be preheated enters the heat-insulating tank of the preheating device. The powder falls onto the screen plate in the powder hopper. The vibrator is started to drive the screen plate to vibrate, which quickly disperses the agglomerated powder. Particles that meet the particle size requirements can pass through the screen holes and fall into the preheating chamber below, and enter each preheating tube unit. Multiple preheating tube units preheat the powder fully.

[0038] S3. After the preheating device completes heating, open the powder outlet seat to allow the preheated powder to fall into the heat preservation cylinder; open the gas storage tank valve to release the drying gas, which enters the classifying plate through the air flow pipe; and the powder entering the heat preservation cylinder enters the classifying plate through the powder feeding pipe.

[0039] S4. The powder is classified by particle size using a classifying disc. Powder that meets the particle size requirements is discharged through the powder supply pipe and aligned with the powder feeding head or powder spreading device of the additive manufacturing equipment. The remaining powder or agglomerates are separated and discharged into the removal tank through a fixed pipe for centralized collection.

[0040] Compared with the prior art, the beneficial effects of the present invention are:

[0041] In this invention, the powder used for additive manufacturing can be fully preheated in a preheating device and then transferred to a classifying plate. Drying gas enters the classifying plate from the gas storage tank, comes into contact with the powder and mixes to complete online drying, separation and atmosphere protection, thereby removing fine powder and agglomerates from the powder, making the particle size distribution of the additive manufacturing powder more concentrated, thus improving the density and consistency of the cladding layer.

[0042] The main preheating device employs multiple vertically distributed preheating tube units. After entering the heat-conducting tube, the powder can pass through the annular gap between it and the airbag column. The powder layer thickness is small, resulting in a significant preheating effect and achieving uniform powder preheating temperature. Each airbag column can continuously rotate within the heat-conducting tube, and during the rotation, the contact and engagement of the toothed ring and the toothed ring achieve high-frequency axial vibration. This not only prevents the powder from remaining in the same position for a long time and sintering, but also effectively squeezes and releases the powder in the annular gap, further improving heat exchange with the powder particles. In addition, the high-frequency axial movement of each airbag column is accompanied by dynamic slight expansion and contraction. When the airbag column expands radially, the width of the annular gap decreases, applying radial pressure to the powder and forcing it to flow. When it contracts, the width of the annular gap increases, allowing the powder to fall quickly and preventing powder from adhering to the tube wall. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0044] Figure 2 This is the front view of the present invention;

[0045] Figure 3 This is a schematic diagram of the internal structure of the preheating device in this invention;

[0046] Figure 4 This is a schematic diagram of the internal structure of the preheating cavity in this invention;

[0047] Figure 5 This is a schematic diagram of the distribution structure of the heater in this invention;

[0048] Figure 6 This is a schematic diagram of the preheating pipe unit in this invention;

[0049] Figure 7 This is a schematic diagram of the internal structure of the heat pipe in this invention;

[0050] Figure 8 This is a schematic diagram of the toothed ring and the convex toothed ring in this invention;

[0051] In the diagram: 1. Support frame; 11. Conveying pipe; 12. Powder outlet seat; 13. Insulation cylinder; 14. Grading disc; 15. Powder feeding pipe; 16. Air storage tank; 17. Airflow pipe; 18. Removal tank; 19. Powder supply pipe; 2. Preheating device; 21. Insulation tank; 22. Powder silo; 23. Screen plate; 24. Baffle plate; 25. Discharge seat; 3. Preheating chamber; 31. Upper partition plate; 32. Lower partition plate; 3 3. Heater; 34. Support plate; 4. Preheating tube unit; 41. Heat conduction tube; 42. Powder inlet sleeve; 43. Connecting plate; 44. Air passage pipe; 45. Airbag column; 46. Cut-off plate; 47. Mounting bracket; 48. Airflow pump; 49. Branch pipe; 5. Drive shaft; 51. Connecting pipe; 52. Section pipe; 53. Linkage shaft; 6. Toothed ring; 61. Convex toothed ring; 62. Shaft plug; 63. Secondary cavity. Detailed Implementation

[0052] Please see Figures 1-8 In this embodiment of the invention, a preheating auxiliary device for additive manufacturing includes:

[0053] Support frame 1, with a preheating device 2 vertically fixed on one side. Support frame 1 is welded from square steel pipe or high-strength aluminum alloy profile, and rolling casters can be installed at the bottom.

[0054] A conveying pipe 11 is horizontally connected to the outer wall of the preheating device 2. One end of the conveying pipe 11 is connected to the powder feeder for continuously feeding powder into the preheating device 2. A powder outlet seat 12 is sealed and installed below the preheating device 2.

[0055] The heat preservation cylinder 13 is located below the preheating device 2 and connected to the powder outlet seat 12. The preheated powder can enter the heat preservation cylinder 13 through the powder outlet seat 12. The heat preservation cylinder 13 has a double-layer structure, with the inner layer being stainless steel and the outer layer being carbon steel, and the middle layer being filled with nano aerogel or ceramic fiber insulation cotton.

[0056] The grading disc 14 is fixed on the support frame 1 and located on one side of the preheating device 2. A powder feeding pipe 15 is vertically connected to the middle of the upper end face of the grading disc 14. The other end of the powder feeding pipe 15 is connected to the heat preservation cylinder 13. The grading disc 14 is equipped with a cyclone separation structure or an inertial impact plate, which uses centrifugal force to classify the powder according to the particle size.

[0057] A gas storage tank 16 is disposed on the side of the support frame 1 away from the preheating device 2, and an airflow pipe 17 is connected between the gas storage tank 16 and the distribution plate 14.

[0058] The removal tank 18 is located inside the support frame 1 below the grading disc 14. A fixed pipe is connected between the removal tank 18 and the grading disc for collecting the separated powder.

[0059] In this embodiment, the gas storage tank 16 stores dry gas, which is a high-purity inert gas or other gas. For example, for active metals such as titanium alloys, high-purity argon is preferred. The gas storage tank 16 is equipped with a pressure reducing valve, a pressure gauge, and a safety valve, which can provide atmosphere protection for the powder in the classification plate 14. A powder supply pipe 19 is connected to one side of the lower end face of the classification plate 14. The powder supply pipe 19 is used to connect to the powder feeding head or powder spreading device of the additive manufacturing equipment to deliver the preheated powder in a timely manner.

[0060] In a preferred embodiment, the preheating device 2 includes:

[0061] The heat-insulating tank 21 has a powder hopper 22 fixed inside and above. The side wall of the powder hopper 22 has an opening that seals and connects with the conveying pipe 11, and the top cover of the hopper is removable to facilitate cleaning the screen plate and replacing the screen.

[0062] A screen plate 23 is horizontally fixed inside the powder hopper 22, and the lower end face of the powder hopper 22 is provided with a powder discharge port;

[0063] A lever 24 is disposed inside the powder hopper 22 and above the screen plate 23. A rotating shaft is rotatably connected to the center of the powder hopper 22, and the lever 24 is fixed coaxially with the rotating shaft.

[0064] The vibrators (not shown in the figure) are multiple in a circular arrangement, and each vibrator is installed on the lower end face of the screen plate 23, so that the powder can be prevented from accumulating on the screen plate 23 during continuous powder feeding.

[0065] The preheating chamber 3 is located inside the heat insulation tank 21 and below the powder hopper 22. The preheating chamber 3 is provided with multiple preheating pipe units 4.

[0066] The discharge seat 25 is fixed below the heat insulation tank 21.

[0067] In this embodiment, an upper partition 31 and a lower partition 32 are horizontally arranged above and below the interior of the preheating cavity 3, and multiple preheating pipe units 4 are equidistantly distributed and vertically fixed on the upper partition 31 and the lower partition 32.

[0068] Multiple heaters 33 are vertically fixed on the lower partition plate 32. Each heater 33 is distributed at intervals with the preheating tube unit 4, thereby ensuring that each preheating tube unit 4 in the heat insulation tank 21 is heated uniformly and avoiding local overheating.

[0069] A heat-conducting medium is filled between the upper partition 31 and the lower partition 32; a support plate 34 is fixed parallel to the lower partition 32, and the lower end of each preheating pipe unit 4 is fixed through the support plate 34.

[0070] In this embodiment, the preheating pipe unit 4 includes:

[0071] The heat pipe 41 has a powder inlet sleeve 42 fixed inside and above. The powder in the powder hopper 22 can fall into the preheating chamber 3 through the powder outlet, and then enter the heat pipe 41 through the powder inlet sleeve 42.

[0072] The connecting disk 43 is axially arranged inside the heat-conducting pipe 41. Multiple connecting holes are opened on the inner circumference of the connecting disk 43. The multiple connecting disks 43 can axially and evenly divide the heat-conducting pipe 41 into multiple guide cavities. The powder is heated by passing through each guide cavity in sequence and then discharged.

[0073] The air passage 44 is coaxially and vertically arranged inside the heat pipe 41;

[0074] The airbag columns 45 are arranged axially in multiple ways, and each airbag column 45 is spaced apart from the connecting plate 43 and is sleeved and fixed outside the air passage tube 44.

[0075] Side vents are formed on the side wall of the air passage 44 and are arranged one-to-one with the airbag columns 45. This means that during powder preheating, each airbag column 45 on the air passage 44 can be inflated, forming an annular gap between it and the heat-conducting pipe 41. The powder can flow through this annular gap, thus making full contact with the inner wall of the heat-conducting pipe 41 and achieving heat exchange. This eliminates the temperature gradient of "cold center, hot wall" in traditional stacking heating. This arrangement also avoids the direct contact between powder and exposed heating pipes caused by traditional drum preheating methods, which can lead to localized overheating and powder sintering into hard lumps that adhere to the pipe surface and solidify.

[0076] In addition, the width of the circumferential slit can be adjusted by controlling the inflation pressure of the airbag column 45, thereby adjusting the amount of powder introduced.

[0077] In this embodiment, a flow-blocking plate 46 is rotatably installed below each of the connecting plates 43. The flow-blocking plate 46 has a through hole corresponding to the connecting hole. In this way, the feeding speed of the powder in the annular gap can be changed by the deflection of the flow-blocking plate 46, so as to adjust the powder preheating residence time according to different powder characteristics.

[0078] The outer wall of the heat insulation tank 21 is fixed with a mounting bracket 47, and an air pump 48 is fixed on the mounting bracket 47. The air pump 48 has multiple exhaust ports distributed on it, and each exhaust port is horizontally connected to a branch pipe 49. A solenoid valve is installed on the branch pipe 49.

[0079] Each of the branch pipes 49 is provided with a plurality of vertically distributed connecting pipes 51. A section pipe 52 is slidably provided below the connecting pipe 51 and is connected to each of the air passage pipes through the section pipe. In this way, when the solenoid valve is opened, the air pump 48 sends gas into each air passage pipe 44 through the corresponding branch pipe 4, thereby adjusting the expansion and contraction of the airbag column 45 and effectively controlling the size of the circumferential seam.

[0080] In a preferred embodiment, a plurality of drive shafts 5 are provided at the lower interior of the heat insulation tank 21, which are parallel to the branch pipes 49. A linkage shaft 53 is vertically rotatably connected to the lower part of each air pipe 44, and the upper end of the linkage shaft 53 is connected to the air pipe 44.

[0081] The upper end of the air passage 44 is rotatably and sealed to the section tube 52. The lower end of the linkage shaft 53 is fixed with a transmission gear, and the transmission shaft 5 is distributed with multiple bevel gears corresponding to the linkage shaft 53. The bevel gears mesh with the transmission gears. An external motor 54 is fixed to the outside of the heat insulation tank 21. The output end of the external motor 54 is fixed to the transmission shaft 5. When the external motor 54 rotates, it can drive each linkage shaft 53 to rotate synchronously using the transmission shaft 5. Each linkage shaft 53 drives the air passage 44 to rotate during rotation. In this way, the air bladder column 45 on the air passage 44 can rotate continuously inside the heat conduction tube 41, promoting the full flow of powder in the annular gap, avoiding stagnation, and further improving the preheating uniformity.

[0082] In this embodiment, the linkage shaft 53 is composed of two upper shafts and a support shaft that slide vertically. A support spring is provided between the upper shafts and the support shaft. A toothed ring 6 is fixed inside the heat pipe 41 below the air passage pipe 44, and a convex toothed ring 61 is fixed outside the upper shaft below the toothed ring 6. The convex toothed ring 61 and the toothed ring 6 are in contact. With this arrangement, the upper shaft can keep the convex toothed ring 61 in contact with the toothed ring 6 under the elastic support of the support spring. When the linkage shaft 53 rotates, the upper shaft moves axially downward due to the alternating movement of the tooth peaks and grooves of the convex toothed ring 61 and the toothed ring 6. This allows the air passage pipe 44 above the linkage shaft 53 to generate high-frequency axial reciprocating motion during rotation. This makes the powder in the annular gap highly fluid and can effectively break up agglomerates and avoid blockage. In addition, the powder particles can be fully rolled and squeezed in the annular gap to release, further improving the preheating effect of the powder particles.

[0083] In this embodiment, a secondary cavity 63 is provided below the air passage 44. A shaft plug 62 is slidably and sealed inside the secondary cavity 63. The lower part of the shaft plug 62 slides through the upper shaft and is fixed to the support shaft. When the air passage 44 above the linkage shaft 53 moves axially upward during rotation, the shaft plug 62 can draw the gas in each airbag column 45 into the secondary cavity 63 under negative pressure, causing each airbag column 45 to undergo slight contraction deformation. When the air passage 44 above the linkage shaft 53 moves axially downward during rotation, the gas in the secondary cavity 63 re-enters each airbag column 45, and the airbag column 45 resumes expansion. This configuration utilizes the contraction and expansion of the airbag columns to achieve instantaneous increase and decrease in the width of the circumferential seam. On the one hand, it can force the circumferential redistribution of powder, avoiding the phenomenon of local preheating caused by the single trajectory of powder flow, and achieving uniform heating of the entire surface of the powder. On the other hand, it forms a creeping extrusion effect to promote powder falling and prevent powder from stagnating on the pipe wall or causing blockage.

[0084] A preheating auxiliary method for additive manufacturing includes the following steps:

[0085] S1. The additive manufacturing powder to be preheated is fed into the preheating device 2 through the conveying pipe 11. The preheating device 1 is started and the powder is heated according to the preset preheating temperature curve.

[0086] S2. The powder to be preheated enters the heat insulation tank 21 of the preheating device 2. The powder falls onto the screen plate 23 in the powder hopper 22. The vibrator is started to drive the main body of the screen plate 23 to vibrate, so that the agglomerated powder can be quickly dispersed. Particles that meet the particle size requirements can fall through the screen holes into the preheating chamber 3 below and enter each preheating tube unit 4. Multiple preheating tube units 4 preheat the powder fully, so that the powder as a whole reaches a uniform and suitable temperature state, which is ready for subsequent dispersion and printing.

[0087] S3. After the preheating device 2 completes heating, the powder outlet seat 12 is opened, allowing the preheated powder to fall into the heat preservation cylinder 13; the valve of the gas storage tank 16 is opened to release the drying gas, which enters the classifying plate 14 through the air flow pipe 17 to protect the powder atmosphere; while the powder entering the heat preservation cylinder 13 enters the classifying plate 14 through the powder feeding pipe 15.

[0088] S4. The powder is classified by the grading disc 14. Powder that meets the particle size requirements is discharged through the powder supply pipe 19 and aligned with the powder feeding head or powder spreading device of the additive manufacturing equipment, thereby ensuring that the powder particle size distribution is uniform and there is no agglomeration, improving the density and surface quality of the printed parts. The remaining powder or agglomerates are separated and discharged into the removal tank 18 through the fixed pipe for centralized collection.

[0089] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A preheating auxiliary device for additive manufacturing, characterized in that, It includes: A support frame (1) has a preheating device (2) vertically fixed on one side; A conveying pipe (11) is horizontally connected to the outer wall of the preheating device (2), and a powder outlet seat (12) is sealed and installed below the preheating device (2). The heat preservation cylinder (13) is located below the preheating device (2) and connected to the powder outlet seat (12); The grading disc (14) is fixed on the support frame (1) and located on one side of the preheating device (2). A powder feeding pipe (15) is vertically connected to the middle of the upper end face of the grading disc (14), and the other end of the powder feeding pipe (15) is connected to the heat preservation cylinder (13). An air storage tank (16) is located on the side of the support frame (1) away from the preheating device (2), and an air flow pipe (17) is connected between the air storage tank (16) and the distribution plate (14). The desorption tank (18) is located inside the support frame (1) below the grading plate (14), and a fixed pipe connects the desorption tank (18) and the grading plate.

2. The preheating auxiliary device for additive manufacturing according to claim 1, characterized in that: The gas storage tank (16) stores dry gas; a powder supply pipe (19) is connected to one side of the lower end face of the grading disc (14).

3. The preheating auxiliary device for additive manufacturing according to claim 1, characterized in that, The preheating device (2) includes: The heat-insulating tank (21) has a powder hopper (22) fixed inside and above. The powder hopper (22) has an opening on its side wall that is sealed to the conveying pipe (11). A screen plate (23) is horizontally fixed inside the powder hopper (22), and the lower end face of the powder hopper (22) is provided with a powder discharge port; A lever (24) is disposed inside the powder hopper (22) and above the screen plate (23). A rotating shaft is rotatably connected to the center of the powder hopper (22), and the lever (24) is fixed coaxially with the rotating shaft. The vibrators are multiple in a circle, and each vibrator is installed on the lower end face of the screen plate (23); The preheating chamber (3) is located inside the heat insulation tank (21) and below the powder silo (22). Multiple preheating tube units (4) are provided in the preheating chamber (3). The discharge seat (25) is fixed below the heat insulation tank (21).

4. The preheating auxiliary device for additive manufacturing according to claim 3, characterized in that: The preheating chamber (3) is horizontally provided with an upper partition (31) and a lower partition (32) at the top and bottom respectively. Multiple preheating pipe units (4) are equidistantly distributed and vertically fixed on the upper partition (31) and the lower partition (32). Multiple heaters (33) are vertically fixed on the lower partition plate (32), and each heater (33) is spaced apart from the preheating tube unit (4); The space between the upper partition (31) and the lower partition (32) is filled with a heat-conducting medium; a support plate (34) is fixed parallel to the lower partition (32), and the lower end of each preheating pipe unit (4) is fixed through the support plate (34).

5. The preheating auxiliary device for additive manufacturing according to claim 3, characterized in that, The preheating pipe unit (4) includes: A heat pipe (41) has a powder inlet sleeve (42) fixed inside its upper part. A connecting plate (43) is axially arranged inside the heat pipe (41), and multiple connecting holes are provided on the inner circumference of the connecting plate (43); The air passage (44) is coaxially and vertically arranged inside the heat pipe (41); The airbag columns (45) are arranged axially in multiple ways. Each airbag column (45) is spaced apart from the connecting plate (43) and is sleeved and fixed outside the air passage tube (44). Side air vents are provided on the side wall of the air passage (44) and are provided in a one-to-one correspondence with the airbag column (45).

6. The preheating auxiliary device for additive manufacturing according to claim 5, characterized in that: Each of the connecting plates (43) is rotatably mounted with a flow-stopping plate (46) below it, and the flow-stopping plate (46) has a through hole corresponding to the connecting hole; The outer wall of the heat insulation tank (21) is fixed with a mounting bracket (47), and an air pump (48) is fixed on the mounting bracket (47). The air pump (48) has multiple exhaust ports distributed on it, and each exhaust port is horizontally connected to a branch pipe (49). A solenoid valve is installed on the branch pipe (49). Each of the branch pipes (49) is provided with a plurality of vertically distributed connecting pipes (51), and a section pipe (52) is slidably provided below the connecting pipe (51), and is connected to each of the air passage pipes through the section pipe.

7. The preheating auxiliary device for additive manufacturing according to claim 6, characterized in that: The heat insulation tank (21) has multiple drive shafts (5) arranged parallel to the branch pipe (49) at the bottom inside. Each air pipe (44) is vertically rotatably connected to a linkage shaft (53) at the bottom. The upper end of the linkage shaft (53) is connected to the air pipe (44). The upper end of the air pipe (44) is sealed and rotatably connected to the joint pipe (52). The lower end of the linkage shaft (53) is fixed with a transmission gear, and the transmission shaft (5) is distributed with multiple bevel gears corresponding to the linkage shaft (53). The bevel gears mesh with the transmission gears. An external motor (54) is fixed outside the heat insulation tank (21), and the output end of the external motor (54) is fixed to the transmission shaft (5).

8. The preheating auxiliary device for additive manufacturing according to claim 7, characterized in that: The linkage shaft (53) is composed of two upper shafts and a support shaft that slide vertically. A support spring is provided between the upper shafts and the support shaft. A toothed ring (6) is fixed inside the heat pipe (41) below the air pipe (44), and a convex toothed ring (61) is fixed outside the upper shaft below the toothed ring (6). The convex toothed ring (61) and the toothed ring (6) are in contact with each other.

9. A preheating auxiliary device for additive manufacturing according to claim 8, characterized in that: A secondary cavity (63) is provided below the air passage (44), and a shaft plug (62) is slidably disposed in the secondary cavity (63). The shaft plug (62) slides through the upper shaft and is fixed to the support shaft below.

10. A preheating auxiliary method for additive manufacturing, comprising using a preheating auxiliary device for additive manufacturing as described in any one of claims 1-9, characterized in that, It includes the following steps: S1. The additive manufacturing powder to be preheated is fed into the preheating device (2) through the conveying pipe (11), the preheating device (1) is started, and the powder is heated according to the preset preheating temperature curve; S2. The powder to be preheated enters the heat insulation tank (21) of the preheating device (2), and the powder falls onto the screen plate (23) in the powder hopper (22). The vibrator is started to drive the main body of the screen plate (23) to vibrate, so that the agglomerated powder can be quickly dispersed. Particles that meet the particle size requirements can fall through the sieve holes into the preheating chamber (3) below and enter each preheating tube unit (4). The powder is fully preheated by multiple preheating tube units (4). S3. After the preheating device (2) completes the heating, open the powder outlet seat (12) to let the preheated powder fall into the heat preservation cylinder (13); open the valve of the gas storage tank (16) to release the drying gas, and the drying gas enters the classifying plate (14) through the air flow pipe (17); while the powder entering the heat preservation cylinder (13) enters the classifying plate (14) through the powder feeding pipe (15). S4. The powder is classified by the grading plate (14). The powder that meets the particle size requirements is discharged through the powder supply pipe (19) and aligned with the powder feeding head or powder spreading device of the additive manufacturing equipment. The remaining powder or agglomerates are separated and discharged into the removal tank (18) through the fixed pipe for centralized collection.

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