Solid-phase resistance spot bonding device

Abstract

To miniaturize a drive mechanism of an electrode.SOLUTION: A solid-phase spot joining device includes a drive source 30, and a joining unit 10. The joining unit 10 is driven in an axial direction by the drive source 30. The joining unit 10 includes a pressurization shaft 100, an electrode 110, and an elastic member 150. The pressurization shaft 100 presses a plurality of overlapped joined objects 2 from the axial direction in a plastic deformable manner. The electrode 110 is arranged around the pressurization shaft 100, and applies a voltage to the plurality of joined objects 2. The elastic member 150 energizes the electrode 110 toward the plurality of joined objects 2. The drive source 30 drives the joint unit 10, and thereby brings the electrode 110 into contact with the joined object 2a positioned on the side of the electrode 110 out of the plurality of joined objects 2, and presses the pressurization shaft 100 against the plurality of joined objects 2 while pressing the electrode 110 against the plurality of joined objects 2 by energization force of the elastic member 150.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a solid-phase resistance spot welding apparatus.

Background Art

[0002] As a prior art document that discloses a solid-phase resistance spot welding apparatus, there is International Publication No. 2021 / 182444 (Patent Document 1). The solid-phase resistance spot welding apparatus described in Patent Document 1 includes a central pressure shaft and a copper electrode. The central pressure shaft applies an external stress equal to or greater than the yield strength of the metal plate at the welding temperature to the metal plate. The copper electrode conducts an electric current through the metal plate to heat the metal plate. The copper electrode is controlled by a separate drive from the central pressure shaft. The electrode is driven by an air cylinder to apply a load to the metal plate.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the solid-phase resistance spot welding apparatus described in Patent Document 1, there is room for miniaturizing the drive mechanism of the electrode pressed against the workpiece by an air cylinder.

[0005] The present invention has been made to solve the above problems, and an object thereof is to provide a solid-phase resistance spot welding apparatus capable of miniaturizing the drive mechanism of the electrode.

Means for Solving the Problems

[0006] The solid-phase resistance spot bonding apparatus according to the present invention comprises a drive source and a bonding unit. The bonding unit is driven axially by the drive source. The bonding unit includes a pressure shaft, electrodes, and an elastic member. The pressure shaft presses a plurality of stacked objects to be bonded in a plastically deformable manner from the axial direction. The electrodes are arranged around the pressure shaft and apply a voltage to the plurality of objects to be bonded. The elastic member biases the electrodes toward the plurality of objects to be bonded. By driving the bonding unit, the drive source brings the electrodes into contact with the object located on the electrode side of the plurality of objects to be bonded, and the biasing force of the elastic member presses the electrodes toward the plurality of objects to be bonded while simultaneously pressing the pressure shaft toward the plurality of objects to be bonded.

[0007] In this case, the pressure shaft and electrodes located in the joining unit are driven by a drive source, and the electrodes are biased by an elastic member located in the joining unit, thereby allowing the electrodes to be pressed against the workpiece independently of the pressure shaft. As a result, the electrodes can be pressed against the workpiece by the elastic member, and the electrode drive mechanism can be made smaller compared to when an air cylinder is used for the electrode drive mechanism.

[0008] In one embodiment of the present invention, the bonding unit further includes a base member that extends in the axial direction and has a connecting end that can be connected to the electrode. The elastic member contacts the base member and biases the electrode via the base member.

[0009] In this case, by providing a base portion in the bonding unit, the volume occupied by electrodes that are frequently replaced can be reduced.

[0010] In one embodiment of the present invention, the base member has a flange portion that is aligned with the elastic member in the axial direction. The elastic member contacts the flange portion and biases the electrode via the base member.

[0011] In this case, by providing a flange portion on the base member, the volume of the base member can be reduced, thus allowing the base member to be miniaturized.

[0012] In one embodiment of the present invention, the bonding unit further includes a case member positioned around a pressurizing axis and housing an elastic member inside, and in contact with the elastic member from the opposite side of the electrode in the axial direction. The case member is provided with a groove extending along the axial direction. The elastic member is housed in the groove.

[0013] In this case, by providing a case member to the joining unit, the elastic member can be positioned while being protected by the case member.

[0014] In one embodiment of the present invention, the joining unit further includes a lid and a sphere. The lid is connected to the electrode-side end of the case member, facing the flange. The sphere is positioned between the lid and the flange. The base member is conductive. A first recess is provided on the lid side of the flange. A second recess is provided on the flange side of the lid. The sphere can make line contact with each of the first and second recesses.

[0015] In this case, by arranging spheres to create line contact between the base member and the lid, the contact area can be reduced, making it less likely for heat generated by the electrodes connected to the base member to be transferred to other components of the bonding unit. [Effects of the Invention]

[0016] According to the present invention, the electrode driving mechanism can be miniaturized. [Brief explanation of the drawing]

[0017] [Figure 1] This is a front view showing the configuration of a solid-phase resistance spot bonding apparatus according to one embodiment of the present invention. [Figure 2] This is a cross-sectional view showing the configuration around the bonding unit of a solid-phase resistance spot bonding apparatus according to one embodiment of the present invention. [Figure 3] This is a cross-sectional view showing the state of the device before the objects to be joined are joined, with section III in Figure 2 enlarged. [Figure 4]It is a cross-sectional view showing the state of the apparatus immediately after the workpieces are joined by the solid-phase resistance spot joining apparatus according to an embodiment of the present invention. [Figure 5] It is a cross-sectional view showing the configuration of the solid-phase resistance spot joining apparatus according to a modification of an embodiment of the present invention.

Embodiments for Carrying Out the Invention

[0018] Hereinafter, the solid-phase resistance spot joining apparatus according to an embodiment of the present invention will be described with reference to the drawings. In the following description of the embodiments, the same or corresponding parts in the drawings are denoted by the same reference numerals, and the description thereof will not be repeated.

[0019] In the drawings, the direction orthogonal to the axial direction of the pressing shaft and parallel to the extending direction of the connection conductor is defined as the X direction. Also, the axial direction of the pressing shaft is defined as the Y direction. Further, the direction orthogonal to the axial direction of the pressing shaft and the extending direction of the connection conductor is defined as the Z direction.

[0020] FIG. 1 is a front view showing the configuration of the solid-phase resistance spot joining apparatus according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing the configuration around the joining unit of the solid-phase resistance spot joining apparatus according to an embodiment of the present invention.

[0021] As shown in FIGS. 1 and 2, the solid-phase resistance spot joining apparatus 1 according to an embodiment of the present invention is an apparatus that forms a softened region in a plurality of stacked workpieces 2 by passing an electric current through the plurality of workpieces 2, and plastically deform the softened region to join the plurality of workpieces 2 in a solid state.

[0022] The solid-phase resistance spot joining apparatus 1 includes a first joining unit 10 and a second joining unit 20 as joining units, a drive source 30, and a power supply unit 40.

[0023] The first joining unit 10 is a unit for pressing multiple objects to be joined 2 in a way that allows for plastic deformation, and for applying a voltage to the multiple objects to be joined 2. The first joining unit 10 is driven axially (in the Y direction) by a drive source 30. The configuration of the first joining unit 10 will be described later.

[0024] The second bonding unit 20 is a unit that, together with the first bonding unit 10, presses multiple objects to be bonded 2 and applies voltage to the multiple objects to be bonded 2. The second bonding unit 20 is fixed to the housing of the solid-phase resistance spot bonding apparatus 1.

[0025] As shown in Figure 2, the second joining unit 20 in this embodiment has the same configuration as the first joining unit 10, but is symmetrical with respect to the XZ plane. However, the second joining unit 20 is not limited to this configuration, and may have a configuration in which, for example, the elastic member 150 described later is not provided.

[0026] As shown in Figure 1, the drive source 30 drives the first joining unit 10 in the Y direction. In this embodiment, the drive source 30 is, for example, a servo press machine.

[0027] The power supply unit 40 applies voltage to the first junction unit 10 and the second junction unit 20. The power supply unit 40 has a power supply side conductor 41. The power supply side conductor 41 is connected to the first junction unit 10 and the second junction unit 20, respectively.

[0028] The objects to be joined 2 by the solid-phase resistance spot bonding apparatus 1 are, for example, steel plates such as high-tensile steel. However, the objects to be joined 2 are not limited to steel plates; they may also be aluminum plates or dissimilar materials such as steel plates and aluminum plates.

[0029] The first joining unit 10 will now be described. Figure 3 is a cross-sectional view showing the state of the device before the objects to be joined are joined, by enlarging part III in Figure 2.

[0030] As shown in Figures 2 and 3, the first joining unit 10 in one embodiment of the present invention comprises a pressurizing shaft 100, an electrode 110, a base member 120, a case member 130, a lid 140, a sphere 142, an elastic member 150, a guide member 160, a plate-shaped member 170, a connecting conductor 180, and a wiring member 190. The elastic member 150 in this embodiment has a plurality of first elastic members 151 and one second elastic member 152.

[0031] The pressurizing shaft 100 is a cylindrical member extending in the Y direction. The material of the pressurizing shaft 100 is, for example, tungsten carbide. However, the material of the pressurizing shaft 100 is not particularly limited as long as it can apply the necessary pressing force to the workpiece 2, and may be tool steel, heat-resistant steel, or ceramics, etc.

[0032] As shown in Figure 3, the pressurizing shaft 100 has a tip 101 and a rear end 102. The tip 101 is the part that contacts the workpiece 2a located on the first joining unit side of the plurality of workpieces 2. The rear end 102 is connected to a holder 103 that supports the pressurizing shaft 100. The rear end 102 has a tapered shape and engages with the inner circumferential surface of the holder 103.

[0033] The pressurizing shaft 100 presses the multiple stacked objects 2 in an axial direction (Y direction) in a way that allows for plastic deformation. Specifically, in this embodiment, the pressurizing shaft 100 presses the multiple objects 2 with a pressing force of 30 to 50 kN when driven by the drive source 30.

[0034] The electrode 110 is driven by the drive source 30 together with the pressurizing shaft 100. The electrode 110 is positioned around the pressurizing shaft 100 with a gap between it and the shaft. In this embodiment, the tip 111 of the electrode 110 has a cylindrical shape when viewed from the Y direction.

[0035] The electrode 110 is conductive. The electrode 110 is made of, for example, copper. The electrode 110 applies a voltage to the multiple objects to be joined 2. By applying a voltage to the multiple objects to be joined 2, the electrode 110 heats the multiple objects to be joined 2 by passing a current of 3500 to 10000 A through them.

[0036] The base member 120 is conductive and extends in the axial direction (Y direction). The base member 120 is made of, for example, copper. The base member 120 is arranged around the pressurizing shaft 100 with a gap between it and the pressurizing shaft 100.

[0037] The base member 120 has a main body portion 121, a connecting end portion 122, and a flange portion 123. The main body portion 121 is the cylindrical portion of the base member 120 that extends in the Y direction.

[0038] The connecting end 122 is located on the side of the main body 121 that is to be joined, in the Y direction. The connecting end 122 extends axially (Y direction) with a gap surrounding the pressurizing shaft 100. At the connecting end 122, the base member 120 can be connected to the electrode 110.

[0039] The flange portion 123 extends in the XZ plane from the end of the main body portion 121 opposite to the side where the connecting end portion 122 is located. The flange portion 123 is aligned with the elastic member 150 in the axial direction (Y direction).

[0040] The flange portion 123 has a contact surface 124. The flange portion 123 is in contact with a plurality of first elastic members 151 at the contact surface 124.

[0041] A first recess 125 is provided on the lid portion 140 side of the flange portion 123. The first recess 125 in this embodiment has a conical surface shape. However, the first recess 125 is not limited to a conical surface shape and may be a curved surface.

[0042] The electrode 110 has a range of tilting capability in the axial direction (Y direction) defined by the gap between the electrode 110 and the base member 120 relative to the respective pressure shafts 100. Therefore, when the object to be joined 2, which extends in the XZ plane, is tilted relative to the XZ plane, the electrode 110 can tilt in the Y direction while in contact with the object to be joined 2.

[0043] The case member 130 is positioned around the pressurizing shaft 100 and houses the elastic member 150 inside. The case member 130 is made of, for example, an insulating material.

[0044] The case member 130 is provided with a groove 131 extending along the axial direction (Y direction). Multiple first elastic members 151 are housed in the groove 131. The case member 130 is in contact with the elastic members 150 from the side opposite to the electrode 110 in the axial direction (Y direction).

[0045] The lid portion 140 is a member that supports the flange portion 123 via the sphere 142. The lid portion 140 faces the flange portion 123 and is connected to the electrode 110 side end of the case member 130. The lid portion 140 is made of, for example, steel.

[0046] A second recess 141 is provided on the flange portion 123 side of the lid portion 140. The second recess 141 in this embodiment has a conical surface shape. However, the second recess 141 is not limited to a conical surface shape and may be a curved surface.

[0047] The sphere 142 is positioned between the lid portion 140 and the flange portion 123. The sphere 142 is, for example, a steel ball. Multiple spheres 142 are arranged in the Y direction alongside the multiple first elastic members 151, each corresponding to one of the multiple first elastic members 151.

[0048] The sphere 142 can make line contact with each of the first recess 125 and the second recess 141. This reduces the contact resistance between the flange portion 123 and the sphere 142, making it easier for the electrode 110 and the base member 120 to tilt in the Y direction. In addition, the line contact of the sphere 142 makes it difficult for heat from the current supplied to the electrode 110 to be transferred from the flange portion 123 to the cover portion 140, thereby improving the heat resistance of the first joining unit 10.

[0049] The elastic member 150 biases the electrode 110 toward the multiple objects to be joined 2. In this embodiment, the electrode 110 presses the multiple objects to be joined 2 with a pressing force of, for example, 1 to 2 kN due to the biasing force of the elastic member 150.

[0050] Multiple first elastic members 151 contact the base member 120 and bias the electrode 110 via the base member 120. Specifically, multiple first elastic members 151 contact the contact surface 124 of the flange portion 123 and bias the electrode 110 via the base member 120.

[0051] In this embodiment, eight first elastic members 151 are arranged at equal intervals on the circumference of a circle in the XZ plane with the pressurizing axis 100 as the center. The number of first elastic members 151 is not limited to eight; it is sufficient that the electrode 110 and the base member 120 can be tilted in either direction with respect to the Y direction, and at least three or more are acceptable.

[0052] Each of the multiple first elastic members 151 has an elastic body 153 and a base portion 154. In this embodiment, the elastic body 153 is, for example, a spring. However, the elastic body 153 is not limited to a spring and may be other elastic materials such as rubber.

[0053] The base portion 154 is positioned at the end of the elastic body 153 on the base member 120 side. In this embodiment, the base portion 154 is, for example, a spring support.

[0054] The base portion 154 has a spherical surface 155 on the base member 120 side. The spherical surface 155 makes point contact with the contact surface 124 of the flange portion 123. As a result, when the contact surface 124 is inclined with respect to the XZ plane, compared to the case where the base portion 154 is cylindrical, it is possible to suppress uneven contact between the base portion 154 and the contact surface 124, thereby preventing the biasing force from being applied unevenly from the multiple first elastic members 151 to the contact surface 124.

[0055] One second elastic member 152 is positioned inside the plurality of first elastic members 151 around the pressurizing shaft 100. One second elastic member 152 is, for example, a spring. However, the second elastic member 152 is not limited to a spring and may be another elastic material such as rubber.

[0056] One second elastic member 152 biases the electrode 110 toward the multiple objects to be joined 2 via the guide member 160. The second elastic member 152 has the role of correcting the inclination of the base member 120 when the first joining unit 10 is separated from the objects to be joined 2 after the electrode 110 and the base member 120 have joined the objects to be joined 2 while inclined with respect to the XZ plane.

[0057] It is desirable that the Young's modulus in the Y direction of each of the multiple first elastic members 151 is higher than that of one of the second elastic members 152. This makes it easier to bring the electrode 110 into close contact with the workpiece 2 by the biasing force of the multiple first elastic members 151 when the electrode 110 and the base member 120 are tilted from the Y direction.

[0058] The guide member 160 is positioned around the pressurizing shaft 100, leaving a gap between it and the pressurizing shaft 100. The guide member 160 is provided with a plurality of through holes 161 that penetrate in the axial direction (Y direction). A corresponding first elastic member 151 from a plurality of first elastic members 151 is inserted through each of the plurality of through holes 161. In this way, the guide member 160 supports each of the plurality of first elastic members 151.

[0059] The position of the guide member 160 is fixed by being biased in the Y direction by a second elastic member 152. The position of the guide member 160 can be easily fixed by the second elastic member 152 without using fixing methods such as bolt fastening.

[0060] The plate-shaped member 170 is conductive and is connected to the circumferential surface of the main body portion 121 of the base member 120. The connecting conductor 180 is fixed to the drive source 30 side of the first joining unit 10. One end of the connecting conductor 180 is connected to the power supply side conductor 41. The wiring member 190 electrically connects the plate-shaped member 170 and the connecting conductor 180. The wiring member 190 is made of, for example, copper wire.

[0061] The current supplied from the power supply unit 40 flows in the following order: power supply side conductor 41, connecting conductor 180, wiring member 190, plate-shaped member 170, base member 120, and electrode 110, and then flows to the object to be joined 2. In the solid-phase resistance spot bonding apparatus 1, the pressure applied by the pressure shaft 100 and electrode 110 to the object to be joined 2 causes the objects to be joined 2a and 2b to come into close contact at their contact surfaces, thereby reducing the contact resistance. As a result, the contact surface with reduced contact resistance becomes a current-carrying path, and current flows through this current-carrying path.

[0062] In addition, one second elastic member 152 is not necessarily required in the first joint unit 10. If one second elastic member 152 is not provided in the first joint unit 10, the guide member 160 is fixed to the base member 120 by a known connection method such as bolt fastening.

[0063] The following describes the solid-phase resistance spot bonding of the objects to be bonded 2 using the solid-phase resistance spot bonding apparatus 1. Figure 4 is a cross-sectional view showing the state of the apparatus immediately after the objects to be bonded have been bonded using the solid-phase resistance spot bonding apparatus according to one embodiment of the present invention.

[0064] The operation of solid-phase resistance spot bonding of the workpiece 2 by the solid-phase resistance spot bonding apparatus 1 is as follows: First, as shown in Figures 1 to 3, the drive source 30 drives the first bonding unit 10, causing the electrode 110 to come into contact with the workpiece 2a located on the electrode 110 side of the first bonding unit 10, among the multiple workpieces 2. By bringing the electrode 110 into contact with the workpiece 2a in front of the pressurizing shaft 100 and applying prepressure, the workpiece 2 can be temporarily positioned. In addition, the electrode 110 of the second bonding unit 20 comes into contact with the workpiece 2b, among the multiple workpieces 2.

[0065] Next, a voltage is applied from the electrode 110 to the multiple objects to be joined 2. The contact surfaces where the objects to be joined 2 are in close contact and have low contact resistance become current-carrying paths, and current flows through these paths. As a result, the multiple objects to be joined 2 are heated, and a softened region R is formed between the multiple objects to be joined 2.

[0066] Next, as shown in Figure 4, the biasing force of the elastic member 150 presses the electrode 110 against the multiple objects to be joined 2, while simultaneously pressing the pressurizing shaft 100 against the multiple objects to be joined 2.

[0067] Specifically, the drive source 30 further drives the first joining unit 10, causing the pressurizing shaft 100 to plastically deform the softening region R between the objects to be joined 2. At this time, the electrode 110 is biased by the elastic member 150 via the base member 120, and therefore drives independently of the pressurizing shaft 100 in the first joining unit 10, pressing the multiple objects to be joined 2 by the biasing force of the elastic member 150. The driving of the electrode 110 creates a gap in the Y direction between the first recess 125 of the flange portion 123 and the sphere 142.

[0068] As current is passed from the electrode 110 to the object to be joined 2 and it is pressed by the pressurizing shaft 100, the softened region R of the object to be joined 2 undergoes plastic deformation. The object to be joined 2 undergoes plastic deformation at positions other than the softened region R, creating gaps between the objects 2a and 2b. Due to the plastic deformation of the softened region R, a new surface is formed in the softened region R. As these new surfaces come into contact with each other, the objects to be joined 2a and 2b are solid-phase resistance spot bonded together.

[0069] The order in which the pressurizing shaft 100 and the electrode 110 contact the object to be joined 2 is not limited. The pressurizing shaft 100 may contact the object to be joined 2 before the electrode 110, or the pressurizing shaft 100 and the electrode 110 may contact the object to be joined 2 simultaneously.

[0070] In this embodiment, the electrode 110 is supported in such a way that its orientation can be changed so that it contacts the contact surface with the object to be joined 2a located on the electrode 110 side. This allows the electrode 110 to be tilted with respect to the axial direction (Y direction) of the pressurizing shaft 100, so that the electrode 110 can be made to contact the object to be joined 2 uniformly when the object to be joined 2 is positioned at an angle. As a result, an electrical path is secured between the electrode 110 and the object to be joined 2, and a uniform softening region R can be formed on the object to be joined 2, thereby suppressing bonding defects.

[0071] After the objects to be joined 2 are joined, the first joining unit 10 is driven away from the objects to be joined 2 in the Y direction. At this time, one second elastic member 152 biases the electrode 110 and the base member 120 in the Y direction via the guide member 160. As a result, if the electrode 110 and the base member 120 were tilted in the Y direction to match the tilt of the objects to be joined 2, the tilt of the electrode 110 and the base member 120 can be corrected to their original parallel state with respect to the XZ plane.

[0072] In a solid-phase resistance spot bonding apparatus 1 according to one embodiment of the present invention, the pressure shaft 100 and electrode 110 arranged in the first bonding unit 10 are driven by a drive source 30, and the electrode 110 is biased by an elastic member 150 arranged in the first bonding unit 10, thereby allowing the electrode 110 to be pressed against the workpiece 2 independently of the pressure shaft 100. As a result, since the electrode 110 can be pressed against the workpiece 2 by the elastic member 150, the drive mechanism of the electrode 110 can be made smaller compared to when an air cylinder is used for the drive mechanism of the electrode 110.

[0073] In a solid-phase resistance spot bonding apparatus 1 according to one embodiment of the present invention, by providing a base member 120 in the first bonding unit 10, the occupied volume of the electrode 110, which is frequently replaced, can be reduced.

[0074] In a solid-phase resistance spot bonding apparatus 1 according to one embodiment of the present invention, the volume of the base member 120 can be reduced by providing a flange portion 123 on the base member 120, thereby enabling miniaturization of the base member 120.

[0075] In a solid-phase resistance spot bonding apparatus 1 according to one embodiment of the present invention, by providing a case member 130 on the first bonding unit 10, the elastic member 150 can be positioned while the elastic member 150 is protected by the case member 130.

[0076] In a solid-phase resistance spot bonding apparatus 1 according to one embodiment of the present invention, by arranging a sphere 142 to make the contact between the base member 120 and the lid portion 140 a line contact, the contact area can be reduced, making it difficult for heat generated at the electrode 110 connected to the base member 120 to be transferred to other components of the first bonding unit 10. Consequently, the heat resistance of the first bonding unit 10 can be improved.

[0077] Hereinafter, a solid-phase resistance spot bonding apparatus according to a modified embodiment of the present invention will be described with reference to the figures. Since the configuration of the first bonding unit in this modified solid-phase resistance spot bonding apparatus differs from that of the solid-phase resistance spot bonding apparatus 1 according to one embodiment of the present invention, the same configuration as that of the solid-phase resistance spot bonding apparatus 1 according to one embodiment of the present invention will not be repeated in the description.

[0078] Figure 5 is a cross-sectional view showing the configuration of a solid-phase resistance spot bonding apparatus according to a modified embodiment of the present invention. As shown in Figure 5, the solid-phase resistance spot bonding apparatus 1A according to this modified embodiment comprises a first bonding unit 10A, a second bonding unit 20, a drive source, and a power supply unit.

[0079] The first joining unit 10A and the second joining unit 20 are units for pressing multiple objects to be joined 3 in a way that allows for plastic deformation, and for applying a voltage to the multiple objects to be joined 3.

[0080] The object to be joined by the solid-phase resistance spot bonding device 1A consists of an object to be joined 3a having a protrusion C and a flat object to be joined 3b.

[0081] In this modified example, the first joining unit 10A has a pressurizing shaft 200 and a base member 220.

[0082] The pressurizing shaft 200 is longer in the Y direction compared to the pressurizing shaft 100 in the second joining unit 20.

[0083] The base member 220 is longer in the Y direction compared to the base member 120 in the second joining unit 20. Specifically, the base member 220 has a main body portion 221, a connecting end portion 122, and a flange portion 123. The main body portion 221 is longer in the Y direction compared to the main body portion 121 of the base member 120 in the second joining unit 20.

[0084] Compared to the length to which the pressure shaft 100 and base member 120 protrude from the plate-shaped member 170 toward the object to be joined 3 in the second joining unit 20, the length to which the pressure shaft 200 and base member 220 protrude toward the object to be joined 3 from the plate-shaped member 170 in the first joining unit 10A is longer. As a result, the pressure shaft 200 and electrode 110 can be pressed against the object to be joined 3 without the first joining unit 10A coming into contact with the protrusion C of the object to be joined 3a, and the object to be joined 3 can be joined by the solid-phase resistance spot bonding device 1A.

[0085] The pressurizing shaft 200 and base member 220 can be replaced with other pressurizing shafts and base members of different lengths by removing other components such as the lid portion 140 and the plate-shaped member 170. Therefore, the length of the first joining unit 10A in the Y direction can be easily changed to suit various workpiece shapes.

[0086] In a solid-phase resistance spot bonding apparatus 1A according to a modified embodiment of the present invention, the length of the first bonding unit 10A can be changed to match the shape of the object to be bonded 3 by making the length of the pressurizing shaft 200 and base member 220 in the Y direction of the first bonding unit 10A longer than that of the pressurizing shaft 100 and base member 120 of the second bonding unit 20. This makes it possible to configure the solid-phase resistance spot bonding apparatus 1A to accommodate objects having various shapes.

[0087] In the embodiments described above, a so-called direct bonding method was explained, in which a pair of electrodes are arranged in one direction and the objects to be bonded are held between the pair of electrodes. However, the present invention is not limited to the direct bonding method. The present invention can also be applied to other resistance bonding methods such as the indirect bonding method or the series bonding method.

[0088] Furthermore, although the above-described embodiment described a stationary solid-phase resistance spot bonding device, the invention is not limited to this configuration. The present invention can also be applied to gun-type bonding devices attached to the tip of a robot or the like.

[0089] The embodiments disclosed herein are illustrative in all respects and do not constitute a limiting interpretation. Therefore, the technical scope of this disclosure is not limited to the embodiments described above. Furthermore, all modifications within the meaning and scope of equivalence to the claims are included. In the description of the embodiments above, combinatorial configurations may be combined with each other. [Explanation of symbols]

[0090] 1,1A Solid-phase resistance spot bonding device, 2,2a,2b,3,3a,3b Workpieces to be bonded, 10,10A First bonding unit, 30 Drive source, 100,200 Pressure shaft, 110 Electrode, 120,220 Base member, 122 Connection end, 123 Flange portion, 125 First recess, 130 Case member, 131 Groove portion, 140 Cover portion, 141 Second recess, 142 Sphere, 150 Elastic member.

Claims

1. Power source and A joining unit driven axially by the aforementioned drive source, The unit comprises a power supply unit that applies voltage to the aforementioned bonding unit, The bonding unit is A pressing shaft that presses multiple overlapping objects to be joined in a way that allows for plastic deformation from the axial direction, An electrode is arranged around the pressurizing shaft, supplied with current from the power supply unit without passing through the plurality of objects to be joined, and applies voltage to the plurality of objects to be joined, The electrodes include an elastic member that biases the plurality of objects to be joined, The drive source drives the bonding unit, thereby bringing the electrode into contact with the object to be bonded located on the electrode side among the plurality of objects to be bonded, and pressing the electrode against the plurality of objects to be bonded by the biasing force of the elastic member, while pressing the pressurizing shaft against the plurality of objects to be bonded. The solid-phase resistance spot bonding apparatus comprises a plurality of first elastic members arranged at intervals from each other around the pressure shaft, and a second elastic member arranged inside the plurality of first elastic members through which the pressure shaft is inserted.

2. The bonding unit further includes a base member that extends in the axial direction and has a connecting end that can be connected to the electrode, The solid-phase resistance spot bonding apparatus according to claim 1, wherein the elastic member contacts the base member and biases the electrode via the base member.

3. The base member has a flange portion that is aligned with the elastic member in the axial direction, The solid-phase resistance spot bonding apparatus according to claim 2, wherein the elastic member contacts the flange portion and biases the electrode via the base member.

4. The bonding unit further includes a case member positioned around the pressurizing shaft, housing the elastic member inside, and contacting the elastic member from the opposite side of the electrode in the axial direction, The case member is provided with a groove that extends along the axial direction, The solid-phase resistance spot bonding apparatus according to claim 3, wherein the elastic member is housed in the groove.

5. The bonding unit is A lid portion that faces the flange portion and is connected to the electrode-side end of the case member, The present invention further includes a sphere disposed between the lid portion and the flange portion, The base member has electrical conductivity, A first recess is provided on the lid side of the flange portion. A second recess is provided on the flange side of the lid. The solid-phase resistance spot bonding apparatus according to claim 4, wherein the sphere is capable of line contact with each of the first recess and the second recess.

6. A drive source and A joining unit driven axially by the aforementioned drive source, The unit comprises a power supply unit that applies voltage to the aforementioned bonding unit, The bonding unit is A pressing shaft that presses multiple overlapping objects to be joined in a way that allows for plastic deformation from the axial direction, An electrode is arranged around the pressurizing shaft, supplied with current from the power supply unit without passing through the plurality of objects to be joined, and applies voltage to the plurality of objects to be joined, The electrodes include an elastic member that biases the plurality of objects to be joined, The drive source drives the bonding unit, thereby bringing the electrode into contact with the object to be bonded located on the electrode side among the plurality of objects to be bonded, and pressing the electrode against the plurality of objects to be bonded by the biasing force of the elastic member, while pressing the pressurizing shaft against the plurality of objects to be bonded. The bonding unit further includes a base member that extends in the axial direction and has a connecting end that can be connected to the electrode, The elastic member contacts the base member and biases the electrode via the base member. The base member has a flange portion that is aligned with the elastic member in the axial direction, The elastic member contacts the flange portion and biases the electrode via the base member. The bonding unit further includes a case member positioned around the pressurizing shaft, housing the elastic member inside, and contacting the elastic member from the opposite side of the electrode in the axial direction, The case member is provided with a groove that extends along the axial direction, The elastic member is housed in the groove, The bonding unit is A lid portion that faces the flange portion and is connected to the electrode-side end of the case member, The present invention further includes a sphere disposed between the lid portion and the flange portion, The base member has electrical conductivity, A first recess is provided on the lid side of the flange portion. A second recess is provided on the flange side of the lid. The sphere is capable of line contact with each of the first and second recesses in a solid-phase resistance spot bonding device.

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