Novel welding method for eliminating friction stir welding seam thinning amount

Abstract

The invention belongs to the technical field of friction stir welding, and particularly relates to a novel welding method for eliminating friction stir welding seam thinning amount, which comprises the following steps: (a) a clamping stage: fixing a profiling cover plate above a welding seam of a test plate to be welded by virtue of a cover plate fixing frame, so that the lower surface of the profiling cover plate is tightly matched with the upper surface of the test plate to be welded, the to-be-welded test plate, the profiling cover plate and the cover plate fixing frame are fixed to a workbench of friction stir welding equipment; (b) a welding stage: inserting a stirring tool into the profiling cover plate and the test plate to be welded, and starting welding; and (c) post-welding treatment: removing the redundant profiling cover plate material in a machining manner to eliminate the friction stir welding seam thinning amount. The friction stir welding seam thinning amount can be eliminated, the method is particularly suitable for thick plate friction stir welding, and the elimination cost of the friction stir welding seam thinning amount can be saved.

Description

Technical Field

[0001] The invention belongs to the technical field of stir friction welding, and in particular relates to a novel welding method for eliminating the thinning amount of stir friction welding welds. Background Art

[0002] Friction stir welding has been widely used in manufacturing fields such as aviation, aerospace, high-speed ships, automobile industry, and high-speed trains due to its many advantages such as low heat input, small welding deformation, good weld microstructure and mechanical properties.

[0003] In order to overcome the limitations of traditional friction stir welding technology such as welding thinning, the shoulder and the stirring needle were separated on the basis of traditional FSW, and the stationary shoulder friction stir welding technology was developed. For example, a stationary shoulder friction stir welding device disclosed in the Chinese invention patent application with application publication number CN106001905A and application publication date 2016.10.12, a stationary shoulder welding device for friction stir welding disclosed in the Chinese utility model patent with authorization publication number CN203843367U and authorization publication date 2014.09.24, a new type of friction stir welding tool with no thinning of the surface of the material after welding disclosed in the Chinese invention patent application with application publication number CN106077946A and application publication date 2016.11.09, and a non-inclination stationary shoulder friction stir welding welding tool disclosed in the Chinese utility model patent with authorization publication number CN205798685U and authorization publication date 2016.12.14, all proposed the problem of reducing the thinning of the friction stir welding weld by using the stationary shoulder friction stir welding technology. Compared with conventional friction stir welding technology, the static shoulder friction stir welding technology reduces the heat generation during welding due to the static shoulder, and the life of the stirring tool, welding efficiency, process range, and joint performance are greatly reduced. Therefore, it is more difficult to apply to the connection of thick and ultra-thick plate materials, especially difficult to apply to the welding of materials with high melting points. At the same time, the static shoulder friction stir welding technology is also difficult to completely eliminate the friction stir welding weld thinning on the product surface. For products that require surface flatness, it can only rely on reserving the product surface machining allowance, and machining after welding to remove the thinning, which greatly increases the cost.

[0004] A stationary shoulder for friction stir welding used for welding non-planar plates is disclosed in the Chinese utility model patent with the authorization announcement number CN208977064U and the authorization announcement date 2019.06.14. A new type of stationary shoulder friction stir welding tool is disclosed in the Chinese invention patent application with the application publication number CN107030371A and the application publication date 2017.05.20. Both of the above technical solutions propose to use the stationary shoulder friction stir welding technology to achieve the welding problem of non-planar plates with constant weld position curvature. As mentioned above, compared with the conventional friction stir welding technology, the stationary shoulder friction stir welding technology reduces the heat generation during the welding process due to the stationary shoulder, and the life of the stirring tool, welding efficiency, process range, and joint performance are greatly reduced. Therefore, it is more difficult to apply to the connection of thick plates and ultra-thick plates, especially difficult to apply to the welding of materials with higher melting points. At the same time, the stationary shoulder friction stir welding technology is difficult to achieve the welding of non-planar plates with variable curvature due to the stationary shoulder and fixed curvature.

[0005] In the Chinese invention patent application with application publication number CN102528274A and application publication date 2012.07.04, a process for eliminating surface depressions of a stir friction welding joint and special equipment for extruding edges are disclosed. A method for eliminating the thinning amount of a stir friction welding weld by prefabricated bosses is proposed. However, this method requires the use of special equipment for extruding edges to pre-extrude small bosses from the connection area of ​​the workpiece to be welded, which is costly and has poor applicability.

[0006] Therefore, the technical problem of difficult to eliminate weld thinning in the existing friction stir welding technology needs to be solved urgently. Summary of the invention

[0007] The technical problem to be solved by the present invention is to provide a new welding method for eliminating the thinning amount of stir friction welding welds in view of the shortcomings of the prior art. The present invention can eliminate the thinning amount of stir friction welding welds, and is particularly suitable for stir friction welding of thick plates. It can significantly save the cost of eliminating the thinning amount of stir friction welding welds, and can quickly realize the strengthening of stir friction welding welds, stir friction welding of plates of unequal thickness and test plates to be welded with arbitrary upper surface shapes.

[0008] This solution is achieved through the following technical measures: A new welding method to eliminate the thinning of the stir friction welding weld, which includes the following steps: (a) Clamping stage: Fix the profiling cover plate above the weld of the test plate to be welded by means of the cover plate fixing frame, so that the lower surface of the profiling cover plate is closely matched with the upper surface of the test plate to be welded, and fix the test plate to be welded, the profiling cover plate and the cover plate fixing frame on the workbench of the friction stir welding equipment; (b) Welding stage: insert the stirring tool into the contoured cover plate and the test plate to be welded, and start welding; (c) Post-weld processing: After welding is completed, the excess contoured cover material is removed by mechanical processing to eliminate the thinning of the stir friction welding weld.

[0009] Preferably, the two test plates to be welded are test plates of equal thickness or test plates of unequal thickness.

[0010] Preferably, the upper surfaces of the two test plates to be welded are flat, stepped or curved.

[0011] Preferably, the lower surface of the contoured cover plate is a plane, a stepped surface or a curved surface adapted to the shape of the upper surfaces of the two test plates to be welded.

[0012] Preferably, the thickness of the profiling cover plate is 1-2 mm greater than the thinning amount of the friction stir welding process, the width of the profiling cover plate is 1-2 mm greater than the shoulder diameter of the stirring tool, and the material of the profiling cover plate is the same as that of the test plate to be welded.

[0013] Preferably, the thickness of the cover plate fixing frame is greater than or equal to the thickness of the contoured cover plate.

[0014] Preferably, the cover plate fixing frame and the contoured cover plate are clearance-matched and the clearance is 1-10 mm, and the cover plate fixing frame and the contoured cover plate are tightened and fixed by bolts.

[0015] Preferably, a filler gap is left between the two test plates to be welded; during the clamping stage, the powder and block materials used to strengthen the stir friction welding weld are filled in the filler gap, and the contoured cover plate is made of the same material; during the welding stage, the stir friction welding weld is strengthened by stirring with a stirring needle and friction and upsetting of the shaft shoulder.

[0016] Preferably, the width of the filler gap is less than 1 / 2 of the diameter of the small end of the stirring needle.

[0017] Preferably, the material used for friction stir welding weld reinforcement is an alloy material or a carbon fiber or ceramic non-alloy reinforcement material.

[0018] Beneficial effects of the present invention: The present invention relies on a cover plate fixing frame to fix the profiling cover plate above the weld of the test plate to be welded. After the friction stir welding is completed, the profiling cover plate is removed by mechanical processing to eliminate the thinning amount of the friction stir welding weld. It is especially suitable for friction stir welding of thick plates, which can significantly save the cost of eliminating the thinning amount of the friction stir welding weld. At the same time, this method can quickly achieve friction stir welding weld alloy strengthening, unequal thickness plates, and friction stir welding of test plates to be welded with any upper surface shape. The method is simple in design, easy to install, and has wide applicability. It can be seen that compared with the prior art, the present invention has outstanding substantive characteristics and significant progress, and the beneficial effects of its implementation are also obvious. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of friction stir welding when the test plate to be welded is a flat plate of equal thickness; Figure 2 This is a schematic diagram of clamping when the test plate to be welded is a flat plate of equal thickness; Figure 3 It is a schematic diagram of the friction stir welding process when the test plate to be welded is a flat plate of equal thickness; Figure 4 This is a schematic diagram of strengthening clamping of the friction stir welding weld when the test plate to be welded is a flat plate of equal thickness; Figure 5 This is a schematic diagram of the friction stir welding clamping when the test plates to be welded are plates of unequal thickness.

[0020] Figure 6 This is a schematic diagram of the friction stir welding clamping when the test plate to be welded is a curved plate.

[0021] In the figure: 1-test plate to be welded, 11-upper surface of the test plate to be welded, 12-thin plate to be welded, 13-thick plate to be welded, 2-profile cover plate, 21-lower surface of the profile cover plate, 22-lower convex surface of the profile cover plate, 23-lower concave surface of the profile cover plate, 3-cover plate fixing frame, 4-stirring tool, 41-stirring needle, 42-shaft shoulder, 5-bolt, 6-weld, 7-filler gap. DETAILED DESCRIPTION

[0022] In order to clearly illustrate the technical features of this solution, this solution is described below through specific implementation methods and in conjunction with the accompanying drawings.

[0023] A novel welding method for eliminating the thinning amount of stir friction welding weld includes the following steps: (a) Clamping stage: The profiling cover plate 2 is fixed above the weld of the test plate 1 to be welded by means of the cover plate fixing frame 3, so that the lower surface 21 of the profiling cover plate is closely matched with the upper surface 11 of the test plate to be welded, and the test plate 1 to be welded, the profiling cover plate 2 and the cover plate fixing frame 3 are fixed on the workbench of the friction stir welding equipment; (b) Welding stage: insert the stirring tool 4 into the contoured cover plate 2 and the test plate 1 to be welded, and start welding; (c) Post-weld processing: After welding is completed, the excess material of the contoured cover plate 2 is removed by mechanical processing to eliminate the thinning of the stir friction welding weld. This is especially suitable for stir friction welding of thick plates and can significantly save the cost of eliminating the thinning of the stir friction welding weld.

[0024] Among them, the two test plates 1 to be welded are test plates of equal thickness or unequal thickness, the upper surfaces 11 of the two test plates to be welded are planes, stepped surfaces or curved surfaces, and the lower surface 21 of the profiling cover plate is a plane, stepped surface or curved surface adapted to the shape of the upper surfaces 11 of the two test plates to be welded. In the clamping stage, the lower surface 21 of the profiling cover plate is closely matched with the upper surface 11 of the test plates to be welded. For example, when the two test plates 1 to be welded are test plates of equal thickness, the lower surface 21 of the profiling cover plate is a plane. When the two test plates 1 to be welded are test plates of unequal thickness (thin plates 12 to be welded and thick plates 13 to be welded), the lower surface 21 of the profiling cover plate is a stepped surface (including the lower convex surface 22 of the profiling cover plate in contact with the thin plate 12 to be welded and the lower concave surface 23 of the profiling cover plate in contact with the thick plate 13 to be welded). In the welding stage, the stirring tool 4 is inserted into the profiling cover plate 2 and the test plate 1 to be welded, and the welding is started. After welding, the excess material of the contoured cover plate 2 is removed by mechanical processing, so as to realize the friction stir welding of the test plate 1 to be welded with any upper surface shape, and eliminate the thinning amount of the friction stir welding weld.

[0025] The thickness of the profiling cover plate 2 is greater than the process thinning amount of the stir friction welding by 1-2mm, so as to effectively eliminate the thinning amount of the weld after welding, and at the same time, save the material of the profiling cover plate 2 as much as possible, thereby reducing costs. The width of the profiling cover plate 2 is greater than the diameter of the shoulder 42 of the stirring tool 4 by 1-2mm, so as to avoid the friction between the shoulder 42 of the stirring tool 4 and the cover plate fixing frame 3, and at the same time, save the material of the profiling cover plate 2 as much as possible, thereby reducing costs. The material of the profiling cover plate 2 is the same as that of the test plate 1 to be welded, so as to obtain a well-formed weld. In the present invention, the profiling cover plate 2, which is the same material as the test plate 1 to be welded, is plasticized during welding to fill the thinning amount of the weld, thereby achieving the purpose of eliminating the thinning amount of the stir friction welding weld.

[0026] The thickness of the cover plate fixing frame 3 is greater than or equal to the thickness of the contoured cover plate 2 to prevent the edge of the contoured cover plate 2 from being squeezed and deformed by the shoulder 42 of the stirring tool 4 during welding, thereby preventing welding defects.

[0027] The cover plate fixing frame 3 and the contoured cover plate 2 are clearance-matched and the clearance is 1-10 mm. The cover plate fixing frame 3 and the contoured cover plate 2 are tightened and fixed by bolts 5, which can not only facilitate the installation of the cover plate fixing frame 3, but also facilitate the fixing of the contoured cover plate 2 after the installation is completed.

[0028] A filler gap 7 is left between the two test plates 1 to be welded, and the width of the filler gap 7 is less than 1 / 2 of the diameter of the small end of the stirring needle 41, so that the stirring needle 41 can cover the test plates 1 to be welded on both sides of the weld 6 and the filler gap 7. During the welding process, the filling materials of the test plates 1 to be welded on both sides of the weld 6 and the filler gap 7 can be fully stirred by the stirring needle 41, thereby forming an effective weld. In the clamping stage, the powder and block materials used for strengthening the friction stir welding weld are filled in the filler gap 7, and the contoured cover plate 2 uses the same material; in the welding stage, the friction stir welding weld is strengthened by the stirring of the stirring needle 41 and the friction and upsetting effect of the shoulder 42. After welding is completed, the excess material of the contoured cover plate 2 is removed by mechanical processing to strengthen the friction stir welding weld and eliminate the thinning of the friction stir welding weld.

[0029] The materials used for friction stir welding weld reinforcement are alloy materials or carbon fiber and ceramic non-alloy reinforcement materials.

[0030] Technical features not described in the present invention can be implemented by existing technologies and will not be described in detail here. The present invention is not limited to the above specific embodiments, and changes, modifications, additions or substitutions made by ordinary technicians in the field within the essential scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A new welding method for eliminating the thinning of the friction stir welding weld, characterized in that: It includes the following steps: (a) Clamping stage: Fix the profiling cover plate above the weld of the test plate to be welded by means of the cover plate fixing frame, so that the lower surface of the profiling cover plate is closely matched with the upper surface of the test plate to be welded, and fix the test plate to be welded, the profiling cover plate and the cover plate fixing frame on the workbench of the friction stir welding equipment; (b) Welding stage: insert the stirring tool into the contoured cover plate and the test plate to be welded, and start welding; (c) Post-weld processing: After welding is completed, the excess contoured cover material is removed by mechanical processing to eliminate the thinning of the stir friction welding weld.

2. The novel welding method for eliminating the thinning amount of the friction stir welding weld according to claim 1 is characterized in that: The two test plates to be welded are of equal thickness or unequal thickness.

3. The novel welding method for eliminating the thinning amount of the friction stir welding weld according to claim 2 is characterized in that: The upper surfaces of the two test plates to be welded are flat, stepped or curved.

4. The novel welding method for eliminating the thinning amount of the friction stir welding weld according to claim 3 is characterized in that: The lower surface of the contoured cover plate is a plane, a stepped surface or a curved surface adapted to the shape of the upper surfaces of the two test plates to be welded.

5. The novel welding method for eliminating the thinning amount of the friction stir welding weld according to claim 4 is characterized in that: The thickness of the profiling cover plate is 1-2 mm greater than the thinning amount of the friction stir welding process, the width of the profiling cover plate is 1-2 mm greater than the shoulder diameter of the stirring tool, and the material of the profiling cover plate is the same as that of the test plate to be welded.

6. The novel welding method for eliminating the thinning amount of the friction stir welding weld according to claim 5 is characterized in that: The thickness of the cover plate fixing frame is greater than or equal to the thickness of the contoured cover plate.

7. The novel welding method for eliminating the thinning amount of the friction stir welding weld according to claim 6 is characterized in that: The cover plate fixing frame and the contoured cover plate are clearance matched and the matching clearance is 1-10mm. The cover plate fixing frame and the contoured cover plate are fixed by bolts.

8. The novel welding method for eliminating the thinning amount of the friction stir welding weld according to claim 7 is characterized in that: A filler gap is left between the two test plates to be welded; during the clamping stage, the powder and block materials used to strengthen the stir friction welding weld are filled in the filler gap, and the contoured cover plate uses the same material; during the welding stage, the stir friction welding weld is strengthened through stirring with a stirring needle and friction and upsetting of the shaft shoulder.

9. The novel welding method for eliminating the thinning amount of the friction stir welding weld according to claim 8 is characterized in that: The width of the filler gap is less than 1 / 2 of the diameter of the small end of the stirring needle.

10. The novel welding method for eliminating the thinning amount of the friction stir welding weld according to claim 9 is characterized in that: The materials used for friction stir welding weld reinforcement are alloy materials or carbon fiber and ceramic non-alloy reinforcement materials.

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