Friction stirring point engagement device

Abstract

To provide a friction stir spot welding device that can reduce extra manufacturing costs, in painting a welded material subjected to friction stir welding.SOLUTION: A friction stir spot welding device 1, which subjects a plurality of materials including a tabular first material and a second material arranged to contact an opposing surface of the first material to friction stir-welding, comprises a probe 2 that can rotate around a central axis line C. The probe 2 has a pin part 5 protruding along the central axis line C from a bottom surface 4 of a columnar shoulder part 3, and an inner wall surface 11 provided with circumferential surfaces 12 protruding from the shoulder part 3 and having certain distances from the central axis line C and separated surfaces 13 formed consecutively to the circumferential surfaces 12 and separated to outside more than the circumferential surfaces 12.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a friction stir spot welding apparatus. [Background technology]

[0002] Patent Document 1 discloses a friction stir welding tool used for spot joining of workpieces comprising a cylindrical main body shaft portion, a shoulder surface formed on one end of the main body shaft portion, and a pin portion protruding from the shoulder surface and having a smaller diameter than the shoulder surface, the workpiece being made by stacking a plurality of plate-shaped materials including at least an upper plate and a lower plate, and the tool has a configuration including a lift-up prevention portion protruding radially outward from the outer circumferential surface of the main body shaft portion.

[0003] In this technology, a gap is formed on the underside of the floating prevention part from the main body shaft part toward the outside in the radial direction. This gap is formed between the outer circumferential surface of the main body shaft part and the outer circumferential edge part of the floating prevention part, and serves as a space for burrs generated near the joint during joining to enter. By ensuring a space in which the burrs can protrude, it plays a role in preventing the burrs from coming into contact with the floating prevention part and welding, and in preventing the plastic flow near the joint from being hindered. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2010-23068 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, even with the technology of Patent Document 1, a space is provided in the gap where the burr can protrude, and the burr is formed with its tip expanding outward (see reference numeral 9 in FIG. 8 of Patent Document 1, etc.). Therefore, when the materials are spot-joined by friction stir welding and then the materials are electrocoated, coating defects are likely to occur in the burr area. Therefore, in order to prevent such coating defects, a process of removing the burr must be added after the friction stir welding process, and the additional process increases the manufacturing cost.

[0006] Therefore, an object of the present invention is to provide a friction stir spot welding apparatus that can reduce unnecessary manufacturing costs when attempting to paint the workpieces after friction stir welding. [Means for solving the problem]

[0007] The present invention provides a friction stir spot welding device for friction stir welding a plurality of materials including a plate-shaped first material and a second material arranged so as to abut against an opposing surface of the first material, the device comprising a probe rotatable about a central axis, the probe having a pin portion protruding along the central axis from a bottom surface of a cylindrical shoulder portion, a circumferential surface protruding from the shoulder portion and at a constant distance from the central axis, and an inner wall surface provided with a separation surface that is continuous with the circumferential surface and spaced outward from the circumferential surface. The shape of the inner wall surface as viewed from the insertion direction of the probe is polygonal, an imaginary circle showing the circular shape of the circumferential surface and the separating surface are continuously in contact with each other, and the separating surface and the circumferential surface appear alternately in the inner circumferential direction of the inner wall surface. It is characterized by: Effect of the Invention

[0008] According to the present invention, it is possible to provide a friction stir spot welding apparatus that can reduce unnecessary manufacturing costs when attempting to paint the workpieces after friction stir welding. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a plan view of the friction stir spot welding apparatus according to embodiment 1, as viewed from the press-fitting side. [Diagram 2] FIG. 1 is a perspective view of a friction stir spot welding apparatus according to a first embodiment as viewed from a press-fitting side. [Diagram 3] 3A to 3C are vertical sectional views for explaining the operation of the friction stir spot welding apparatus according to the first embodiment over time. [Figure 4] 3A to 3C are vertical sectional views for explaining the operation of the friction stir spot welding apparatus according to the first embodiment over time. [Diagram 5] 3A to 3C are vertical sectional views for explaining the operation of the friction stir spot welding apparatus according to the first embodiment over time. [Figure 6] FIG. 2 is a vertical sectional view of workpieces after friction stir welding according to the first embodiment. [Figure 7] FIG. 2 is a plan view of workpieces after friction stir welding according to the first embodiment. [Figure 8] FIG. 11 is a plan view of the friction stir spot welding apparatus according to the second embodiment, as viewed from the press-fitting side. [Figure 9] FIG. 11 is a perspective view of a friction stir spot welding apparatus according to a second embodiment as viewed from the press-fitting side. [Figure 10] FIG. 11 is a plan view of the friction stir spot welding apparatus according to the third embodiment, as viewed from the press-fitting side. [Figure 11] FIG. 11 is a perspective view of a friction stir spot welding apparatus according to a third embodiment, as viewed from the press-fitting side. [Figure 12] FIG. 11 is a vertical sectional view of workpieces during friction stir welding in embodiment 3. [Figure 13] 13 is a cross-sectional view taken along line AA in FIG. 12. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Several embodiments of the present invention will now be described. [Embodiment 1] The friction stir spot welding apparatus in each embodiment is an apparatus for spot joining multiple materials (workpieces) including a plate-shaped first material and a second material arranged so as to abut against the opposing surface of the first material by friction stir welding.

[0011] Fig. 1 is a plan view of the friction stir spot welding apparatus according to embodiment 1 as viewed from the press-fitting side, and Fig. 2 is a perspective view of the friction stir spot welding apparatus as viewed from the press-fitting side. This friction stir spot welding apparatus 1 is equipped with a probe 2 that is rotatable around a central axis C. Figures 1 and 2 show only the press-in side (tip side) of this probe 2. The base end side of the probe 2 is supported by a robot arm (not shown) or the like, and is configured to be able to spot-join desired positions of the materials to be joined (any point in the portion where the first material and the second material are overlapped) by friction stir welding.

[0012] The tip side of the probe 2 is provided with a cylindrical shoulder portion 3. A cylindrical pin portion 5 is provided on a bottom surface 4 of the shoulder portion 3, the pin portion 5 having a central axis C as its axis and protruding toward the press-fit side (tip side) along the central axis C. A recess 6 is formed around the pin portion 5 on the bottom surface 4, recessed toward the base end side of the probe 2. A protrusion 7 is formed on the outer periphery of the recess 6, protruding toward the press-fit side (tip side).

[0013] The inner wall surface 11, which is the inner peripheral surface of the protrusion 7, protrudes from the shoulder portion 3 toward the press-fit side (tip side), and is provided so that a circumferential surface 12, which is a surface at a constant distance from the central axis C, and a separated surface 13, which is a surface provided continuously with the circumferential surface 12 and spaced outward from the circumferential surface 12, appear alternately in the circumferential direction. The circumferential surface 12 is a surface in which a part of an arc of an imaginary circle 18 shown by a broken line in FIG. 1 is continued in the length direction of the probe 2 with the central axis C as the center. However, in this embodiment 1, the circumferential surface 12 is a very narrow surface that is only approximately tangent to the circle 18, and is an approximately linear surface. The shape of the inner wall surface 11 when viewed from the insertion direction of the probe 2 is a polygonal shape. In the example of FIG. 1 and FIG. 2, this is a quadrangle shape, but it may be a triangle shape or a pentagon shape. Therefore, the inner wall surface 11 has a corner portion 14, which is the part spaced outwardly from the separated surface 13.

[0014] Next, the operation of the friction stir spot welding apparatus 1 will be described. FIGS. 3 to 5 are longitudinal sectional views for explaining the operation of the friction stir spot welding apparatus 1 over time in this order. In FIG. 3, the workpiece 101 to be welded by the friction stir spot welding apparatus 1 is made of a plurality of materials including a plate-shaped first material 102 and a second material 104 arranged so as to abut against an opposing surface 103 of the first material 102. In this example, the workpiece 101 also includes a third material 106 arranged so as to abut against an opposing surface 105 of the second material 104. Of course, the workpiece 101 may be only the first material 102 and the second material 104, or may further include a fourth material. Each material of the workpiece 101 is generally a metal material such as aluminum or iron.

[0015] First, the probe 2 (with both the shoulder portion 3 and the pin portion 5 rotating integrally) is operated by the robot arm or the like described above to press the tip of the probe 2 against the workpiece 101 and rotate the probe 2. This causes plastic flow around the pin portion 5 in the workpiece 101, and the pin portion 5 is pressed into the workpiece 101. Next, as shown in Fig. 4, the pin portion 5 is pressed deeper into the workpiece 101 than in the stage of Fig. 3. As a result, a burr 111 is formed around the part of the workpiece 101 where the pin portion 5 is pressed in, spreading outward toward the tip.

[0016] Next, as shown in Fig. 5, the pin portion 5 is pressed deeper into the workpiece 101 than in the stage of Fig. 4. At this time, if the first material 102, the second material 104, and the third material 106 are the same material, they undergo plastic flow and are mixed together. At this time, it is possible to restrict the burr 111 from protruding outward beyond the pin portion 5 and the inner wall surface 11 between the pin portion 5 and the inner wall surface 11. In other words, by forming the outer periphery of the burr 111 into a circular ring shape by the circumferential surface 12 and providing the separating surface 13, it is possible to suppress the plastic flow of the burr 111 caused by frictional heat between the circumferential surface 12 and the burr 111, and to prevent the burr 111 from flowing outward beyond the lower end of the inner wall surface 11.

[0017] Then, the lower end portion (tip portion of protrusion 7) of inner wall surface 11 comes into contact with the surface of first material 102 when pin portion 5 is pressed into workpiece 101 to the target depth. Whether pin portion 5 has been pressed into workpiece 101 to the target depth can be determined by detecting the current position of the tip portion of probe 2 or by sensing the surface of workpiece 101, and therefore probe 2 is designed so that the lower end portion (tip portion of protrusion 7) of inner wall surface 11 comes into contact with the surface of first material 102 when pin portion 5 is pressed into workpiece 101 to the target depth.

[0018] Through the above-mentioned steps, the workpieces 101 are friction stir welded. FIG. 6 is a vertical cross-sectional view of the workpieces after friction stir welding, and FIG. 7 is a plan view of the same. After friction stir welding, the pin portion 5 is pulled out of the workpieces 101, leaving a hole 121. The inner periphery of this hole 121 was heated and stirred during the friction stir welding operation, but after the operation is completed, it is cooled and solidified, and the first material 102, the second material 104, and the third material 106 are joined. An annular protrusion 122 is formed around the outer surface of the hole 121. The protrusion 122 is formed from the burr 111, and its vertical cross-sectional shape is approximately rectangular.

[0019] In this way, after friction stir welding of the workpieces 101, no burrs 111 with tips warped outward remain, but protrusions 122 with a rectangular cross section remain. Therefore, even if the workpieces 101 are electrodeposition-coated without removing the protrusions 122 after the friction stir welding process, poor coating is unlikely to occur around the protrusions 122. Therefore, the workpieces 101 can be appropriately electrodeposition-coated without providing a process for removing the protrusions 122 after the friction stir welding process, so that unnecessary manufacturing costs can be reduced when attempting to paint the workpieces 101 after friction stir welding.

[0020] Furthermore, the lower end of the inner wall surface 11 comes into contact with the surface of the first material 102 when the pin portion 5 is pressed into the workpiece 101 to a target depth. Therefore, by bringing the lower end of the inner wall surface 11 into contact with the surface of the workpiece 101, it is possible to prevent the burrs 111 removed by cutting from going out of the inner wall surface 11, and the work of removing the burrs 111 can be reduced. Furthermore, the inner wall surface 11 has a polygonal shape when viewed from the tip side of the probe 2. That is, the inner wall surface 11 has a simple shape. Therefore, the inner wall surface 11 can be easily processed in the manufacturing process of the probe 2, and the manufacturing cost can be reduced.

[0021] [Embodiment 2] In each embodiment described below, the same components as those in the embodiment described previously are designated by the same reference numerals as those in the embodiment, and detailed description thereof will be omitted.

[0022] Fig. 8 is a plan view of the friction stir spot welding apparatus according to the second embodiment as viewed from the press-fitting side, and Fig. 9 is a perspective view of the friction stir spot welding apparatus as viewed from the press-fitting side. The friction stir spot welding apparatus 1A according to the second embodiment differs from the friction stir spot welding apparatus 1 according to the first embodiment in the following respect. That is, the range of the circumferential surface 12 of the inner wall surface 11 viewed from the insertion direction of the probe 2 is wider than the range of the separation surface 13. In the first embodiment, the range of the circumferential surface 12 is narrow, so that the circumferential surface 12 is a substantially straight surface, but in the second embodiment, the circumferential surface 12 forms an arc-shaped surface of an imaginary circle 18. Therefore, unlike the first embodiment, in the second embodiment, the shape of the inner wall surface 11 viewed from the insertion direction of the probe 2 does not form a simple polygonal shape, but is a little more complicated.

[0023] In this way, the range of the circumferential surface 12 on the inner wall surface 11 as viewed from the insertion direction of the probe 2 is wider than the range of the separation surface 13, and therefore, in this embodiment 2, an effect is achieved that cannot be achieved in the embodiment 1, as follows. That is, during friction stir welding, the circumferential surface 12 is a surface at a certain distance from the central axis C, and only forms the burr 111, so the burr 111 does not provide excessively large resistance to the circumferential surface 12. And, the range of the circumferential surface 12 on the inner wall surface 11 is wide. On the other hand, since the separation surface 13 forms or cuts the burr 111, the burr 111 provides a certain degree of resistance to the separation surface 13, but the range of the separation surface 13 is narrow. In addition, the time required for the burr, which is heated by frictional heat between the circumferential surface 12 and the burr, to be cooled by the separating surface 13 is shortened, so that the resistance applied during forming or cutting is reduced. Therefore, it is possible to suppress the fluctuation in torque when the probe 2 rotates during friction stir welding, and therefore it is possible to reduce the size of the probe 2 and extend its life.

[0024] [Embodiment 3] Fig. 10 is a plan view of the friction stir spot welding apparatus according to embodiment 3 as viewed from the press-fitting side, and Fig. 11 is a perspective view of the friction stir spot welding apparatus as viewed from the press-fitting side. The friction stir spot welding apparatus 1B according to the third embodiment differs from the friction stir spot welding apparatus 1A according to the second embodiment in the following respects: That is, among the boundary portions between the circumferential surface 12 and the separating surface 13, at least the boundary portion (boundary portion 41) located on the rear side in the rotation direction (arrow 43 direction) of the probe 2 has a radial cross-sectional shape that forms an acute angle θ.

[0025] FIG. 12 is a longitudinal sectional view of the workpieces during friction stir welding in the third embodiment, and FIG. 13 is a sectional view taken along the line AA in FIG. 12. As shown in FIG. 13, the protrusion 122 in the process of being formed during friction stir welding may have a protruding portion 122a protruding from the protrusion 122 in the process of being formed. However, the boundary portion 41 located on the rear side in the rotation direction of the probe 2 has a radial cross-sectional shape in which the circumferential surface 12 and the separation surface 13 form an acute angle θ. That is, the boundary portion 41 is sharp. Therefore, the protruding portion 122a is also reliably cut off by the sharp boundary portion 41. Therefore, burrs are unlikely to remain on the outer periphery of the protrusion 122, and the load on the probe 2 can be reduced. In addition, since the protrusion 122 can be formed into a clean annular shape, defects in the subsequent electrocoating are even less likely to occur.

[0026] Although each embodiment has been described above, it goes without saying that each embodiment is merely an example configuration of the present invention, and the present invention can be embodied in various other forms. [Explanation of symbols]

[0027] 1,1A,1B Friction stir spot welding equipment 2. Probe 3 Shoulder section 4 Bottom 5 Pin section 11 Inner wall surface 12 Circumferential surface 13 Separation surface 41 Boundary part 42 Tip 101 Material to be joined 102 1st material 104 Second material C center axis

Claims

1. A friction stir spot welding apparatus for friction stir welding a plurality of materials including a plate-shaped first material and a second material arranged so as to abut on an opposing surface of the first material, A probe rotatable about a central axis, The probe comprises: a pin portion protruding from a bottom surface of a cylindrical shoulder portion along the central axis; an inner wall surface including a circumferential surface protruding from the shoulder portion and spaced apart from the central axis at a constant distance; and a spaced apart surface that is continuous with the circumferential surface and spaced apart outward from the circumferential surface; having A friction stir spot welding device characterized in that the shape of the inner wall surface when viewed from the insertion direction of the probe is polygonal, a virtual circle indicating the circular shape of the circumferential surface and the separating surface are continuously in contact, and the separating surface and the circumferential surface appear alternately in the inner circumferential direction of the inner wall surface.

2. 2. The friction stir spot welding apparatus according to claim 1, wherein a lower end of the inner wall surface comes into contact with a surface of the first material when the pin portion is pressed into the plurality of materials to a target depth.

3. 2. The friction stir spot welding apparatus according to claim 1, wherein the range of the circumferential surface of the inner wall surface as viewed from the insertion direction of the probe is wider than the range of the separating surface.

4. 2. The friction stir spot welding device according to claim 1, wherein at least the boundary portion between the circumferential surface and the separating surface, which is located on the rear side in the rotation direction of the probe, has a radial cross-sectional shape that forms an acute angle.

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