A dual-motor coaxial drive backfill stirring friction spot welding equipment

Abstract

This invention discloses a dual-motor coaxial drive backfill friction stir spot welding device, relating to the field of friction stir spot welding technology. It includes an electric spindle and a welding fixture composed of a stirring pin, a stirring sleeve, and a clamping sleeve. The device also includes a stirring pin drive system and a stirring sleeve drive system, respectively used to drive the stirring pin and stirring sleeve to move axially. The stirring pin drive system, the stirring sleeve drive system, and the electric spindle are coaxially arranged and coincide with the rotation center of the welding fixture. The electric spindle drives the stirring pin and stirring sleeve to rotate. This invention solves the problem of bending moment generated by off-axis drive by having the drive sources of the two systems coaxial with the electric spindle. The entire dual-motor coaxial drive structure is compact and ingenious, with high system stability, guaranteed welding accuracy, good welding quality, and improved service life of the entire welding device.

Description

Technical Field

[0001] This invention relates to the field of friction stir spot welding technology, specifically a dual-motor coaxial drive backfill friction stir spot welding device. Background Technology

[0002] Friction stir spot welding (FSW) is a novel solid-state welding technology developed based on friction stir welding (FSW) technology. FSW can form lap joints similar to resistance spot welding and riveting, offering advantages such as high joint quality, stable weld quality, minimal deformation, and high energy efficiency, effectively overcoming the shortcomings of resistance spot welding and riveting. The emergence of backfill-type FSW has successfully solved the problem of keyholes remaining in the center of the weld after traditional FSW, allowing for the production of keyhole-free lap joints with superior mechanical properties in a single operation. This results in high production efficiency and ease of automation.

[0003] During spot welding, precise control of the displacement and pressure changes of the stirring pin is required. However, existing technologies, due to installation space and structural design difficulties, typically employ either off-axis driven displacement adjustment or spring-like elastic components for passive displacement adjustment. Both methods have drawbacks: off-axis driving generates bending moments, leading to a loss of welding position accuracy; passive displacement adjustment requires pressure sensors for feedback, but this introduces hysteresis. Therefore, we propose a dual-motor coaxial drive backfill friction stir spot welding device. Summary of the Invention

[0004] The purpose of this invention is to provide a dual-motor coaxial drive backfill stirring friction spot welding device to solve the above-mentioned problems.

[0005] The present invention can be achieved through the following technical solution: a dual-motor coaxial drive backfill friction stir spot welding device, including an electric spindle and a welding fixture composed of a stirring pin, a stirring sleeve and a clamping sleeve. The device is also provided with a stirring pin drive system and a stirring sleeve drive system for driving the stirring pin and the stirring sleeve to move axially, respectively. The stirring pin drive system, the stirring sleeve drive system and the electric spindle are coaxially arranged and coincide with the rotation center of the welding fixture. The electric spindle is used to drive the stirring pin and the stirring sleeve to rotate.

[0006] A further improvement of the present invention is that: a spindle is provided in the electric spindle, and a stirring needle shaft is connected to the spindle in the form of a spline, and the stirring needle is fixedly installed on the stirring needle shaft.

[0007] A further improvement of the present invention is that: a rectangular plane structure is provided at the bottom of the stirring needle shaft, and a rectangular plane structure is provided at the upper end of the stirring needle. The two rectangular plane structures cooperate with each other to restrict the rotation of the stirring needle relative to the stirring needle shaft, and at the same time, the stirring needle and the stirring needle shaft are axially locked and fixed by a locking nut.

[0008] A further improvement of the present invention is that the stirring needle drive system includes a transmission structure, the power source of which is a hollow direct drive motor fixedly installed in the outer shell, and the output end of the hollow direct drive motor is provided with a lead screw transmission assembly, which drives the stirring needle shaft to move up and down.

[0009] A further improvement of the present invention is that: the lead screw drive assembly includes a lead screw and a lead screw nut, the lead screw and the lead screw nut are connected by a threaded drive, the lead screw nut is fixedly connected to the rotor part of the hollow direct drive motor, the lead screw is axially fixed to the stirring needle shaft, and the stirring needle shaft can rotate relative to the lead screw.

[0010] A further improvement of the present invention is that the transmission structure of the stirring sleeve drive system is exactly the same as the transmission structure of the stirring needle drive system. The stirring sleeve drive system includes a stirring sleeve shaft, which is sleeved on the outside of the stirring needle shaft and the two can move relative to each other. A stirring sleeve is fixed at the bottom of the stirring sleeve shaft. The transmission structure of the stirring sleeve drive system drives the stirring sleeve shaft to move up and down, and the lead screw in the stirring sleeve drive system can rotate.

[0011] A further improvement of the present invention is that the stirring sleeve is slidably disposed in the lower opening of the clamping sleeve, and the contact surface between the stirring sleeve and the clamping sleeve, and the contact surface between the stirring sleeve and the stirring needle are both set as mirror surfaces with a surface roughness of less than 0.08 μm.

[0012] Compared with the prior art, the present invention has the following beneficial effects:

[0013] This invention solves the problem of bending moment caused by off-axis drive by coaxially arranging an electric spindle, a stirring needle drive system, and a stirring sleeve drive system in the main spindle. During the welding process, the stirring sleeve and stirring needle can rotate and move axially, and the drive source is coaxial with the stirring needle. This ensures the rigidity of the system during the welding process.

[0014] Friction stir spot welding is achieved through the combination of dual motor drive and electric spindle. This structure has a wide range of applications and can be used in any friction stir welding equipment, such as moving and stationary shaft shoulder friction stir welding, gantry type and robotic arm type. The control program for the pressure and displacement relationship is embedded in the dual motor drive system, and the pressure and displacement can be controlled by the hollow direct drive motor. The entire dual motor coaxial drive structure is compact and ingenious, with high system stability, guaranteed welding accuracy, good welding quality, and can extend the service life of the entire welding device. Attached Figure Description

[0015] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to the accompanying drawings.

[0016] Figure 1 This is a cross-sectional view of the overall structure of the present invention;

[0017] Figure 2 For the present invention Figure 1 A detailed magnified view of area A in the middle;

[0018] Figure 3 This is a partial schematic diagram of the stirring sleeve drive system of the present invention.

[0019] In the diagram: 1. Outer shell; 2. Stirring needle shaft; 3. Spindle; 4. Spacer; 5. Angular contact ball bearing 1; 6. Hollow direct drive motor 1; 7. Lead screw nut 1; 8. Lead screw 1; 9. Thrust bearing 1; 10. Stirring needle; 11. Stirring sleeve; 12. Clamping sleeve; 13. Stirring sleeve spline nut; 14. Stirring sleeve shaft; 15. Hollow direct drive motor 2; 16. Lead screw nut 2; 17. Lead screw 2; 18. Thrust bearing 2; 19. Angular contact ball bearing 2; 20. Electric spindle. Detailed Implementation

[0020] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided.

[0021] Please see Figure 1-3 As shown, a dual-motor coaxial drive backfill friction stir spot welding device includes a housing 1, an electric spindle 20, and a welding fixture composed of a stirring needle 10, a stirring sleeve 11, and a clamping sleeve 12. The electric spindle 20 is located on the upper part of the housing 1 and the two are fixed together by connecting bolts. A mandrel 3 is fixedly installed in the middle of the electric spindle 20. A spline is provided on the top of the stirring needle shaft 2. A spline groove is opened on the inner wall of the mandrel 3. The mandrel 3 is connected to the stirring needle shaft 2 by the spline. The mandrel 3 and the stirring needle shaft 2 slide relative to each other and cannot rotate.

[0022] The clamping sleeve 12 is coaxially disposed at the lower part of the outer shell 1 and is fixedly connected to the outer shell 1 by the clamping sleeve locking nut. It is used to clamp the workpiece to be welded. The stirring sleeve 11 is slidably disposed in the lower opening of the clamping sleeve 12. The stirring sleeve 11 wraps around the lower end of the stirring needle 10 to ensure that it will not bend under stress. The lower part of the stirring needle shaft 2 fixes the stirring needle 10. Specifically, the bottom of the stirring needle shaft 2 is provided with a rectangular plane structure, and the upper end of the stirring needle 10 is provided with a rectangular plane structure. The rectangular plane is used to restrict the rotation of the stirring needle 10 relative to the stirring needle shaft 2. At the same time, the stirring needle 10 and the stirring needle shaft 2 are locked and fixed by the locking nut to restrict the axial movement of the stirring needle 10 relative to the stirring needle shaft 2.

[0023] It should be noted that the contact surfaces between the stirring sleeve 11 and the clamping sleeve 12, as well as the contact surfaces between the stirring sleeve 11 and the stirring needle 10, are all set to mirror surfaces with a surface roughness of less than 0.08 μm.

[0024] The outer casing 1 is also equipped with two drive systems, namely a stirring needle drive system and a stirring sleeve drive system. The stirring needle drive system is used to control and adjust the up and down movement of the stirring needle 10. In the stirring needle drive system, the power source is a hollow direct drive motor 6. The hollow direct drive motor 6 is installed in the outer casing 1 near the upper part, and angular contact ball bearings 5 ​​are provided on both the upper and lower sides. Spacers 4 are fixedly abutted on both sides of the angular contact ball bearings 5. The outer ring of the angular contact ball bearings 5 ​​axially limits the stator part of the hollow direct drive motor 6. The rotor part of the hollow direct drive motor 6 is fixedly connected to the lead screw nut 7. The inner ring of the angular contact ball bearings 5 ​​axially limits the lead screw nut 7. The rotor of the hollow direct drive motor 6 is connected to the lead screw 8 through the lead screw nut 7.

[0025] The lead screw 8 is mounted on the outside of the stirring needle shaft 2 and the two are connected by a thrust bearing 9. The thrust bearing 9 is provided with a bearing cover and a bearing locking nut on the top and bottom respectively, which axially fixes the lead screw 8 and the stirring needle shaft 2, but does not affect the relative rotation between the stirring needle shaft 2 and the lead screw 8.

[0026] When the hollow direct drive motor 6 is powered on and started, the rotor rotates, which drives the screw nut 7 fixedly connected to it to rotate. The screw nut 7 can only rotate and will not have axial displacement. The screw 8 cannot rotate under the restriction of the spline groove, so the screw 8 can only move up and down under the rotation of the screw nut 7, which drives the stirring needle shaft 2 to move up and down. The stirring needle 10 fixed at the lower part of the stirring needle shaft 2 moves up and down accordingly.

[0027] The stirring sleeve drive system is located below the stirring needle drive system. The stirring sleeve drive system is used to control and adjust the up and down movement of the stirring sleeve 11. In the stirring sleeve drive system, the power source is a hollow direct drive motor 15. The hollow direct drive motor 15 is fixedly installed in the lower part of the outer shell 1. The rotor of the hollow direct drive motor 15 is fixedly connected to the lead screw nut 16. The inner thread of the lead screw nut 16 is connected to the lead screw 17. Thus, the rotor of the hollow direct drive motor 15 is connected to the lead screw nut 16 and the lead screw 17. The upper and lower sides of the hollow direct drive motor 15 are provided with angular contact ball bearings 19, and the outer ring of the angular contact ball bearings 19 axially positions the motor stator. The inner ring of the angular contact ball bearings 19 axially positions the lead screw nut 16.

[0028] The second lead screw 17 is sleeved and installed on the outside of the stirring sleeve shaft 14, and the two are connected by the second thrust bearing 18. The second thrust bearing 18 is provided with a bearing cover 2 and a bearing locking nut 2 on the upper and lower sides, respectively, to fix the second lead screw 17 and the stirring sleeve shaft 14 axially, but without affecting the relative rotation between the stirring sleeve shaft 14 and the second lead screw 17.

[0029] When the hollow direct drive motor 15 is powered on and started, its motor rotor rotates, thereby driving the screw nut 16 fixedly connected to it to rotate. The screw nut 16 can only rotate and will not have axial displacement. The screw nut 16 and the screw 17 are driven by threaded meshing. The screw 17 cannot rotate under the restriction of the spline groove, but can only move up and down. The up and down movement of the screw 17 drives the up and down movement of the stirring sleeve shaft 14.

[0030] It should be noted that the stirring sleeve shaft 14 is sleeved on the outside of the stirring needle shaft 2 via a spline connection. The stirring sleeve shaft 14 and the stirring needle shaft 2 can only move vertically. The bottom of the stirring sleeve shaft 14 is fixedly connected to the stirring sleeve 11 via a stirring sleeve spline nut 13.

[0031] In use, this invention supplies power to two hollow direct-drive motors and an electric spindle 20, thereby causing the mandrel 3 to drive the stirring needle shaft 2 to rotate. During welding, the clamping sleeve 12 is positioned and pressed onto the workpiece to be welded. The working state of the two motors is coordinated and controlled by the relationship between pressure and displacement. The stirring needle shaft 2 and the stirring sleeve 11 are adjusted for lifting and lowering respectively. Through the cooperation of the two motors and the electric spindle 20, magnetic field controlled stirring friction spot welding is achieved, thereby precisely realizing the welding mode that controls the relationship between pressure and displacement for accurate welding.

[0032] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A dual-motor coaxial drive backfill friction stir spot welding device, comprising an electric spindle (20) and a welding fixture composed of a stirring needle (10), a stirring sleeve (11), and a clamping sleeve (12), characterized in that, The equipment is also equipped with a stirring pin drive system and a stirring sleeve drive system for driving the stirring pin (10) and the stirring sleeve (11) to move axially, respectively. The stirring pin drive system, the stirring sleeve drive system and the electric spindle (20) are coaxially arranged and coincide with the rotation center of the welding tool. The electric spindle (20) is used to drive the stirring pin (10) and the stirring sleeve (11) to rotate. The stirring needle drive system includes a transmission structure. The power source of the transmission structure is a hollow direct drive motor fixedly installed in the outer shell (1). The output end of the hollow direct drive motor is provided with a screw transmission assembly, which drives the stirring needle shaft (2) to move up and down. The lead screw drive assembly includes a lead screw and a lead screw nut, which are connected by a threaded drive. The lead screw nut is fixedly connected to the rotor part of the hollow direct drive motor. The lead screw is axially fixed to the stirring needle shaft (2), and the stirring needle shaft (2) can rotate relative to the lead screw. The transmission structure of the stirring sleeve drive system is exactly the same as that of the stirring needle drive system. The stirring sleeve drive system includes a stirring sleeve shaft (14), which is sleeved on the outside of the stirring needle shaft (2) and can move relative to each other. A stirring sleeve (11) is fixed at the bottom of the stirring sleeve shaft (14). The transmission structure of the stirring sleeve drive system drives the stirring sleeve shaft (14) to move up and down, and the lead screw in the stirring sleeve shaft (14) of the stirring sleeve drive system can rotate.

2. The dual-motor coaxial drive backfilling friction stir spot welding equipment according to claim 1, characterized in that, The electric spindle (20) is provided with a spindle (3), and a stirring needle shaft (2) is connected to the spindle (3) in a spline manner. The stirring needle (10) is fixedly installed on the stirring needle shaft (2).

3. The dual-motor coaxial drive backfilling friction stir spot welding equipment according to claim 2, characterized in that, The bottom of the stirring needle shaft (2) is provided with a rectangular plane structure, and the upper end of the stirring needle (10) is provided with a rectangular plane structure. The two rectangular plane structures cooperate with each other to restrict the rotation of the stirring needle (10) relative to the stirring needle shaft (2). At the same time, the stirring needle (10) and the stirring needle shaft (2) are axially locked and fixed by the locking nut.

4. The dual-motor coaxial drive backfilling friction stir spot welding equipment according to claim 1, characterized in that, The stirring sleeve (11) is slidably disposed in the lower opening of the clamping sleeve (12), and the contact surfaces between the stirring sleeve (11) and the clamping sleeve (12) and between the stirring sleeve (11) and the stirring needle (10) are both set as mirror surfaces with a surface roughness of less than 0.08μm.

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