Electrodes and solid-phase resistance spot bonding apparatus for solid-phase resistance spot bonding

Abstract

To provide an electrode for solid-phase resistance spot bonding that can suppress the deterioration of bonding quality. [Solution] The solid-phase resistance spot bonding electrode 10 comprises a cylindrical portion 11 that extends in the axial direction and has one end portion 12 in the axial direction. The end portion 12 includes a tip surface 14 that is pressed against the workpieces 301, 302. The end portion 12 is divided into multiple pieces that are spaced apart from each other in the circumferential direction of the cylindrical portion 11 when viewed from the tip surface 14 side, by having multiple slits 50 cut into it in the axial direction.

Description

Technical Field

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[0001] The present invention relates to an electrode for solid-phase resistance spot welding and a solid-phase resistance spot welding apparatus provided with the same.

Background Art

[0002] For example, Japanese Patent Application Laid-Open No. 2010-131666 (Patent Document 1) discloses an electrode for spot welding. In this electrode for spot welding, a cylindrical hollow portion that does not contact the workpiece is provided at the central portion near the tip of the electrode, and only the peripheral edge portion of the cylindrical hollow portion contacts the workpiece. The portion of the electrode for spot welding that contacts the workpiece (that is, the tip portion of the peripheral edge portion of the cylindrical hollow portion) is formed in a flat shape.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the electrode as described in Patent Document 1 above, since the portion that contacts the workpiece is formed in a flat shape, when the contact between the electrode and the workpiece becomes uneven due to the curvature of the workpiece or the like, there is a problem that the joining quality deteriorates.

[0005] Therefore, the present invention has been made to solve the above-described problems, and an object thereof is to provide an electrode for solid-phase resistance spot welding and a solid-phase resistance spot welding apparatus capable of suppressing a decrease in joining quality.

Means for Solving the Problems

[0006] The solid-phase resistance spot bonding electrode according to the present invention comprises a cylindrical portion that extends in the axial direction and has one end in the axial direction. The end includes a tip surface that is pressed against a workpiece. The end is divided into multiple pieces that are spaced apart from each other in the circumferential direction of the cylindrical portion, as viewed from the tip surface side, by having multiple slits cut into it in the axial direction.

[0007] By configuring it in this way, it is possible to create a solid-phase resistance spot bonding electrode that can suppress the deterioration of bonding quality.

[0008] In the solid-phase resistance spot bonding electrode according to the present invention described above, the cylindrical portion may have a base portion provided adjacent to the one end portion in the axial direction. The plurality of slits may be cut in the axial direction so as to penetrate the one end portion and reach a part of the base portion. The one end portion may be widened in a flange-like manner relative to the base portion.

[0009] By configuring it in this way, the elastic deformation of one end is promoted at the base of the part that is configured to have lower rigidity than the other end, and as a result, uneven contact between the tip surface and the workpiece is dramatically suppressed.

[0010] In the solid-phase resistance spot bonding electrode according to the present invention described above, the one end and the base may be formed integrally.

[0011] By configuring it in this way, the deterioration of bonding quality can be suppressed without providing other components to the solid-phase resistance spot bonding electrode, resulting in lower costs and improved maintainability.

[0012] In the solid-phase resistance spot bonding electrode according to the present invention described above, the outer edge of the tip surface may be inclined such that it approaches the base in the axial direction as it approaches the outer edge of the tip surface.

[0013] This configuration makes it easier to make the tip surface conform to the surface of the workpiece.

[0014] The solid-phase resistance spot bonding apparatus according to the present invention comprises a solid-phase resistance spot bonding electrode according to the present invention and a pressure shaft capable of applying pressure to the workpiece. The pressure shaft is provided inside the solid-phase resistance spot bonding electrode.

[0015] By configuring it in this way, a solid-phase resistance spot bonding apparatus can be created that can suppress the deterioration of bonding quality. [Effects of the Invention]

[0016] According to the present invention, it is possible to provide a solid-phase resistance spot bonding electrode and a solid-phase resistance spot bonding apparatus that can suppress a decrease in bonding quality. [Brief explanation of the drawing]

[0017] [Figure 1] This is a schematic cross-sectional view illustrating a solid-phase resistance spot bonding apparatus according to an embodiment. [Figure 2] This is a perspective view of an electrode for solid-phase resistance spot bonding according to an embodiment. [Figure 3] Figure 2 is a side view of the solid-phase resistance spot bonding electrode shown. [Figure 4] Figure 2 is a bottom view of the solid-phase resistance spot bonding electrode shown. [Figure 5] Figure 2 is a plan view of the electrode for solid-phase resistance spot bonding shown in Figure 2. [Figure 6] Figure 2 is a schematic cross-sectional view showing a solid-phase resistance spot bonding process using the solid-phase resistance spot bonding electrode shown. [Figure 7] Figure 2 is a schematic cross-sectional view showing a solid-phase resistance spot bonding process using the solid-phase resistance spot bonding electrode shown. [Modes for carrying out the invention]

[0018] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the embodiments shown below, the same or common parts are denoted by the same reference numerals in the drawings, and the description thereof will not be repeated.

[0019] (Embodiment) <A. Schematic Configuration of Solid-Phase Resistance Spot Joining Device> FIG. 1 is a schematic cross-sectional view schematically showing a solid-phase resistance spot joining device according to an embodiment. Hereinafter, with reference to FIG. 1, a schematic configuration of the solid-phase resistance spot joining device 1 including the solid-phase resistance spot joining electrode 10 according to the present embodiment will be described.

[0020] The solid-phase resistance spot joining device 1 is a device used for so-called solid-phase resistance spot joining, in which a plurality of workpieces are joined to each other in a solid state at a low temperature range without melting. Specifically, the solid-phase resistance spot joining device 1 forms a softened region in a plurality of stacked workpieces by applying a voltage thereto, and plastically deform the softened region by applying a load to the plurality of workpieces in a state where the softened region is formed.

[0021] In the present embodiment, plate-like workpieces 301 and 302 are joined to each other by the solid-phase resistance spot joining device 1. The number of workpieces is not particularly limited to two, and may be three or more. Also, in the present embodiment, the direction orthogonal to the in-plane direction of the workpieces 301 and 302 is also referred to as the Z-axis direction.

[0022] The workpieces 301 and 302 are made of, for example, a steel plate such as a high-tensile material. The workpieces 301 and 302 are not particularly limited to those made of a steel plate, and may be made of an aluminum plate or the like. Also, the workpieces 301 and 302 may be made of different materials such as a steel plate and an aluminum plate.

[0023] As shown in Figure 1, the solid-phase resistance spot bonding apparatus 1 comprises a first bonding unit 110 and a second bonding unit 120. The first bonding unit 110 and the second bonding unit 120 are designed to press and clamp multiple overlapping workpieces.

[0024] The first bonding unit 110 includes a first electrode 111 and a first pressing shaft 112. The first bonding unit 110 is driven in the Z-axis direction by a drive device such as a servo press (not shown). Power is supplied to the first bonding unit 110 from a power supply (not shown) (not shown).

[0025] The first electrode 111 has a substantially cylindrical shape. The first electrode 111 is positioned around the first pressure shaft 112 such that it is radially spaced away from the first pressure shaft 112. The first electrode 111 applies voltage to the workpieces 301 and 302. The detailed configuration of the first electrode 111 will be described in detail later.

[0026] The first pressurizing shaft 112 has a substantially cylindrical portion. The first pressurizing shaft 112 causes plastic deformation of the stacked workpieces 301 and 302 by applying pressure along the Z-axis direction. The first pressurizing shaft 112 is located inside the first electrode 111.

[0027] The second bonding unit 120 has a second electrode 121 and a second pressure shaft 122. Power is supplied to the second bonding unit 120 from a power source (not shown) (not shown).

[0028] The second electrode 121 has a substantially cylindrical shape. The second electrode 121 is positioned around the second pressure shaft 122 such that it is radially spaced away from the second pressure shaft 122. The second electrode 121 applies voltage to the workpieces 301 and 302. The detailed configuration of the second electrode 121 will be described in detail later.

[0029] The second pressing shaft 122 has a substantially cylindrical portion. The second pressing shaft 122 plastically deform the overlapped workpieces 301, 302 by pressing them along the Z-axis direction. The second pressing shaft 122 is provided inside the second electrode 121.

[0030] The materials of the first electrode 111 and the second electrode 121 are, for example, copper. The materials of the first pressing shaft 112 and the second pressing shaft 122 are, for example, tungsten carbide. Note that the materials of the first pressing shaft 112 and the second pressing shaft 122 are not particularly limited to tungsten carbide as long as they can press the workpieces 301, 302 so that they can be plastically deformed, and may be tool steel, heat-resistant steel, ceramics, or the like.

[0031] The first electrode 111 and the second electrode 121 have the same configuration, and in the present embodiment, each of them corresponds to an electrode for solid-phase resistance spot welding. Therefore, hereinafter, when the first electrode 111 and the second electrode 121 are not distinguished, they are collectively referred to as the solid-phase resistance spot welding electrode 10.

[0032] Also, in the present embodiment, each of the first pressing shaft 112 and the second pressing shaft 122 corresponds to a pressing shaft.

[0033] <C The first joining unit 110 and the second joining unit 120 are attached to a gun arm (not shown) or the like, and are coaxially positioned and face each other in the Z-axis direction.

[0034] The first joining unit 110 is driven in the Z-axis direction by a driving device as described above. Thereby, the first joining unit 110 is configured to be relatively movable with respect to the second joining unit 120 along the Z-axis direction.

[0035] <B. Detailed Configuration of Electrode for Solid-Phase Resistance Spot Welding> Figure 2 is a perspective view of a solid-phase resistance spot bonding electrode according to an embodiment. Figure 3 is a side view of the solid-phase resistance spot bonding electrode shown in Figure 2. Figure 4 is a bottom view of the solid-phase resistance spot bonding electrode shown in Figure 2. Figure 5 is a plan view of the solid-phase resistance spot bonding electrode shown in Figure 2. Hereinafter, the detailed configuration of the solid-phase resistance spot bonding electrode 10 according to this embodiment will be described with reference to Figures 2 to 5 and the aforementioned Figure 1.

[0036] As shown in Figures 1 to 5, the solid-phase resistance spot bonding electrode 10 has a cylindrical portion 11 that extends in the axial direction. When the solid-phase resistance spot bonding electrode 10 is assembled to the solid-phase resistance spot bonding apparatus 1, the axial direction coincides with the Z-axis direction.

[0037] The cylindrical portion 11 has an axial end 12 and a base 13 provided adjacent to the end 12 in the axial direction. The entire cylindrical portion 11, including the end 12 and the base 13, is integrally formed.

[0038] One end portion 12 is flanged in diameter relative to the base portion 13. More specifically, one end portion 12 is flanged in diameter relative to the end portion 12 side of the base portion 13. Therefore, the rigidity of at least the end portion 12 side of the base portion 13 is lower than the rigidity of the flanged one end portion 12.

[0039] One end portion 12 includes a tip surface 14 that is pressed against the workpiece during solid-phase resistance spot bonding. When viewed along the axial direction, the tip surface 14 has a substantially annular shape (see Figure 4).

[0040] The outer edge portion 14a of the tip surface 14 is inclined so that it approaches the base portion 13 in the axial direction as it approaches the outer edge of the tip surface 14. The inner edge portion 14b of the tip surface 14 is inclined so that it approaches the base portion 13 in the axial direction as it approaches the inner edge of the tip surface 14.

[0041] The end of the base 13 opposite to the end on the side of the one end 12 is connected to a holder (not shown) that holds the solid-phase resistance spot welding electrode 10. Specifically, a male screw (not shown) is provided at the above-mentioned end of the base 13. By screwing this male screw into the female screw of the holder, the solid-phase resistance spot welding electrode 10 is held by the holder.

[0042] The base 13 has a flange portion 13a in the intermediate portion in the axial direction. In the state where the holder is connected to the solid-phase resistance spot welding electrode 10, the end face of the holder abuts against the flange portion 13a. The power of the power source is supplied to the solid-phase resistance spot welding electrode 10 through the holder. The main surface located on the side opposite to the one end 12 side of the flange portion 13a functions as the power supply surface of the solid-phase resistance spot welding electrode 10.

[0043] A plurality of slits 50 are cut in the axial direction in the one end 12. As a result, when viewed from the tip surface 14 side, the one end 12 is divided into a plurality of pieces arranged at intervals in the circumferential direction of the cylindrical portion 11 (see FIG. 4). The plurality of slits 50 are cut in the axial direction so as to penetrate the one end 12 and reach a part of the base 13. Specifically, the plurality of slits 50 are cut from the one end 12 to reach the portion of the base 13 on the side of the one end 12 rather than the flange portion 13a.

[0044] In the present embodiment, six slits 50 are provided radially when viewed from the tip surface 14 side. The number of slits 50 is not particularly limited to six, and two or more are sufficient.

[0045] <C. Solid-phase resistance spot welding> FIGS. 6 and 7 are cross-sectional views schematically showing the state of solid-phase resistance spot welding using the solid-phase resistance spot welding electrode shown in FIG. 2. Hereinafter, with reference to FIGS. 6 and 7, the state of solid-phase resistance spot welding using the solid-phase resistance spot welding electrode 10 will be described.

[0046] As shown in Figure 6, when joining workpieces 301 and 302 to each other using the solid-phase resistance spot bonding apparatus 1, first, the workpieces 301 and 302 are pressed from both sides by sandwiching them in the Z-axis direction with the first pressing shaft 112 and the second pressing shaft 122. The pressing force on the workpieces 301 and 302 by the first pressing shaft 112 and the second pressing shaft 122 is, for example, 30kN to 70kN.

[0047] Next, as shown in Figure 7, a voltage is applied to the workpieces 301 and 302 by pressing the first electrode 111 and the second electrode 121 against the workpieces 301 and 302 while a pressing force is applied to them. This heats the workpieces 301 and 302, forming softened regions, and the workpieces 301 and 302 are joined together in these softened regions. The current supplied to the workpieces 301 and 302 is, for example, 3.5kA to 10kA.

[0048] In this case, the surface of the workpiece against which the solid-phase resistance spot bonding electrode 10 is pressed may not be flat. This is because the surface of the workpiece may not have been formed flat to begin with, or the surface of the workpiece, which was originally flat, may be deformed by the pressure axis.

[0049] In this regard, as described above, the solid-phase resistance spot bonding electrode 10 according to this embodiment is divided into multiple pieces by having multiple slits 50 cut into one end portion 12, which includes the tip surface 14.

[0050] With this configuration, even when the surface of the workpiece is not flat, when the tip surface 14 is pressed against the workpiece, each piece constituting one end 12 elastically deforms so as to spread radially outward to follow the surface of the workpiece (see arrow AR in Figure 7). As a result, the gap between the tip surface 14 of each piece and the surface of the workpiece is filled, and the deterioration of bonding quality caused by uneven contact between the tip surface 14 and the workpiece is effectively suppressed.

[0051] Therefore, by configuring the solid-phase resistance spot bonding electrode 10 according to this embodiment, it is possible to suppress a decrease in bonding quality.

[0052] Furthermore, in this embodiment, as described above, one end portion 12 is flanged and widened relative to the base portion 13, and multiple slits 50 are cut through the one end portion 12 and reach a part of the base portion 13.

[0053] By configuring it in this way, the elastic deformation of the aforementioned piece is promoted at the base 13 of the part that is configured to have lower rigidity than the end 12, and as a result, uneven contact between the tip surface 14 and the workpiece is dramatically suppressed.

[0054] Furthermore, in this embodiment, as described above, the outer edge 14a of the tip surface 14 is inclined so that it approaches the base 13 in the axial direction as it approaches the outer edge of the tip surface 14. This configuration makes it easier to make the tip surface 14 conform to the surface of the workpiece.

[0055] Furthermore, in this embodiment, as described above, the inner edge portion 14b of the tip surface 14 is inclined such that it approaches the base portion 13 in the axial direction as it approaches the inner edge of the tip surface 14.

[0056] With this configuration, when the tip surface 14 is pressed against the workpiece, a reaction force from the workpiece is applied radially outward to the inner edge 14b. This reaction force promotes the elastic deformation of the aforementioned piece, and as a result, uneven contact between the tip surface 14 and the workpiece is further suppressed.

[0057] In this embodiment, the example shown is that the base 13 has a flange portion 13a. However, if, for example, the screw-fitting relationship between the male thread of the base 13 and the female thread of the holder is reversed (i.e., the base 13 has a female thread and the holder has a male thread), and the power supply path to the solid-phase resistance spot bonding electrode 10 is appropriately adjusted, the base 13 does not necessarily have to have a flange portion 13a.

[0058] (Note) The characteristic configurations of the solid-phase resistance spot bonding electrode and the solid-phase resistance spot bonding apparatus equipped therewith disclosed in the above-described embodiment can be summarized as follows.

[0059] [Note 1] It comprises a cylindrical portion that extends in the axial direction and has one end in the axial direction, The above end includes a tip surface that is pressed against the workpiece, The above end is divided into multiple pieces that are spaced apart from each other in the circumferential direction of the cylindrical portion, as viewed from the tip side, by having multiple slits cut in the axial direction, and is used as a solid-phase resistive spot bonding electrode.

[0060] [Note 2] The cylindrical portion has a base portion provided adjacent to the one end portion in the axial direction, The above-mentioned multiple slits are cut in the axial direction so as to penetrate one end and reach a part of the base, The above-mentioned end is flanged in diameter relative to the base, and is a solid-phase resistance spot bonding electrode as described in Appendix 1.

[0061] [Note 3] The above-mentioned end portion and the above-mentioned base portion are integrally formed, and the electrode for solid-phase resistance spot bonding as described in Appendix 2.

[0062] [Note 4] The solid-phase resistive spot bonding electrode according to Appendix 2 or 3, wherein the outer edge of the tip surface is inclined so as it approaches the outer edge of the tip surface, it approaches the base in the axial direction.

[0063] [Note 5] A solid-phase resistive spot bonding electrode described in any one of the appendices 1 to 4, The system includes a pressurizing shaft capable of pressurizing the above workpiece, The above-mentioned pressure shaft is provided inside the above-mentioned solid-phase resistance spot bonding electrode, in a solid-phase resistance spot bonding apparatus.

[0064] (Other forms, etc.) The shape, configuration, size, number, material, etc., of each part shown in the above-described embodiment can be modified in various ways as long as they do not depart from the spirit of the present invention.

[0065] Furthermore, the characteristic configurations shown in the above-described embodiments can naturally be combined with each other without departing from the spirit of the present invention.

[0066] Thus, the embodiments disclosed herein are illustrative in all respects and not restrictive. The technical scope of the present invention is defined by the claims and includes all modifications within the meaning and scope of equivalents to the claims. [Explanation of symbols]

[0067] 1 Solid-phase resistance spot bonding apparatus, 10 Electrode for solid-phase resistance spot bonding, 11 Cylindrical section, 12 One end, 13 Base, 14 Tip surface, 14a Outer edge, 50 Slit, 301, 302 Workpiece.

Claims

1. It comprises a cylindrical portion that extends in the axial direction and has one end in the axial direction, The aforementioned end includes a tip surface that is pressed against the workpiece, The aforementioned end portion is divided into multiple pieces that are spaced apart from each other in the circumferential direction of the cylindrical portion, as viewed from the tip surface side, by having multiple slits cut in the axial direction, thereby providing a solid-phase resistance spot bonding electrode.

2. The cylindrical portion has a base portion provided adjacent to the one end in the axial direction, The plurality of slits are cut in the axial direction so as to penetrate one end and reach a part of the base, The solid-phase resistance spot bonding electrode according to claim 1, wherein one end is flanged in diameter relative to the base.

3. The solid-phase resistive spot bonding electrode according to claim 2, wherein the one end and the base are formed integrally.

4. The solid-phase resistance spot bonding electrode according to claim 2, wherein the outer edge of the tip surface is inclined to approach the base in the axial direction as it approaches the outer edge of the tip surface.

5. A solid-phase resistance spot bonding electrode according to any one of claims 1 to 4, The system includes a pressurizing shaft capable of pressurizing the aforementioned workpiece, A solid-phase resistance spot bonding apparatus, wherein the pressure shaft is provided inside the solid-phase resistance spot bonding electrode.

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