Spot joining electrode and spot joining device

Abstract

To provide a spot-welding electrode that can suppress degradation in joint quality, and to provide a resistance spot joint device.SOLUTION: A spot joining electrode 100 includes: an electrode body 110 including a flat tip surface 111; and a flexible conductor 120 connected to the tip surface 111 of the electrode body 110. The flexible conductor 120 is elastically deformable so as to fill a gap between the tip surface 111 and workpieces W1, W2 when the electrode body 110 is pressed onto the workpieces W1, W2.SELECTED DRAWING: Figure 11

Description

[Technical field]

[0001] The present disclosure relates to a spot bonding electrode and a spot bonding device. [Background technology]

[0002] For example, JP 2010-131666 A discloses a spot welding electrode. This spot welding electrode has a cylindrical hollow portion in the center near the tip of the electrode that is not in contact with the workpiece, and only the peripheral portion of the cylindrical hollow portion is in contact with the workpiece. The portion of the spot welding electrode that is in contact with the workpiece (the tip of the peripheral portion of the cylindrical hollow portion) is formed flat. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2010-131666 A Summary of the Invention [Problem to be solved by the invention]

[0004] In an electrode such as that described in JP 2010-131666 A, the portion that comes into contact with the workpiece is formed flat, so if the contact between the electrode and the workpiece becomes uneven due to curvature of the workpiece or the like, the joining quality will decrease.

[0005] An object of the present disclosure is to provide a spot welding electrode and a resistance spot joining apparatus that are capable of suppressing deterioration in joining quality. [Means for solving the problem]

[0006] A spot joining electrode according to one aspect of the present disclosure is a spot joining electrode used for spot joining, comprising: an electrode body having a flat tip surface; and a flexible conductor connected to the tip surface of the electrode body, wherein the flexible conductor is elastically deformable so as to fill a gap between the tip surface and the workpiece when the electrode body is pressed against the workpiece.

[0007] Furthermore, a spot joining device according to one aspect of the present disclosure includes the spot joining electrode and a pressure shaft capable of applying pressure to a workpiece, wherein the electrode body of the spot joining electrode is formed in a cylindrical shape, and the pressure shaft is provided inside the electrode body. Effect of the Invention

[0008] According to the present disclosure, it is possible to provide a spot welding electrode and a resistance spot joining apparatus that are capable of suppressing deterioration in joining quality. [Brief description of the drawings]

[0009] [Figure 1] FIG. 2 is a front view of a spot bonding electrode in the first embodiment of the present disclosure. [Diagram 2] FIG. 4 is a bottom view of the spot bonding electrode. [Diagram 3] FIG. 2 is a perspective view of a spot bonding electrode. [Figure 4] FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. [Diagram 5] FIG. 2 is a plan view of a flexible conductor prior to connection to an electrode assembly. [Figure 6] FIG. 2 is a plan view of the flexible conductor after connection to the electrode body. [Figure 7] FIG. 13 is a plan view of a modified example of a flexible conductor before connection to an electrode body. [Figure 8] FIG. 13 is a plan view of a modified example of the flexible conductor after connection to the electrode body. [Figure 9] FIG. 13 is a plan view of a modified example of a flexible conductor before connection to an electrode body. [Figure 10]FIG. 13 is a plan view of a modified example of the flexible conductor after connection to the electrode body. [Figure 11] 10A and 10B are diagrams illustrating an example of contact between a flexible conductor of a spot bonding electrode and a workpiece. [Figure 12] FIG. 11 is a perspective view of a spot joining device according to a second embodiment of the present disclosure. [Figure 13] FIG. [Figure 14] 14 is a cross-sectional view taken along line XIV-XIV in FIG. 13. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present disclosure will now be described with reference to the accompanying drawings, in which the same or corresponding components are designated by the same reference numerals.

[0011] (First embodiment) Fig. 1 is a front view of a spot bonding electrode in a first embodiment of the present disclosure, Fig. 2 is a bottom view of the spot bonding electrode, Fig. 3 is a perspective view of the spot bonding electrode, and Fig. 4 is a cross-sectional view taken along line IV-IV in Fig. 2.

[0012] As shown in FIGS. 1 to 4, the spot bonding electrode 100 includes an electrode body 110 and a flexible conductor 120. The electrode body 110 and the flexible conductor 120 are made of a material such as aluminum.

[0013] The electrode body 110 is made of, for example, copper. The electrode body 110 has a tip surface 111 and a tapered surface 112.

[0014] The tip surface 111 is formed to be flat. In this embodiment, the tip surface 111 is formed to be circular.

[0015] The tapered surface 112 has a ring-shaped configuration that slopes away from the tip surface 111 in the axial direction (up and down direction in Figure 1) of the electrode body 110 as it moves away from the tip surface 111 in the radial direction (left and right direction in Figure 1) of the electrode body 110.

[0016] The flexible conductor 120 is connected to the tip surface 111 of the electrode body 110. The flexible conductor 120 is elastically deformable so as to fill the gap between the tip surface 111 and the workpieces W1, W2 when the electrode body 110 is pressed against the workpieces W1, W2 (see FIG. 11). In this embodiment, the flexible conductor 120 is made of a stranded wire such as copper. That is, the flexible conductor 120 includes an air gap. As shown in FIG. 2 and FIG. 3, the flexible conductor 120 is formed in an annular shape. However, the shape of the flexible conductor 120 is not limited to an annular shape.

[0017] As shown in FIGS. 1 to 4, the flexible conductor 120 has a flexible portion 122 and a joint portion .

[0018] The flexible portion 122 is elastically deformed when the electrode body 110 is pressed against the workpieces W1 and W2.

[0019] The joint 124 is recessed from the flexible portion 122 toward the tip surface 111, and is joined to the tip surface 111. The compressive elastic modulus of the joint 124 in the pressing direction (downward in FIG. 1) in which the tip surface 111 is pressed against the workpieces W1, W2 is greater than the compressive elastic modulus of the flexible portion 122 in the pressing direction. In this embodiment, the joint 124 is connected to the tip surface 111 by ultrasonic welding.

[0020] FIG. 5 is a plan view of the flexible conductor before connection to the electrode body. FIG. 6 is a plan view of the flexible conductor after connection to the electrode body. As shown in FIG. 5 and FIG. 6, the flexible conductor 120 is joined to the distal end surface 111 by ultrasonic welding after two or more strands of twisted wire are twisted and formed into a ring shape. However, as shown in FIG. 7 and FIG. 8, one strand of twisted wire may be braided into a lily-knitted shape and then joined to the distal end surface 111 by ultrasonic welding. Alternatively, as shown in FIG. 9 and FIG. 10, three strands of twisted wire may be braided into a ring shape and then joined to the distal end surface 111 by ultrasonic welding.

[0021] As described above, in the spot joining electrode 100 of this embodiment, even if the surfaces of the workpieces W1, W2 are not flat, as shown in FIG. 11, when the tip surface 111 of the electrode body 110 is pressed against the workpieces W1, W2, the flexible portion 122 of the flexible conductor 120 elastically deforms so as to fill the gap between the tip surface 111 and the surfaces of the workpieces W1, W2, thereby suppressing a deterioration in joining quality caused by uneven contact between the flexible conductor 120 and the workpieces W1, W2.

[0022] Furthermore, since the compressive elastic modulus of the joint 124 in the pressing direction is greater than the compressive elastic modulus of the flexible part 122 in the pressing direction, by utilizing the difference in the compressive elastic modulus between the flexible part 122 and the joint 124, it is possible to detect that the joint 124 has come into contact with the workpieces W1, W2, i.e., the wear of the flexible part 122.

[0023] For example, contact of the joint 124 with the workpieces W1 and W2 can be detected by determining whether or not the load required to move the electrode body 110 a preset distance in the pressing direction exceeds a reference value.

[0024] Second embodiment Next, a spot joining device 1 according to a second embodiment of the present disclosure will be described with reference to Figs. 12 to 14. Fig. 12 is a perspective view of the spot joining device according to the second embodiment of the present disclosure. Fig. 13 is a bottom view of the spot joining device. Fig. 14 is a cross-sectional view taken along line XIV-XIV in Fig. 13. Note that in the second embodiment, only parts different from the first embodiment will be described, and descriptions of the same structure, action, and effect as those in the first embodiment will not be repeated.

[0025] The spot welding device 1 is a device for forming softened regions in multiple workpieces W1, W2 stacked on top of each other by passing an electric current through the multiple workpieces W1, W2 and joining the multiple workpieces W1, W2 together in a solid phase by plastically deforming the softened regions. The spot welding device 1 includes a pair of spot welding electrodes 100 and a pair of pressure shafts 200.

[0026] The electrode body 110 of the spot bonding electrode 100 in this embodiment is formed in a cylindrical shape. That is, the tip surface 111 is formed in an annular shape.

[0027] The pair of pressure applying shafts 200 apply pressure to the workpieces W1, W2 from both sides in the thickness direction thereof during spot joining. The pair of pressure applying shafts 200 are driven by a drive source (such as a servo press machine) not shown. The pressure applying shaft 200 is provided inside the electrode body 110. The pressure applying shaft 200 is formed in a cylindrical shape. A gap is formed between the outer peripheral surface of the pressure applying shaft 200 and the electrode body 110. The pressure applying shaft 200 can apply pressure to the workpieces W1, W2 so that the workpieces W1, W2 are plastically deformed. The pressure applying shaft 200 is made of, for example, tungsten carbide.

[0028] The pair of spot bonding electrodes 100 are capable of passing electricity through the workpieces W1, W2 in a state of contacting the areas surrounding the areas of the workpieces W1, W2 that are pressed by the pair of pressing shafts 200.

[0029] It will be appreciated by those skilled in the art that the exemplary embodiments described above are examples of the following aspects.

[0030] [Aspect 1] A spot bonding electrode used for spot bonding, An electrode body having a flat tip surface; a flexible conductor connected to the distal end surface of the electrode body; The flexible conductor is elastically deformable so as to fill a gap between the tip surface and the workpiece when the electrode body is pressed against the workpiece.

[0031] With this spot joining electrode, even if the surface of the workpiece is not flat, when the tip surface of the electrode body is pressed against the workpiece, the flexible conductor elastically deforms to fill the gap between the tip surface and the surface of the workpiece, thereby preventing a decrease in joining quality due to uneven contact between the flexible conductor and the workpiece.

[0032] [Aspect 2] 2. The spot bonding electrode according to claim 1, wherein the flexible conductor is formed in a ring shape.

[0033] In this embodiment, a large diameter of the nugget is ensured, and therefore the joining strength is increased.

[0034] [Aspect 3] The flexible conductor includes: a flexible portion that elastically deforms when the electrode body is pressed against the workpiece; a joint portion recessed from the flexible portion toward the tip surface and joined to the tip surface, 3. The spot joining electrode according to aspect 1 or 2, wherein a compressive elastic modulus of the joining portion in a pressing direction in which the tip surface is pressed against the workpiece is greater than a compressive elastic modulus of the flexible portion in the pressing direction.

[0035] In this embodiment, by utilizing the difference in compressive elastic modulus between the flexible portion and the joint portion, it is possible to detect the contact of the joint portion with the workpiece, i.e., the wear of the flexible portion.

[0036] [Aspect 4] The spot bonding electrode according to aspect 2, A pressure shaft capable of applying pressure to a workpiece, The electrode body of the spot bonding electrode is formed in a cylindrical shape, A spot bonding device, wherein the pressure shaft is provided inside the electrode body.

[0037] It should be noted that the embodiments disclosed herein are illustrative in all respects and should not be considered as limiting. The scope of the present invention is indicated by the claims, not by the description of the embodiments above, and further includes all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0038] 1 spot bonding device, 100 spot bonding electrode, 110 electrode body, 111 tip surface, 120 flexible conductor, 122 flexible portion, 124 bonding portion, 200 pressure shaft, W1 first workpiece, W2 second workpiece.

Claims

1. A spot bonding electrode used for spot bonding, An electrode body having a flat tip surface; a flexible conductor connected to the distal end surface of the electrode body; The flexible conductor is elastically deformable so as to fill a gap between the tip surface and the workpiece when the electrode body is pressed against the workpiece.

2. The spot bonding electrode according to claim 1 , wherein the flexible conductor is formed in a ring shape.

3. The flexible conductor includes: a flexible portion that elastically deforms when the electrode body is pressed against the workpiece; a joint portion recessed from the flexible portion toward the tip surface and joined to the tip surface, The spot joining electrode according to claim 1 or 2, wherein a compressive elastic modulus of the joining portion in a pressing direction in which the tip end surface is pressed against the workpiece is greater than a compressive elastic modulus of the flexible portion in the pressing direction.

4. The spot bonding electrode according to claim 2 ; A pressure shaft capable of applying pressure to a workpiece, The electrode body of the spot bonding electrode is formed in a cylindrical shape, A spot bonding device, wherein the pressure shaft is provided inside the electrode body.

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