A friction stir spot welding weld and weld repair method and device

Abstract

The present invention provides a stir friction spot welding weld and a weld repair method and device, wherein the cross section of the weld is an inverted Ω shape with a narrow top and a wide bottom, wherein the two side walls of the weld are elliptical arcs protruding inward, and the bottom is a concave elliptical arc, and the elliptical arcs of the two side walls are tangent to the elliptical arcs of the bottom and are smoothly connected, and the welding method includes groove processing, stirring needle contacting the groove, hot melt filling, and reverse exit, and the welding device is designed according to different welding methods. The weld has a special inverted Ω-shaped structure, so that the weld can fit closely with the filler, and its structure is narrow at the top and wide at the bottom, so that the weld filler is not easy to fall off after the weldment is stressed, and the surface after welding has good mechanical properties and corrosion resistance. The present invention can quickly complete stir friction welding and defect repair, the weld filler is not easy to fall off after the weldment is stressed, and it is ensured that the weldment surface after welding has good mechanical properties and corrosion resistance, and the structure is simple, the production quality is high, and the cost is low.

Description

Technical Field

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

[0002] Friction stir welding (FSW) is a new solid phase welding technology. Its welding principle is that the high-speed rotating stirring head is pressed into the workpiece to be welded under the action of axial force. Due to the effect of friction, the rotating stirring head directly contacts the workpiece to be welded and generates heat. The material around the contact area of ​​the workpiece to be welded is softened by heat and undergoes plastic deformation. Under the pressure-maintaining and retracting action of the stirring head, a weld with a dense structure is formed. Compared with traditional connection technologies such as fusion welding and resistance spot welding, the quality of the welded joint of friction stir welding has excellent mechanical properties, and the welding tools have a long service life, low energy consumption, low cost, simple operation, and low pollution in the process. It is an economical and efficient "green welding process".

[0003] Among the several types of stir friction welding, direct insertion spot welding is the most widely used one in practical applications. This type of spot welding will inevitably leave a "keyhole" defect after welding, which destroys the integrity of the joint, affects the corrosion resistance and mechanical properties of the joint, and seriously affects the reliability of the joint in some important structural parts. Therefore, in the process of engineering application, the defects need to be repaired.

[0004] In order to avoid keyhole defects, the German HZG Research Center (formerly GKSS) first invented the backfill friction stir spot welding process in 1999. This process requires the equipment to have high control accuracy, and the equipment structure is complex, and the initial investment cost is large. In addition, the easily worn parts, the stirring head, also increase the production cost.

[0005] The Chinese patent application with publication number CN114406443A discloses a stir friction welding keyhole repair method based on the solid-state connection principle. The method is specifically as follows: a split welding tool is designed, including a consumable filling welding column, a non-consumable shoulder, a clamping body and a fastening screw. First, the welding tool is fixed to the stir friction welding tool handle and is on the same vertical axis as the weld keyhole defect, and the automatic operation program parameters are set to make the welding tool slowly rotate and press down; secondly, the welding column and the keyhole are heated by friction, so that they are thermoplastic solid connection; finally, an overload force is applied in the horizontal direction, and the stress concentration point on the welding column is used to cut off the welding column to fill the keyhole defect. This method can effectively realize the repair of the stir friction welding keyhole defect of thick plate aluminum alloy, with low cost, clear and complete surface after welding, and high mechanical properties. It is an innovative and efficient way to solve the stir friction welding keyhole defect. However, this method fills the keyhole in an inverted cone shape with a wide top and a narrow bottom. The filling material is easy to fall off from the keyhole when subjected to force, and the reliability of the weld after the defect repair cannot be guaranteed. Summary of the invention

[0006] The purpose of the present invention is to provide a stir friction spot welding weld and weld repair method and device which can quickly complete stir friction welding and defect repair, prevent the weld filler from falling off after the weldment is subjected to force, ensure that the weldment surface has good mechanical properties and corrosion resistance after welding, and has a simple structure, high production quality and low cost.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0008] A friction stir spot welding weld comprises a weld formed on the surface of an aluminum alloy plate to be welded, wherein the cross section of the weld is an inverted Ω shape which is narrow at the top and wide at the bottom, wherein the two side walls of the weld are inwardly convex elliptical arcs, and the bottom is a concave elliptical arc, the elliptical arcs of the two side walls are tangent to the elliptical arcs of the bottom and are smoothly connected, the ratio of the major diameter to the minor diameter of the elliptical arcs of the side walls and the elliptical arcs of the bottom are both 1.6 to 2:1, and the angle between the connecting line of the center of the ellipse where the side wall is located and the ellipse where the bottom is located and the horizontal direction is set as the interlocking angle θ, and the interlocking angle θ is 22° to 26°.

[0009] Furthermore, the ellipse where the side wall is located is exactly the same as the ellipse where the bottom is located, the major diameter of the ellipse is 3.6 mm, the minor diameter is 2 mm, and the interlocking angle θ is 25°. The three ellipses are staggered up and down, and the two ellipses at the top are in the same horizontal position to form the two side walls of the weld, and the ellipse at the bottom forms the bottom of the weld.

[0010] The present invention also provides a method for repairing a friction stir spot welding weld, comprising the following steps:

[0011] S1, selecting a metal material with a higher hardness and a higher melting point than the first aluminum alloy plate to be welded as a raw material for the first stirring pin, wherein the first aluminum alloy plate to be welded includes an original weld;

[0012] S2, processing a first stirring needle, wherein the shape of a first stirring needle head of the first stirring needle is the same as the shape of the weld;

[0013] S3, the first stirring needle rotates at high speed and aligns with the original weld, so that it is on the same vertical axis and then starts to press down, the contact speed of the first stirring needle head ω 1-0 , axial pressure force F y1-0 Both are smaller than the welding speed ω0 and the axial pressure force F when the original weld was formed. y0 , after contacting the surface of the first aluminum alloy plate to be welded, keep rotating in place for 8 to 12 seconds;

[0014] S4, the first stirring needle keeps rotating and continues to press down, and its speed ω 1-1 The welding speed ω0 is smaller than the original weld formation, and the axial pressure force F y1-1 Greater than the axial pressure F during the original weld formation y0 , the first stirring needle fills the weld;

[0015] S5, wait for the first stirring needle to be pressed down to the preset depth, keep it still for 2 to 5 seconds, then reverse and move it upward to withdraw the first stirring needle, and its speed ω 2-2 Contact speed with the first stirring needle ω 1-0 Be consistent.

[0016] Further, in S3, the contact speed ω of the first stirring needle head is 1-0 , axial pressure force F y1-0 The welding speed ω0 and axial pressure force F when the original weld was formed are both y0 5% to 10% smaller.

[0017] Further, in S4, the speed of the first stirring needle ω 1-1 The welding speed is 20% to 40% of the original weld formation speed ω0, and the axial pressure force F y1-1 is the axial pressure force F during the original weld formation y0 1.2 to 1.5 times of.

[0018] The present invention also provides a device for repairing a friction stir spot welding weld, wherein the first stirring needle comprises a first stirring needle head insertion needle, a shaft shoulder and a first stirring needle head, wherein the first stirring needle head is arranged at the bottom of the first stirring needle head insertion needle and is keyed to the first stirring needle head, wherein the surface of the first stirring needle head is smooth and a concave key is arranged at the top, wherein the first stirring needle head insertion needle passes through the shaft shoulder downward and is threadedly connected to the shaft shoulder, and a convex key matching the concave key is arranged at the bottom of the first stirring needle head insertion needle. The shape and size of the first stirring needle head are the same as the weld, and the first stirring needle head is preferably made of a material that does not deform when heated, and the first stirring needle head fills the weld when the first aluminum alloy plate to be welded is heated and melted and deformed, and the first stirring needle head fills the weld, and the first stirring needle head insertion needle is separated from the first stirring needle head, so that the first stirring needle is retained and fixed in the weld to complete the weld filling, and since the weld itself structure and the first stirring needle head structure are both smooth surfaces, they can be closely fitted to the surface of the first stirring needle head without leaving a gap, and the weld filler is not easy to fall off after the weldment is stressed, and the quality of friction stir welding can be improved, and the structure is simple and the operation is convenient.

[0019] Furthermore, the first stirring needle insertion needle includes a threaded connector, a truncated cone connecting section, a cylindrical section and a convex key from top to bottom, the threaded connector is M10, and the height h 1-1-1 15mm, diameter d 1-1-1 is 10 mm, the diameter d of the cylindrical section 1-1-3 The taper α of the truncated cone connecting section is 40° to 50°. The top and bottom of the truncated cone connecting section are connected to the threaded connector and the cylindrical section respectively. The height h of the truncated cone connecting section is 1-1-2 is 3 mm, the depth of the convex key δ 1-1-4 The shaft shoulder includes a cylindrical boss, a truncated cone connecting section and a cylindrical portion from top to bottom, and the shaft shoulder also includes an internal threaded hole penetrating the cylindrical boss, the truncated cone connecting section and the cylindrical portion, the internal threaded hole matches the thread of the threaded connector, and the bottom of the internal threaded hole is an outwardly expanded oblique opening, and the taper of the oblique opening is α 1-2-5 The first stirring needle has a simple structure, is easy to manufacture, and has a low production cost.

[0020] The present invention also provides another method for repairing a friction stir spot welding weld, comprising the following steps:

[0021] S1, selecting a metal material whose hardness and melting point are lower than the second aluminum alloy plate to be welded to make a second stirring pin;

[0022] S2. Drill a positioning hole in the center of the repaired weld or keyhole defect of the second aluminum alloy plate to be welded, which already has the original weld, and expand the positioning hole into the first groove of the same size as the weld. The total cavity volume is Calculation: The volume of the groove cavity formed by the first groove from the smallest diameter to the bottom of the groove cavity is the minimum effective cavity volume V of the groove. 2-3-2 ;

[0023] S3, rotate the second stirring needle at high speed and align it with the first groove, so that it is on the same vertical axis and then pressed down to contact the bottom of the groove cavity. The friction between the second stirring needle and the first groove generates heat, so that the second stirring needle begins to melt due to the heat. The volume V of the second stirring needle is 2-1-4 Greater than V 2-3-2 , the contact speed of the second stirring needle ω 2-0 , insertion speed υ 2-0 , axial pressure force F y2-0 All of them are smaller than the welding speed ω0, insertion speed υ0 and axial pressure force F when the original weld was formed. y0 , after contacting the bottom of the groove cavity, keep rotating in place for 4 to 6 seconds;

[0024] S4, continue to apply vertical downward pressure to the second stirring needle to make it continue to move downward, the second stirring needle head is heated and melted and plastically deformed to fill the groove cavity, the speed of the second stirring needle head ω 2-1 95%~100%ω0, axial pressure force F y2-1 95%~100%F y0 ;

[0025] S5. Control the second stirring needle to continue to move downward in the vertical direction to complete the groove filling. The second stirring needle head that is melted and deformed by heat forms a thermosetting connection with the first groove. After the downward pressure is completed, the second stirring needle is rotated in the opposite direction and withdrawn upward, so that the force on the second stirring needle head is cut off, and the defect repair is completed.

[0026] Furthermore, in S3, the contact speed ω of the second stirring needle head is 2-0 , insertion speed υ 2-0 , axial pressure force F y2-0 The welding speed ω0, insertion speed υ0 and axial pressure force F when the original weld was formed are all higher than y0 5% to 10% smaller.

[0027] The present invention also provides another device for repairing a friction stir spot welding weld, which comprises, from top to bottom, a threaded connection section, a conical cylindrical connection section, a cylindrical connection section and a second stirring needle head, wherein the threaded connection section is M10×12, and the taper of the conical cylindrical connection section is α 2-1-2 The root diameter is 30°~50°, and the root diameter d 2-1-2 The front diameter is 10mm. 2-1-3 3mm, height h 2-1-2 is 6 mm, the diameter d of the cylindrical connecting section 2-1-3 3mm, height h 2-1-3The diameter of the second stirring needle is 19 mm, and the second stirring needle head is a smooth hemispherical structure.

[0028] The present invention has the following advantages and beneficial effects:

[0029] The present invention can quickly complete friction stir welding and defect repair. The weld filler is not easy to fall off after the weld is subjected to force, ensuring that the weld surface has good mechanical properties and corrosion resistance after welding. The structure is simple, the production quality is high, and the cost is low. The present invention studies the friction stir welding and its defect filling process, designs a weld with a special structure, and proposes a corresponding welding method and device for the friction stir welding and defect repair of the weld. In the first method, the welded material is heated and melted and deformed, and the first stirring needle head that is not deformed by heat fills the weld by causing the welded material to be heated and deformed. The first stirring needle head of the first stirring needle set for this method can be separated, and the first stirring needle head is separated from the first stirring needle head insertion needle so that the first stirring needle head remains in the weld seam; in the second method, the second stirring needle head is heated and melted and deformed, and fills the weld on the welded material by self-consumption. Both welding methods form welds with special structural shapes. Due to the smooth weld structure, the weld can fit closely with the filler, and its structure is narrow at the top and wide at the bottom, so that the weld filler is not easy to fall off after the weldment is subjected to force. The surface after welding has good mechanical properties and corrosion resistance. The operation is simple and the efficiency is high. Compared with the equipment used for backfill stir friction spot welding, it is simpler and more economical. At the same time, it solves the defects of direct plug-in stir friction welding and improves the quality of stir friction welding and its defect filling. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the weld structure of the present invention.

[0031] Figure 2 This is a schematic diagram of the structure of the first stirring needle of the present invention.

[0032] Figure 3 It is a schematic diagram of the structure of the second stirring needle of the present invention.

[0033] Figure 4 It is a schematic diagram of the groove cavity structure of the present invention.

[0034] Figure 5 This is a schematic diagram of the structure of the first stirring needle head of the present invention.

[0035] Figure 6 This is a schematic diagram of the first stirring needle insertion needle structure of the present invention.

[0036] Figure 7 This is a schematic diagram of the structure of the second stirring needle head of the present invention.

[0037] Figure 8 It is a schematic diagram of the shoulder structure of the present invention.

[0038] Fig. 9 This is a diagram of the first stirring needle welding process of the present invention.

[0039] Fig.10 This is a diagram of the second stirring needle welding process of the present invention.

[0040] Among them, 1-1 the first stirring needle insertion needle, 1-1-1 threaded connector, 1-1-2 truncated cone connecting section, 1-1-3 cylindrical section, 1-1-4 convex key, 1-2 shoulder, 1-2-1 cylindrical boss, 1-2-2 truncated cone connecting section, 1-2-3 cylindrical part, 1-2-4 internal threaded hole, 1-2-5 bevel, 1-3 the first stirring needle, 1-3-1 concave key, 1-4 the first aluminum alloy plate to be welded, 2-1 the second stirring needle, 2-1-1 threaded connecting section, 2-1-2 conical cylindrical connecting section, 2-1-3 cylindrical connecting section, 2-1-4 the second stirring needle, 2-2 the second aluminum alloy plate to be welded, 2-3 the first groove, 2-4 groove cavity, 2-4-2 the thinnest diameter, 2-4-3 groove cavity bottom surface, 3 weld. DETAILED DESCRIPTION

[0041] For a better understanding of the present invention, the following examples are provided to further illustrate the present invention, but the present invention is not limited to the following examples.

[0042] Figure 1 The stir friction spot welding weld shown in the figure includes a weld 3 formed on the surface of the aluminum alloy plate to be welded, and the cross-section of the weld 3 is an inverted Ω shape that is narrow at the top and wide at the bottom, wherein the two side walls of the weld 3 are elliptical arcs convex inwardly, and the bottom is a concave elliptical arc, the elliptical arcs of the two side walls are tangent to the elliptical arcs at the bottom and are smoothly connected, the ratio of the major diameter to the minor diameter of the elliptical arcs of the side walls and the elliptical arcs at the bottom are both 1.6 to 2:1, and the angle between the center connecting line of the ellipse where the side wall is located and the ellipse where the bottom is located and the horizontal direction is set as the interlocking angle θ, and the interlocking angle θ is 22° to 26°.

[0043] As a preferred embodiment, the ellipse where the side wall is located is exactly the same as the ellipse where the bottom is located, the major diameter of the ellipse is 3.6 mm, the minor diameter is 2 mm, and the interlocking angle θ is 25°. Figure 1 As shown, three ellipses are staggered up and down, wherein the two ellipses at the top are in the same horizontal position, forming the two side walls of the weld, and the ellipse at the bottom forms the bottom of the weld.

[0044] Example 1

[0045] The present invention provides a method for repairing a friction stir spot welding weld, comprising the following steps:

[0046] S1, selecting a metal material with a higher hardness and a higher melting point than the first aluminum alloy plate (1-4) to be welded as a first stirring pin raw material, wherein the first aluminum alloy plate (1-4) to be welded includes an original weld;

[0047] S2, processing the first stirring needle, the shape of the first stirring needle head 1-3 of the first stirring needle is the same as the shape of the weld 3, and the depth of the concave key 1-3-1 is δ 1-3-1 =0.5mm, its volume is V 1-3 ≈136mm 3 The material of the first stirring needle head 1-3 is an aluminum alloy material having a higher thermal melting temperature than the first aluminum alloy plate 1-4 to be welded;

[0048] S3, the first stirring needle rotates at high speed and aligns with the original weld, so that it is on the same vertical axis and then starts to press down, the contact speed of the first stirring needle head 1-3 is ω 1-0 , axial pressure force F y1-0 Both are smaller than the welding speed ω0 and the axial pressure force F when the original weld was formed. y0 , after contacting the surface of the first aluminum alloy plate 1-4 to be welded, keep rotating in place for 8 to 12 seconds;

[0049] S4, the first stirring needle head inserts needle 1-1 and keeps rotating and continues to press down, and its speed ω 1-1 The welding speed ω0 is smaller than the original weld formation, and the axial pressure force F y1-1 Greater than the axial pressure F during the original weld formation y0 , the first stirring needle 1-3 fills the weld 3;

[0050] S5, wait for the shoulder 1-2 to contact the surface of the first aluminum alloy plate 1-4 to be welded, keep still for 2 to 5 seconds in the original position, then rotate in the reverse direction to withdraw the first stirring needle head and insert the needle 1-1 upward, and its speed ω 2-2 Contact speed ω with the first stirring needle 1-3 1-0 Be consistent.

[0051] Preferably, in S3, the contact speed ω of the first stirring needle head 1-3 is 1-0 , axial pressure force F y1-0 The welding speed ω0 and axial pressure force F when the original weld was formed are both y0 5% to 10% smaller.

[0052] Preferably, in S4, the speed of the first stirring needle ω 1-1 The welding speed is 20% to 40% of the original weld formation speed ω0, and the axial pressure force F y1-1 is the axial pressure force F during the original weld formation y0 1.2 to 1.5 times of.

[0053] In response to the above-mentioned welding method, the present invention designs a device for the repair method of the stir friction spot welding weld, including a first stirring needle, the first stirring needle including a first stirring needle head insertion needle 1-1, a shoulder 1-2 and a first stirring needle head 1-3, the first stirring needle head 1-3 is arranged at the bottom of the first stirring needle head insertion needle 1-1 and is keyed to it, the surface of the first stirring needle head 1-3 is smooth and a concave key 1-3-1 is arranged on the top, the first stirring needle head insertion needle 1-1 penetrates downwardly through the shoulder 1-2 and is threadedly connected to the shoulder 1-2, and a convex key 1-1-4 matching the concave key 1-3-1 is arranged at the bottom of the first stirring needle head insertion needle 1-1. The shape and size of the first stirring needle are the same as those of the weld, and the first stirring needle is preferably made of a metal material that does not deform when heated. For example, the first stirring needle is made of heat-treated mold steel 4Cr5MoV, and the first aluminum alloy plate to be welded is made of 2024-O aluminum alloy. The first aluminum alloy plate to be welded is melted and deformed by heat, and the first stirring needle fills the weld. The insertion needle of the first stirring needle is separated from the first stirring needle, so that the first stirring needle is retained and fixed in the weld to complete the weld filling. Since the structure of the weld itself and the structure of the first stirring needle are both smooth surfaces, they can fit tightly with the surface of the first stirring needle without leaving any gaps. After the weldment is subjected to force, the weld filler is not easy to fall off, which can improve the quality of stir friction welding. The structure is simple and the operation is convenient.

[0054] Preferably, the first stirring needle insertion needle 1-1 comprises from top to bottom a threaded connector 1-1-1, a truncated cone connecting section 1-1-2, a cylindrical section 1-1-3 and a convex key 1-1-4, wherein the threaded connector 1-1-1 is M10 and has a height h 1-1-1 15mm, diameter d 1-1-1 10mm, cylindrical section 1-1-3 shoulder 1-2 diameter d 1-1-3 The taper α of the truncated cone connecting section 1-1-2 is 40° to 50°. The top and bottom of the truncated cone connecting section 1-1-2 are connected to the threaded connector 1-1-1 and the cylindrical section 1-1-3 respectively. The height h of the truncated cone connecting section 1-1-2 is 1-1-2 3mm, the depth of the key 1-1-4 is 1-1-4 The shaft shoulder 1-2 includes a cylindrical boss 1-2-1, a truncated cone connecting section 1-2-2 and a cylindrical portion 1-2-3 from top to bottom. The shaft shoulder 1-2 also includes an internal threaded hole 1-2-4 that penetrates the cylindrical boss 1-2-1, the truncated cone connecting section 1-2-2 and the cylindrical portion 1-2-3. The internal threaded hole 1-2-4 matches the thread of the threaded connector 1-1-1, and the bottom of the internal threaded hole 1-2-4 is an outwardly expanded oblique opening 1-2-5, and the taper of the oblique opening 1-2-5 is α 1-2-5 The first stirring needle has a simple structure, is easy to manufacture, and has a low production cost.

[0055] Example 2

[0056] The present invention also provides another method for repairing a friction stir spot welding weld, comprising the following steps:

[0057] S1, select a metal material whose hardness and melting point are lower than the second aluminum alloy plate 2-2 to be welded to make the second stirring pin 2-1;

[0058] S2, a positioning hole is drilled in the center of the repaired weld or keyhole defect of the second aluminum alloy plate 2-2 to be welded, and the positioning hole is expanded into the first groove 2-3 of the same size as the weld 3. The distance between the two elliptical long diameters at the top and the upper surface of the second aluminum alloy plate 2-2 to be welded is δ=1.5mm, and the depth is The total cavity volume of the first groove 2-3 is Calculate, V 2-3 ≈144mm 3 The volume of the groove cavity 2-4 formed by the first groove 2-3 from the smallest diameter 2-4-2 to the groove cavity bottom surface 2-4-3 is the minimum effective cavity volume V of the groove. 2-3-2 , V 2-3-2 ≈119mm 3 ;

[0059] S3, align the second stirring needle 2-1 with the first groove 2-3, make them on the same vertical axis and then press down, the second stirring needle head 2-1-4 is made of aluminum alloy material with a lower hot melting temperature than the second aluminum alloy plate 2-2 to be welded, and the volume V of the second stirring needle head 2-1-4 is 2-1-4 =141mm 3 , control the second stirring needle head 2-1-4 to rotate at high speed to contact the first groove 2-3, the second stirring needle head 2-1-4 and the first groove 2-3 rub to generate heat, the second stirring needle head 2-1-4 begins to melt due to the heat, and the volume V of the second stirring needle head 2-1-4 2-1-4 Greater than V 2-3-2 , the contact speed of the second stirring needle 2-1 ω 2-0 , insertion speed υ 2-0 , axial pressure force F y2-0 All of them are smaller than the welding speed ω0, insertion speed υ0 and axial pressure force F when the original weld was formed. y0 , after contacting the bottom of the groove cavity 2-4, keep rotating in place for 4-6 seconds;

[0060] S4, continuously apply vertical downward pressure to the second stirring needle 2-1 to make it continue to move downward, the second stirring needle head 2-1-4 is melted by heat and plastically deformed to fill the groove cavity 2-4, and the rotation speed ω of the second stirring needle head 2-1-4 is 2-1 95%~100%ω0, axial pressure force F y2-1 95%~100%F y0 ;

[0061] S5. Control the second stirring needle 2-1 to continue to move downward in the vertical direction to complete the groove filling. The second stirring needle head 2-1-4 that is melted and deformed by heat forms a thermosetting connection with the first groove 2-3. After the downward pressure is completed, the second stirring needle 2-1 is rotated in the opposite direction and withdrawn upward, so that the force on the second stirring needle head 2-1-4 is cut off, and the defect repair is completed.

[0062] Preferably, in S3, the contact speed ω of the second stirring needle head 2-1-4 is 2-0 , insertion speed υ 2-0 , axial pressure force F y2-0 The welding speed ω0, insertion speed υ0 and axial pressure force F when the original weld was formed are all higher than y0 5% to 10% smaller.

[0063] In view of the above method, the present invention designs a device for the repair method of the stir friction spot welding weld, comprising a second stirring needle 2-1, the second stirring needle 2-1 comprises a threaded connection section 2-1-1, a conical cylindrical connection section 2-1-2, a cylindrical connection section 2-1-3 and a second stirring needle head 2-1-4 from top to bottom, the threaded connection section 2-1-1 is M10×12, and the taper of the conical cylindrical connection section 2-1-2 is α 2-1-2 The root diameter is 30°~50°, and the root diameter d 2-1-2 The front diameter is 10mm. 2-1-3 3mm, height h 2-1-2 6mm, diameter d of cylindrical connecting section 2-1-3 2-1-3 3mm, height h 2-1-3 The second stirring needle head 2-1-4 is a smooth hemispherical structure. The second stirring needle head is preferably made of ER4043, and the second aluminum alloy plate to be welded is preferably 6061 aluminum alloy. The second stirring needle head is heated, melted and deformed to fill the groove cavity and complete the weld filling.

[0064] The above is only a preferred embodiment of the present invention, which certainly cannot be used to limit the scope of rights of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and changes can be made without departing from the principle of the present invention, and these improvements and changes are also regarded as the protection scope of the present invention.

Claims

1. A friction stir spot welding weld, characterized in that: The invention comprises a weld (3) formed on the surface of an aluminum alloy plate to be welded, wherein the cross section of the weld (3) is an inverted Ω shape which is narrow at the top and wide at the bottom, wherein the two side walls of the weld (3) are inwardly convex elliptical arcs, and the bottom is a concave elliptical arc, the elliptical arcs of the two side walls are tangent to the elliptical arcs of the bottom and are smoothly connected, the ratio of the major diameter to the minor diameter of the elliptical arcs of the side walls and the elliptical arcs of the bottom are both 1.6 to 2:1, and the angle between the connecting line of the center of the ellipse where the side wall is located and the ellipse where the bottom is located and the horizontal direction is set as the interlocking angle θ, and the interlocking angle θ is 22° to 26°.

2. The friction stir spot welding weld according to claim 1, characterized in that: The ellipse where the side wall is located is exactly the same as the ellipse where the bottom is located, the major diameter of the ellipse is 3.6 mm, the minor diameter is 2 mm, and the interlocking angle θ is 25°.

3. A method for repairing a friction stir spot welding weld as claimed in claim 1, characterized in that: The following steps are involved: S1, selecting a metal material with a higher hardness and a higher melting point than the first aluminum alloy plate (1-4) to be welded as a first stirring pin raw material, wherein the first aluminum alloy plate (1-4) to be welded includes an original weld; S2, processing a first stirring needle, wherein the shape of a first stirring needle head (1-3) of the first stirring needle is the same as the shape of the welding seam (3); S3, the first stirring needle rotates at high speed and aligns with the original weld, so that it is on the same vertical axis and then starts to press down, the contact speed of the first stirring needle head (1-3) ω 1-0 , axial pressure force F y1-0 Both are smaller than the welding speed ω0 and the axial pressure force F when the original weld was formed. y0 , after contacting the surface of the first aluminum alloy plate (1-4) to be welded, keep rotating in place for 8 to 12 seconds; S4, the first stirring needle keeps rotating and continues to press down, and its speed ω 1-1 The welding speed ω0 is smaller than the original weld formation, and the axial pressure force F y1-1 Greater than the axial pressure force F during the original weld formation y0 , the first stirring needle head (1-3) fills the weld (3); S5, wait for the first stirring needle to be pressed down to the preset depth, keep it still for 2 to 5 seconds, then reverse and move it upward to withdraw the first stirring needle, and its speed ω 2-2 Contact speed ω with the first stirring needle (1-3) 1-0 Be consistent.

4. The method for repairing a friction stir spot welding weld according to claim 3, characterized in that: In S3, the contact speed ω of the first stirring needle head (1-3) is 1-0 , axial pressure force F y1-0 The welding speed ω0 and axial pressure force F when the original weld was formed are both y0 5% to 10% smaller.

5. The method for repairing a friction stir spot welding weld according to claim 3, characterized in that: In S4, the speed of the first stirring needle ω 1-1 The welding speed is 20% to 40% of the original weld formation speed ω0, and the axial pressure force F y1-1 is the axial pressure force F during the original weld formation y0 1.2 to 1.5 times of.

6. A device for the method for repairing a friction stir spot welding seam according to any one of claims 3 to 5, characterized in that: The invention comprises a first stirring needle, wherein the first stirring needle comprises a first stirring needle head insertion needle (1-1), a shaft shoulder (1-2) and a first stirring needle head (1-3); the first stirring needle head (1-3) is arranged at the bottom of the first stirring needle head insertion needle (1-1) and is key-connected thereto; the surface of the first stirring needle head (1-3) is smooth and a concave key (1-3-1) is arranged on the top; the first stirring needle head insertion needle (1-1) passes through the shaft shoulder (1-2) downward and is threadedly connected to the shaft shoulder (1-2); a convex key (1-1-4) matching the concave key (1-3-1) is arranged at the bottom of the first stirring needle head insertion needle (1-1).

7. The device for repairing a friction stir spot welding seam according to claim 6, characterized in that: The first stirring needle insertion needle (1-1) comprises, from top to bottom, a threaded connector (1-1-1), a truncated cone connecting section (1-1-2), a cylindrical section (1-1-3) and a convex key (1-1-4); the threaded connector (1-1-1) is M10 and has a height h 1-1-1 15mm, diameter d 1-1-1 is 10 mm, the diameter d of the cylindrical section (1-1-3) shoulder (1-2) 1-1-3 The taper α of the truncated cone connecting section (1-1-2) is 40° to 50°. The top and bottom of the truncated cone connecting section (1-1-2) are connected to the threaded connector (1-1-1) and the cylindrical section (1-1-3) respectively. The height h of the truncated cone connecting section (1-1-2) is 1-1-2 is 3 mm, the depth δ of the convex key (1-1-4) 1-1-4 The shaft shoulder (1-2) comprises, from top to bottom, a cylindrical boss (1-2-1), a truncated cone connecting section (1-2-2) and a cylindrical portion (1-2-3); the shaft shoulder (1-2) further comprises an internal threaded hole (1-2-4) penetrating the cylindrical boss (1-2-1), the truncated cone connecting section (1-2-2) and the cylindrical portion (1-2-3); the internal threaded hole (1-2-4) matches the thread of the threaded connector (1-1-1); the bottom of the internal threaded hole (1-2-4) is an outwardly expanding oblique opening (1-2-5); the taper α of the oblique opening (1-2-5) is 1-2-5 It is 30°~40°.

8. A method for repairing a friction stir spot welding weld as claimed in claim 1, characterized in that: The following steps are involved: S1, selecting a metal material with a lower hardness and melting point than the second aluminum alloy plate to be welded (2-2) to make a second stirring needle (2-1); S2, a positioning hole is drilled in the center of the repaired weld or keyhole defect of the second aluminum alloy plate to be welded (2-2) where the original weld already exists, and the positioning hole is expanded into a first groove (2-3) of the same size as the weld (3), and the depth is The total cavity volume is The volume of the groove cavity (2-4) formed by the first groove (2-3) from the smallest diameter (2-4-2) to the bottom surface (2-4-3) of the groove cavity is the minimum effective cavity volume V of the groove. 2-3-2 ; S3, the second stirring needle (2-1) is rotated at high speed and aligned with the first groove (2-3), so that they are on the same vertical axis and then pressed downward to contact the bottom of the groove cavity (2-4), the second stirring needle head (2-1-4) and the first groove (2-3) generate heat by friction, so that the second stirring needle head (2-1-4) begins to melt due to the heat, and the volume V of the second stirring needle head (2-1-4) is 2-1-4 Greater than V 2-3-2 , the contact speed of the second stirring needle (2-1) ω 2-0 , insertion speed υ 2-0 , axial pressure force F y2-0 All of them are smaller than the welding speed ω0, insertion speed v0 and axial pressure force F when the original weld was formed. y0 , after contacting the bottom of the groove cavity (2-4), keep rotating in place for 4 to 6 seconds; S4, continuously applying vertical downward pressure to the second stirring needle (2-1) to make it continue to move downward, the second stirring needle head (2-1-4) is melted by heat and plastically deformed to fill the groove cavity (2-4), and the rotation speed ω of the second stirring needle head (2-1-4) is 2-1 95%~100%ω0, axial pressure force F y2-1 95%~100%F y0 ; S5. Control the second stirring needle (2-1) to continue to move downward in the vertical direction to complete the groove filling. The second stirring needle head (2-1-4) that is melted and deformed by heat forms a thermosetting connection with the first groove (2-3). After the downward pressure is completed, the second stirring needle (2-1) is rotated in the opposite direction and withdrawn upward, so that the force on the second stirring needle head (2-1-4) is cut off, and the defect repair is completed.

9. The method for repairing a friction stir spot welding weld according to claim 8, characterized in that: In S3, the contact speed ω of the second stirring needle head (2-1-4) 2-0 , insertion speed v 2-0 , axial pressure force F y2-0 The welding speed ω0, insertion speed v0 and axial pressure F of the original weld are all higher than those of the original weld. y0 5% to 10% smaller.

10. A device for the method for repairing a friction stir spot welding seam according to claim 8 or 9, characterized in that: The invention comprises a second stirring needle (2-1), wherein the second stirring needle (2-1) comprises, from top to bottom, a threaded connection section (2-1-1), a conical cylindrical connection section (2-1-2), a cylindrical connection section (2-1-3) and a second stirring needle head (2-1-4), wherein the threaded connection section (2-1-1) is M10×12, and the conical cylindrical connection section (2-1-2) has a taper α 2-1-2 The root diameter is 30°~50°, and the root diameter d 2-1-2 The front diameter is 10mm. 2-1-3 3mm, height h 2-1-2 is 6 mm, the diameter d of the cylindrical connecting section (2-1-3) is 2-1-3 3mm, height h 2-1-3 The diameter of the second stirring needle (2-1-4) is 19 mm, and the second stirring needle head (2-1-4) is a smooth hemispherical structure.

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