JP7798710B2 - Solid resistance spot bonding equipment - Google Patents

Description

The present invention relates to a solid-state resistance spot joining device.

Prior art that discloses a solid-state resistance spot joining device is WO 2021/182444 (Patent Document 1). The solid-state resistance spot joining device described in Patent Document 1 comprises a central pressure shaft and a copper electrode. The central pressure shaft applies an external stress to the metal sheet that is equal to or greater than the yield strength of the metal sheet at the joining temperature. The copper electrode heats the metal sheet by passing an electric current through it. The copper electrode is controlled by a separate drive from the central pressure shaft. The electrode is driven by an air cylinder and applies a load to the metal sheet.

International Publication No. 2021/182444

In the solid-state resistance spot welding device described in Patent Document 1, an electrode pressed against the workpiece by an air cylinder is driven in the axial direction of a central pressure shaft. If the workpiece extends in a direction perpendicular to this axial direction and is positioned at an angle, the electrode may make uneven contact with the workpiece.

The present invention has been made to solve the above-mentioned problems, and aims to provide a solid-state resistance spot joining device that can bring electrodes into uniform contact with the workpieces when the workpieces are positioned at an angle.

A solid-state resistance spot bonding apparatus according to the present invention comprises a drive source and a bonding unit. The bonding unit is driven in the axial direction by the drive source. The bonding unit includes a pressure shaft, an electrode, and multiple first elastic members. The pressure shaft presses the stacked objects in the axial direction in a manner that allows plastic deformation. The electrode is arranged around the pressure shaft with a gap therebetween and applies a voltage to the objects. The multiple first elastic members are arranged around the pressure shaft with a gap therebetween and urge the electrode toward the objects. The drive source drives the bonding unit to bring the electrode into contact with the objects located on the electrode side of the multiple objects, and the urging force of each of the multiple first elastic members presses the electrode against the objects, while the pressure shaft presses against the objects. The electrode is supported in a position that can be changed so that it abuts along the contact surface with the objects located on the electrode side. Each of the multiple first elastic members elastically deforms according to the position of the electrode when it comes into contact with the object to be bonded located on the electrode side.

In this case, by arranging multiple first elastic members around the pressure axis and biasing the electrodes, when the objects to be welded are placed at an angle, each of the multiple first elastic members can elastically deform to match the angle of the objects to be welded. This allows the electrodes to be tilted relative to the axial direction of the pressure axis, so that when the objects to be welded are placed at an angle, the electrodes can be brought into uniform contact with the objects to be welded.

In one embodiment of the present invention, the joining unit further includes a base member. The base member extends in the axial direction with a gap surrounding the pressure axis, and has a connection end connected to the electrode and a flange portion aligned with the multiple first elastic members in the axial direction. Each of the multiple first elastic members abuts against the flange portion and biases the electrode via the base member. The range within which the electrode can tilt in the axial direction is determined by the gap between the electrode and the base member and the pressure axis.

In this case, by providing a base member and abutting multiple first elastic members against the flange portion of the base member, the multiple first elastic members can be abutted over a wider area than when the multiple first elastic members are abutted directly against the electrodes, allowing the electrodes to be stably biased by the multiple first elastic members via the base member.

In one embodiment of the present invention, the joining unit further includes a guide member. The guide member is arranged around the pressure shaft with a gap therebetween and supports a plurality of first elastic members. The guide member has a plurality of through holes that penetrate in the axial direction. A corresponding one of the plurality of first elastic members is inserted into each of the plurality of through holes.

In this case, by providing a guide member, it is possible to prevent the positional deviation of the multiple first elastic members.

In one embodiment of the present invention, the joining unit further includes a second elastic member. The second elastic member is disposed inside the first elastic members around the pressure shaft and biases the electrode toward the objects via the guide member.

In this case, by biasing the electrode from near the center using a single second elastic member, when the electrode is separated from the objects to be welded after the objects are welded, the electrode, which has tilted in relation to the objects to be welded, can be corrected from its tilted state to its original state.

In one embodiment of the present invention, the joining unit further includes a case member, a lid, and a sphere. The case member is positioned around the pressure shaft and houses multiple first elastic members therein, abutting against the multiple first elastic members from the side opposite the electrode in the axial direction. The lid portion faces the flange portion and is connected to the electrode side end of the case member. The sphere is disposed between the lid portion and the flange portion. 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 portion. The sphere is capable of line contact with each of the first recess and the second recess.

In this case, by making the contact between the base member and the lid portion a line contact, the contact resistance of the contacting members can be reduced, making it easier to tilt the electrode relative to the object to be bonded.

According to the present invention, even when the workpiece is placed at an angle, the electrodes can be brought into uniform contact with the workpiece.

1 is a front view showing a configuration of a solid-state resistance spot joining apparatus according to an embodiment of the present invention; 1 is a cross-sectional view showing a configuration of a joining unit and its surroundings of a solid-state resistance spot joining apparatus according to an embodiment of the present invention. 3 is an enlarged cross-sectional view of a portion III in FIG. 2 showing the state of the apparatus before the objects to be bonded are bonded. FIG. FIG. 2 is a perspective view showing a configuration around a plurality of first elastic members in a first joining unit of a solid-state resistance spot joining device according to an embodiment of the present invention. 1 is a cross-sectional view showing a state of the solid-state resistance spot joining device according to an embodiment of the present invention immediately after objects to be joined are joined by the device. FIG. 10 is a schematic diagram showing a configuration when an electrode in a first joining unit of a solid-state resistance spot joining apparatus according to an embodiment of the present invention is tilted. FIG. 10 is a cross-sectional view showing a configuration of a solid-state resistance spot joining apparatus according to a modified example of an embodiment of the present invention.

A solid-state resistance spot welding apparatus according to one embodiment of the present invention will be described below with reference to the drawings. In the following description of the embodiment, the same or equivalent parts in the drawings will be designated by the same reference numerals, and their description will not be repeated.

In the drawings, the direction perpendicular to the axial direction of the pressure shaft and parallel to the extension direction of the connecting conductor is defined as the X direction. The axial direction of the pressure shaft is defined as the Y direction. The direction perpendicular to the axial direction of the pressure shaft and the extension direction of the connecting conductor is defined as the Z direction.

Figure 1 is a front view showing the configuration of a solid-state resistance spot joining device according to one embodiment of the present invention. Figure 2 is a cross-sectional view showing the configuration of the joining unit and its surroundings of a solid-state resistance spot joining device according to one embodiment of the present invention.

As shown in Figures 1 and 2, a solid-state resistance spot welding apparatus 1 according to one embodiment of the present invention is an apparatus that passes an electric current through multiple overlapping objects 2 to form softened regions in the objects 2, and then plastically deforms the softened regions to weld the multiple objects 2 together while maintaining the objects 2 in a solid state.

The solid-state resistance spot joining device 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.

The first joining unit 10 is a unit that presses the multiple objects 2 to allow plastic deformation and applies a voltage to the multiple objects 2. The first joining unit 10 is driven in the axial direction (Y direction) by a drive source 30. The configuration of the first joining unit 10 will be described later.

The second joining unit 20 is a unit that presses the multiple workpieces 2 together with the first joining unit 10 and applies voltage to the multiple workpieces 2. The second joining unit 20 is fixed to the housing of the solid-state resistance spot joining apparatus 1.

As shown in FIG. 2, the second joining unit 20 in this embodiment has the same configuration as the first joining unit 10, and is plane-symmetrical with respect to the XZ plane. However, the second joining unit 20 is not limited to this configuration, and may, for example, be configured without the elastic member 150 described below.

As shown in FIG. 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.

The power supply unit 40 applies voltage to the first joining unit 10 and the second joining unit 20. The power supply unit 40 has a power supply side conductor 41. The power supply side conductor 41 is connected to each of the first joining unit 10 and the second joining unit 20.

The workpieces 2 to be joined by the solid-state resistance spot joining device 1 are, for example, steel plates such as high-tensile steel. Note that the workpieces 2 are not limited to steel plates, but may also be aluminum plates or other materials, such as steel and aluminum plates.

The first joining unit 10 will now be described. Figure 3 is an enlarged cross-sectional view of part III in Figure 2, showing the state of the apparatus before the workpieces are joined. Figure 4 is a perspective view showing the configuration of the area around a plurality of first elastic members in the first joining unit of a solid-state resistance spot joining apparatus according to one embodiment of the present invention. Note that in Figure 4, the case member is shown in perspective to facilitate understanding of the invention.

As shown in Figures 2 to 4, the first joining unit 10 in one embodiment of the present invention includes a pressure shaft 100, an electrode 110, a base member 120, a case member 130, a lid portion 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 multiple first elastic members 151 and one second elastic member 152.

The pressure shaft 100 is a cylindrical member extending in the Y direction. The material of the pressure shaft 100 is, for example, tungsten carbide. However, the material of the pressure 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, ceramics, or the like.

As shown in FIG. 3, the pressure shaft 100 has a front end 101 and a rear end 102. The front end 101 is the part that comes into contact with the workpiece 2a, one of the multiple workpieces 2, that is located on the first joining unit side. The rear end 102 is connected to a holder 103 that supports the pressure shaft 100. The rear end 102 has a tapered shape and engages with the inner circumferential surface of the holder 103.

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

The electrode 110 is driven together with the pressure shaft 100 by the driving source 30. The electrode 110 is arranged around the pressure shaft 100 with a gap between them. In this embodiment, the tip 111 of the electrode 110 has a cylindrical shape when viewed from the Y direction.

The electrode 110 is electrically conductive. The electrode 110 is made of, for example, copper. The electrode 110 applies a voltage to the multiple objects 2. By applying a voltage to the multiple objects 2, the electrode 110 passes a current of 3,500 to 10,000 A through the multiple objects 2, heating the multiple objects 2.

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 pressure shaft 100 with a gap between it and the pressure shaft 100.

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 a cylindrical portion of the base member 120 that extends in the Y direction.

The connection end 122 is located on the Y-direction side of the main body 121, on the object 2 side. The connection end 122 extends in the axial direction (Y-direction) with a gap so as to surround the pressure shaft 100. The connection end 122 is connected to the electrode 110.

The flange portion 123 extends in the XZ plane from the end of the main body portion 121 opposite the end where the connection end portion 122 is located. The flange portion 123 is aligned with the multiple first elastic members 151 in the axial direction (Y direction).

The flange portion 123 has a contact surface 124. The flange portion 123 contacts multiple first elastic members 151 at the contact surface 124.

A first recess 125 is provided on the lid portion 140 side of the flange portion 123. In this embodiment, the first recess 125 has a conical surface shape. However, the first recess 125 is not limited to a conical surface shape and may also have a curved surface.

The range within which the electrode 110 can tilt in the axial direction (Y direction) is determined by the gap between the electrode 110 and the base member 120 and the pressure axis 100. Therefore, when the workpiece 2 extending in the XZ plane tilts with respect to the XZ plane, the electrode 110 and the base member 120 can tilt in the Y direction while the electrode 110 is in contact with the workpiece 2.

As shown in Figures 2 to 4, the case member 130 is positioned around the pressure shaft 100 and houses multiple first elastic members 151 and one second elastic member 152 inside. The case member 130 is made of, for example, an insulating material.

As shown in Figures 3 and 4, the case member 130 has multiple grooves 131 extending along the axial direction (Y direction). Each of the multiple grooves 131 houses a corresponding one of multiple first elastic members 151. The case member 130 abuts against the multiple first elastic members 151 from the side opposite the electrode 110 in the axial direction (Y direction).

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

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

The spheres 142 are disposed between the lid portion 140 and the flange portion 123. The spheres 142 are, for example, steel balls. The spheres 142 are arranged in line with the multiple first elastic members 151 in the Y direction so as to correspond to each of the multiple first elastic members 151.

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 base member 120 to tilt in the Y direction. Furthermore, the line contact of the sphere 142 makes it more difficult for heat generated by current flow to the electrode 110 to be transferred from the flange portion 123 to the lid portion 140, thereby improving the heat resistance of the first joining unit 10.

The elastic member 150 biases the electrode 110 toward the multiple objects 2. In this embodiment, the electrode 110 is biased by the elastic member 150, and presses the multiple objects 2 with a pressing force of, for example, 1 to 2 kN.

The multiple first elastic members 151 are arranged at intervals around the pressure shaft 100 and urge the electrode 110 toward the multiple objects 2. Specifically, the multiple first elastic members 151 abut against the flange portion 123 of the base member 120 and urge the electrode 110 via the base member 120.

In this embodiment, eight first elastic members 151 are arranged at equal intervals around the circumference of the XZ plane, centered on the pressure axis 100. Note that the number of first elastic members 151 is not limited to eight; it is sufficient that the electrode 110 and base member 120 can be tilted in either direction with respect to the Y direction, and that there are at least three or more.

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. Note that the elastic body 153 is not limited to a spring and may be another elastic body such as rubber.

The base portion 154 is disposed 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 bearing.

The pedestal portion 154 has a spherical surface 155 on the base member 120 side. The spherical surface 155 is in point contact with the contact surface 124 of the flange portion 123. As a result, when the contact surface 124 is tilted with respect to the XZ plane, the pedestal portion 154 can be prevented from making uneven contact with the contact surface 124 and applying a biased biasing force from the multiple first elastic members 151 to the contact surface 124, compared to when the pedestal portion 154 is cylindrical.

One second elastic member 152 is arranged inside the multiple first elastic members 151 around the pressure shaft 100. One second elastic member 152 is, for example, a spring. Note that the second elastic member 152 is not limited to a spring and may be another elastic body such as rubber.

The single second elastic member 152 biases the electrode 110 toward the multiple objects 2 via the guide member 160. The single second elastic member 152 serves to correct the inclination of the base member 120 when the first joining unit 10 is separated from the objects 2 after the electrode 110 and base member 120 have joined the objects 2 while inclined relative to the XZ plane.

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 the single second elastic member 152. This makes it easier for the electrode 110 to be tightly attached to the workpiece 2 by the biasing force of the multiple first elastic members 151 when the electrode 110 and base member 120 are tilted from the Y direction.

The guide member 160 is arranged around the pressure shaft 100 with a gap therebetween. The guide member 160 has a plurality of through holes 161 that penetrate in the axial direction (Y direction). A corresponding one of the plurality of first elastic members 151 is inserted into 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.

The guide member 160 is fixed in position by being biased in the Y direction by a single second elastic member 152. The single second elastic member 152 can simply fix the position of the guide member 160 without using a fastening method such as bolt tightening.

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

The current supplied from the power supply unit 40 flows in the order of the power supply side conductor 41, connecting conductor 180, wiring member 190, plate-like member 170, base member 120, and electrode 110, and then flows through the workpiece 2. In the solid-state resistance spot welding apparatus 1, the pressure applied by the pressure shaft 100 and electrode 110 to the workpiece 2 causes the workpieces 2a, 2b to come into close contact with each other at their contact surfaces, thereby reducing contact resistance. As a result, the contact surfaces with reduced contact resistance become a current path, and current flows through this current path.

Note that one second elastic member 152 is not necessarily required in the first joining unit 10. If one second elastic member 152 is not provided in the first joining unit 10, the guide member 160 is fixed to the base member 120 using a known connection method such as bolt fastening.

The following describes solid-state resistance spot welding of workpieces 2 using the solid-state resistance spot welding apparatus 1. Figure 5 is a cross-sectional view showing the state of the apparatus immediately after the workpieces have been joined using the solid-state resistance spot welding apparatus according to one embodiment of the present invention.

The movement of the solid-state resistance spot welding apparatus 1 for solid-state resistance spot welding of the workpieces 2 is as follows: first, as shown in Figures 1 to 3, the drive source 30 drives the first joining unit 10, causing the electrode 110 to abut against the workpiece 2a, of the multiple workpieces 2, which is located on the electrode 110 side of the first joining unit 10. By bringing the electrode 110 into contact with the workpiece 2a before the pressure shaft 100 and applying a preload, the workpiece 2 can be provisionally positioned. Furthermore, the electrode 110 of the second joining unit 20 abuts against the workpiece 2b, of the multiple workpieces 2.

Next, a voltage is applied from the electrode 110 to the multiple objects 2 to be bonded. The contact surfaces where the objects 2 are in close contact with each other and have low contact resistance become electrical paths, and current flows through these electrical paths. This heats the multiple objects 2 to be bonded, forming softened regions R between the multiple objects 2.

Next, as shown in FIG. 4, the electrode 110 is pressed against the multiple objects 2 by the biasing force of each of the multiple first elastic members 151, while the pressure shaft 100 is pressed against the multiple objects 2.

Specifically, the drive source 30 further drives the first joining unit 10, causing the pressure shaft 100 to plastically deform the softened region R between the objects 2. At this time, the electrode 110 is biased by the elastic member 150 via the base member 120, so it is driven independently of the pressure shaft 100 in the first joining unit 10 and presses the multiple objects 2 together with the biasing force of the elastic member 150. Driving the electrode 110 creates a gap in the Y direction between the first recess 125 of the flange portion 123 and the sphere 142.

When current is passed through the electrode 110 and the workpiece 2 is pressed by the pressure shaft 100, the softened region R of the workpiece 2 undergoes plastic deformation. The workpiece 2 undergoes plastic deformation, creating a gap between the workpieces 2a, 2b at positions other than the softened region R. The plastic deformation of the softened region R forms a new surface in the softened region R. When these new surfaces come into contact with each other, the workpieces 2a, 2b are solid-state resistance spot welded together.

The order in which the pressure shaft 100 and the electrode 110 come into contact with the workpiece 2 is not limited. The pressure shaft 100 may come into contact with the workpiece 2 before the electrode 110, or the pressure shaft 100 and the electrode 110 may come into contact with the workpiece 2 at the same time.

Figure 6 is a schematic diagram showing the configuration of a first joining unit of a solid-state resistance spot joining device according to one embodiment of the present invention when the electrode is tilted.

As shown in Figure 6, when joining the workpieces 2 using the solid-state resistance spot joining apparatus 1 described above, the workpieces 2 may be positioned at an angle to the XZ plane due to misalignment when positioning the workpieces 2 relative to the solid-state resistance spot joining apparatus 1 or variations in the thickness of the workpieces 2.

If the electrode is driven in the Y direction by an air cylinder or the like, the surface of the electrode tip that comes into contact with the workpiece 2 is parallel to the XZ plane. Therefore, if the workpiece 2 is positioned at an angle to the XZ plane, the surface of the electrode tip that comes into contact with the workpiece 2 may come into uneven contact with the workpiece 2, such as making one-sided contact. As a result, the electrode does not apply uniform pressure to the contact surfaces of the workpieces 2a, 2b, so a uniform current path cannot be ensured, and a softened region cannot be secured, which could result in poor welding.

On the other hand, as shown in Figure 6, the electrode 110 in this embodiment is supported so that its posture can be changed so that it abuts along the contact surface with the article 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 pressure shaft 100, so that the electrode 110 can be brought into uniform contact with the article 2 when the article 2 is positioned at an angle. As a result, a current path between the electrode 110 and the article 2 is secured, allowing a uniform softened region R to be formed in the article 2, thereby suppressing the occurrence of poor welding.

Furthermore, if the electrode is biased by a single elastic member, the single elastic member will elastically deform mainly in the Y direction. Therefore, if the object 2 is positioned at an angle relative to the XZ plane, it will be difficult to tilt the electrode in response to the angle of the object 2.

On the other hand, in this embodiment, each of the multiple first elastic members 151 elastically deforms in accordance with the posture of the electrode 110 when it comes into contact with the object 2a located on the electrode 110 side. As a result, each of the multiple first elastic members 151 arranged at a corresponding position elastically deforms in the Y direction by the amount that the object 2 is tilted, allowing the electrode 110 and base member 120 to be tilted.

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

In a solid-state resistance spot welding apparatus 1 according to one embodiment of the present invention, by arranging a plurality of first elastic members 151 around the pressure shaft 100 and biasing the electrode 110, when the workpiece 2 is positioned at an angle, each of the plurality of first elastic members 151 can elastically deform in accordance with the angle of the workpiece 2. This allows the electrode 110 to be tilted with respect to the axial direction (Y direction) of the pressure shaft 100, so that when the workpiece 2 is positioned at an angle, the electrode 110 can be brought into uniform contact with the workpiece 2. Furthermore, by ensuring a current path between the electrode 110 and the workpiece 2, a softened region R can be formed uniformly in the workpiece 2, thereby suppressing the occurrence of poor welding.

In a solid-state resistance spot bonding apparatus 1 according to one embodiment of the present invention, a base member 120 is provided and multiple first elastic members 151 are abutted against the flange portion 123 of the base member 120. This allows the multiple first elastic members 151 to abut over a wider area than when the multiple first elastic members 151 are directly abutted against the electrode 110, and therefore the electrode 110 can be stably biased by the multiple first elastic members 151 via the base member 120.

In the solid-state resistance spot welding apparatus 1 according to one embodiment of the present invention, the guide member 160 is provided to prevent misalignment of the multiple first elastic members 151.

In the solid-state resistance spot welding apparatus 1 according to one embodiment of the present invention, the electrode 110 is biased from near the center by a single second elastic member 152, so that when the electrode 110 is separated from the workpieces 2 after the workpieces 2 are joined, the electrode 110, which is tilted relative to the workpieces 2, can be corrected from its tilted state to its original state.

In the solid-state resistance spot welding apparatus 1 according to one embodiment of the present invention, the contact between the base member 120 and the lid portion 140 is made to be a line contact, thereby reducing the contact resistance of the contacting members, and making it easier to tilt the electrode 110 relative to the workpiece 2.

A solid-state resistance spot welding apparatus according to a modified example of an embodiment of the present invention will be described below with reference to the drawings. The solid-state resistance spot welding apparatus according to this modified example differs in the configuration of the first welding unit from the solid-state resistance spot welding apparatus 1 according to an embodiment of the present invention, and therefore, a description of the configuration that is similar to that of the solid-state resistance spot welding apparatus 1 according to an embodiment of the present invention will not be repeated.

Figure 7 is a cross-sectional view showing the configuration of a solid-state resistance spot welding apparatus according to a modified embodiment of the present invention. As shown in Figure 7, the solid-state resistance spot welding apparatus 1A according to this modified embodiment includes a first welding unit 10A, a second welding unit 20, a drive source, and a power supply unit.

The first joining unit 10A and the second joining unit 20 are units for pressing multiple objects 3 to allow plastic deformation and applying voltage to the multiple objects 3.

The workpieces 3 to be joined by the solid-state resistance spot joining apparatus 1A are composed of a workpiece 3a having a convex portion C and a flat workpiece 3b.

The first joining unit 10A in this modified example has a pressure shaft 200 and a base member 220.

The pressure shaft 200 is longer in the Y direction than the pressure shaft 100 in the second joining unit 20.

The base member 220 is longer in the Y direction than the base member 120 in the second joining unit 20. Specifically, the base member 220 has a main body portion 221, a connection end portion 122, and a flange portion 123. The main body portion 221 is longer in the Y direction than the main body portion 121 of the base member 120 in the second joining unit 20.

Compared to the length by which the pressure shaft 100 and base member 120 protrude from the plate-like member 170 toward the workpiece 3 in the second joining unit 20, the length by which the pressure shaft 200 and base member 220 protrude from the plate-like member 170 in the first joining unit 10A toward the workpiece 3 is longer. This allows the pressure shaft 200 and electrode 110 to be pressed against the workpiece 3 without the first joining unit 10A coming into contact with the convex portion C of the workpiece 3a, and therefore the workpiece 3 can be joined using the solid-state resistance spot joining apparatus 1A.

The pressure shaft 200 and base member 220 can be replaced with other pressure shafts and base members of different lengths by removing other components such as the lid portion 140 and plate-shaped member 170. This makes it easy to change the Y-direction length of the first joining unit 10A to suit various workpiece shapes.

In the solid-state resistance spot welding apparatus 1A according to a modified embodiment of the present invention, the length of the pressure shaft 200 and base member 220 in the first welding unit 10A in the Y direction is made longer relative to the pressure shaft 100 and base member 120 of the second welding unit 20 to match the shape of the workpieces 3, making it possible to change the length of the first welding unit 10A to match the shape of the workpieces 3. This allows the solid-state resistance spot welding apparatus 1A to be configured to accommodate workpieces having various shapes.

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

Furthermore, while the above-described embodiment describes a stationary solid-state resistance spot welding device, the present invention is not limited to this configuration. For example, the present invention can also be applied to a gun-type welding device attached to the tip of a robot or the like.

The above-disclosed embodiments are illustrative in all respects and are not intended to be limiting. Therefore, the technical scope of this disclosure should not be interpreted solely in terms of the above-disclosed embodiments. Furthermore, all modifications within the scope and meaning equivalent to the claims are included. In the description of the above-disclosed embodiments, combinable configurations may be combined with each other.

1, 1A: solid-state resistance spot welding device; 2, 2a, 2b, 3, 3a, 3b: workpieces to be welded; 10, 10A: first welding unit; 30: driving source; 100, 200: pressure shaft; 110: electrode; 120, 220: base member; 122: connection end portion; 123: flange portion; 125: first recess; 130: case member; 140: lid portion; 141: second recess; 142: sphere; 151: first elastic member; 152: second elastic member; 160: guide member; 161: through hole.

Claims (5)

A driving source;
a joining unit driven in the axial direction by the drive source,
The joining unit is
a pressure shaft that presses the stacked objects in the axial direction so as to be plastically deformable;
an electrode that is arranged around the pressure shaft with a gap therebetween and applies a voltage to the plurality of objects to be bonded;
a plurality of first elastic members arranged around the pressure shaft at intervals and biasing the electrode toward the plurality of objects to be bonded;
The driving source drives the joining unit, thereby bringing the electrode into contact with an article to be joined that is located on the electrode side among the plurality of articles to be joined, and pressing the electrode against the plurality of articles to be joined by the biasing forces of the plurality of first elastic members, while pressing the pressure shaft against the plurality of articles to be joined;
the electrode is supported so as to be able to change its posture so as to conform to and come into contact with a contact surface of the object to be bonded located on the electrode side,
a first elastic member that is in contact with an object to be joined located on the electrode side and that is elastically deformed in accordance with the posture of the electrode when the first elastic member is in contact with the object to be joined located on the electrode side; the joining unit further includes a base member extending in the axial direction with a gap therebetween so as to surround the pressurizing shaft, the base member having a connection end connected to the electrode and a flange portion aligned with the plurality of first elastic members in the axial direction,
each of the plurality of first elastic members contacts the flange portion and biases the electrode via the base member;
2. The solid-state resistance spot joining apparatus according to claim 1, wherein a range within which the electrode can be tilted with respect to the axial direction is defined by a gap between the electrode and the base member and the pressure axis. the joining unit further includes a guide member that is disposed around the pressure shaft with a gap therebetween and that supports the plurality of first elastic members;
The guide member is provided with a plurality of through holes penetrating in the axial direction,
3. The solid-state resistance spot joining device according to claim 1, wherein a corresponding one of the plurality of first elastic members is inserted into each of the plurality of through holes. The solid-state resistance spot joining device of claim 3, wherein the joining unit further includes a second elastic member arranged inside the plurality of first elastic members around the pressure shaft and biasing the electrode toward the plurality of workpieces via the guide member. The joining unit is
a case member that is positioned around the pressurizing shaft, that houses the plurality of first elastic members therein, and that abuts against the plurality of first elastic members from a side opposite to the electrode in the axial direction;
a cover portion connected to the end of the case member on the electrode side while facing the flange portion;
a sphere disposed between the lid portion and the flange portion,
a first recess is provided on the lid side of the flange,
a second recess is provided on the flange portion side of the lid portion,
The solid resistance spot joining apparatus according to claim 2 , wherein the sphere is capable of making line contact with each of the first recess and the second recess.