A back pressure supported powder stirred frictional additive device

Abstract

The application provides a back pressure support type powder stirring friction additive device, which comprises a shaft shoulder and a stirring shaft which are rotatably inserted together, a spiral channel is formed between the stirring shaft and the shaft shoulder, a storage cylinder on the upper side of the stirring shaft is in communication with the spiral channel, a support part comprises a thrust ball bearing which is mounted on the shaft shoulder, a bearing structure which is mounted on the thrust ball bearing, and a back pressure support structure which is mounted on the bearing structure, the bearing structure is detachably mounted on the shaft ring of the thrust ball bearing through a hanger rod, a support shaft of the back pressure support structure is slidably mounted on the hanger rod, and a support roller is rotatably sleeved on the support shaft. The bearing structure is detachably mounted on the shaft ring, the bearing structure and the back pressure support structure can be separated from the additive part, the powder stirring friction additive device can process normal workpieces, after the bearing structure and the back pressure support structure are mounted, the additive part can process workpieces which need back pressure support, and collapse of corresponding regions is avoided.

Description

Technical Field

[0001] This invention belongs to the field of friction stir additive manufacturing, and specifically relates to a back pressure supported powder friction stir additive manufacturing device. Background Technology

[0002] When using friction stir additive manufacturing (FSM) to produce workpieces, a substrate needs to be placed on a worktable, which serves as a support mechanism and provides back pressure to withstand the downward pressure from the stirring head. Therefore, the workpiece shape is relatively regular, mainly flat or ring-shaped. When the workpiece shape becomes more complex, it is necessary to first fabricate a regular flat or ring-shaped workpiece before cutting it, resulting in reduced work efficiency. However, when the workpiece has a recessed structure at the bottom, a corresponding recessed structure needs to be created in the substrate. This recessed area cannot independently support the downward pressure from the stirring head, causing it to collapse and affecting the additive manufacturing process. Therefore, a matching support structure is required. Since different workpieces require different support structures, a large number of support structures are needed, severely limiting the application of the friction stir additive manufacturing method. Summary of the Invention

[0003] To address the problem in existing technologies where a recessed area at the bottom of a workpiece cannot independently support the downward pressure of the stirring head, leading to collapse in that area, this application proposes a back-pressure supported powder stirring friction additive manufacturing device. This device includes an additive manufacturing section and a back-pressure support section. The additive manufacturing section includes a shoulder and a stirring shaft. The stirring shaft is rotatably mounted in the inner cavity of the shoulder, forming a spiral channel between the stirring shaft and the shoulder. A storage cylinder is formed on the upper side of the stirring shaft. An end plate is located between the stirring shaft and the storage cylinder, and a discharge hole is located on the end plate, connecting the inner cavity of the storage cylinder to the spiral channel.

[0004] The back pressure support includes a thrust ball bearing, a load-bearing structure, and a back pressure support structure. The seat ring of the thrust ball bearing is fixed on the shaft shoulder, the load-bearing structure is installed on the shaft ring of the thrust ball bearing, and the back pressure support structure is installed on the load-bearing structure. The back pressure support structure is located below the stirring shaft.

[0005] The load-bearing structure includes two opposing suspension rods that extend vertically, with the upper ends of the suspension rods detachably mounted on the shaft ring of a thrust ball bearing. The back pressure support structure includes a support shaft and a support roller. The two ends of the support shaft are slidably mounted on a suspension rod and can reciprocate vertically. The support roller is rotatably sleeved on the support shaft.

[0006] In this application, because the bearing structure is detachably mounted on the shaft ring, the bearing mechanism and other components mounted on the bearing structure can be removed from the additive manufacturing unit. This allows the powder stirring friction additive manufacturing apparatus of this application to process conventional workpieces. After installing the bearing structure and its connected components, additive manufacturing can be performed on workpieces requiring back pressure support, preventing collapse in the corresponding area. By adjusting the position of the support shaft on the hanger, the distance between the support roller and the shoulder can be adjusted to accommodate substrates of different thicknesses and different additive thicknesses required by the workpiece. After processing one additive layer, the position of the support roller on the hanger is adjusted, and the additive manufacturing unit is simultaneously lifted upwards until the distance between the shoulder and the uppermost additive layer reaches the thickness of one additive layer. The support roller is then supported on the lower surface of the substrate, and the formation of the next additive layer continues. This process is repeated until the entire component is produced. The additive layer is also called a deposited layer.

[0007] When it is necessary to adjust the orientation of the back pressure support relative to the additive manufacturing part, the entire back pressure support can be rotated around the central axis of the shoulder by rotating the shaft ring. This adjusts the orientation of the back pressure support relative to the additive manufacturing part, so that during the production process, there is no need to adjust the orientation of the additive manufacturing part. The direction of movement of the entire powder stirring friction additive manufacturing device can be changed while maintaining the orientation of the additive manufacturing part.

[0008] Furthermore, to facilitate the adjustment of the position of the back pressure support structure on the hanger rod, thereby adjusting the distance between the support shaft and the shoulder to adapt to substrates of different thicknesses and to enable the formation of multiple additive layers, a stepless adjustment mechanism is provided below the back pressure support structure. This stepless adjustment mechanism includes a lead screw, a mandrel, and a tapered roller. The two ends of the lead screw are rotatably mounted on a hanger rod. The lead screw includes a first threaded section and a second threaded section, with the threads on the first and second threaded sections having opposite helical directions. A mandrel meshes with each of the first and second threaded sections. A tapered roller is rotatably mounted on each mandrel, with the small end of each tapered roller facing the other tapered roller. The tapered roller can rotate freely relative to its mandrel. The support roller includes a straight cylindrical section and tapered sections located at both ends of the straight cylindrical section. The large end of each tapered section faces the other tapered section, and each tapered roller is supported on a tapered section.

[0009] A limiting mechanism is provided on the suspension rod to restrict the spindle from rotating around its own central axis. When the lead screw rotates, it can drive the spindle to move towards or away from each other in the axial direction, and the spindle cannot rotate relative to its own central axis. When the spindle drives the conical roller to move back and forth in the axial direction, it can drive the back pressure support structure to move back and forth in the vertical direction.

[0010] Due to gravity, the tapered sections at both ends of the support roller press against the corresponding tapered rollers. When the screw is turned, when the two mandrels drive the tapered rollers to move towards each other, they push the support roller upwards. When the two mandrels drive the tapered rollers to move away from each other, the tapered rollers tend to move away from the support rollers. The support rollers, under the influence of gravity, move downwards to rest on the tapered rollers. This allows for smooth adjustment of the distance between the support rollers and the shoulder. Because both the tapered sections of the tapered rollers and the support rollers are tapered, the height of the support rollers can be continuously and smoothly adjusted, resulting in stepless adjustment. This, in turn, allows for stepless adjustment of the distance between the support rollers and the shoulder, accommodating the formation of additive layers of varying thicknesses.

[0011] Specifically, the limiting mechanism includes a guide rod and a sliding member. Both ends of the guide rod are mounted on a suspension rod. For each mandrel, a sliding member is provided. One end of the sliding member is slidably mounted on the guide rod and can slide along the axial direction of the guide rod, while the other end is fixed to the corresponding mandrel. By utilizing the limiting effect of the sliding member, rotation of the mandrel around its central axis is prevented, while the reciprocating movement of the mandrel along the axial direction is not affected, ensuring the stepless adjustment mechanism can adjust the distance between the support roller and the shoulder.

[0012] Furthermore, to improve the flexibility of the tapered roller rotating on the mandrel, the tapered roller is rotatably mounted on the mandrel via bearings.

[0013] Furthermore, to improve control flexibility, a drive motor is mounted on a boom, and the output shaft of this drive motor is connected to the lead screw. In actual production, this drive motor can also be integrated into an automatic control system to improve control over the lead screw rotation.

[0014] Specifically, to facilitate the disassembly of the back pressure support, a pressure ring is fixed on the shaft ring. The upper end of the lifting rod passes freely from bottom to top through the lifting rod hole on the pressure ring and is then screwed with a lifting rod nut to connect the lifting rod to the pressure ring. When the workpiece being processed is annular, it is impossible to directly insert the workpiece substrate between the stirring shaft and the back pressure support structure, and after the workpiece processing is completed, it is also impossible to remove the powder stirring friction additive manufacturing device from the workpiece. In this case, it is only necessary to unscrew the lifting rod nut from the lifting rod to separate the entire back pressure support and additive manufacturing part. After inserting the substrate between the back pressure support and additive manufacturing part, or after removing the workpiece, the lifting rod is then installed on the pressure ring via the lifting rod nut.

[0015] Furthermore, to facilitate control of the rotation of the back pressure support relative to the additive manufacturing section, a steering mechanism is also included. This steering mechanism comprises a ring gear and a steering motor. The ring gear is fixedly mounted on the upper surface of the pressure ring, and the steering motor is mounted on a shoulder. The gear on the output shaft of the steering motor meshes with the ring gear. When it is necessary to adjust the direction of the back pressure support relative to the additive manufacturing section, the steering motor can be used to drive the pressure ring to rotate relative to the shoulder, thereby adjusting the direction of the back pressure support relative to the additive manufacturing section. This allows the entire powder stirring friction additive manufacturing device to change its direction of movement while maintaining the orientation of the additive manufacturing section during production, without needing to adjust the orientation of the additive manufacturing section.

[0016] Furthermore, to prevent bridging of metal powder within the storage cylinder and thus ensure normal production, a stirring device is installed. This device includes a support rod and a stirring rod. One end of the support rod is mounted on a shoulder, and one end of the stirring rod is slidably mounted on the other end of the support rod. The other end of the stirring rod extends into the bottom of the storage cylinder, and the stirring rod can reciprocate vertically relative to the support rod. A cone protruding upwards is formed in the center of the upper surface of the end plate, located inside the storage cylinder. A rubber plate is installed at the lower end of the stirring rod, with its lower end face pressing against the bottom surface of the storage cylinder and the side surface of the cone. In the radial direction of the storage cylinder, each discharge hole is located between the inner wall of the storage cylinder and the outer circumference of the cone. Because the stirring device is mounted on the shoulder, when the stirring shaft rotates, the stirring rod can agitate the metal powder within the storage cylinder, preventing bridging. The rubber plate is mainly used to sweep the metal powder on the bottom surface of the storage cylinder and the side of the cone at the end of production or when there is little metal powder, so as to maximize the use of all the metal powder in the workpiece processing. After setting the cone, the metal powder can flow into the discharge hole to the maximum extent when there is only a small amount of metal powder, thereby improving the utilization rate of metal powder.

[0017] Furthermore, to facilitate the installation of the powder stirring friction additive manufacturing device, a mounting part is provided on the shaft shoulder, and a connecting part is provided on the stirring shaft. The mounting part is used to connect the shaft shoulder to the non-rotating part of the machining equipment, and the connecting part is used to connect the stirring shaft to the rotating spindle rotor of the machining equipment. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of an embodiment of this application.

[0019] Figure 2 for Figure 1 The attached figure shows a partial view after the back pressure support has been removed.

[0020] Figure 3 for Figure 1 Enlarged view of section A.

[0021] Figure 4 for Figure 3 A view from the center (BB direction). Detailed Implementation

[0022] See Figures 1-4 A back-pressure supported powder stirring friction additive manufacturing device includes an additive manufacturing section and a back-pressure support section. The additive manufacturing section includes a shoulder 16 and a stirring shaft 24. The shoulder 16 is cylindrical, and the stirring shaft is rotatably mounted in the inner cavity of the shoulder, with the shoulder 16 and the stirring shaft 24 coaxially arranged. The upper end of the shoulder extends radially outward to form a flange 18, which serves as a mounting part for connecting the shoulder to a non-rotating part of a machining equipment. A mounting hole 181 is provided on the flange 18.

[0023] The stirring shaft 24 is a spiral conveying rod, specifically comprising a vertically downward extending rod body 241 and spiral blades 242 formed on the outer circumferential surface of the rod body. A stirring head 26 is formed on the lower side of the rod body, and a downwardly protruding stirring needle 27 is provided on the lower surface of the stirring head 26. The lower end face of the rod body forms the stirring shaft end face 251. A spiral channel 243 is formed between the stirring shaft and the shaft shoulder. A storage cylinder 21 is integrally formed on the upper side of the stirring shaft, and the inner cavity of the storage cylinder 21 forms a storage chamber 22. An end plate 23 is provided between the storage cylinders, and six discharge holes 231 are provided on the end plate. The six discharge holes are evenly spaced around the central axis of the stirring shaft, and each discharge hole 231 connects the storage chamber 22 and the spiral channel 243.

[0024] A connecting flange 211 is provided on the outer circumferential surface of the storage cylinder. This connecting flange is used to connect the stirring shaft to the rotating spindle rotor of the machining equipment, and a connecting hole 212 is provided on the connecting flange. This connecting flange forms a connecting part. That is, the connecting part is indirectly installed on the stirring shaft via the storage cylinder.

[0025] During operation, the rotating spindle rotor of the machining equipment drives the stirring shaft to rotate, pressing the stirring head 26 into the substrate 81. Metal powder in the storage chamber enters the spiral channel through the discharge hole. Driven by the spiral conveyor rod, the metal powder moves downwards and exits the spiral channel. Then, under the pressure of the stirring shaft, it is stirred and rubbed against the surface of the substrate or on the already formed additive layer, continuously forming the additive layer 82 until the production of the workpiece 80 is completed. The lower end face 163 of the shoulder 16 smooths the surface of the additively formed workpiece.

[0026] To maintain a seal, a sealing element 165 is provided between the shoulder 16 and the storage cylinder 21. Specifically, in this embodiment, the sealing element 165 is an O-ring.

[0027] To ensure that the metal powder in the storage chamber 22 flows smoothly downward, this embodiment also includes a stirring device 30. The stirring device includes a support rod 31 and a stirring rod 32. The support rod 31 is L-shaped and specifically includes a vertically arranged upright rod 311 and a horizontally arranged crossbar 312. The support rod is formed by bending a steel rod, wherein the lower end of the upright rod is screwed onto the flange flange 18 by a thread, that is, the support rod is installed on the shoulder.

[0028] The stirring rod 32 extends vertically, with its upper end slidably mounted on the end of the crossbar away from the vertical bar, and its lower end extending into the bottom of the storage cylinder.

[0029] An upwardly protruding cone 28 is formed in the center of the upper surface of the end plate 23. The cone 28 is located in the storage chamber 22. A rubber plate 33 is installed at the lower end of the stirring rod 32. The lower end face of the rubber plate 33 presses against the bottom surface of the storage cylinder and the side surface of the cone.

[0030] When the stirring shaft rotates, the stirring rod 32 rotates relative to the storage chamber 22, agitating the metal powder within the chamber and preventing bridging. Simultaneously, the rubber plate scrapes the bottom surface of the storage cylinder and the side of the cone, evenly distributing the metal powder at the bottom of the storage chamber 22 into each discharge hole. In the radial direction of the storage cylinder, each discharge hole is located between the inner wall of the cylinder and the outer circumference of the cone. When the amount of metal powder in the storage cylinder is low, the rubber plate can still push the powder into the discharge holes, reducing the amount of residual metal powder in the storage cylinder.

[0031] Because this application incorporates a back pressure support, before performing friction stir additive manufacturing, the height of the shoulder needs to be limited. Then, the stirring shaft is raised and the height of the support roller is adjusted so that the support roller presses against the lower surface of the substrate, and the distance between the shoulder and the upper surface of the substrate reaches the thickness of one additive layer. The stirring shaft is then rotated and pressed down, causing the stirring head to penetrate the substrate for friction stir additive manufacturing. Since the stirring shaft moves vertically relative to the shoulder before each additive manufacturing process, and the shoulder cannot move up and down synchronously with the stirring shaft, to avoid the stirring rod negatively impacting this movement, the stirring rod is mounted on the support rod in a sliding manner, allowing the stirring shaft to drive the stirring rod to move up and down synchronously.

[0032] Specifically, in this embodiment, an annular flange 321 is provided on the upper part of the stirring rod, which is located below the crossbar 312. The upper end of the stirring rod is inserted into the insertion hole 313 on the crossbar 312 from bottom to top. A reaction spring 322, which is a helical compression spring, is provided between the annular flange and the crossbar and sleeved on the stirring rod. When the stirring shaft moves upward relative to the shoulder, the stirring rod moves upward synchronously under the push of the storage cylinder, compressing the reaction spring. When the stirring shaft moves downward relative to the shoulder, the stirring rod moves downward under the push of the reaction spring and the action of gravity, thereby avoiding the influence of the stirring rod on the up-and-down movement of the stirring shaft.

[0033] The back pressure support includes a thrust ball bearing 41, a load-bearing structure 40, and a back pressure support structure 50. A support ring 42 is fitted onto the shoulder 16 and is bolted to the outer wall of the shoulder. The thrust ball bearing 41 includes a housing ring 411, a shaft ring 412 located above the housing ring, and balls located between the housing ring and the shaft ring. The shaft ring is rotatably supported on the housing ring by the balls, and the housing ring 411 of the thrust ball bearing 41 is fixed to the upper side of the support ring 42.

[0034] The load-bearing structure 40 includes two opposing hanger rods 44 and a pressure ring 43. The pressure ring is fitted onto the shaft shoulder and presses against the upper surface of the shaft ring 412 of the thrust ball bearing 41. Both hanger rods are mounted on the pressure ring. The hanger rods extend vertically and have a support flange 441 at their upper part. An external threaded section is provided on the hanger rod above the support flange. The external threaded section passes through the hanger rod hole 431 of the pressure ring 43 from bottom to top and is screwed with a hanger rod nut 442, thus suspending the hanger rod on the pressure ring 43 and detachably mounting the upper end of the hanger rod onto the shaft ring.

[0035] To ensure a stable connection with the thrust ball bearing 41, a lower groove is provided on the upper side of the support ring 42, and the seat ring 411 is tightly held in the lower groove. An upper groove is provided on the lower side of the pressure ring 43, and the shaft ring 412 is tightly held in the upper groove.

[0036] A back pressure support structure 50 is mounted on the bearing structure 40 and is located below the stirring shaft. The back pressure support structure 50 includes a support shaft 51 and a support roller 52. Both ends of the support shaft are connected to a suspension rod, and the support roller is rotatably mounted on the support shaft. Specifically, in this embodiment, to allow the support roller to rotate flexibly on the support shaft, both ends of the support roller are rotatably mounted on the support shaft via an angular contact bearing A53. A shoulder A is formed at both ends of the inner cavity of the support roller, and a locking nut A54 is screwed onto both ends of the support shaft. The locking nut A presses against the inner ring of the angular contact bearing A, and the outer ring of the angular contact bearing A presses against the shoulder step surface 523 of the shoulder A, allowing the support roller 52 to rotate freely and be held on the support shaft 51. The mounting method of the angular contact bearing A uses existing mature technology and will not be described in detail. It is understood that in another embodiment, the angular contact bearing A can be omitted, and the support roller 52 can be directly rotatably mounted on the support shaft.

[0037] To enable the back pressure support structure 50 to be adjusted according to the thickness of different workpieces and different thickness areas of the same workpiece, so as to maintain the contact between the support roller and the lower surface of the workpiece and provide support for the workpiece, a groove 443 is provided on each hanger rod. The groove 443 extends vertically and passes through the opposite sides of the hanger rod along the axial direction of the support shaft. The two ends of the support shaft are respectively formed as support ends 511, and each support end is inserted into the groove of a hanger rod. To prevent the support shaft from moving along its axial direction, an anti-movement nut 512 is screwed on each support end 511. The anti-movement nut is located on the outside of the hanger rod. The groove 443 allows the two ends of the support shaft to be slidably mounted on a hanger rod and to move back and forth in the vertical direction.

[0038] It is understood that, in another embodiment, a slide rail can be installed on the inner side of the boom, and corresponding sliders can be installed at both ends of the support shaft so that the sliders are held in place on the slide rail.

[0039] To facilitate the adjustment of the height of the back pressure support structure 50, thereby adjusting the distance between the support roller 52 and the shoulder, and adapting to processing areas of different workpiece thicknesses or substrates of different thicknesses, this embodiment also provides a stepless adjustment mechanism 60, which is located below the back pressure support structure.

[0040] The continuously variable adjustment mechanism 60 specifically includes a lead screw 61, a spindle 63, and a tapered roller 64. The two ends of the lead screw are each formed as an optical shaft 613, which are rotatably mounted on a suspension rod. The lead screw includes a first threaded section 611 and a second threaded section 612, with opposite helical directions. A spindle 63 meshes with each of the first and second threaded sections. A tapered roller 64 is rotatably mounted on each spindle 63, and the tapered roller can rotate freely relative to its corresponding spindle. The tapered roller is conical, with the small end of each tapered roller facing the other tapered roller. In this embodiment, the optical shaft is directly rotatably mounted in a corresponding shaft hole on the suspension rod. It can be understood that in another embodiment, the optical shaft can be mounted in the corresponding shaft hole via a bearing.

[0041] In this embodiment, each tapered roller is rotatably mounted on its corresponding mandrel via two angular contact bearings B65 and locked in place by lock nuts B66. The mounting method of the angular contact bearings B uses existing mature technology and will not be described in detail. It is understood that in another embodiment, the angular contact bearings B can be omitted, and the tapered roller can be directly rotatably fitted onto the mandrel.

[0042] The support roller 52 includes a straight cylindrical section 521 and tapered sections 522 located at both ends of the straight cylindrical section 521. The tapered sections are tapered, and the large end of each tapered section faces the other tapered section. Each tapered roller is supported on a tapered section.

[0043] During operation, the straight section 521 of the support roller 52 is supported on the lower surface of the workpiece 80, and each conical roller 64 is supported on a conical section 522. For clarity, in the attached drawings, there is a distance between the straight section 521 of the support roller 52 and the workpiece 80, and a distance between the conical roller 64 and the conical section 522.

[0044] To facilitate the driving of the lead screw, a drive motor 62 is installed on a boom, and the output shaft of the drive motor is connected to the lead screw.

[0045] To prevent the mandrel from rotating with the lead screw during its rotation, a limiting mechanism 70 is provided on the suspension rod. This limiting mechanism restricts the mandrel from rotating around its own central axis and is located below the continuously variable adjustment mechanism. The limiting mechanism 70 includes a guide rod 71 and a sliding member 72. Both ends of the guide rod are fixed to the suspension rod by a connecting bolt 73. A sliding member 72 is provided for each mandrel. Each sliding member 72 includes a sliding rod 722 and a connecting screw 723. A collar 721 is welded to one end of the sliding rod 722. This collar 721 freely fits onto the guide rod and can slide freely along the axial direction of the guide rod. The connecting screw 723 secures the other end of the sliding rod 722 to the end face of the corresponding mandrel 63.

[0046] Under the constraint of the limiting mechanism, when the lead screw rotates, it can drive the mandrel to move towards or away from each other in the axial direction, and the mandrel cannot rotate relative to its own central axis; when the mandrel drives the conical roller to move back and forth in the axial direction, it can drive the back pressure support structure to move back and forth in the vertical direction.

[0047] To facilitate rotation of the back pressure support structure, allowing the additive manufacturing unit to change its direction of travel without changing its orientation, a steering mechanism is also provided in this embodiment. This steering mechanism includes an annular gear ring 46 and a steering motor 47. The annular gear ring 46 is fixedly mounted on the upper surface of the pressure ring 43, and the steering motor 47 is mounted on the outer wall of the shoulder. A gear 48 on the output shaft of the steering motor meshes with the annular gear ring. The annular gear ring, thrust ball bearing, stirring shaft, and shoulder are coaxially arranged.

[0048] In this application, both the drive motor 62 and the directional motor 47 are servo motors for precise control.

[0049] In this embodiment, during operation, the substrate 81 is first inserted between the stirring shaft and the back pressure support structure 50. Then, the drive motor 62 drives the lead screw to rotate, causing the two mandrels 63 to move the corresponding conical rollers 64 axially. This adjusts the height of the back pressure support structure 50, so that the support rollers 52 support the lower surface of the upwardly recessed area of ​​the substrate, providing support for the downward pressure of the stirring head and preventing the recessed area from sinking downward under the pressure of the stirring head. After the formation of one additive layer 82 is completed, the two mandrels 63 drive the corresponding conical rollers 64 to move axially in opposite directions, and the additive parts move upward synchronously until the distance between the shoulder and the uppermost additive layer reaches the thickness of one additive layer. Then, the formation of the next additive layer continues, and this process is repeated until the production of the entire component is completed.

Claims

1. A back-pressure supported powder stirring friction additive manufacturing device, characterized in that, The device includes an additive manufacturing section, a back pressure support section, and a steering mechanism. The additive manufacturing section includes a shoulder and a stirring shaft. The stirring shaft is rotatably mounted in the inner cavity of the shoulder, forming a spiral channel between the stirring shaft and the shoulder. A storage cylinder is formed on the upper side of the stirring shaft. An end plate is provided between the stirring shaft and the storage cylinder. A discharge hole is provided on the end plate, which connects the inner cavity of the storage cylinder and the spiral channel. The back pressure support includes a thrust ball bearing, a load-bearing structure, and a back pressure support structure. The seat ring of the thrust ball bearing is fixed on the shaft shoulder, the load-bearing structure is installed on the shaft ring of the thrust ball bearing, and the back pressure support structure is installed on the load-bearing structure. The back pressure support structure is located below the stirring shaft. A stepless adjustment mechanism is provided below the back pressure support structure. The stepless adjustment mechanism includes a lead screw, a mandrel, and a conical roller. The two ends of the lead screw are rotatably mounted on a suspension rod. The lead screw includes a first threaded section and a second threaded section. The helical directions of the threads on the first threaded section and the second threaded section are opposite. A mandrel is meshed on the first threaded section and the second threaded section, respectively. A conical roller is rotatably mounted on each mandrel. The small end of each conical roller faces the other conical roller. The conical roller can rotate freely relative to the mandrel it is on. The support roller includes a straight cylindrical section and conical sections located at both ends of the straight cylindrical section. The large end of each conical section faces the other conical section. Each conical roller is supported on a conical section. The load-bearing structure includes two opposing suspension rods that extend vertically, with the upper ends of the suspension rods detachably mounted on the shaft ring of a thrust ball bearing; the back pressure support structure includes a support shaft and a support roller, with the two ends of the support shaft slidably mounted on a suspension rod and capable of reciprocating vertically, and the support roller rotatably sleeved on the support shaft; A limiting mechanism is installed on the suspension rod to restrict the rotation of the mandrel around its own central axis. When the lead screw rotates, it can drive the mandrel to move in opposite directions along the axial direction, but the mandrel cannot rotate relative to its own central axis. When the mandrel drives the tapered roller to reciprocate along the axial direction, it can drive the back pressure support structure to reciprocate along the vertical direction. The steering mechanism includes a ring gear and a steering motor. The ring gear is fixedly mounted on the upper surface of the pressure ring, and the steering motor is mounted on the shaft shoulder. The gear on the output shaft of the steering motor meshes with the ring gear.

2. The powder stirring friction additive manufacturing device according to claim 1, characterized in that, The limiting mechanism includes a guide rod and a sliding member. The two ends of the guide rod are respectively mounted on a hanging rod. For each mandrel, a sliding member is provided. One end of the sliding member is slidably mounted on the guide rod and can slide along the axial direction of the guide rod. The other end of the sliding member is fixed on the corresponding mandrel.

3. The powder stirring friction additive manufacturing device according to claim 1, characterized in that, The tapered roller is rotatably mounted on the mandrel via bearings.

4. The powder stirring friction additive manufacturing device according to claim 1, characterized in that, A drive motor is mounted on a boom, and the output shaft of the drive motor is connected to a lead screw.

5. The powder stirring friction additive manufacturing device according to claim 1, characterized in that, A pressure ring is fixed on the shaft ring. The upper end of the lifting rod passes freely from bottom to top through the lifting rod hole on the pressure ring and then a lifting rod nut is screwed on to connect the lifting rod to the pressure ring.

6. The powder stirring friction additive manufacturing device according to claim 1, characterized in that, A stirring device is also provided, which includes a support rod and a stirring rod. One end of the support rod is mounted on a shoulder, and one end of the stirring rod is slidably mounted on the other end of the support rod. The other end of the stirring rod extends into the bottom of the storage cylinder. The stirring rod can reciprocate vertically relative to the support rod. An upwardly protruding cone is formed in the center of the upper surface of the end plate. The cone is located inside the storage cylinder. A rubber plate is installed at the lower end of the stirring rod. The lower end face of the rubber plate abuts against the bottom surface of the storage cylinder and the side surface of the cone. In the radial direction of the storage cylinder, each discharge hole is located between the inner wall of the storage cylinder and the outer circumferential surface of the cone.

7. The powder stirring friction additive manufacturing device according to claim 1, characterized in that, A mounting part is provided on the shaft shoulder, and a connecting part is provided on the stirring shaft.

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