Adjustable stirring needle for friction stir welding tool and using method of adjustable stirring needle

Abstract

The invention relates to the technical field of friction stir welding, and discloses an adjustable stirring needle for a friction stir welding tool and a using method thereof.The adjustable stirring needle comprises a welding tool assembly provided with a stirring needle assembly.When the aperture length of the stirring needle assembly is adjusted, the stirring needle assembly can be adjusted by rotating a rotating column and then under the cooperation of a diameter adjusting assembly; the stirring needle assembly can extend out of the welding tool assembly, the third stirring needle and the second stirring needle can be controlled to retract according to the required diameter length of the stirring needle along with continuous rotation of the rotating column, so that the function of adapting to different required diameter lengths of the stirring needle is achieved, and workpieces of different sizes and shapes can be adapted by adjusting the diameter of the stirring needle; according to the welding device, the welding application range is wide, the adjustability of the diameter of the stirring needle provides more selection spaces for welding workers, and the most suitable diameter of the stirring needle can be flexibly selected according to specific welding requirements and workpiece characteristics, so that the optimal welding effect is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of friction stir welding, in particular to an adjustable stirring needle for a friction stir welding tool and a use method thereof. Background Art

[0002] Friction stir welding refers to the use of heat generated by the friction between the high-speed rotating welding tool and the workpiece to partially melt the welded material. When the welding tool moves forward along the welding interface, the plasticized material flows from the front of the welding tool to the back under the action of the rotating friction of the welding tool, and forms a dense solid phase weld under the extrusion of the welding tool. In the patent application with application announcement number CN111922505B, the friction stir welding tool has a fitting gap between the stirring needle and the stationary shoulder, a containing cavity between the expanded diameter section and the inner wall of the stationary shoulder, and a discharge hole in the stationary shoulder. The fitting gap, the containing cavity and the discharge hole are interconnected to form a passage for guiding the material entering the fitting gap back to the weld. Moreover, under the action of the stirring of several protrusion structures to form a driving force, the softened metal material entering the containing cavity is discharged from the discharge hole to the weld, thereby preventing the material from accumulating in the shoulder, realizing self-filling in the welding process, supplementing the missing material at the weld, and ensuring the quality of the weld.

[0003] In the prior art including the above-mentioned patents, the stirring needle of the existing friction stir welding usually needs to be disassembled to adapt to different welding requirements. In actual operation, the selection of the stirring needle diameter often needs to be determined according to the material, thickness and welding requirements of the workpiece. Therefore, in order to meet different welding requirements, it is necessary to replace stirring needles of different diameters, which will undoubtedly increase the difficulty of operation and welding time, thereby reducing welding efficiency and limiting the application scope of friction stir welding. Summary of the invention

[0004] The problem to be solved by the present invention is that the stirring pin of the existing friction welding tool is difficult to adapt to different welding requirements.

[0005] In order to solve the above technical problems, the technical solution of the present invention is: an adjustable stirring pin for a friction stir welding tool and a method of using the same, comprising a welding tool assembly equipped with a stirring pin assembly, a diameter adjustment component is arranged inside the welding tool assembly, a synchronous plug-in component is arranged inside the welding tool assembly below the diameter adjustment component, and a limit position component is arranged on the arc-shaped outer wall of the welding tool assembly; The welding tool assembly comprises an upper welding tool shell, a lower welding needle protection shell is fixedly arranged at the bottom end of the upper welding tool shell, the stirring needle assembly is slidably connected to the inner wall of the lower welding needle protection shell, and a support cylinder is fixedly arranged on the inner wall of the upper welding tool shell; The stirring needle assembly comprises a first stirring needle slidably connected to the inner wall of the lower welding needle protection shell, a second stirring needle slidably connected to the inner wall of the first stirring needle, and a third stirring needle slidably connected to the inner wall of the second stirring needle; The limiting assembly includes a rotating column rotatably connected to the upper welding tool housing; The gear train is a gear that is fixedly mounted on the support frame, and the gear train is a gear that is mounted on the support frame and is in engagement with the gear train, the gear train being a gear that is mounted on the support frame and is in engagement with the gear train. The synchronous plug-in assembly includes a plurality of plug-in strips fixedly arranged on the inner wall of the lower welding pin protective shell, and the plurality of plug-in strips are all penetrated from the outer wall of the first stirring pin to the outer wall of the third stirring pin, and the stirring pin assembly is provided with a plurality of plug-in grooves matching the plurality of plug-in strips.

[0006] Preferably, a connecting tube is fixedly provided between the bevel gear ring and the threaded rod, a plurality of plug-in rods are fixedly provided at the bottom end of the support tube, and the plurality of plug-in rods are all slidably connected to the threaded sleeve, and the plurality of plug-in rods are all passed through from the top of the threaded sleeve to the bottom thereof, and the threaded sleeve is provided with plug-in holes matching the plurality of plug-in rods.

[0007] Preferably, each of the guide seats is provided with a straight slide groove matching the square block, a plurality of the guide seats are distributed in a circular array, a lower through groove matching the square block is provided at the bottom end of each straight slide groove, and a plurality of the arc-shaped through grooves are distributed in a circular array on the guide plate.

[0008] Preferably, each of the telescopic rod assemblies includes a first telescopic rod fixed between the magnetic limit rod and the first stirring needle, a third telescopic rod is fixedly arranged between each of the magnetic limit rods and the third stirring needle, and the third telescopic rod is located on one side of the first telescopic rod, and a second telescopic rod is fixedly arranged between each of the magnetic limit rods and the second stirring needle, and the second telescopic rod is located between the first telescopic rod and the third telescopic rod.

[0009] Preferably, the limit assembly also includes a limit cylinder fixed on the upper welding tool shell, and the limit cylinder is sleeved on the outside of the rotating column, and the limit cylinder is rotatably connected to the rotating column, a plurality of inner hook blocks are fixed on the arc-shaped outer wall of the rotating column, a pull rod is slid on the limit cylinder, and an outer hook block in contact with the inner hook block is fixed at the bottom end of the pull rod.

[0010] Preferably, a movable through hole matching the pull rod is provided on the limit cylinder, and a reset spring fixedly connected to the inner wall of the limit cylinder is fixedly arranged on the pull rod, and the reset spring is sleeved on the outside of the pull rod, and a plurality of the inner hook blocks are distributed on the rotating column in a ring array.

[0011] S1: When adjusting the aperture length of the stirring needle assembly, the rotating column can be rotated, and then the plurality of trapezoidal bars located inside the upper welding tool housing can be driven to move axially with the cooperation of the diameter adjustment component, so that the stirring needle assembly can be pushed to slide toward the bottom end of the welding tool assembly; S2: A plurality of trapezoidal bars are located inside the upper welding tool shell and move axially, and can be located inside the upper welding tool shell and move radially at the same time, and gradually approach each other. When the required target diameter length is equal to the total diameter of the second stirring needle and the third stirring needle, the plurality of trapezoidal bars can be separated from the first stirring needle by rotating the rotating column, and at the same time, with the cooperation of the first telescopic rod, the first stirring needle can be driven to reset and the first stirring needle can be adsorbed to the magnetic limit rod. When the required target diameter length is equal to the diameter of the third stirring needle, the plurality of trapezoidal bars can be moved to a position separated from the second stirring needle by rotating the rotating column, and at the same time, with the cooperation of the second telescopic rod and the first telescopic rod, the first stirring needle and the second stirring needle can be driven to reset and adsorbed to the magnetic limit rod. S3: While the rotating column is rotating, with the cooperation of the limiting assembly, the pull rod on the limiting cylinder can engage with one of the inner hook blocks on the rotating column, thereby self-locking the rotating column.

[0012] Compared with the prior art, the technical solution of the present invention has the following advantages: (1) When adjusting the aperture length of the stirring needle assembly, the present invention can rotate the rotating column, and then, with the cooperation of the diameter adjustment component, the stirring needle assembly can be extended to the outside of the welding tool assembly. As the rotating column continues to rotate, the retraction of the third stirring needle and the second stirring needle can be controlled according to the required stirring needle diameter length, thereby achieving the effect of adapting to different required stirring needle diameter lengths. By adjusting the diameter of the stirring needle, it can adapt to workpieces of different sizes and shapes, and realize a wider range of welding applications. In addition, the adjustability of the stirring needle diameter provides welding workers with more choices. According to specific welding requirements and workpiece characteristics, the most suitable stirring needle diameter can be flexibly selected to achieve the best welding effect; (2) When adjusting the aperture length of the stirring needle assembly, the present invention can adjust the diameter length of the stirring needle by rotating the rotating column and with the cooperation of the diameter adjustment component. In this process, the rotating position of the rotating column can be limited with the cooperation of the limit component, so as to prevent the stirring needle assembly from retracting into the lower welding needle protective shell when subjected to downward pressure during welding, thereby achieving a self-locking effect. The self-locking function of the stirring needle can ensure that the stirring needle will not loosen or shift due to force or vibration during welding, which helps to maintain stable welding conditions, thereby ensuring the quality and consistency of the weld. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of the overall structure of the present invention; Figure 2 It is a schematic diagram of the cross-sectional structure of the welding tool assembly of the present invention; Figure 3 For the present invention Figure 2 A partial enlarged view of middle A; Figure 4 This is a schematic diagram of the structure of the diameter adjustment component of the present invention; Figure 5 It is a schematic diagram of the cross-sectional structure of the diameter adjustment component of the present invention; Figure 6 For the present invention Figure 5 A partial enlarged view of B in the middle; Figure 7 This is a schematic diagram of the structure of the stirring needle assembly of the present invention; Figure 8 For the present invention Figure 7 A partial enlarged view of middle C; Fig. 9 It is a structural schematic diagram of the synchronous plug-in assembly of the present invention; Fig.10 It is a schematic diagram of the structure of the limit assembly of the present invention; Fig.11 It is a schematic diagram of the local structure of the limiting cylinder of the present invention.

[0014] In the figure: 1. welding tool assembly; 11. upper welding tool housing; 12. lower welding needle protective housing; 13. stirring needle assembly; 131. first stirring needle; 132. second stirring needle; 133. third stirring needle; 14. support cylinder; 15. magnetic limit rod; 2. Diameter adjustment assembly; 21. Bevel gear; 22. Bevel gear ring; 23. Threaded rod; 24. Threaded sleeve; 25. Guide seat; 251. Straight slide groove; 26. Guide plate; 261. Arc-shaped through groove; 27. Guide column; 271. Square block; 28. Trapezoidal bar; 29. ​​Telescopic rod assembly; 291. First telescopic rod; 292. Second telescopic rod; 293. Third telescopic rod; 3. Synchronous plug-in assembly; 31. Plug-in strip; 32. Plug-in slot; 4. Limiting assembly; 41. Rotating column; 42. Limiting cylinder; 43. Inner hook block; 44. Pull rod; 441. Return spring; 45. Outer hook block. DETAILED DESCRIPTION

[0015] In order to make the purpose, technical solution and advantages of the embodiments of the present disclosure clearer, the technical solution of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings of the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0016] Unless otherwise defined, the technical terms or scientific terms used in the present disclosure should be understood by people with ordinary skills in the field to which the present disclosure belongs. "Include" or "comprise" and other similar words used in the present disclosure mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and other similar words are not limited to physical or mechanical connections, but may also include electrical connections, whether direct or indirect. "Up", "down", "left", "right", etc. are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0017] like Figures 1 to 11 As shown, the present invention provides an adjustable stirring needle for a friction stir welding tool and a method of using the same, comprising a welding tool assembly 1 equipped with a stirring needle assembly 13, a diameter adjustment component 2 is provided inside the welding tool assembly 1, a synchronous plug-in component 3 is provided inside the welding tool assembly 1 and below the diameter adjustment component 2, and a limit position component 4 is provided on the arc-shaped outer wall of the welding tool assembly 1; The welding tool assembly 1 comprises an upper welding tool housing 11, a lower welding needle protection housing 12 is fixedly arranged at the bottom end of the upper welding tool housing 11, a stirring needle assembly 13 is slidably connected to the inner wall of the lower welding needle protection housing 12, and a support cylinder 14 is fixedly arranged on the inner wall of the upper welding tool housing 11; The stirring needle assembly 13 includes a first stirring needle 131 slidably connected to the inner wall of the lower welding needle protection shell 12, a second stirring needle 132 slidably connected to the inner wall of the first stirring needle 131, and a third stirring needle 133 slidably connected to the inner wall of the second stirring needle 132; The limiting assembly 4 includes a rotating column 41 rotatably connected to the upper welding tool housing 11; The diameter adjustment assembly 2 includes a bevel gear 21 fixed on the rotating column 41, a bevel gear ring 22 is rotatably connected to the top of the support cylinder 14, and the bevel gear ring 22 is meshed with the bevel gear 21, a threaded rod 23 is fixedly arranged at the bottom of the bevel gear ring 22, and the threaded rod 23 is located below the support cylinder 14, and a threaded sleeve 24 is threadedly connected to the outer wall of the threaded rod 23, and a plurality of guide seats 25 are fixedly arranged at the bottom of the threaded sleeve 24, and a guide plate 26 is arranged at the bottom of the threaded rod 23, and a square block 271 is slidably arranged inside each guide seat 25, and each square block 271 is fixedly arranged with a threaded sleeve 24. The guide plate 26 is slidably connected to the guide column 27, and each guide column 27 is penetrated from the top of the guide plate 26 to the bottom thereof. The guide plate 26 is provided with an arc-shaped through groove 261 matching with the plurality of guide columns 27. The bottom end of each guide column 27 is fixedly provided with a trapezoidal bar 28 in contact with the top end of the stirring needle assembly 13. The inner wall of the upper welding tool housing 11 is fixedly provided with a plurality of magnetic limit rods 15, and the bottom end of the magnetic limit rod 15 is in contact with the top end of the stirring needle assembly 13. A telescopic rod assembly 29 is fixedly provided between the bottom end of the magnetic limit rod 15 and the stirring needle assembly 13. The synchronous plug-in component 3 includes a plurality of plug-in strips 31 fixedly arranged on the inner wall of the lower welding pin protective shell 12, and the plurality of plug-in strips 31 are all penetrated from the outer wall of the first stirring pin 131 to the outer wall of the third stirring pin 133, and a plurality of plug-in grooves 32 matching the plurality of plug-in strips 31 are opened on the stirring pin assembly 13.

[0018] A connecting tube is fixedly arranged between the bevel gear ring 22 and the threaded rod 23, and a plurality of plug-in rods are fixedly arranged at the bottom end of the support tube 14. The plurality of plug-in rods are all slidably connected to the threaded sleeve 24, and the plurality of plug-in rods are all penetrated from the top of the threaded sleeve 24 to the bottom thereof, and the threaded sleeve 24 is provided with plug-in holes matching the plurality of plug-in rods.

[0019] Each guide seat 25 is provided with a straight slide groove 251 matching the square block 271, and multiple guide seats 25 are distributed in a circular array. The bottom end of each straight slide groove 251 is provided with a lower through groove matching the square block 271, and multiple arc through grooves 261 are distributed in a circular array on the guide plate 26.

[0020] Each telescopic rod assembly 29 includes a first telescopic rod 291 fixed between the magnetic limit rod 15 and the first stirring needle 131, a third telescopic rod 293 is fixedly arranged between each magnetic limit rod 15 and the third stirring needle 133, and the third telescopic rod 293 is located on one side of the first telescopic rod 291, a second telescopic rod 292 is fixedly arranged between each magnetic limit rod 15 and the second stirring needle 132, and the second telescopic rod 292 is located between the first telescopic rod 291 and the third telescopic rod 293.

[0021] When adjusting the aperture length of the stirring needle assembly 13, the rotating column 41 can be rotated to drive the bevel gear 21 fixedly connected thereto to rotate, and at the same time drive the bevel gear ring 22 meshing with the bevel gear 21 to rotate around the connection position with the support cylinder 14. At this time, the threaded rod 23 and the guide plate 26 can be driven to rotate under the connection of the connecting cylinder; like Figure 4 At this time, the rotation of the threaded rod 23 can drive the threaded sleeve 24 slidably connected to the multiple plug-in rods to slide downward, and the multiple guide seats 25 fixed at the bottom end of the threaded sleeve 24 can push the guide column 27 fixedly connected to the square block 271 to move downward. At this time, the trapezoidal bar 28 fixed at the bottom end of the guide column 27 can push the stirring needle assembly 13 to slide axially downward, while stretching the multiple telescopic rod assemblies 29, and the plug-in bar 31 can slide inside the plug-in groove 32 opened on the stirring needle assembly 13. At the same time, the self-rotation of the guide plate 26 can drive the guide column 27 sliding inside the arc-shaped through groove 261 to move. Because the square block 271 fixed at the top of the guide column 27 slides inside the straight slide groove 251, the multiple guide columns 27 slide toward the central axis direction of the upper welding tool housing 11 and gradually approach each other, while driving the multiple trapezoidal bars 28 to move toward the central axis direction of the upper welding tool housing 11; like Figure 3 , when the plurality of trapezoidal bars 28 are separated from the first stirring needle 131 at the same time, the first stirring needle 131 can slide upward under the elastic force of the plurality of first telescopic rods 291, and at the same time, the first stirring needle 131 can be adsorbed with the magnetic attraction limiting rod 15 under the magnetic attraction of the magnetic attraction limiting rod 15. At this time, the third stirring needle 133 and the second stirring needle 132 extending from the lower welding needle protective shell 12 can adapt to one welding requirement. With the continuous movement of the trapezoidal bars 28, when the plurality of trapezoidal bars 28 are moved to separate from the second stirring needle 132 at the same time, the second stirring needle 132 can slide upward under the elastic force of the plurality of second telescopic rods 292, and at the same time, the second stirring needle 132 can be adsorbed with the magnetic attraction limiting rod 15 under the magnetic attraction of the magnetic attraction limiting rod 15. At this time, the third stirring needle 133 extending from the lower welding needle protective shell 12 can adapt to another welding requirement; During the process of adjusting the diameter length of the stirring needle assembly 13, the connecting strip 31 can slide inside the connecting groove 32 opened on the stirring needle assembly 13, and the function of the connecting strip 31 is that while the welding tool assembly 1 rotates, it can drive the first stirring needle 131, the second stirring needle 132 and the third stirring needle 133 inside the welding tool assembly 1 to rotate synchronously with the welding tool assembly 1. When the required diameter adjustment length of the stirring needle assembly 13 is only the diameter length of the third stirring needle 133, the setting of the connecting strip 31 can prevent the first stirring needle 131, the second stirring needle 132 and the third stirring needle 133 from rotating synchronously due to the mutual friction force while the lower welding needle protective shell 12 rotates, and the mutual friction between the first stirring needle 131, the second stirring needle 132 and the third stirring needle 133 will increase the overall wear of the stirring needle assembly 13 and reduce the welding efficiency.

[0022] The limiting assembly 4 also includes a limiting cylinder 42 fixed on the upper welding tool housing 11, and the limiting cylinder 42 is sleeved on the outside of the rotating column 41, and the limiting cylinder 42 is rotatably connected to the rotating column 41, and a plurality of inner hook blocks 43 are fixed on the arc-shaped outer wall of the rotating column 41, and a pull rod 44 is slidably arranged on the limiting cylinder 42, and an outer hook block 45 in contact with the inner hook block 43 is fixed at the bottom end of the pull rod 44.

[0023] The limit cylinder 42 is provided with an active through hole matching the pull rod 44. The pull rod 44 is fixedly provided with a reset spring 441 fixedly connected to the inner wall of the limit cylinder 42, and the reset spring 441 is sleeved on the outside of the pull rod 44. Multiple inner hook blocks 43 are distributed on the rotating column 41 in a ring array.

[0024] While the rotating column 41 is rotating, multiple inner hook blocks 43 rotating with the outer wall of the rotating column 41 can be driven to contact the outer hook block 45 fixed at the bottom end of the pull rod 44 one after another. During this process, one of the inner hook blocks 43 located on the rotating column 41 contacts the bottom end of the outer hook block 45, and the pull rod 44 can be pushed to slide upward along the outer wall of the inner hook block 43 and slide on the inner wall of the limiting cylinder 42. At the same time, the reset spring 441 can be compressed. When the inner hook block 43 is separated from the outer hook block 45, the outer hook block 45 can be driven to slide downward under the action of the elastic force of the reset spring 441 and the deadweight of the pull rod 44, and the inner hook block 43 can be clamped to prevent the stirring needle assembly 13 from retracting into the lower welding needle protective shell 12 when subjected to downward pressure during welding, thereby achieving a self-locking effect.

[0025] S1: When adjusting the aperture length of the stirring needle assembly 13, the rotating column 41 can be rotated, and then the plurality of trapezoidal bars 28 can be driven to move axially inside the upper welding tool housing 11 with the cooperation of the diameter adjustment component 2, so as to push the stirring needle assembly 13 to slide toward the bottom end of the welding tool assembly 1; S2: The plurality of trapezoidal bars 28 are located inside the upper welding tool housing 11 and move axially, and can be located inside the upper welding tool housing 11 and move radially at the same time, and gradually approach each other. When the required target diameter length is equal to the total diameter of the second stirring needle 132 and the third stirring needle 133, the plurality of trapezoidal bars 28 can be separated from the first stirring needle 131 by rotating the rotating column 41. At the same time, the first stirring needle 131 can be driven to reset and the first stirring needle 131 can be adsorbed to the magnetic limiting rod 15 with the cooperation of the first telescopic rod 291. When the required target diameter length is equal to the diameter of the third stirring needle 133, the plurality of trapezoidal bars 28 can be moved to a position separated from the second stirring needle 132 by rotating the rotating column 41. At the same time, the first stirring needle 131 and the second stirring needle 132 can be driven to reset and adsorbed to the magnetic limiting rod 15 with the cooperation of the second telescopic rod 292 and the first telescopic rod 291. S3: While the rotating column 41 is rotating, with the cooperation of the limiting assembly 4, the pull rod 44 located on the limiting cylinder 42 can engage with one of the inner hook blocks 43 on the rotating column 41, thereby self-locking the rotating column 41 The working principle and use process of the present invention are as follows: when adjusting the aperture length of the stirring needle assembly 13, the rotating column 41 can be rotated, and then the plurality of trapezoidal bars 28 can be driven to move axially inside the upper welding tool housing 11 with the cooperation of the diameter adjustment component 2, and the stirring needle assembly 13 can be pushed to slide toward the bottom end of the welding tool assembly 1. The plurality of trapezoidal bars 28 are located inside the upper welding tool housing 11 and move axially, and can also be located inside the upper welding tool housing 11 and move radially, and gradually approach each other. When the required target diameter length is equal to the total diameter of the second stirring needle 132 and the third stirring needle 133, the plurality of trapezoidal bars 28 can be separated from the first stirring needle 131 by rotating the rotating column 41, and can be moved on the first telescopic rod at the same time. With the cooperation of the second telescopic rod 292 and the first telescopic rod 291, the first stirring needle 131 is driven to reset and the first stirring needle 131 is adsorbed with the magnetic limit rod 15. When the required target diameter length is equal to the diameter of the third stirring needle 133, the plurality of trapezoidal bars 28 can be moved to a position separated from the second stirring needle 132 by rotating the rotating column 41. At the same time, with the cooperation of the second telescopic rod 292 and the first telescopic rod 291, the first stirring needle 131 and the second stirring needle 132 can be driven to reset and adsorbed with the magnetic limit rod 15. While the rotating column 41 is rotated, with the cooperation of the limit assembly 4, the pull rod 44 located on the limit cylinder 42 can engage with one of the inner hook blocks 43 on the rotating column 41, thereby self-locking the rotating column 41.

[0026] The above embodiments are only exemplary embodiments of the present invention and are not intended to limit the present invention. The protection scope of the present invention is defined by the claims. Those skilled in the art may make various modifications or equivalent substitutions to the present invention within the essence and protection scope of the present invention, and such modifications or equivalent substitutions shall also be deemed to fall within the protection scope of the present invention.

Claims

1. An adjustable stirring needle for a friction stir welding tool, comprising a welding tool assembly (1) equipped with a stirring needle assembly (13), characterized in that: A diameter adjustment component (2) is provided inside the welding tool assembly (1); a synchronous plug-in component (3) is provided inside the welding tool assembly (1) below the diameter adjustment component (2); and a limit position component (4) is provided on the arc-shaped outer wall of the welding tool assembly (1); The welding tool assembly (1) comprises an upper welding tool housing (11), a lower welding needle protection housing (12) being fixedly disposed at the bottom end of the upper welding tool housing (11), the stirring needle assembly (13) being slidably connected to the inner wall of the lower welding needle protection housing (12), and a support cylinder (14) being fixedly disposed on the inner wall of the upper welding tool housing (11); The stirring needle assembly (13) comprises a first stirring needle (131) slidably connected to the inner wall of the lower welding needle protective shell (12), a second stirring needle (132) slidably connected to the inner wall of the first stirring needle (131), and a third stirring needle (133) slidably connected to the inner wall of the second stirring needle (132); The limiting assembly (4) comprises a rotating column (41) rotatably connected to the upper welding tool housing (11); The diameter adjustment assembly (2) comprises a bevel gear (21) fixed on a rotating column (41); a bevel gear ring (22) is rotatably connected to the top of the support cylinder (14), and the bevel gear ring (22) is meshed with the bevel gear (21); a threaded rod (23) is fixedly arranged at the bottom end of the bevel gear ring (22), and the threaded rod (23) is located below the support cylinder (14); a threaded sleeve (24) is threadedly connected to the outer wall of the threaded rod (23); a plurality of guide seats (25) are fixedly arranged at the bottom end of the threaded sleeve (24); a guide plate (26) is arranged at the bottom end of the threaded rod (23); a square block (271) is slidably arranged inside each of the guide seats (25); and each of the square blocks (271) is provided with a guide plate (26). A guide column (27) is fixedly provided which is slidably connected to the guide plate (26), and each guide column (27) extends from the top of the guide plate (26) to the bottom thereof; an arc-shaped through groove (261) matching the plurality of guide columns (27) is provided on the guide plate (26); a trapezoidal bar (28) in contact with the top of the stirring needle assembly (13) is fixedly provided at the bottom end of each guide column (27); a plurality of magnetic limit rods (15) are fixedly provided on the inner wall of the upper welding tool housing (11), and the bottom end of the magnetic limit rod (15) is in contact with the top of the stirring needle assembly (13); a telescopic rod assembly (29) is fixedly provided between the bottom end of the magnetic limit rod (15) and the stirring needle assembly (13); The synchronous plug-in assembly (3) comprises a plurality of plug-in strips (31) fixedly arranged on the inner wall of the lower welding pin protective shell (12), and the plurality of plug-in strips (31) are all extended from the outer wall of the first stirring pin (131) to the outer wall of the third stirring pin (133), and the stirring pin assembly (13) is provided with a plurality of plug-in slots (32) matching the plurality of plug-in strips (31).

2. The adjustable stirring needle for a friction stir welding tool according to claim 1, characterized in that: A connecting cylinder is fixedly arranged between the bevel gear ring (22) and the threaded rod (23); a plurality of plug-in rods are fixedly arranged at the bottom end of the support cylinder (14); the plurality of plug-in rods are slidably connected to the threaded sleeve (24); the plurality of plug-in rods are passed through the threaded sleeve (24) from the top to the bottom thereof; and the threaded sleeve (24) is provided with plug-in holes matching the plurality of plug-in rods.

3. The adjustable stirring needle for a friction stir welding tool according to claim 1, characterized in that: Each guide seat (25) is provided with a straight slide groove (251) matching the square block (271), a plurality of guide seats (25) are distributed in a ring array, a lower through groove matching the square block (271) is provided at the bottom end of each straight slide groove (251), and a plurality of arc-shaped through grooves (261) are distributed in a ring array on the guide plate (26).

4. The adjustable stirring needle for a friction stir welding tool according to claim 1, characterized in that: Each of the telescopic rod assemblies (29) comprises a first telescopic rod (291) fixed between the magnetic limit rod (15) and the first stirring needle (131); a third telescopic rod (293) is fixedly arranged between each of the magnetic limit rods (15) and the third stirring needle (133), and the third telescopic rod (293) is located on one side of the first telescopic rod (291); a second telescopic rod (292) is fixedly arranged between each of the magnetic limit rods (15) and the second stirring needle (132), and the second telescopic rod (292) is located between the first telescopic rod (291) and the third telescopic rod (293).

5. The adjustable stirring needle for a friction stir welding tool according to claim 1, characterized in that: The limiting assembly (4) further comprises a limiting cylinder (42) fixed on the upper welding tool housing (11), and the limiting cylinder (42) is sleeved on the outside of the rotating column (41), and the limiting cylinder (42) is rotatably connected to the rotating column (41), a plurality of inner hook blocks (43) are fixed on the arc-shaped outer wall of the rotating column (41), a pull rod (44) is slidably disposed on the limiting cylinder (42), and an outer hook block (45) in contact with the inner hook block (43) is fixedly disposed at the bottom end of the pull rod (44).

6. The adjustable stirring needle for a friction stir welding tool according to claim 5, characterized in that: The limiting cylinder (42) is provided with a movable through hole matching the pull rod (44), and the pull rod (44) is fixedly provided with a return spring (441) fixedly connected to the inner wall of the limiting cylinder (42), and the return spring (441) is sleeved on the outside of the pull rod (44), and the plurality of inner hook blocks (43) are distributed on the rotating column (41) in a ring array.

7. The method for using an adjustable stirring needle for a friction stir welding tool according to claim 1, characterized in that: The operation process steps are as follows: S1: When adjusting the aperture length of the stirring needle assembly (13), the rotating column (41) can be rotated, and then the plurality of trapezoidal bars (28) located inside the upper welding tool housing (11) can be driven to move axially with the cooperation of the diameter adjustment component (2), thereby pushing the stirring needle assembly (13) to slide toward the bottom end of the welding tool assembly (1); S2: The plurality of trapezoidal bars (28) are located inside the upper welding tool housing (11) and move axially, and can also be located inside the upper welding tool housing (11) and move radially, and gradually approach each other. When the required target diameter length is equal to the total diameter of the second stirring needle (132) and the third stirring needle (133), the plurality of trapezoidal bars (28) can be separated from the first stirring needle (131) by rotating the rotating column (41), and the first stirring needle (131) can be driven to retract with the cooperation of the first telescopic rod (291). The first stirring needle (131) is positioned and the first stirring needle (131) is attracted to the magnetic limiting rod (15). When the target diameter length is equal to the diameter of the third stirring needle (133), the plurality of trapezoidal bars (28) can be moved to a position separated from the second stirring needle (132) by rotating the rotating column (41). At the same time, the first stirring needle (131) and the second stirring needle (132) can be driven to reset and be attracted to the magnetic limiting rod (15) under the cooperation of the second telescopic rod (292) and the first telescopic rod (291); S3: While the rotating column (41) is rotating, the pull rod (44) located on the limiting cylinder (42) can be engaged with one of the inner hook blocks (43) on the rotating column (41) with the cooperation of the limiting assembly (4), thereby self-locking the rotating column (41).

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