Double-shoulder friction stir welding tool and friction stir welding method

Abstract

The present invention relates to a double-shouldered friction stir welding tool and a friction stir welding method, comprising a stirring head body and a stirring needle coaxially arranged at one end of the stirring head body; a static shoulder is arranged hollow along the axial direction and coaxially sleeved on the stirring head, and the shoulder surface of the static shoulder has an inclined surface; a lower shoulder is coaxially connected to the stirring needle; during friction stir welding, the stirring head, the static shoulder and the lower shoulder move along the welding trajectory, the stirring head and the lower shoulder rotate, the static shoulder does not rotate, and the axis of the stirring head forms a welding inclination angle with the normal of the workpiece to be welded. The present invention can obtain a joint with a smooth upper surface without burrs, no internal defects, small welding deformation, stable welding quality and high strength. Due to the welding inclination angle, it inherits the advantages of conventional single-shouldered friction stir welding and completely solves the bottleneck problem of conventional double-shouldered welding with unstable quality and inability to achieve engineering application. It is suitable for high-quality and stable welding of hollow profiles for rail transportation and large thin-walled parts of rocket tanks.

Description

Technical Field

[0001] The present invention relates to the technical field of welding, in particular to a double-shoulder friction stir welding tool and a friction stir welding method. Background Art

[0002] Since its invention in 1991, friction stir welding (FSW) has been used to weld aluminum, magnesium, and copper alloys due to its environmentally friendly and wire-free properties. However, FSW only welds one of the top and bottom surfaces of the workpiece, resulting in defects such as incomplete root penetration and weak bonding after welding.

[0003] To achieve this, double-shouldered friction stir welding utilizes a self-supporting stirring tool with upper and lower shoulders, connected by a stirring pin that is approximately the same thickness as the workpiece. During welding, the upper and lower shoulders rotate in unison with the pin, interacting with the workpiece to achieve the desired weld. Because double-shouldered friction stir welding simultaneously welds both the top and bottom surfaces, it fundamentally eliminates defects such as incomplete penetration and weak joints at the root.

[0004] However, because coaxially connected dual shoulders lack the characteristic of a conventional single shoulder, which allows for welding angles, the shoulder parallel to the workpiece during welding is less adaptable to welding deformation and flatness changes. Furthermore, the plasticized material exhibits poor fluidity, encapsulation, and forging density, often resulting in surface flash, furrows, and internal tunneling defects. Therefore, conventional dual-shoulder friction stir welding is unsuitable for welding applications such as hollow rail transit profiles and large, thin-walled rocket tanks, which require high weld stability and quality. Summary of the Invention

[0005] To this end, the technical problem to be solved by the present invention is to overcome the defects of the workpiece to be welded caused by the lack of welding inclination of the traditional double-axis shoulder, and to provide a double-axis shoulder stir friction welding tool and stir friction welding method with high stability, long service life, and the ability to achieve high-quality and stable welding.

[0006] The present invention provides a double-shoulder friction stir welding tool, comprising a stirring head, wherein the stirring head comprises a stirring head body and a stirring needle coaxially arranged at one end of the stirring head body; a static shoulder, wherein the static shoulder is hollowly arranged along the axial direction and is coaxially sleeved on the stirring head, and the shoulder surface of the static shoulder has an inclined surface; and a lower shoulder, wherein the lower shoulder is coaxially connected to the stirring needle; wherein, during friction stir welding, the stirring head, the static shoulder and the lower shoulder move along a welding trajectory, the stirring head and the lower shoulder rotate, and the static shoulder does not rotate, and the axis of the stirring head forms a welding inclination angle with the normal of the workpiece to be welded.

[0007] In one embodiment of the present invention, the welding inclination angle is a forward inclination angle.

[0008] In one embodiment of the present invention, the welding inclination angle is 0-5°.

[0009] In one embodiment of the present invention, the angle of the inclined surface is 1-2 times the angle of the welding inclination angle.

[0010] In one embodiment of the present invention, the stirring head is clearance-matched with the static shaft shoulder.

[0011] In one embodiment of the present invention, the diameter of the shoulder surface of the stirring head is 0.2-2 mm smaller than the inner hole diameter of the shoulder surface of the static shoulder.

[0012] In one embodiment of the present invention, the shoulder surface of the stirring head is retracted into the shoulder surface of the static shoulder.

[0013] In one embodiment of the present invention, the retraction depth of the shoulder surface of the stirring head is 0-5 mm.

[0014] The present invention also provides a friction stir welding method, which uses any one of the double-shouldered friction stir welding tools described above to weld the workpieces to be welded, comprising:

[0015] S10, clamping and fixing the workpiece to be welded;

[0016] S20, moving the dual-shoulder friction stir welding tool to the edge of the workpiece to be welded, ensuring that the stirring needle is located at the center of the weld seam of the workpiece to be welded;

[0017] S30, moving the dual-shoulder friction stir welding tool along the welding track according to preset welding parameters to perform welding until the welding is completed.

[0018] In one embodiment of the present invention, it further comprises:

[0019] S11, determining appropriate parameters of the dual-shoulder friction stir welding tool;

[0020] S12, preset a pressing amount, and adjust the shoulder surface positions of the static shoulder and the lower shoulder according to the preset pressing amount;

[0021] The parameters should satisfy the following relationship:

[0022]

[0023] The preset pressing amount should satisfy the following relationship:

[0024]

[0025]

[0026] δ1+δ2=t0-t2

[0027] Among them, the units used are mm, t0 is the thickness of the workpiece to be welded, t1 is the distance between the shoulder surface of the stirring head and the shoulder surface of the lower shoulder, t2 is the distance between the shoulder surface of the static shoulder and the shoulder surface of the lower shoulder, d1 is the shoulder surface diameter of the stirring head, d2 is the inner hole diameter of the shoulder surface of the static shoulder, d3 is the shoulder surface diameter of the lower shoulder, d4 is the shoulder surface diameter of the static shoulder, α1 is the welding inclination angle, α2 is the angle of the inclined surface of the static shoulder shoulder, δ1 is the press-in amount during the static shoulder welding process, and δ2 is the press-in amount during the lower shoulder welding process.

[0028] The above technical solution of the present invention has the following advantages over the prior art:

[0029] The double-shoulder friction stir welding tool and friction stir welding method described in the present invention use a static shoulder for rigid assistance during friction stir welding, thereby improving the stability of the welding process and the life of the stirring needle. The setting of the welding inclination angle is coordinated with the shoulder surface of the lower shoulder and the shoulder surface of the static shoulder to pull the welding at the same time, and the moving direction is unified. It is possible to obtain a welded joint with a smooth upper surface without burrs, no internal defects, small welding deformation, stable welding quality, and high strength. In addition, the present invention is simple to operate and easy to implement. Compared with the traditional double-shoulder, the present invention inherits the advantages of conventional single-shoulder friction stir welding due to the welding inclination angle, and completely solves the bottleneck problem of unstable welding quality of conventional double-shoulder welding and the inability to achieve engineering application. It is particularly suitable for high-quality and stable welding of hollow profiles in rail transportation and large thin-walled parts of rocket tanks. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments of the present invention in conjunction with the accompanying drawings, wherein

[0031] Figure 1 Schematic diagram of the exploded structure of a double-shoulder friction stir welding tool in a preferred embodiment of the present invention;

[0032] Figure 2 A schematic diagram of the cross-sectional structure of a dual-shoulder friction stir welding tool during welding in a preferred embodiment of the present invention;

[0033] Figure 3 This is a schematic diagram of the assembly dimensions of the stirring head in a preferred embodiment of the present invention;

[0034] Figure 4 Schematic diagram of the structure and dimensions of the static shaft shoulder in a preferred embodiment of the present invention;

[0035] Figure 5 This is a schematic diagram of the shoulder assembly relationship in a preferred embodiment of the present invention;

[0036] Figure 6 A schematic diagram of key dimensions of the welding process in a preferred embodiment of the present invention;

[0037] Figure 7 Schematic diagram of welding direction in a preferred embodiment of the present invention.

[0038] Explanation of the reference numerals in the specification: 10, stirring head; 11, stirring head body; 12, shoulder surface of the stirring head; 13, stirring needle; 20, static shoulder; 21, shoulder surface of the static shoulder; 30, lower shoulder; 31, shoulder surface of the lower shoulder; 40, workpiece to be welded. DETAILED DESCRIPTION

[0039] The present invention will be further described below with reference to the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention.

[0040] The present invention discloses a double-shoulder friction stir welding tool, comprising a stirring head 10, wherein the stirring head 10 comprises a stirring head body 11 and a stirring needle 13 coaxially arranged at one end of the stirring head body 11; a static shoulder 20, wherein the static shoulder 20 is hollowly arranged in the axial direction and is coaxially sleeved on the stirring head 10, and the shoulder surface 21 of the static shoulder 20 has an inclined surface; a lower shoulder 30, wherein the lower shoulder 30 is coaxially connected to the stirring needle 13; wherein, during friction stir welding, the stirring head 10, the static shoulder 20 and the lower shoulder 30 move along the welding trajectory, the stirring head 10 and the lower shoulder 30 rotate, the static shoulder 20 does not rotate, and the axis of the stirring head 10 forms a welding inclination angle with the normal of the workpiece 40 to be welded.

[0041] Reference Figure 1 and Figure 2As shown, the double-shouldered friction stir welding tool of the present invention is composed of three parts: a coaxially mounted stirring head 10, a static shoulder 20 and a lower shoulder 30. The stirring head body 11 is located at one end away from the stirring needle 13 and can be coaxially connected to an external robotic arm, or a spindle tool holder of the friction stir welding equipment, and other structures according to actual needs. During the welding process, the stirring head 10 moves along the welding trajectory and rotates at high speed at the same time; and the lower shoulder 30 is connected to the stirring needle 13. During the welding process, the lower shoulder 30 moves along the welding trajectory with the stirring head 10 and rotates at high speed at the same time. The shoulder surface 12 of the stirring head 10 and the shoulder surface 31 of the lower shoulder 30 both interact with the surface of the workpiece 40 to be welded to achieve welding. Therefore, compared with conventional single-shoulder friction stir welding, the dual-shoulder friction stir welding tool described in the present invention has moderate upsetting pressure, which improves the operability of friction stir welding of complex structural parts such as curves, narrow cavities and cylinders. At the same time, it does not require a rigid back support plate, saves tooling costs, reduces assembly time, and eliminates defects such as incomplete root welding and weak bonding during welding.

[0042] Traditional double-shouldered friction stir welding does not have a welding inclination angle, because the shoulder surfaces of its upper and lower shoulders are parallel to each other. Therefore, when performing friction stir welding, the welding inclination angle can only be set to 0°, that is, welding without a welding inclination angle can ensure that the upper and lower shoulders and the upper and lower surfaces of the workpiece to be welded are in good contact and friction stir. If a welding inclination angle is forcibly increased, when it moves along the welding trajectory, one of the two shoulders will shovel the workpiece and the other will pull it. This not only makes it impossible to unify the direction of movement, resulting in the plasticized and flowing material unable to be forged into a dense and defect-free weld; it also makes the stirring needle more susceptible to force vibration, bending, and breaking, affecting its service life. In addition, during the welding process, the shoulder parallel to the workpiece has poor adaptability to welding deformation and flatness changes, and has poor fluidity, wrapping, and forging density of the plasticized material, resulting in surface flash, furrows, and internal tunnel defects.

[0043] For this purpose, refer to Figure 2 and Figure 4As shown, the dual-shoulder friction stir welding tool of the present invention has a shoulder surface 21 of the static shoulder 20 coaxially sleeved on the stirring head with an inclined surface. During the welding process, the static shoulder 20 moves along the welding trajectory with the stirring head 10, but it does not rotate; at the same time, the axis of the stirring head 10 forms a welding inclination angle with the normal of the workpiece 40 to be welded. The setting of this structure provides rigid assistance to the stirring head 10 through the static shoulder 20, effectively improving the stability of the welding process. The static shoulder 20 and the lower shoulder 30 assist the stirring needle, and the force is evenly applied, ensuring the service life of the stirring needle 13 and preventing it from being damaged by force during the welding process. The shoulder surface 31 of the lower shoulder 30 and the shoulder surface 21 of the static shoulder 20 are pulled together for welding, and are in more complete contact with the workpiece 40 to be welded. At the same time, the moving direction of the two shoulder surfaces is unified, effectively ensuring that the plasticized flowing material can be forged and formed, and the fluidity, wrapping and forging density of the plasticized material are good, so as to form a dense and defect-free weld. It effectively avoids surface flash, furrows, and internal tunnel defects, has good adaptability to welding deformation and flatness changes, and provides high-quality and stable welding.

[0044] In summary, the dual-shouldered friction stir welding tool described herein can produce welded joints with smooth, flash-free upper surfaces, no internal defects, minimal weld deformation, stable weld quality, and high strength. Furthermore, the present invention is simple to operate and easy to implement. Compared to conventional dual-shouldered tools, the tool possesses a welding inclination angle, inheriting the advantages of conventional single-shouldered friction stir welding and completely resolving the bottleneck of conventional dual-shouldered tools, which suffer from unstable welding quality and hinder engineering applications. The present invention is particularly suitable for high-quality, stable welding of hollow rail transit profiles and large, thin-walled rocket tanks.

[0045] It should be noted that the normal line of the welding workpiece 40 refers to the normal line of the surface where the workpiece and the shoulder surface are in contact. It should be noted that the reason why the stirring head body 11, the stirring needle 13, the static shoulder 20 and the lower shoulder 30 are limited to be coaxial is to avoid the adverse effects of the eccentric structure on welding. Preferably, the static shoulder 20 is connected to the retaining frame of the spindle housing of the stir friction welding equipment to ensure that it can move along the welding trajectory with the stirring head 10 and remain stationary, thereby providing stable rigid assistance to the stirring head 10. Preferably, the surface of the stirring needle 13 is provided with a thread to ensure a better welding effect. Preferably, the stirring needle and the lower shoulder 30 are detachably connected; specifically, the two are connected by a thread, and the direction of the thread is opposite to the direction of rotation thereof, so as to ensure that parts can be easily replaced while parts are not easily detached during the welding process. Of course, it is not limited to threaded connection. In some other embodiments, one-piece molding and other structures can also be selected.

[0046] Preferably, the static shoulder 20 has a cylindrical structure and a truncated cone structure is provided at one end close to its shoulder surface 21. Compared with a completely cylindrical structure, the truncated cone structure can reduce the contact area between the static shoulder 20 and the workpiece 40 to be welded, improve the stir friction welding effect, and ensure high-quality and stable welding.

[0047] Reference Figure 2 and Figure 7 As shown, in some embodiments of the dual-shouldered friction stir welding tool of the present invention, the welding inclination angle is a forward inclination angle. The forward inclination angle indicates that the welding inclination angle is on the same side of the welding direction; correspondingly, the welding inclination angle of a conventional single-shouldered tool is also known as a backward inclination angle, which is on the opposite side of the welding direction. The difference between the two is that a conventional single-shouldered tool tilts backward along the direction of travel, shoveling during welding, while the dual-shouldered friction stir welding tool of the present invention tilts forward along the direction of travel, pulling during welding. Furthermore, the lack of a lower shoulder makes the stirring pin of a conventional single-shouldered tool susceptible to bending. In contrast, the dual-shouldered friction stir welding tool of the present invention, because the shoulder surface 31 of the lower shoulder 30 and the shoulder surface 21 of the static shoulder 20 simultaneously pull during welding, not only provides more complete contact with the workpiece 40 to be welded, but also aligns the travel directions of the two shoulder surfaces. The static shoulder 20 and the lower shoulder 30 support the stirring pin 13, evenly applying force, ensuring the service life of the stirring pin 13 and preventing damage caused by stress during welding.

[0048] Furthermore, in the dual-shoulder friction stir welding tool described in the present invention, in some embodiments, the welding inclination angle is 0-5°. When the welding inclination angle is 0°, it corresponds to conventional dual-shoulder friction stir welding, and the static shoulder 20 can provide rigid assistance for the stirring head 10. When the welding inclination angle is greater than 0° and less than or equal to 5°, this is the optimal welding inclination angle obtained by technicians based on actual welding conditions. If it is greater than 5°, the stirring needle 13 needs to be further retracted into the shoulder surface 21 of the static shoulder 20, and the length of the stirring needle 13 needs to be longer, then the stirring needle 13 needs to be thickened or the material needs to be replaced, otherwise it is prone to damage, and thickening means that it cannot be well applied to different workpieces 40 to be welded, and replacing materials means an increase in cost, so no restriction is made here.

[0049] Furthermore, in some embodiments of the double-shoulder friction stir welding tool of the present invention, the angle of the bevel is 1-2 times the angle of the welding inclination. Figure 4As shown, the angle of the bevel of the shoulder surface 21 of the static shoulder 20 is the angle between the bevel and a plane perpendicular to the axis of the static shoulder 20. When the angle of the bevel is 1-2 times the angle of the welding inclination angle, this is the optimal angle of the bevel obtained by technicians based on actual welding conditions. If the welding inclination angle is 0°, the angle of the bevel is also 0°, so that the static shoulder 20 can provide rigid assistance to the stirring head 10. If the thickness of the workpiece 40 to be welded is relatively thick, a static shoulder 20 with a slightly larger bevel angle can be selected, so that the static shoulder 20 and the lower shoulder 30 are pressed in more, and are in more complete contact with the workpiece 40 to be welded, thereby providing high-quality and stable welding. When the bevel angle is greater than this range, it is easy to cause the sum of the pressing amounts of the static shoulder 20 and the lower shoulder 30 to be equal to the thickness of the workpiece, so no restriction is made here.

[0050] Reference Figure 3 As shown, in the dual-shoulder friction stir welding tool of the present invention, in some embodiments, the stirring head 10 and the static shoulder 20 are clearance-fitted. The clearance fit enables the two to operate independently without interfering with each other, thereby ensuring welding quality and efficiency.

[0051] Furthermore, in the dual-shoulder friction stir welding tool described in the present invention, in some embodiments, the diameter of the shoulder surface 12 of the stirring head 10 is 0.2-2 mm smaller than the inner hole diameter of the shoulder surface 21 of the static shoulder 20. When the difference between the two is 0.2 mm, the structures of the two are compact, so that the static shoulder 20 can provide rigid assistance to the stirring head 10 well, ensuring the welding quality and service life. When the difference between the two is 2 mm, there is a certain movable gap between the two, which is convenient for flexible adjustment of the position during welding to ensure the welding quality. When the difference between the two is greater than 2 mm, the relative gap is large, resulting in the static shoulder 20 being unable to provide rigid assistance to the stirring head 10 well, so no restriction is made here.

[0052] Reference Figure 5 As shown, in the dual-shouldered friction stir welding tool of the present invention, in some embodiments, the shoulder surface 12 of the stirring head 10 is retracted into the shoulder surface 21 of the static shoulder 20. The reason for limiting the retraction is to prevent the shoulder surface 12 of the stirring head 10 from shoveling the workpiece forward during the welding process, thereby causing welding defects. Figure 5 For example, the leftmost side of the shoulder surface 12 of the stirring head 10 shown in the figure should be indented within or parallel to the shoulder surface 21 of the corresponding static shoulder 20. This structure can effectively ensure that the shoulder surface 31 of the lower shoulder 30 and the shoulder surface 21 of the static shoulder 20 are pulled together for welding, with the same moving direction, thereby obtaining a welded joint with a smooth upper surface without burrs, no internal defects, minimal welding deformation, stable welding quality, and high strength.

[0053] Furthermore, in the dual-shouldered friction stir welding tool described in the present invention, in some embodiments, the retraction depth of the shoulder surface 12 of the stirring head 10 is 0-5mm. 0mm means parallel; the 0-5mm range is limited. This is the optimal retraction depth obtained by technicians based on actual welding conditions, and can be applied to welding of various workpieces to be welded. If it exceeds 5mm, the length of the stirring needle 13 needs to be longer, and the stirring needle 13 needs to be thickened or the material needs to be replaced, otherwise it is prone to damage, and thickening means that it cannot be well applied to different workpieces to be welded, and replacing materials means an increase in cost, so no restriction is made here.

[0054] The present invention discloses a friction stir welding method, which utilizes a dual-shouldered friction stir welding tool as described in any of the above-described embodiments to weld a workpiece. The friction stir welding method of the present invention, because it includes the dual-shouldered friction stir welding tool described in the above-described embodiments, possesses all the advantages of the friction stir welding method, and thus, description thereof is omitted. Specifically, the method comprises the following steps:

[0055] S10, clamping and fixing the workpiece 40 to be welded;

[0056] S20, moving the dual-shoulder friction stir welding tool to the edge of the workpiece 40 to be welded, ensuring that the stirring needle 13 is located at the center of the weld seam of the workpiece 40 to be welded;

[0057] S30, moving the dual-shoulder friction stir welding tool along the welding track according to preset welding parameters to perform welding until the welding is completed.

[0058] Limit the stirring needle to the center of the weld seam of the workpiece to be welded so that it is evenly stressed and not easily damaged, thus ensuring service life and welding quality. Preferably, the following welding parameters are used:

[0059] The spindle speed is 50-3000 r / min, and the welding speed is 10-2000 mm / min. These welding parameters are well applicable to friction stir welding of various workpieces 40 to be welded.

[0060] Further, refer to Figure 3-6 As shown, the friction stir welding method of the present invention, in some embodiments, further includes:

[0061] S11, determining appropriate parameters of the dual-shoulder friction stir welding tool;

[0062] S12, preset a pressing amount, and adjust the positions of the shoulder surface 21 of the static shoulder 20 and the shoulder surface 31 of the lower shoulder 30 according to the preset pressing amount;

[0063] The parameters should satisfy the following relationship:

[0064]

[0065] The preset pressing amount should satisfy the following relationship:

[0066]

[0067]

[0068] δ1+δ2=t0-t2

[0069] Among them, the units used are mm, t0 is the thickness of the workpiece 40 to be welded, t1 is the distance between the shoulder surface 12 of the stirring head 10 and the shoulder surface 31 of the lower shoulder 30, t2 is the distance between the shoulder surface 21 of the static shoulder 20 and the shoulder surface 31 of the lower shoulder 30, d1 is the diameter of the shoulder surface 12 of the stirring head 10, d2 is the inner hole diameter of the shoulder surface 21 of the static shoulder 20, d3 is the diameter of the shoulder surface 31 of the lower shoulder 30, d4 is the diameter of the shoulder surface 21 of the static shoulder 20, α1 is the welding inclination angle, α2 is the angle of the inclined surface of the shoulder surface 21 of the static shoulder 20, δ1 is the pressing amount of the static shoulder 20 during the welding process, and δ2 is the pressing amount of the lower shoulder 30 during the welding process.

[0070] Through this step, the most suitable dual-shoulder friction stir welding tool can be selected for different workpieces 40 to be welded, providing high-quality and stable welding.

[0071] The working principle of the dual-shoulder friction stir welding tool and the friction stir welding method described in the present invention is:

[0072] First, the workpiece 40 to be welded is clamped and fixed, and its thickness is measured. Next, a double-shoulder friction stir welding tool that satisfies the above relationship is selected according to the thickness of the workpiece 40 to be welded. Then, according to the preset pressing amount, the double-shoulder friction stir welding tool is moved to the edge position of the workpiece 40 to be welded, ensuring that the stirring needle 13 is located at the center of the weld seam of the workpiece 40 to be welded, and. Finally, according to the preset welding parameters, the double-shoulder friction stir welding tool is moved along the welding trajectory and welding is performed until the welding is completed. The double-shoulder friction stir welding tool and the friction stir welding method described in the present invention use the static shoulder 20 for rigid assistance during friction stir welding, thereby improving the stability of the welding process and the life of the stirring needle 13. The setting of the welding inclination angle is coordinated with the shoulder surface 31 of the lower shoulder 30 and the shoulder surface 21 of the static shoulder 20 to pull the welding at the same time, and the moving direction is unified. A weld joint with a smooth upper surface without burrs, no internal defects, small welding deformation, stable welding quality and high strength can be obtained. Furthermore, this invention is simple to operate and implement. Compared to conventional double-shoulder friction stir welding, its inclination angle allows it to inherit the advantages of conventional single-shoulder friction stir welding, completely resolving the bottleneck of unstable welding quality and the inability to achieve engineering applications. It is particularly suitable for high-quality and stable welding of hollow profiles for rail transportation and large, thin-walled components such as rocket tanks.

[0073] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A double-shouldered friction stir welding tool, characterized in that: include: A stirring head, the stirring head comprising a stirring head body and a stirring needle coaxially arranged at one end of the stirring head body; A static shoulder, wherein the static shoulder is hollow in the axial direction and is coaxially sleeved on the stirring head, and a shoulder surface of the static shoulder has an inclined surface; A lower shaft shoulder, wherein the lower shaft shoulder is coaxially connected to the stirring needle; During friction stir welding, the stirring head, static shoulder and lower shoulder move along the welding trajectory, the stirring head and lower shoulder rotate, the static shoulder does not rotate, and the axis of the stirring head forms a welding inclination angle with the normal of the workpiece to be welded.

2. The dual-shoulder friction stir welding tool according to claim 1, characterized in that: The welding inclination angle is a forward inclination angle.

3. The dual-shoulder friction stir welding tool according to claim 1 or 2, characterized in that: The welding inclination angle is 0-5°.

4. The dual-shoulder friction stir welding tool according to claim 3, characterized in that: The angle of the inclined surface is 1-2 times the angle of the welding inclination.

5. The dual-shoulder friction stir welding tool according to claim 1, characterized in that: The stirring head is clearance-matched with the static shaft shoulder.

6. The dual-shoulder friction stir welding tool according to claim 5, characterized in that: The diameter of the shaft shoulder surface of the stirring head is 0.2-2 mm smaller than the inner hole diameter of the shaft shoulder surface of the static shaft shoulder.

7. The dual-shoulder friction stir welding tool according to claim 1 or 6, characterized in that: The shoulder surface of the stirring head is retracted into the shoulder surface of the static shoulder.

8. The dual-shoulder friction stir welding tool according to claim 7, characterized in that: The retraction depth of the shoulder surface of the stirring head is 0-5 mm.

9. A friction stir welding method, characterized in that: The double-shoulder friction stir welding tool according to any one of claims 1 to 8 is used to weld the workpiece to be welded, comprising: S10, clamping and fixing the workpiece to be welded; S20, moving the dual-shoulder friction stir welding tool to the edge of the workpiece to be welded, ensuring that the stirring needle is located at the center of the weld seam of the workpiece to be welded; S30, moving the dual-shoulder friction stir welding tool along the welding track according to preset welding parameters to perform welding until the welding is completed.

10. The friction stir welding method according to claim 9, wherein: Also includes: S11, determining appropriate parameters of the dual-shoulder friction stir welding tool; S12, preset a pressing amount, and adjust the shoulder surface positions of the static shoulder and the lower shoulder according to the preset pressing amount; The parameters should satisfy the following relationship: The preset pressing amount should satisfy the following relationship: δ1+δ2=t0-t2 Among them, the units used are mm, t0 is the thickness of the workpiece to be welded, t1 is the distance between the shoulder surface of the stirring head and the shoulder surface of the lower shoulder, t2 is the distance between the shoulder surface of the static shoulder and the shoulder surface of the lower shoulder, d1 is the shoulder surface diameter of the stirring head, d2 is the inner hole diameter of the shoulder surface of the static shoulder, d3 is the shoulder surface diameter of the lower shoulder, d4 is the shoulder surface diameter of the static shoulder, α1 is the welding inclination angle, α2 is the angle of the inclined surface of the static shoulder shoulder, δ1 is the press-in amount during the static shoulder welding process, and δ2 is the press-in amount during the lower shoulder welding process.

Images