A dynamic-static biaxial shoulder stirring head for spherical weld friction stir welding
The design of the dynamic-static dual-shoulder stirring head solves the problem of inefficient connection of spherical welds, achieving efficient welding without rigid support, with excellent weld formation and uniform structure.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- HUNAN AUTOMOTIVE ENG VOCATIONAL COLLEGE
- Filing Date
- 2025-08-09
- Publication Date
- 2026-07-21
AI Technical Summary
Existing friction stir welding technology cannot achieve efficient connection of spherical welds, especially for components such as rocket tube bottom locking flaps and nuclear fusion target spheres, where high-quality connection cannot be achieved without rigid support on the back.
The device employs a dynamic-static dual-shoulder stirring head. The dynamic shoulder contacts the inner surface of the spherical workpiece to provide frictional heat and pressure, while the static shoulder contacts the outer surface of the spherical workpiece to provide static support. The rotation and feeding motion of the stirring pins form a highly efficient weld seam within a closed space.
It achieves efficient connection of spherical welds without rigid support on the back, with excellent weld surface formation, no welding flash or thinning, uniform structure, and complete penetration.
Smart Images
Figure CN224526212U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of friction stir welding technology, specifically a dynamic-static dual-shoulder stirring head for friction stir welding of spherical welds. Background Technology
[0002] Friction stir welding (FSW) is a green solid-state welding technology invented by the Welding Institute (TWI) in the UK in 1991. Compared with traditional fusion welding, FSW has significant advantages in welding non-ferrous lightweight metals, and therefore it was first applied in military fields such as aerospace. However, traditional FSW technology only allows for plate-to-plate butt joints, plate-to-plate lap joints, plate-to-plate butt lap joints, and single stationary axis shoulder joints. These joint types all require the weld to be a two-dimensional planar curve and require rigid support on the back of the weld. Robotic friction stir welding can achieve the welding of three-dimensional curved surfaces with small radii of curvature.
[0003] Dual-shoulder friction stir welding technology can achieve high-quality connections for planar butt joints without rigid back support. However, if the weld is a spherical surface, such as the bottom flap of a rocket tube or a nuclear fusion target sphere, existing friction stir devices cannot achieve this. Summary of the Invention
[0004] To address the problems existing in the prior art, this utility model provides a dynamic-static dual-shoulder stirring head for friction stir welding of spherical welds, so as to realize friction stir welding connection of spherical welds without rigid support on the back.
[0005] The technical solution adopted in this utility model is as follows: A dynamic-static dual-shoulder stirring head for friction stir welding of spherical welds includes a stirring pin, a dynamic shoulder, and a static shoulder; the stirring pin is conical in shape and has a right-hand thread and three evenly distributed cross-sections on its surface; the bottom end of the stirring pin is fixedly connected to the dynamic shoulder, and the upper end is a connecting end connected to the rotating main shaft of the friction stir welding equipment; the connecting end of the stirring pin passes through the cylindrical body of the static shoulder; the static shoulder is adjustablely mounted on the outer ring mechanism of the main shaft, and the distance between the dynamic shoulder and the static shoulder can be adjusted by adjusting its axial position to adapt to the plate thickness of the workpiece to be welded; the shoulder surface of the dynamic shoulder is an outwardly convex spherical surface, and the shoulder surface of the static shoulder is an inwardly concave spherical surface, and the radius of curvature of the outwardly convex spherical surface is equal to the radius of curvature of the inner surface of the workpiece to be welded, and the radius of curvature of the inwardly concave spherical surface is equal to the radius of curvature of the outer surface of the workpiece to be welded.
[0006] Furthermore, the stirring needle and the moving shaft shoulder are coaxially integrally formed.
[0007] Furthermore, the connecting end of the stirring needle is provided with a square flat part and an axial internal thread hole.
[0008] Furthermore, the fixed end of the stationary shaft shoulder is provided with multiple evenly distributed keyways on its outer circumference, and is locked to the outer ring mechanism of the spindle by set screws.
[0009] Furthermore, the axial distance d between the stationary shoulder and the moving shoulder satisfies: d = t - (0.1 mm ~ 0.2 mm), where t is the thickness of the workpiece to be welded.
[0010] The beneficial effects of this invention are as follows: Based on the fundamental principle of friction stir welding, this invention utilizes the frictional heat generated by the mutual friction between the stirring head and the workpiece, as well as the latent heat of plastic deformation of the metal, as the welding heat source. The moving shoulder has the same curvature as the spherical workpiece, and during high-speed rotation, it fits tightly against the workpiece without any interference and provides rigid back support, ensuring complete weld penetration. The stationary shoulder slides on the surface of the spherical workpiece, and its curvature is the same as the workpiece, forming a closed space. In summary, the stationary shoulder slides on the workpiece surface, while the stirring pin and moving shoulder perform a feeding motion while rotating at high speed. Under the clamping of the moving and stationary shoulders, the weld metal forms a closed space and becomes highly thermoplastic. Driven by the stirring pin, it undergoes efficient transfer, ultimately forming the weld. The weld surface has excellent shape, with no welding flash or thinning, complete weld penetration, uniform structure along the thickness direction, and no overheating on the bottom surface. Attached Figure Description
[0011] Figure 1 This is a schematic diagram of the overall structure of this utility model.
[0012] Figure 2 This is a schematic diagram of the structure of the stirring needle and the moving shaft shoulder of this utility model.
[0013] Figure 3 This is a structural schematic diagram of the static shoulder of this utility model.
[0014] Figure 4 This is a schematic diagram of the working state of this utility model. Detailed Implementation
[0015] To facilitate understanding of this utility model, it will be described more comprehensively and in detail below with reference to the accompanying drawings and preferred embodiments. However, the scope of protection of this utility model is not limited to the following specific embodiments.
[0016] like Figures 1-4 As shown in the figure, this embodiment provides a dynamic-static dual-shoulder stirring head for friction stir welding of spherical welds, including a stirring pin 1, a dynamic shoulder 2, and a static shoulder 3.
[0017] The stirring pin 1 is conical in shape and features right-hand threads and three evenly distributed cross-sections on its surface. This design guides the material to flow along the thread direction, promoting uniform mixing of the material in the weld zone and enhancing the stirring effect. The bottom end of the stirring pin 1 is fixedly connected to the moving shoulder 2, which is coaxially integrated with the stirring pin 1 and rotates with it. The upper end of the stirring pin 1 is a connecting end 11 connected to the rotating spindle of the friction stir welding equipment. The connecting end 11 has a square flat section and an axial internal threaded hole for reliable connection with the rotating spindle of the welding machine. The connecting end 11 of the stirring pin 1 penetrates the cylindrical body of the stationary shoulder 3, which is adjustablely mounted on the outer ring mechanism of the spindle. By adjusting its axial position, the distance between the moving shoulder 2 and the stationary shoulder 3 can be adjusted to suit the thickness of the workpiece to be welded. Specifically, the outer circumference of the fixed end of the stationary shoulder 3 is provided with multiple evenly distributed keyways 31, which are locked to the outer ring mechanism of the spindle by set screws. The keyway 31 is used for positioning (preventing rotation) and transmitting static force, and the set screw enables axial position adjustment to adjust the distance between the moving and stationary shaft shoulders.
[0018] The moving shoulder 2 has a convex spherical surface, and the stationary shoulder 3 has a concave spherical surface. The radius of curvature of the convex spherical surface is equal to the radius of curvature of the inner surface of the workpiece to be welded, and the radius of curvature of the concave spherical surface is equal to the radius of curvature of the outer surface of the workpiece to be welded. The moving shoulder 2 rotates with the stirring needle 1, and the convex spherical surface is in contact with the inner surface of the workpiece (inner side of the spherical weld), providing frictional heat and axial pressure, promoting the flow of material on the inner surface and forming a dense weld. The stationary shoulder 3 is fixed to the outer ring mechanism of the spindle (does not rotate), and the concave spherical surface is in contact with the outer surface of the workpiece (outer side of the spherical weld), providing static support and reverse pressure, balancing the rotational force of the moving shoulder, and stabilizing the welding process.
[0019] The axial distance d between the stationary shoulder 3 and the moving shoulder 2 satisfies: d = t - (0.1 mm ~ 0.2 mm), where t is the thickness of the workpiece to be welded. By setting arc-starting plates at the weld inlet and outlet ends and adjusting the distance between the moving and stationary shoulders to be slightly less than the original thickness of the workpiece, sufficient contact between the shoulders and the workpiece surface can be ensured, providing adequate frictional pressure, promoting material flow, and avoiding welding defects caused by gaps. During welding, the main shaft of the equipment is started, and the stirring pin 1 rotates at high speed while cutting into the arc-starting plate. The stationary shoulder 3 slides on the surface of the spherical workpiece, and the moving shoulder 2 rotates at high speed on the inner arc surface of the workpiece. A closed space is formed inside the stirring pin 1, simultaneously forming a solid-phase weld. The stirring pin cuts out from the arc-starting plate at the outlet end, and the welding is completed.
[0020] With the aid of the teachings present in the foregoing description and related drawings, those skilled in the art will conceive of many modifications and other embodiments of the present invention. Therefore, it is to be understood that the present invention is not limited to the specific embodiments disclosed, and modifications and other embodiments are considered to be included within the scope of the appended claims. Although specific terms are used herein, they are used in a general and descriptive sense only and are not intended to be limiting.
Claims
1. A dynamic-static dual-shoulder stirring head for friction stir welding of spherical welds, characterized in that: The device includes a stirring needle (1), a moving shoulder (2), and a stationary shoulder (3). The stirring needle (1) is conical in shape and has a right-hand thread and three evenly distributed cross-sections on its surface. The bottom end of the stirring needle (1) is fixedly connected to the moving shoulder (2), and the upper end is a connecting end (11) connected to the rotating spindle of the friction stir welding equipment. The connecting end (11) of the stirring needle (1) passes through the cylinder of the stationary shoulder (3). The stationary shoulder (3) is adjustablely mounted on the outer ring mechanism of the spindle. By adjusting its axial position, the distance between the moving shoulder (2) and the stationary shoulder (3) can be adjusted to match the plate thickness of the workpiece to be welded. The shoulder surface of the moving shoulder (2) is an outwardly convex spherical surface, and the shoulder surface of the stationary shoulder (3) is an inwardly concave spherical surface. The radius of curvature of the outwardly convex spherical surface is equal to the radius of curvature of the inner surface of the workpiece to be welded, and the radius of curvature of the inwardly concave spherical surface is equal to the radius of curvature of the outer surface of the workpiece to be welded.
2. The dynamic-static dual-shoulder stirring head for friction stir welding of spherical welds as described in claim 1, characterized in that: The stirring needle (1) and the moving shoulder (2) are coaxially integrally formed.
3. The dynamic-static dual-shoulder stirring head for friction stir welding of spherical welds as described in claim 1, characterized in that: The connecting end (11) of the stirring needle (1) is provided with a square flat part and an axial internal thread hole.
4. The dynamic-static dual-shoulder stirring head for friction stir welding of spherical welds as described in claim 1, characterized in that: The fixed end of the stationary shaft shoulder (3) is provided with multiple evenly distributed keyways (31) on its outer circumference, and is locked to the outer ring mechanism of the spindle by set screws.
5. The dynamic-static dual-shoulder stirring head for friction stir welding of spherical welds as described in claim 1, characterized in that: The axial distance d between the static shoulder (3) and the moving shoulder (2) satisfies: d = t - (0.1 mm ~ 0.2 mm), where t is the thickness of the workpiece to be welded.