Friction stir welding device

Abstract

The present invention discloses a friction stir welding device, including a support platform, a pressure control system and a weld deviation detection system. An L-shaped column is arranged on one side of the top of the support platform, and a driving box that can slide up and down is arranged on the vertical part of the L-shaped column. The bottom of the driving box is rotatably connected to a main shaft, and a stirring head is arranged at the bottom of the main shaft. A working platform is arranged on the support platform, and the pressure control system is used to accurately control the pressing force of the stirring head. The friction stir welding device can realize the pressing force control required for friction stir welding through the pressure control system, and can adjust and observe the size of the pressing force in real time. It adopts hydraulic drive, has stable movement, is easy to protect against overload, is easy to control, can improve welding quality, and has low cost, flexible and convenient use.

Description

Technical Field

[0001] The invention belongs to the technical field of friction stir welding, and in particular relates to a friction stir welding device. Background Art

[0002] Welding, also known as fusion, is a manufacturing process and technology that joins metals or other thermoplastic materials such as plastics by heating, high temperature or high pressure. There are many sources of energy for modern welding, including gas flame, arc, laser, electron beam, friction and ultrasound. Among them, stir friction welding is a relatively special welding method. Stir friction welding refers to the use of the heat generated by the friction between the high-speed rotating stirring head 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 force of the welding tool, and forms a dense solid phase weld under the extrusion of the stirring head.

[0003] Friction stir welding relies on the rotation and movement of the stirring head to achieve plate welding. Therefore, the rotation speed of the stirring head, welding pressure, and plate moving speed are its key process parameters. However, the existing friction stir welding welding pressure control accuracy is low and the size is unknown. When the clamping force is insufficient, the weld is prone to form holes or incomplete penetration. When the clamping force is too large, the friction between the shoulder and the weld surface increases, and the frictional heat causes the shoulder to "stick", resulting in defects such as flash and burrs on the weld surface. In addition, during the welding process of existing friction stir welding, the weld path is prone to deviation, which affects the welding quality. Summary of the invention

[0004] The present invention aims to provide a friction stir welding device to solve the technical problems raised in the background technology.

[0005] To achieve the above-mentioned purpose, the specific technical scheme of the present invention is as follows: a stir friction welding device, including a support platform, a pressure control system and a weld deviation detection system, an L-shaped column is arranged on one side of the top of the support platform, and a drive box which can slide up and down is arranged on the vertical part of the L-shaped column, the bottom of the drive box is rotatably connected with a main shaft, a stirring head is arranged at the bottom of the main shaft, a working platform is arranged on the support platform, the pressure control system is used to accurately control the clamping force of the stirring head, and the weld deviation detection system is used to obtain the three-dimensional coordinates of the workpiece surface of the detection point in the sensor coordinate system in real time, and obtain the height information of the plane where the weld is located.

[0006] Preferably, the working platform can move freely in the X direction and the Y direction.

[0007] Preferably, a motor for driving the main shaft to rotate is arranged in the driving box, and the main shaft is rotationally connected to the driving box via a bearing.

[0008] Preferably, the pressure control system includes a hydraulic cylinder arranged at the top of the L-shaped column, and an oil tank for supplying oil to the hydraulic cylinder is arranged on one side of the support platform. The hydraulic cylinder is vertically installed at the top of the L-shaped column, and the bottom of the piston rod of the hydraulic cylinder passes through the horizontal part of the L-shaped column and is fixedly connected to the top of the driving box, the main shaft is composed of an upper connecting shaft and a lower connecting shaft, there is a spacing between the bottom of the upper connecting shaft and the top of the lower connecting shaft, and a pressure sensor is arranged in the middle part of the bottom of the upper connecting shaft, and a trigger block corresponding to the pressure sensor is arranged at the top of the lower connecting shaft, and the upper connecting shaft and the lower connecting shaft are connected by four elastic limit assemblies distributed in a circular array.

[0009] Preferably, the elastic limiting assembly includes a sliding rod, the bottom of the sliding rod is fixedly connected to the top of the lower connecting shaft, the bottom of the upper connecting shaft is provided with a sliding hole connected to the sliding rod for upward and downward sliding, and a spring is sleeved on the sliding rod, the upper and lower ends of the spring are respectively connected to the bottom of the upper connecting shaft and the top of the lower connecting shaft.

[0010] Preferably, inner walls on both sides of the sliding hole are provided with limit grooves with closed upper and lower ends, and both sides of the top end of the sliding rod are provided with limit blocks slidably connected to the limit grooves.

[0011] Preferably, the weld deviation detection system includes a shell sleeved on the outside of the lower connecting shaft, an annular plate is rotatably connected inside the shell, a laser ranging sensor is installed on the side wall of the annular plate, and a driving component for driving the annular plate to rotate is provided on the shell.

[0012] Preferably, the outer shell is fixedly connected to the lower connecting shaft, and the outer shell is a cylindrical structure with an opening at the bottom, and a convex ring plate wrapped around the outer side of the lower connecting shaft is provided in the middle part of the inner cavity of the outer shell.

[0013] Preferably, the drive assembly includes a servo motor mounted on the outer wall of the outer shell, the shaft of the servo motor is connected to a gear, the outer side of the convex ring plate is rotatably connected to a gear ring through a bearing, the gear extends to the inner cavity of the outer shell and is rotatably connected to the gear ring, and the gear ring and the gear are meshed with each other, the bottom of the gear ring is fixedly connected to the top of the annular plate, and the inner diameter of the annular plate is larger than the outer diameter of the convex ring plate.

[0014] Preferably, a side wall of the shell is provided with a movable opening, and the gear extends to the inner cavity of the shell through the movable opening.

[0015] A friction stir welding device of the present invention has the following advantages:

[0016] 1. The friction stir welding device can realize the clamping force control required for friction stir welding through a pressure control system, and can adjust and observe the clamping force in real time. It adopts hydraulic drive, has smooth movement, is easy to protect against overload, is easy to control, can improve welding quality, has low cost, and is flexible and convenient to use.

[0017] 2. This friction stir welding device uses the laser ranging sensor and encoder of the weld deviation detection system to measure the three-dimensional coordinates of the workpiece surface at the laser detection point in the sensor coordinate system in real time, and transmits the data to the industrial computer through the wireless transmission module. The industrial computer processes the pulse information and the measured distance value to obtain the three-dimensional coordinates of the detection point and restore the three-dimensional morphology of the workpiece surface to extract the required welding parameters, thereby obtaining the weld deviation parameters in real time, which can effectively improve the welding quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0020] Figure 2 It is a structural schematic diagram of the main shaft in the present invention;

[0021] Figure 3 for Figure 2 Right view of;

[0022] Figure 4 It is an exploded view of the upper connecting shaft and the lower connecting shaft in the present invention;

[0023] Figure 5 for Figure 4 A magnified view of middle;

[0024] Figure 6 It is a structural schematic diagram of the lower connecting shaft in the present invention;

[0025] Figure 7 It is an exploded view of the housing and the gear ring in the present invention;

[0026] Figure 8 It is the principle diagram of the pressure control system in the present invention;

[0027] Explanation of marks in the figure: 1. Support table; 2. L-shaped column; 3. Working platform; 4. Hydraulic cylinder; 5. Drive box; 6. Oil tank; 7. Housing; 8. Mixing head; 9. Upper connecting shaft; 10. Lower connecting shaft; 11. Trigger block; 12. Ring plate; 13. Laser ranging sensor; 14. Servo motor; 15. Gear; 16. Ring gear; 17. Pressure sensor; 18. Sliding hole; 19. Sliding rod; 20. Spring; 21. Limit block; 22. Limit groove; 23. Convex ring plate; 24. Movable opening. DETAILED DESCRIPTION

[0028] In the following, only some exemplary embodiments are briefly described. As those skilled in the art will appreciate, the described embodiments may be modified in various ways without departing from the spirit or scope of the embodiments of the present invention. Therefore, the drawings and descriptions are considered to be exemplary and non-restrictive in nature.

[0029] In the description of the embodiments of the present invention, it should be understood that the terms "length", "vertical", "horizontal", "top", "bottom", etc. indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present invention.

[0030] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0031] In the embodiments of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or a communication; it can be a direct connection, or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances.

[0032] The disclosure below provides many different embodiments or examples to implement different structures of the embodiments of the present invention. In order to simplify the disclosure of the embodiments of the present invention, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the embodiments of the present invention. In addition, the embodiments of the present invention can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplification and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed.

[0033] In order to better understand the purpose, structure and function of the present invention, a friction stir welding device of the present invention is further described in detail below in conjunction with the accompanying drawings.

[0034] like Figure 1-7 As shown, a friction stir welding device of the present invention comprises a support platform 1, a pressure control system and a weld deviation detection system. An L-shaped column 2 is arranged on one side of the top of the support platform 1, and a driving box 5 which can slide up and down is arranged on the vertical part of the L-shaped column 2. The bottom of the driving box 5 is rotatably connected with a main shaft, and a stirring head 8 is arranged at the bottom of the main shaft. A motor for driving the main shaft to rotate is arranged in the driving box 5, and the main shaft is rotatably connected with the driving box 5 through a bearing. The motor drives the main shaft to rotate, thereby rotating the stirring head 8. A working platform 3 is arranged on the support platform 1, and the working platform 3 can move freely in the X direction and the Y direction. The structure for realizing the movement of the working platform 3 in the X direction and the Y direction is an existing mature technology and will not be elaborated in detail here. The pressure control system is used to accurately control the pressing force of the stirring head 8, and the pressure control system comprises a hydraulic cylinder 4 arranged on the top of the L-shaped column 2, and a pressure control system for the hydraulic cylinder is arranged on one side of the support platform 1. 4 is an oil tank 6 for supplying oil, a hydraulic cylinder 4 is vertically installed at the top of the L-shaped column 2, and the bottom of the piston rod of the hydraulic cylinder 4 passes through the horizontal part of the L-shaped column 2 and is fixedly connected to the top of the driving box 5. The main shaft is composed of an upper connecting shaft 9 and a lower connecting shaft 10. There is a gap between the bottom of the upper connecting shaft 9 and the top of the lower connecting shaft 10, and a pressure sensor 17 is arranged at the middle part of the bottom of the upper connecting shaft 9, and a touch block 11 corresponding to the pressure sensor 17 is arranged at the top of the lower connecting shaft 10, and the upper connecting shaft 9 and the lower connecting shaft 10 are connected by four elastic limit assemblies distributed in a circular array. When the hydraulic cylinder 4 pushes the driving box 5 to move downward, the bottom of the stirring head 8 will contact with the surface of the workpiece, thereby realizing the welding of the workpiece. In the process of the hydraulic cylinder 4 pushing the stirring head 8 to move downward, under the action of the elastic limit assembly, the upper surface of the touch block 11 contacts with the pressure sensor 17, as shown in FIG. Figure 8As shown in the figure, when the electromagnet DT is energized, the oil in the oil inlet passes through the oil tank → filter → hydraulic pump → right chamber of the electromagnetic reversing valve → upper chamber of the hydraulic cylinder; the oil in the oil return passes through the lower chamber of the hydraulic cylinder → one-way sequence valve → right chamber of the electromagnetic reversing valve → oil tank. At this time, the hydraulic cylinder extends, driving the stirring head to descend. When the stirring head reaches the surface of the workpiece, the clamping force is adjusted by the overflow valve, and the pressure of the two chambers of the hydraulic cylinder can be observed in real time through pressure gauges 2 and 3. Therefore, the clamping force during friction stir welding can be calculated by formula (1):

[0035]

[0036] Where: F is the clamping force during friction stir welding (N); p1 is the oil pressure in the upper chamber of hydraulic cylinder 9 (MPa); p2 is the oil pressure in the lower chamber of hydraulic cylinder 9 (MPa); D is the diameter of the hydraulic cylinder piston (mm); d is the diameter of the hydraulic cylinder piston rod (mm); G is the gravity of the spindle box of the drilling and milling machine (N).

[0037] When the electromagnet 2 DT is energized, the oil in the oil inlet passes through the oil tank → filter → hydraulic pump → electromagnetic reversing valve left chamber → one-way sequence valve → hydraulic cylinder lower chamber; the oil in the oil return passes through the hydraulic cylinder upper chamber → electromagnetic reversing valve left chamber → oil tank. At this time, the hydraulic cylinder retracts, driving the stirring head to rise, so that the stirring head leaves the welding workpiece. It can be seen that the pressure control system can realize the lowering, pressing and rising actions of the stirring head, and can adjust and observe the size of the pressing force in real time. It adopts hydraulic drive, has stable movement, is easy to overload protection, and is easy to control.

[0038] When the stirring head speed and welding speed are constant, as the clamping force increases, the friction between the stirring head and the material surface increases, and the heat generated by friction increases. When the clamping force is low, the friction between the stirring head and the material is weak, the heat generated is low, the plasticization of the weld metal is weak, and the flow is insufficient, making the weld surface rough and prone to incomplete penetration; when the clamping force is high, the friction between the stirring head and the material is strong, the heat generated is also high, the plasticization of the weld metal is high, the flow is sufficient, and the weld surface is smooth; when the clamping force is further increased, the heat generated by friction is further increased, the plasticization of the weld metal is enhanced, the rigid resistance to the stirring head is reduced, and the amount of plastic metal extruded under the action of the shoulder is large, resulting in flash and burrs. The pressure control system can realize the clamping force control required for stir friction welding, and can adjust and observe the clamping force in real time. It adopts hydraulic drive, has stable movement, is easy to overload protection, is easy to control, and can improve welding quality.

[0039] The elastic limiting assembly includes a slide bar 19, the bottom of which is fixedly connected to the top of the lower connecting shaft 10, a slide hole 18 is provided at the bottom of the upper connecting shaft 9 to be slidably connected to the slide bar 19, and a spring 20 is sleeved on the slide bar 19, the upper and lower ends of the spring 20 are respectively connected to the bottom of the upper connecting shaft 9 and the top of the lower connecting shaft 10, through the cooperation between the slide bar 19, the slide hole 18 and the spring 20, the upper connecting shaft 9 and the lower connecting shaft 10 can be close to each other under the action of pressure, and move away from each other without the action of pressure. The inner walls on both sides of the slide hole 18 are provided with limiting grooves 22 with closed upper and lower ends, and both sides of the top of the slide bar 19 are provided with limiting blocks 21 slidably connected to the limiting grooves 22, and the cooperation between the limiting blocks 21 and the limiting grooves 22 limits the slide bar 19, so that the slide bar 19 can only move up and down.

[0040] The weld deviation detection system is used to obtain the three-dimensional coordinates of the detection point workpiece surface in the sensor coordinate system in real time, and obtain the height information of the plane where the weld is located. The weld deviation detection system includes a shell 7 mounted on the outside of the lower connecting shaft 10, and a ring plate 12 is rotatably connected in the shell 7. A laser ranging sensor 13 is installed on the side wall of the ring plate 12, and a driving component for driving the ring plate 12 to rotate is arranged on the shell 7. The shell 7 is fixedly connected to the lower connecting shaft 10, and the shell 7 is a cylindrical structure with an opening at the bottom. A convex ring plate 23 wrapped around the outside of the lower connecting shaft 10 is arranged in the middle part of the inner cavity of the shell 7. The driving component includes a servo motor 14 installed on the outer wall of the shell 7, and the shaft of the servo motor 14 The outer side of the convex ring plate 23 is rotatably connected with a gear ring 16 through a bearing. The gear 15 extends to the inner cavity of the shell 7 and is rotatably connected with the gear ring 16, and the gear ring 16 and the gear 15 are meshed with each other. The bottom of the gear ring 16 is fixedly connected to the top of the annular plate 12, and the inner diameter of the annular plate 12 is larger than the outer diameter of the convex ring plate 23. By starting the servo motor 14, the gear 15 drives the gear ring 16 to rotate, so that the gear ring 16 drives the annular plate 12 to rotate, so that the annular plate 12 drives the laser ranging sensor 13 to rotate, and the servo motor 14 has a built-in encoder to detect and collect the motor speed, position information and number of rotations, and the output pulse information is sent to the industrial computer via the orthogonal decoder. The industrial computer processes the received pulse information to calculate the two-dimensional position information of the detection point. The detection point is the end point of the laser beam emitted by the sensor on the surface of the workpiece. By allowing the line laser emitted by the laser ranging sensor 13 to rotate around the stirring head, the height information of the plane where the weld is located is obtained. In the process of stir friction welding, in order to allow the laser ranging sensor to rotate around the main shaft at a constant rotation speed, the stirring head cannot be used directly to provide power for the weld deviation detection system. The servo motor must be selected to provide a rated speed to ensure that the laser detection point is equidistant from the detection point and has good detection accuracy. The servo motor is positioned by the pulse signal and rotates to the corresponding angle. In addition, the encoder inside the servo motor can generate a pulse indicating the position of the input shaft, which cooperates with the received drive pulse signal to ensure the reliability of the number of pulses, thereby achieving good positioning function and closed-loop control. The orthogonal decoder receives the pulse information sent by the motor encoder and processes it into the angle of motor rotation, which is used to calculate the coordinates of the detection point in the industrial computer. The laser diode inside the laser distance sensor emits a laser pulse. When the laser hits the surface of the workpiece, it scatters in all directions. The sensor receiver is responsible for collecting part of the scattered laser. The receiver is equipped with an optical sensor that amplifies the laser signal, which can distinguish tiny light rays. After processing the light signal into a light pulse, it records and processes the time consumed by the laser to go back and forth, and then calculates the distance from the emission point to the measurement point. The function of the weld deviation detection system is to transmit the three-dimensional coordinates of the workpiece surface of the laser detection point in the sensor coordinate system to the industrial computer in real time through the laser distance sensor 13 and the encoder.The data transmission process is that the servo motor encoder collects the pulse signal of the internal encoder of the servo motor, transmits the pulse signal to the orthogonal decoder through the PCI bus, and the industrial computer calculates the angle in the sensor coordinate system. Calculate the coordinates of the xoy plane (x s ,y s The laser distance sensor detects the length h of the laser beam at a frequency of 20kHz, transmits it to the wireless transmitter module via the UDP protocol, and then transmits it to the wireless receiver module of the industrial computer via the Bluetooth protocol. Then z is calculated on the industrial computer. s . The weld deviation detection system consists of a servo motor 14, a motor driver, an orthogonal decoder, a laser ranging sensor 13, and a wireless transmission module. The servo motor pulse signal is decoded and sent through the PCI bus, and the value of the laser ranging sensor 13 rotating around the main axis is transmitted to the wireless transmission module through the UDP protocol and sent. The three-dimensional coordinate information of the weld is calculated in the industrial computer, and the weld deviation parameters are extracted. In order to achieve the performance indicators of fast response and high precision of weld tracking control, the laser ranging sensor 13 in the weld deviation detection system requires a higher detection frequency and detection accuracy. The laser ranging frequency is 20000Hz, the weld deviation detection cycle is 200ms, and the detection frequency is 5Hz. The data is transmitted to the industrial computer through the wireless transmission module. The industrial computer processes the pulse information and the measured distance value to obtain the three-dimensional coordinates of the detection point, restore the three-dimensional morphology of the workpiece surface, and extract the required welding parameters. The side wall of the housing 7 is provided with a movable opening 24 , and the gear 15 extends to the inner cavity of the housing 7 through the movable opening 24 . Through the provision of the movable opening 24 , the gear 15 can extend to the inner cavity of the housing 7 through the movable opening 24 .

[0041] It is to be understood that the present invention is described by some embodiments, and it is known to those skilled in the art that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the scope of protection of the present invention.

Claims

1. A friction stir welding device, characterized in that: The invention comprises a support platform (1), a pressure control system and a weld deviation detection system, wherein an L-shaped column (2) is arranged on one side of the top of the support platform (1), a drive box (5) which can slide up and down is arranged on the vertical part of the L-shaped column (2), a main shaft is rotatably connected to the bottom of the drive box (5), a stirring head (8) is arranged at the bottom of the main shaft, and a working platform (3) is arranged on the support platform (1); wherein: The pressure control system is used to accurately control the pressing force of the stirring head (8); The weld deviation detection system is used to obtain the three-dimensional coordinates of the workpiece surface at the detection point in the sensor coordinate system in real time, and obtain the height information of the plane where the weld is located; The pressure control system comprises a hydraulic cylinder (4) arranged at the top of the L-shaped column (2); an oil tank (6) for supplying oil to the hydraulic cylinder (4) is arranged on one side of the support platform (1); the hydraulic cylinder (4) is vertically installed at the top of the L-shaped column (2); the bottom of the piston rod of the hydraulic cylinder (4) passes through the horizontal part of the L-shaped column (2) and is fixedly connected to the top of the driving box (5); the main shaft is composed of an upper connecting shaft (9) and a lower connecting shaft (10); there is a gap between the bottom of the upper connecting shaft (9) and the top of the lower connecting shaft (10); a pressure sensor (17) is arranged at the middle part of the bottom of the upper connecting shaft (9); a trigger block (11) distributed corresponding to the pressure sensor (17) is arranged at the top of the lower connecting shaft (10); and the upper connecting shaft (9) and the lower connecting shaft (10) are connected by four elastic limit assemblies distributed in a circumferential array; The weld deviation detection system comprises a housing (7) sleeved on the outside of a lower connecting shaft (10), an annular plate (12) being rotatably connected inside the housing (7), a laser distance measuring sensor (13) being mounted on the side wall of the annular plate (12), and a driving component for driving the annular plate (12) to rotate being arranged on the housing (7).

2. A friction stir welding device according to claim 1, characterized in that: The working platform (3) can move freely in the X direction and the Y direction.

3. A friction stir welding device according to claim 1, characterized in that: A motor for driving the main shaft to rotate is arranged in the driving box (5), and the main shaft is rotationally connected to the driving box (5) via a bearing.

4. A friction stir welding device according to claim 1, characterized in that: The elastic limiting assembly comprises a sliding rod (19), the bottom of the sliding rod (19) is fixedly connected to the top of the lower connecting shaft (10), the bottom of the upper connecting shaft (9) is provided with a sliding hole (18) connected to the sliding rod (19) in an upward and downward sliding manner, and a spring (20) is sleeved on the sliding rod (19), and the upper and lower ends of the spring (20) are respectively connected to the bottom of the upper connecting shaft (9) and the top of the lower connecting shaft (10).

5. A friction stir welding device according to claim 4, characterized in that: The inner walls on both sides of the sliding hole (18) are provided with limit grooves (22) with closed ends at upper and lower ends, and both sides of the top end of the sliding rod (19) are provided with limit blocks (21) slidably connected to the limit grooves (22).

6. A friction stir welding device according to claim 1, characterized in that: The outer shell (7) is fixedly connected to the lower connecting shaft (10), and the outer shell (7) is a cylindrical structure with an open bottom. A convex ring plate (23) wrapped around the outer side of the lower connecting shaft (10) is provided in the middle of the inner cavity of the outer shell (7).

7. A friction stir welding device according to claim 6, characterized in that: The drive assembly comprises a servo motor (14) mounted on the outer wall of the housing (7); the shaft of the servo motor (14) is connected to a gear (15); the outer side of the convex ring plate (23) is rotatably connected to a gear ring (16) via a bearing; the gear (15) extends into the inner cavity of the housing (7) and is rotatably connected to the gear ring (16); the gear ring (16) and the gear (15) are meshed with each other; the bottom of the gear ring (16) is fixedly connected to the top of the annular plate (12); and the inner diameter of the annular plate (12) is greater than the outer diameter of the convex ring plate (23).

8. A friction stir welding device according to claim 7, characterized in that: A movable opening (24) is provided on the side wall of the outer shell (7), and the gear (15) extends to the inner cavity of the outer shell (7) through the movable opening (24).

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