JP2024072975A - Resistance welding equipment - Google Patents

Abstract

[Problem] To suppress deterioration of welding quality in resistance welding. [Solution] A resistance welding device applies pressure to a workpiece 100 consisting of multiple stacked materials 101, 102 to be welded and supplies power to the workpiece, thereby welding the multiple materials to be welded. The resistance welding device is equipped with an electrode 2 that comes into contact with the workpiece and applies pressure and power to the workpiece, and the electrode is formed with a coolant passage 26 that extends in the direction of the central axis of the electrode at the radial center, and slits 41-44 that communicate with the coolant passage and open on the outer circumferential surface of the electrode, the slits extending in the circumferential direction on a plane that intersects with the central axis direction, and the electrode has a suppression section (cover 6) that suppresses leakage of the coolant through the slits. [Selected Figure] Figure 2

Description

The technology disclosed herein relates to resistance welding equipment.

Patent Document 1 describes a spot welding device. The spot welding device includes a robot and a welding gun. The robot holds the welding gun and positions it at the welding point on the workpiece. An equalizing mechanism is interposed between the welding gun and the robot. The equalizing mechanism absorbs positional deviations of the workpiece and/or teaching errors of the robot.

Japanese Patent Application Laid-Open No. 59-92181

Spot welding is a type of resistance welding. In resistance welding, multiple materials to be welded are welded through the following process: (1) a first electrode and a second electrode sandwich a workpiece consisting of multiple materials to be welded and apply pressure to the workpiece while supplying power to the workpiece. (2) The materials to be welded come into contact with each other due to the pressure, forming a current path at the joint interface of the workpieces and generating Joule heat at the joint interface. (3) The materials to be welded melt at the joint interface of the workpieces. (4) The molten materials to be welded solidify to form a nugget, completing the welding process.

During the resistance welding process, discharges may occur between the electrode and the material to be welded. Such discharges wear down the tip of the electrode. As welding is repeated, the shape of the electrode tip gradually changes due to wear, which is a problem in the technical field of resistance welding, as a result of which the quality of the weld decreases.

The technology disclosed here prevents deterioration of welding quality during resistance welding.

The inventors of the present application have discovered that discharge occurs when the workpieces soften/melt in steps (2) and/or (3) of the processes (1) to (4) described above.

In more detail, during the welding process, the tip surface of the electrode is pressed against the workpiece. The electrode pressed against the workpiece is constrained by the workpiece and the welding gun. When the material to be welded softens/melts in (2) and/or (3) above, the restraint of the electrode by the workpiece and the welding gun loosens. If the center of the load applied to the electrode is on the central axis of the electrode, even if the restraint loosens, the tip surface of the electrode will not move relative to the surface of the material to be welded, and the electrode will remain pressed against the workpiece in the direction of the central axis of the electrode. Note that in resistance welding, the central axis of the electrode is generally perpendicular to the surface of the workpiece.

However, if the center of the load applied to the electrode is eccentric or tilted relative to the central axis of the electrode, the electrode will become loose and the tip of the electrode will move slightly as if sliding along the surface of the workpiece. During this movement, a misalignment occurs between the electrode and the workpiece, causing a discharge between them.

In the following, when the center of the load applied to the electrode is eccentric with respect to the central axis of the electrode or tilted with respect to the central axis, it is said that the "center of the load is misaligned with the central axis of the electrode."

In view of the above-mentioned mechanism of discharge generation, the inventors of the present application focused on the point of elastically bending the electrode with respect to the central axis. If the electrode can be bent, even if the center of the load applied to the electrode is shifted from the central axis of the electrode, the entire tip surface of the electrode will be uniformly abutted against the surface of the workpiece due to the elastic deformation of the electrode, and the electrode can apply a load to the workpiece in the central axis direction. In this case, even if the workpiece softens/melts and the restraint of the electrode by the workpiece and the welding gun loosens, the tip surface of the electrode will not move or will hardly move relative to the surface of the workpiece. The occurrence of misalignment between the electrode and the workpiece is suppressed, and the occurrence of discharge between the electrode and the workpiece is suppressed.

Because the electrode has a bendable structure, it is possible to form slits in the electrode that open onto the outer circumferential surface of the electrode. However, if a slit is formed in the electrode, the refrigerant used to cool the electrode will leak through the slits.

Therefore, the technology disclosed here is characterized by suppressing the leakage of refrigerant through the slits.

Specifically, the technology disclosed herein relates to a resistance welding apparatus that applies pressure to a workpiece made of a plurality of stacked materials to be welded and supplies power to the workpiece, thereby welding the plurality of materials to be welded.
An electrode is provided which is in contact with the workpiece and applies pressure to and supplies electricity to the workpiece,
The electrodes include
A coolant passage extending in a radial center portion in a direction of a central axis of the electrode;
a slit communicating with the coolant passage and opening in an outer peripheral surface of the electrode, the slit extending in a circumferential direction on a plane intersecting the central axis direction,
The electrode has a suppression portion that suppresses leakage of the refrigerant through the slit.

According to this configuration, the tip surface of the electrode abuts against the workpiece. The base end of the electrode may be supported, for example, by a welding gun. The welding gun presses the tip surface of the electrode against the surface of the material to be welded. The electrode presses the workpiece in the direction of the central axis of the electrode and supplies power to the workpiece.

When the material to be welded softens/melts due to the application of pressure and current to the workpiece, the electrode that is pressed against the workpiece loosens its grip. If the center of the load applied to the electrode is misaligned with the central axis of the electrode, the tip of the electrode may move slightly when the electrode is no longer gripped, causing a misalignment between the tip of the electrode and the surface of the material to be welded.

A slit is formed in the electrode. The slit opens on the outer peripheral surface of the electrode and extends in the circumferential direction on a plane that intersects with the central axis direction. The plane that intersects with the central axis direction is a virtual plane of the electrode. The slit allows the electrode to bend elastically with respect to the central axis of the electrode when the center of the load applied to the electrode is shifted from the central axis of the electrode.

When the electrode is elastically deformed, the entire tip surface of the electrode can be uniformly abutted against the surface of the workpiece. The electrode applies a load to the workpiece through the tip surface that is uniformly abutted against the surface of the workpiece. In this case, when the workpiece is softened/melted and the electrode is no longer restrained, the tip surface of the electrode does not move, or moves very little, against the surface of the workpiece. The workpiece is deformed, but the change in the positional relationship between the tip surface of the electrode and the surface of the workpiece that are in contact with each other is suppressed. Suppressing the misalignment between the tip surface of the electrode and the surface of the workpiece suppresses the occurrence of discharge between the electrode and the workpiece, so that wear of the electrode tip is suppressed. Because wear is suppressed, the shape of the electrode tip does not change, or is less likely to change, even if welding is repeated. The resistance welding device can maintain high welding quality. The resistance welding device is also advantageous in extending the life of the electrode.

The slits formed in the electrode allow the electrode to deform elastically, but also cause the refrigerant to leak. The electrode has a suppression section. The suppression section suppresses the leakage of the refrigerant through the slit. Because the electrode is capable of elastic deformation while maintaining a cooling structure, the resistance welding device can suppress a decrease in welding quality.

The slit is formed in at least one of a first electrode located on a first side of the workpiece and a second electrode located on a second side of the workpiece,
The suppression portion may be attached to the electrode in which the slit is formed.

If at least one of the first electrode and the second electrode is elastically deformable, the resistance welding device can stabilize the welding quality. If both the first electrode and the second electrode are elastically deformable, the resistance welding device can further stabilize the welding quality.

If there are no slits, refrigerant leakage will not occur. The suppression section only needs to be present on the electrode in which the slits are formed.

The suppression portion may be a cover attached to the outer peripheral surface of the electrode and covering the opening of the slit.

The cover covers the slit opening, so any refrigerant that leaks through the slit opening accumulates between the electrode and the cover. This prevents refrigerant from leaking.

the coolant passage has an inner tube that extends to a tip end of the electrode and forms a coolant passage;
the refrigerant passage has a double structure in which a refrigerant return passage is formed on the outside of the inner tube,
The slit may be in communication with the return path.

The refrigerant passes through the inner tube and reaches the tip of the electrode, so the tip of the electrode is cooled efficiently. If the refrigerant passage has a double structure, the supply and discharge of the refrigerant becomes smooth.

The slit extends in a circumferential direction on a plane perpendicular to the central axis direction,
The electrode is
A plurality of slits arranged in the central axis direction;
a base that is formed by a first slit and a second slit that are adjacent to each other in the central axis direction, that is annular and surrounds the refrigerant passage, and that has a thickness that allows the base to be elastically deformed so as to bend in the central axis direction;
and a column formed in each of the first slit and the second slit, extending in the central axis direction and connected to the base.

The column inside the slit and the base to which the column is connected transmit the load in the central axis direction between the tip surface and base end of the electrode. The column inside the slit ensures the rigidity that allows the electrode to apply pressure to the workpiece.

When the base receives a load in the central axis direction through the column, it tries to bend in the central axis direction. The slits adjacent to the base allow the base to bend in the central axis direction. When the base bends in the central axis direction, the slits collapse in the central axis direction, allowing the electrode to be compressed and deformed in the central axis direction.

The electrode has a cap tip that contacts the workpiece, a shank to which the cap tip is attached, and a holder that holds the shank,
The slit is formed in the shank or the holder,
The suppression portion may be attached to the shank or the holder in which the slit is formed.

The cap tip that contacts the workpiece is replaced when it becomes worn. The cap tip is replaced more frequently than the shank or holder.

If a slit is formed in the cap tip, the manufacturing cost of the cap tip increases. High manufacturing costs for a cap tip that is replaced frequently also increase the maintenance costs of the resistance welding equipment. In contrast, the shank or holder is replaced relatively infrequently, making it suitable as a location for forming a slit.

The resistance welding device can prevent misalignment between the tip surface of the electrode and the surface of the workpiece during resistance welding, thereby preventing deterioration of welding quality during resistance welding. The resistance welding device can also prevent refrigerant leakage.

FIG. 1 shows a spot welding device. FIG. 2 shows a first electrode of the spot welding device. FIG. 3 shows the shank of the first electrode. The upper diagram in FIG. 4 is a top view of the shank, and the lower diagram is a cross-sectional view taken along line AA. FIG. 5 shows the procedure for creating the slits. The upper diagram in FIG. 6 shows a state in which the shank is elastically deformed, and the lower diagram shows the cross section taken along line B--B. FIG. 7 shows the shank in a bent state. FIG. 8 shows a variation of the electrode relative to the slit. FIG. 9 shows a variation of the electrodes with respect to the columns. FIG. 10 shows the welding process of the projection welding device. FIG. 11 is an exploded view of the first electrode of the projection welding apparatus. FIG. 12 shows a second electrode of the projection welding device.

Embodiments of a resistance welding device will be described below with reference to the drawings. The resistance welding device described here is an example.

(Overall structure of spot welding device)
Fig. 1 illustrates an entire resistance welding apparatus. The resistance welding apparatus applies pressure to a workpiece 100 consisting of a plurality of stacked workpieces 101, 102 to be welded, and supplies power to the workpiece 100, thereby welding the plurality of workpieces 101, 102 together. The resistance welding apparatus in Fig. 1 is a so-called spot welding apparatus 1. In the spot welding apparatus 1 in Fig. 1, the direction in which pressure is applied to the workpiece 100 is the vertical direction on the page. The pressure direction is not limited to the vertical direction.

The spot welding device 1 welds two workpieces 101 and 102, both of which are plate-shaped. The two workpieces 101 and 102 are metal plates. The two workpieces 101 and 102 may both be iron-based members. The iron-based member is a steel member with high strength and rigidity, such as high-tensile steel. One of the two workpieces 101 and 102 may be an iron-based member and the other an aluminum-based member. The aluminum-based member is an aluminum alloy member. In the example of FIG. 1, the workpiece 100 is made up of two workpieces 101 and 102, but the workpiece 100 may be made up of three or more workpieces. In FIG. 1, the two workpieces 101 and 102 have the same thickness, but the thicknesses of the workpieces 101 and 102 may be different.

The spot welding device 1 illustrated in FIG. 1 includes a welding gun 11. The welding gun 11 is supported, for example, by a robot (not shown). The robot positions the welding gun 11 at a position on the workpiece 100 where welding is to be performed.

The welding gun 11 supports a first electrode 2 and a second electrode 20. The first arm 111 of the welding gun 11 is supported as a cantilever with a fixed base end and an unfixed tip end, and the first arm 111 supports the first electrode 2 at its free end. The second arm 112 is also supported as a cantilever, and the second arm 112 supports the second electrode 20 at its free end.

The first electrode 2 is located on the first side of the workpiece 100. In FIG. 1, the first electrode 2 is located below the workpiece 100. The second electrode 20 is located on the second side of the workpiece 100. In FIG. 1, the second electrode 20 is located above the workpiece 100. The first electrode 2 and the second electrode 20 sandwich the workpiece 100 in the stacking direction of the materials to be welded 101, 102, and apply pressure to the workpiece 100 in the stacking direction.

The first electrode 2 is generally columnar. The second electrode 20 is also generally columnar. The first electrode 2 and the second electrode 20 face each other in the direction of the central axis X of the electrodes.

The welding gun 11 has a pressure device 14. The pressure device 14 moves the second electrode 20 in the direction of the central axis X relative to the workpiece 100. The pressure device 14 is configured to include, for example, an air cylinder, a hydraulic cylinder, or a servo motor. When the welding gun 11 has the tip of the first electrode 2 in contact with the surface of the workpiece 100, the pressure device 14 moves the second electrode 20, whereby the first electrode 2 and the second electrode 20 sandwich the workpiece 100 in the direction of the central axis X and apply pressure to the workpiece 100 in the direction of the central axis X.

The spot welding device 1 is equipped with a controller 12. The controller 12 controls the application of pressure and power to the workpiece 100 in the spot welding device 1. The controller 12 is a controller based on a well-known microcomputer, and includes a CPU (Central Processing Unit), a memory, and an input/output bus. The CPU is a central processing unit that executes computer programs. The computer programs include basic control programs such as an OS (Operating System), and application programs that are started on the OS and realize specific functions. The memory includes a RAM (Random Access Memory) and a ROM (Read Only Memory). The ROM stores various computer programs, data, etc. The RAM is a memory that is provided with a processing area used when the CPU performs a series of processes. The input/output bus inputs and outputs electrical signals to and from the controller 12.

The controller 12 outputs a control signal to the pressure device 14 according to a control program stored in the ROM. The workpiece 100 is pressurized by the first electrode 2 and the second electrode 20. The controller 12 also supplies a welding current from the power source 13 to the workpiece 100 through the first electrode 2 and the second electrode 20.

Here, the welding process performed by the spot welding device 1 will be briefly described.
(1) The first electrode 2 and the second electrode 20 sandwich the workpiece 100 in the direction of the central axis X and apply pressure to the workpiece 100 while supplying power to the workpiece 100.
(2) When the workpieces 101 and 102 come into contact with each other by the application of pressure, a current path is formed at the joint interface of the workpiece 100 and Joule heat is generated at the joint interface of the workpiece 100.
(3) The workpieces 101 and 102 melt at the joining interface of the workpiece 100.
(4) The molten workpieces 101, 102 solidify to form a nugget, completing the welding process.

(Electrode Structure)
2 illustrates the structure of the first electrode 2. The structures of the first electrode 2 and the second electrode 20 are the same except that they are upside down. A description of the structure of the second electrode 20 will be omitted.

The cap tip 21 of the first electrode 2 is located at the tip of the first electrode 2. The cap tip 21 has a tip surface 211 that contacts the workpiece 100. If the tip surface 211 wears down due to repeated welding by the spot welding device 1, the cap tip 21 is replaced.

The cap chip 21 has a recess 212. The recess 212 opens to the base end surface of the cap chip 21 and recesses from the base end surface along the central axis X of the first electrode 2. The recess 212 forms part of the coolant passage 26, as described below.

The shank 22 extends along the central axis X of the first electrode 2. The cap tip 21 is attached to the tip of the shank 22. The shank 22 supports the cap tip 21. The shank 22 has a first hole 221. The first hole 221 extends along the central axis X of the first electrode 2. The first hole 221 opens at both the tip and base ends of the shank 22. The first hole 221 penetrates the shank 22. The shank 22 has a cylindrical shape (see also FIG. 3).

When the cap tip 21 is attached to the tip of the shank 22, the first hole 221 is connected to the recess 212 of the cap tip 21. As described below, the first hole 221 forms part of the coolant passage 26.

An inner tube 222 is disposed within the first hole 221. The inner tube 222 extends along the central axis X of the first electrode 2. The inner tube 222 protrudes from the base end of the shank 22. The inner tube 222 is also inserted into a second hole 231 of the holder 23, which will be described later.

The shank 22 also has slits 41 to 44 formed therein. The first electrode 2 illustrated in FIG. 2 has a plurality of slits 41 to 44. Details of the shapes of the slits 41 to 44 will be described later.

The holder 23 is a cylindrical object that extends along the central axis X of the first electrode 2. The holder 23 has a second hole 231. The second hole 231 extends along the central axis X of the first electrode 2. The second hole 231 passes through the holder 23.

The base end of the shank 22 is inserted into the second hole 231 from the tip of the holder 23. The holder 23 supports the shank 22. The second hole 231 of the holder 23 and the first hole 221 of the shank 22 are in communication.

As described above, the inner tube 222 spans the shank 22 and the holder 23. The inner tube 222 forms a feed path 24 for supplying the refrigerant to the cap tip 21. The tip of the inner tube 222 is connected to the recess 212 of the cap tip 21. The refrigerant is supplied through the inner tube 222 into the recess 212. The refrigerant effectively cools the cap tip 21 (see the arrow in Figure 2).

The space between the first hole 221 of the shank 22 and the inner tube 222 forms part of the coolant return path 25. The space between the second hole 231 of the holder 23 and the inner tube 222 also forms part of the coolant return path 25. The return paths 251 and 252 are connected to each other. The coolant supplied to the recess 212 of the cap tip 21 is reversed in the recess 212 and returns to the base end of the holder 23 through the return paths 251 and 252. The double-structure coolant path 26 including the feed path 24 and the return path 25 can efficiently cool the cap tip 21.

(Slit structure)
The left diagram in Fig. 3 is a perspective view of the shank 22. The center diagram in Fig. 3 is a perspective view showing a cross section of the shank 22 cut at the position of the first slit 41. The right diagram in Fig. 3 is a perspective view showing a cross section of the shank 22 cut at the position of the second slit 42.

As described above, the shank 22 has a plurality of slits 41 to 44. More specifically, the shank 22 is composed of an upper tapered portion 223, a lower tapered portion 224, and an intermediate portion 225. The upper tapered portion 223 tapers upward. The cap tip 21 is attached to the tip of the upper tapered portion 223. The lower tapered portion 224 tapers downward. The base end of the lower tapered portion 224 is supported by the holder 23. The intermediate portion 225 is located between the upper tapered portion 223 and the lower tapered portion 224. The intermediate portion 225 has a constant outer diameter.

The slits 41 to 44 are formed in the intermediate portion 225. The multiple slits 41 to 44 are aligned in the direction of the central axis X of the first electrode 2. The shank 22 in the illustrated example has, in order from the tip to the base end, a first slit 41, a second slit 42, a third slit 43, and a fourth slit 44.

Each of the slits 41 to 44 extends in the circumferential direction in a plane intersecting the central axis X direction, more precisely, in a plane perpendicular to the central axis X direction. The plane perpendicular to the central axis X direction is a virtual plane in the first electrode 2. Each of the slits 41 to 44 opens on the outer peripheral surface of the shank 22. The opening of each of the slits 41 to 44 extends in the circumferential direction in a direction perpendicular to the central axis X direction on the outer peripheral surface of the shank 22. Each of the slits 41 to 44 also communicates with the first hole 221 of the shank 22, as shown in Figures 3 and 4.

In the shank 22 shown in Figures 3 and 4, each of the slits 41 to 44 has the same width in the direction of the central axis X. In addition, the intervals between adjacent slits 41 to 44 in the direction of the central axis X are also the same.

The first base 45 is formed by the first slit 41 and the second slit 42 that are adjacent in the direction of the central axis X. Similarly, the second slit 42 and the third slit 43 form the second base 46, and the third slit 43 and the fourth slit 44 form the third base 47. Each of the bases 45 to 47 is annular and surrounds the first hole 221. In addition, because the spacing between adjacent slits 41 to 44 in the direction of the central axis X is the same, the thickness of each of the bases 45 to 47 in the direction of the central axis X is the same.

Columns 31-33, 34-36 are formed in each of the slits 41-44. The columns 31-36 extend in the direction of the central axis X within the slits 41-44 and are connected to bases 45-47. Since there is no base above the first slit 41, the upper ends of the columns 31-33 formed in the first slit 41 are connected to the upper wall that forms the first slit 41. Similarly, since there is no base below the fourth slit 44, the lower ends of the columns 34-36 formed in the fourth slit 44 are connected to the lower wall that forms the fourth slit 44.

Each of the slits 41 to 44 has three columns 31 to 36 formed therein. More specifically, the first slit 41 has a first column 31, a second column 32, and a third column 33 formed therein. The third slit 43 also has a first column 31, a second column 32, and a third column 33 formed therein.

A fourth column 34, a fifth column 35, and a sixth column 36 are formed in the second slit 42. A fourth column 34, a fifth column 35, and a sixth column 36 are also formed in the fourth slit 44.

As shown in the upper diagram of FIG. 4, the first to sixth columns 31 to 36 all have the same shape, with a cross section that is approximately triangular. The first to third columns 31 to 33 are arranged around the first hole 221 so as to surround the first hole 221. The apex of the triangle of each column 31 to 33 is located radially outward of the first electrode 2. In the illustrated shank 22, the first to third columns 31 to 33 are spaced apart from each other by 120°. Between the first column 31 and the second column 32, a communication port 37 is formed that connects the slits 41, 43 and the first hole 221. Similarly, between the second column 32 and the third column 33, and between the third column 33 and the first column 31, a communication port 37 is formed that connects the slits 41, 43 and the first hole 221.

The fourth to sixth columns 34 to 36 are also arranged around the first hole 221 so as to surround the first hole 221. The apex of the triangle of each column 34 to 36 is located radially outward of the first electrode 2. In the illustrated shank 22, the fourth to sixth columns 34 to 36 are spaced apart from each other by 120°. Between the fourth column 34 and the fifth column 35, between the second column 32 and the third column 33, and between the third column 33 and the first column 31, communication holes 37 are formed, which connect the slits 42, 44 to the first hole 221, respectively.

The first column 31 and the fourth column 34 are offset by an angle of 60° in the circumferential direction. Similarly, the second column 32 and the fifth column 35 are offset by an angle of 60° in the circumferential direction, and the third column 33 and the sixth column 36 are offset by an angle of 60° in the circumferential direction. Therefore, as shown in the upper diagram of Figure 4, all of the columns 31 to 36 formed in two adjacent slits 41 to 44 that sandwich any base 45 to 47 between them are offset in the circumferential direction.

As an example, the creation of the slits and columns in the shank 22 can be performed as follows. Figure 5 shows the procedure for creating the first slit 41 and the first to third columns 31 to 33 in the shank 22.

First, a shank 22 having a first hole 221 formed therein is prepared. In process P1, the shank 22 is fixed, and a cutting tool 5 is moved relative to the outer periphery of the shank 22 in a direction perpendicular to the central axis X. As a result, a bow-shaped portion surrounded by a circular arc and a chord in the cross section of the shank 22 is cut off by the cutting tool 5. The cutting tool 5 is fed radially inward of the shank 22 to a position where the chord interferes with the first hole 221 of the shank 22. In process P1, a slit 41 that opens on the outer periphery of the shank 22 and communicates with the first hole 221 is formed in the shank 22.

Next, in process P2, the shank 22 is rotated 120° around the central axis and fixed. As in process P1, the cutting tool 5 is moved relative to the outer periphery of the shank 22 in a direction perpendicular to the central axis X. As a result, as in process P1, a bow-shaped portion surrounded by a circular arc and a chord in the cross section of the shank 22 is cut off by the cutting tool 5. A slit 41 is formed on the outer periphery of the shank 22 at a position different from the above and communicating with the first hole 221. Also, in process P2, the first column 31 is formed.

Next, in step P3, the shank 22 is rotated another 120° around the central axis to fix the shank 22. Then, as in step P1, the cutting tool 5 is moved relative to the outer periphery of the shank 22 in a direction perpendicular to the central axis X. As a result, as in step P1, the cutting tool 5 cuts off the arch-shaped portion surrounded by the arc and the chord in the cross section of the shank 22. A slit 41 is formed on the outer periphery of the shank 22 at a position different from the above and communicating with the first hole 221. In step P3, the second column 32 and the third column 33 are formed. In the shank 22 shown in the figure, the slits 41 are formed individually in each of the three steps, but the slits 41 are connected to each other through the tip portions of the first column 31, the second column 32, and the third column 33.

After the first slit 41 and the first to third columns 31 to 33 are formed in the shank 22 by steps P1 to P3, the relative positions of the shank 22 and the cutting tool 5 in the direction of the central axis X are changed, and the second slit 42 and the fourth to sixth columns 34 to 36 are formed in the shank 22 by steps P1 to P3 described above. Note that by adjusting the circumferential orientation of the shank 22, the positions of the first to third columns 31 to 33 and the positions of the fourth to sixth columns 34 to 36 are shifted by 60°. The formation of the third slit 43 and the first to third columns 31 to 33, and the formation of the fourth slit 44 and the fourth to sixth columns 34 to 36 in the shank 22 can also be performed in a similar manner.

(Elastic Deformation of Electrodes)
As described above, the first electrode 2 has the slits 41 to 44 and the columns 31 to 36 formed therein. The second electrode 20 also has slits and columns formed therein. The slits 41 to 44 and the columns 31 to 36 elastically deform the first electrode 2 in the intermediate portion between the distal end surface 211 and the base end of the first electrode 2.

Figure 6 illustrates a state in which a load in the direction of the central axis X is applied to the first electrode 2 uniformly on a plane perpendicular to the direction of the central axis X. This is equivalent to the center of the load applied to the first electrode 2 being on the central axis X. The load is transmitted in the direction of the central axis X through the columns 31-36 and bases 45-46 in the shank 22.

6, the first to third columns 31 to 33 of the first slit 41 are positioned at equal intervals in the circumferential direction. In addition, the fourth to sixth columns 34 to 36 of the second slit 42 adjacent to the first slit 41 across the first base 45 are shifted in the circumferential direction relative to the first to third columns 31 to 36. Since the positions of the first to third columns 31 to 33 on the upper side of the first base 45 are shifted from the positions of the fourth to sixth columns 34 to 36 on the lower side of the first base 45, the position where the load in the direction of the central axis X is applied to the first base 45, which expands in a direction perpendicular to the direction of the central axis X, is shifted in the circumferential direction as illustrated by the black arrow in the upper diagram of FIG. 6. As a result, the first base 45 is deflected in the direction of the central axis as illustrated by the two-dot chain line in the upper diagram of FIG. 6. In other words, the thickness of the first base 45 in the direction of the central axis is thick enough to cause deflection when a load is applied.

Similarly, since the fourth to sixth columns 34 to 36 of the second slit 42 and the first to third columns 31 to 33 of the third slit 43 are misaligned in the circumferential direction, the second base 46 bends in the direction of the central axis X, as illustrated by the two-dot chain line in the upper diagram of Figure 6.

The third base 47 also bends in the direction of the central axis X, as shown by the two-dot chain line in the upper diagram of Figure 6, because the first to third columns 31 to 33 of the third slit 43 and the fourth to sixth columns 34 to 36 of the fourth slit 44 are misaligned in the circumferential direction. Note that Figure 6 shows an exaggerated depiction of the bending of each base 45 to 47.

The columns 31-36 promote the deflection of the bases 45-47, and the slits 41-44 allow the bases 45-47 to deflect. When the center of the load applied to the first electrode 2 is on the central axis X, the shank 22 elastically deforms so as to contract in the direction of the central axis X. In other words, the shank 22 can elastically compress and deform while transmitting the load in the direction of the central axis X.

If the center of the load applied to the first electrode 2 is eccentric or inclined with respect to the central axis X of the first electrode 2, the load is applied non-uniformly in a plane perpendicular to the central axis X. In this case, the load applied to the base 45-47 through the three columns 31-36 of each slit 41-44 becomes non-uniform, so that the parts of the base 45-47 to which a relatively large load is applied from the columns 31-36 locally become largely deflected in the direction of the central axis X. For example, FIG. 7 shows an example in which a compressive load is applied to the first electrode 2 along an axis that is eccentric to the left of the central axis X, as shown by the hollow arrow. In this case, the parts of the slits 41-44 on the left side of the page become relatively crushed, so that the shank 22 bends so that the central axis X is inclined (see the arrow in FIG. 7). Because the shank 22 bends, the tip surface 211 of the cap tip 21 maintains a state of abutting against the surface of the workpiece 100. Note that the bending of the shank 22 is exaggerated in FIG.

When the workpieces 101, 102 soften/melt in the above-mentioned welding process (2) and/or (3), the electrodes that were restrained by the welding gun 11 and the workpiece 100 loosen their restraints and attempt to move. More specifically, the first electrode 2 and the second electrode 20 are held by the first arm 111 and the second arm 112, which are cantilevered, respectively, as shown in FIG. 1. Therefore, when the workpieces 101, 102 soften/melt, the first electrode 2 and the second electrode 20 attempt to move so as to tilt in the direction shown by the white arrow in FIG. 1.

At this time, in the electrodes 2, 20 having the slits 41-44 and columns 31-36, the shank 22 bends as described above, so that the tip surface 211 of the cap tip 21 can maintain a state of abutment against the surface of the workpiece 100. As a result, no misalignment occurs between the tip surface 211 of the electrodes 2, 20 and the surfaces of the workpieces 101, 102, and discharge is suppressed between the electrodes 2, 20 and the workpieces 101, 102. Since wear on the tips of the electrodes 2, 20 is suppressed by suppressing discharge, this spot welding device 1 can suppress deterioration of welding quality even when welding is repeated. Furthermore, because wear on the cap tip 21 is suppressed, the life of the cap tip 21 is extended.

In addition, the spot welding device 1 has the advantage that only the electrodes 2 and 20 have a new structure, and the parts other than the electrodes 2 and 20 can be reused from conventional spot welding devices.

(Modifications of slits and columns)
The openings of the slits 41 to 44 extend in the circumferential direction, perpendicular to the central axis X, on the outer peripheral surface of the electrodes 2, 20. This configuration has the advantage that, when the center of the load applied to the electrodes 2, 20 is shifted from the central axis X of the electrodes 2, 20, the electrodes 2, 20 can be stably elastically deformed in the bending direction in the entire circumferential direction of the electrodes 2, 20. The openings of the slits may extend in the circumferential direction on the outer peripheral surface of the electrodes in a plane intersecting with the central axis X. An electrode having this structure can also be elastically deformed in the bending direction when the center of the load applied to the electrodes is shifted from the central axis of the electrodes.

The elastic modulus of the electrodes 2, 20 can be changed by changing the position or number of slits and/or the position or number of columns formed in the electrodes 2, 20. By appropriately setting the elastic modulus of the electrodes 2, 20 according to the welding conditions of the spot welding device 1, it is possible to suppress the occurrence of misalignment between the tip surface 211 of the electrodes 2, 20 and the workpiece 100 while allowing pressure to be applied to the workpiece 100 through the electrodes 2, 20.

The thickness of the base formed on the electrode may be the same for multiple bases, or may be different. In FIG. 8, the thickness H1 of the first base 45 located on the tip side of the electrodes 2, 20 is relatively thick, and the thickness H3 of the third base 47 located on the base side of the electrodes 2, 20 is relatively thin. If the thickness of the base is thick, the bending rigidity of the base is high. In other words, the base is less likely to bend in the direction of the central axis X. If the thickness of the base is thin, the bending rigidity of the base is low. The base is more likely to bend in the direction of the central axis X. By making the thickness of the first base 45 located on the tip side of the electrodes 2, 20 relatively thick and the thickness of the third base 47 located on the base side of the electrodes 2, 20 relatively thin, the electrodes 2, 20 are elastically deformed stably. The occurrence of misalignment between the tip surface 211 of the electrodes 2, 20 and the surface of the workpiece 100 can be more effectively suppressed.

In FIG. 8, the thickness H1 of the first base 45, the thickness H2 of the second base 46, and the thickness H3 of the third base 47 are thinner in that order (H1>H2>H3). The relationship in thickness between the multiple bases is not limited to the illustrated example. For example, the relationship in thickness between the multiple bases may be H1=H2>H3, or H1>H2=H3.

The number of bases is not limited to three. The electrodes 2, 20 need only have at least one base, and therefore the electrodes 2, 20 need only have at least two slits. The number of slits that can be formed in the electrodes 2, 20 depends on the length of the electrodes 2, 20 in the central axis X direction. The electrodes 2, 20 may have a maximum of five slits, for example.

As shown in FIG. 6, all of the columns 31-36 formed on the electrodes 2, 20 are offset in the circumferential direction, allowing the electrodes 2, 20 to stably elastically deform in the bending direction while maintaining the rigidity required of the electrodes 2, 20 in the direction of the central axis X.

Figure 9 illustrates electrodes 2, 20 with a modified column arrangement. In the spot welding device 10 shown in the upper diagram of Figure 9, the shank 220 is bent midway. A shank 220 of this shape can avoid interference with the workpiece 100. In Figure 9, the base end of the shank 220 held in a holder not shown and the tip of the shank 220 supporting the cap tip 21 are misaligned in the horizontal direction (see X1 and X2 in Figure 9). When the first electrode 2 and the second electrode 9 are applying pressure to the workpiece 100, an eccentric load is constantly applied to the cap tip 21 and the shank 220.

The slit 4 is formed in the shank 220. In the case of an electrode structure in which an eccentric load is applied to the cap tip 21, in order to bring the entire tip surface 211 of the cap tip 21 into uniform contact with the surface of the workpiece 100, it is preferable to increase the rigidity of the shank 220 at a location to the right of the axis X1 in FIG. 9 and decrease the rigidity at a location to the left of the axis X1 in FIG. 9.

As shown in the lower diagram of FIG. 9, the three columns 301, 302, and 303 formed in the slit 4 are positioned biased to one side of the axis X1 in the slit 4. The angle between columns 301 and 302 is 90°, and the angle between columns 302 and 303 is also 90°. In this way, the shank 220 has high rigidity on the right side of the paper in FIG. 9 and low rigidity on the left side of the paper. The cap tip 21 can stably pressurize the workpiece 100, and misalignment between the tip surface 211 of the cap tip 21 and the surface of the workpiece 100 is suppressed.

In addition, in the shank 220 of FIG. 9, the three columns 301, 302, and 303 formed in the slit 4 may be circumferentially offset from the columns of the slit 4 adjacent to the slit 4 in the direction of the axis X1.

The number of columns 31-36, 310-330 formed in one slit 41-44, 4 is not limited to three. However, if there are three columns 31-36, 310-330, the plane to which the three columns 31-36, 310-330 are connected is determined to be one. Having three columns 31-36, 310-330 in one slit 41-44, 4 has the advantage that the electrodes 2, 20 bend stably in an electrode structure in which multiple slits 41-44, 4 overlap in the axial direction.

In the shank 22 illustrated in FIG. 3, the radially outermost ends of the columns 31-36 (i.e., the vertices of the roughly triangular columns 31-36 in plan view) are located radially inward from the outer circumferential surface of the shank 22. The radially outermost ends of the columns 31-36 may be located at the same position as the outer circumferential surface of the shank 22. As a result, the columns 31-36 may divide the slits 41-44 into multiple slits in the circumferential direction.

In addition, the cross-sectional shape of the column is not limited to a substantially triangular shape. The column can be formed into any shape.

The slits 41-44, 4 are not limited to being formed in the shank 22, 220. The slits 41-44, 4 may be formed in the holder, for example. The slits 41-44, 4 can also be formed in the cap tip 21. However, forming the slits 41-44, 4 in the cap tip 21 increases the manufacturing cost of the cap tip 21. Increasing the manufacturing cost of the cap tip 21, which is replaced frequently, increases the maintenance cost of the spot welding device 1, 10. The shank 22, 220 or the holder 23 is suitable as a location for forming the slits 41-44, 4 because it is replaced relatively infrequently.

In addition, the slits 41-44, 4 and columns 31-36, 310-330 do not necessarily have to be provided on both the first electrode 2 and the second electrode 20 of the spot welding device 1, 10. Instead, the slits 41-44, 4 and columns 31-36, 310-330 may be provided on either the first electrode 2 or the second electrode 20.

(Structure to prevent refrigerant leakage)
Each of the slits 41 to 44 formed in the shank 22 communicates with the first hole 221 forming the coolant passage 26 via the communication port 37. For this reason, the coolant flowing through the return path 25 of the coolant passage 26 leaks out of the electrodes 2, 20 through the communication port 37 and the slits 41 to 44.

The electrodes 2 and 20 are equipped with a suppression portion that suppresses the leakage of the refrigerant. As shown in FIG. 2, the suppression portion is a cover 6 attached to the shank 22.

The cover 6 covers the openings of the first to fourth slits 41 to 44 formed on the outer peripheral surface of the shank 22. As shown by the arrows in FIG. 2, the refrigerant that leaks out of the electrode 2 from the openings of the first to fourth slits 41 to 44 remains inside the cover 6.

An O-ring 61 is interposed between the shank 22 and the cover 6. The O-rings 61 are attached to both the upper and lower parts of the shank 22. The O-rings 61 prevent the refrigerant from leaking from the gap between the shank 22 and the cover 6.

In this way, in the electrodes 2 and 20 having a cooling structure, elastic deformation due to the slits 41 to 44 and suppression of refrigerant leakage are both achieved.

The suppression section only needs to be attached to the electrodes 2 and 20 in which the slits 41 to 44 and 4 are formed. This is because refrigerant leakage would not occur without the slits 41 to 44 and 4.

(Structure of projection welding device)
The technology disclosed herein is not limited to application to the spot welding device 1. The electrode disclosed herein has a function of elastic deformation, and therefore, in addition to the effect of suppressing the occurrence of misalignment between the tip surface 211 of the electrode and the surface of the workpiece 100, the tip surface 211 of the electrode can exert the effect of uniformly applying a load to the workpiece 100. This effect is useful for a projection welding device that is required to uniformly weld multiple protrusions on the material to be welded. Projection welding is a type of resistance welding.

Figure 10 illustrates a portion of the structure of the first electrode 8 and the second electrode 9 of the projection welding device 7. The workpiece 1000 to be welded by the projection welding device 7 is made up of a first workpiece 1010 and a second workpiece 1020. The first workpiece 1010 is flat. The first workpiece 1010 has a through hole 1011. The through hole 1011 penetrates the first workpiece 1010 in the thickness direction.

The second workpiece 1020 is a nut. The second workpiece 1020 is non-plate-shaped. As shown on the left in FIG. 10, the second workpiece 1020 is substantially square in plan view and has a screw hole 1021 in the center. The second workpiece 1020 is placed on the first workpiece 1010 so that the screw hole 1021 is coaxial with the through hole 1011 of the first workpiece 1010. The second workpiece 1020 also has protrusions 1022 at each of the four corners. Each of the four protrusions 1022 comes into contact with the surface of the first workpiece 1010 when the second workpiece 1020 is placed on the first workpiece 1010.

The first electrode 8 has a cap tip 81 and a guide pin 82. The cap tip 81 abuts against the surface of the first workpiece 1010. The cap tip 81 has a through hole 811. The through hole 811 penetrates the cap tip 81 in the direction of the central axis X.

The guide pin 82 extends in the direction of the central axis X of the first electrode 8. The guide pin 82 is inserted into the through hole 811 of the cap tip 81. The guide pin 82 reciprocates in the direction of the central axis X by the telescopic actuator 88 described later. FIG. 10 shows the protruding state of the guide pin 82. The guide pin 82 is inserted into the through hole 1011 of the first workpiece 1010 and the screw hole 1021 of the second workpiece 1020. The tip of the guide pin 82 protrudes from the second workpiece 1020. The guide pin 82 regulates the relative positions of the first workpiece 1010 and the second workpiece 1020 so that the through hole 1011 and the screw hole 1021 are coaxial. The structure of the first electrode 8 will be described in detail later.

The cap tip 91 of the second electrode 9 has a first recess 911 and a second recess 912. The first recess 911 is formed at the base end of the cap tip 91. The first recess 911 opens at the base end of the cap tip 91 and extends in the direction of the central axis X of the second electrode 9. The first recess 911 forms a part of the coolant path 93 of the second electrode 9, as described below.

The second recess 912 is formed at the tip of the cap tip 91. The second recess 912 opens to the tip surface 913 of the cap tip 91. The periphery of the second recess 912 at the tip surface 913 of the cap tip 91 abuts against the second workpiece 1020. The second recess 912 extends in the direction of the central axis X of the second electrode 9. The first recess 911 and the second recess 912 are not connected. The tip of the guide pin 82 is inserted into the second recess 912 when the first electrode 8 and the second electrode 9 sandwich the workpiece 1000 in the direction of the central axis X.

Here, the welding process by the projection welding device 7 will be described.
(1) The first electrode 8 abuts against the first material to be welded 1010, and the guide pin 82 passes through the through hole 1011 of the first material to be welded 1010 and protrudes toward the second electrode 9 (see P11 in Figure 10).
(2) The second workpiece 1020 is inserted onto the guide pin 82, and the protrusion 1022 of the second workpiece 1020 abuts on the first workpiece 1010 (see P12 in FIG. 10).
(3) The tip surface 913 of the second electrode 9 contacts the second workpiece 1020, and the first electrode 8 and the second electrode 9 clamp the workpiece 1000 in the central axial direction X and apply pressure to the workpiece 1000 while supplying power to the workpiece 1000 (see P13 in Figure 10).
(4) The protrusion 1022 of the second material to be welded 1020 comes into contact with the first material to be welded 1010 by the application of pressure, and a current path is formed at the location of the protrusion 1022, and Joule heat is generated. The protrusion 1022 of the second material to be welded 1020 and the location of the first material to be welded 1010 that comes into contact with the protrusion 1022 melt (see P14 in FIG. 10 ).
(5) The molten first workpiece 1010 and second workpiece 1020 solidify to form a nugget, completing the welding process.

The first electrode 8 and the second electrode 9 of the projection welding device 7 are capable of elastic deformation. This allows a uniform load to be applied to the four protrusions 1022 of the second workpiece 1020, and the projection welding device 7 can uniformly weld the four protrusions 1022 to the first workpiece 1010. The structure of the elastically deformable first electrode 8 and second electrode 9 will be described below with reference to Figures 11 and 12.

Figure 11 shows an exploded view of the first electrode 8. As described above, the cap tip 81 of the first electrode 8 has a through hole 811. The guide pipe 83 is attached to the base end of the cap tip 81 and holds the cap tip 81. The guide pipe 83 also has an inner hole into which the guide pin 82 is inserted. The guide pipe 83 guides the reciprocating movement of the guide pin 82.

The holder 84 holds the guide pipe 83 and the cap tip 81. The holder 84 is cylindrical and has a hole 841 into which the rod 87 described below is inserted. The hole 841 penetrates the holder 84 in the direction of the central axis X.

The first joint 85 is interposed between the holder 84 and the cap chip 81. The first joint 85 is an elastically deformable portion of the first electrode 8. The first joint 85 is cylindrical and has a through hole penetrating in the direction of the central axis X. The guide pin 82 is inserted into this through hole. A slit 851 is formed in the first joint 85. The slit 851 opens on the outer peripheral surface of the first joint 85. The slit 851 extends in the circumferential direction in a plane intersecting the direction of the central axis X, more precisely, in a plane perpendicular to the direction of the central axis X. The first joint 85 illustrated in FIG. 11 has three slits 851. The three slits 851 are aligned in the direction of the central axis X. The number of slits 851 formed in the first joint 85 is not limited to three. A column is formed in each slit 851, and a base is formed between the slits 851 and slits 851 adjacent to each other in the direction of the central axis X. The first joint 85 has two bases. Each of the two bases is annular and surrounds the through hole of the first joint 85, and has a thickness that allows it to elastically deform so as to bend in the direction of the central axis X. These slits 851 and columns allow the first joint 85 to elastically deform in response to a load in the direction of the central axis X.

The second joint 86 is interposed between the guide pin 82 and the rod 87. The second joint 86 connects the guide pin 82 and the rod 87. The rod 87 extends in the direction of the central axis X. The rod 87 connects the guide pin 82 to the telescopic actuator 88.

The telescopic actuator 88 is composed of an air cylinder 881 and a piston rod 882. The piston rod 882 is inserted into the holder 84. When air is supplied to the air cylinder 881, the piston rod 882 extends. As the piston rod 882 extends, the guide pin 82 protrudes toward the second electrode 9.

The first electrode 8 therefore has a mechanism for moving the guide pin 82 back and forth, and is elastically deformable at the first joint 85 between the tip of the cap tip 21 and the base end of the first electrode 8. When the center of the load is shifted from the central axis X of the first electrode 8, the first joint 85 bends, allowing the cap tip 81 to apply a uniform load to the first workpiece 1010 across the entire tip surface.

Figure 12 illustrates the structure of the second electrode 9. The second electrode 9 has a coolant passage 93 for cooling the cap chip 91. As described above, the cap chip 91 has a first recess 911 and a second recess 912.

The holder 92 holds the cap tip 91. The holder 92 is cylindrical. The holder 92 has a holding portion 921 at its tip. The holding portion 921 is a recess that opens into the tip surface of the holder 92. The base end of the cap tip 91 is inserted into the holding portion 921 of the holder 92. The first recess 911 of the cap tip 91 is connected to the holding portion 921 of the holder 92.

The inner hole 922 of the holder 92 is connected to the holding portion 921 and opens to the base end of the holder 92. The inner hole 922 forms part of the refrigerant path 93. The refrigerant is sent to the first recess 911 of the cap tip 91 through the inner hole 922 and the holding portion 921, and returns from the first recess 911 through the holding portion 921 and the inner hole 922. The refrigerant path 93 may have a double structure by arranging the inner tube 222 (see FIG. 2) described above in the inner hole 922 of the holder 92.

In the second electrode 9, slits 923 are formed in the holder 92. The slits 923 open on the outer peripheral surface of the holder 92. The slits 923 extend in the circumferential direction in a plane intersecting the central axis X direction, more precisely, in a plane perpendicular to the central axis X direction. The second electrode 9 illustrated in FIG. 12 has four slits 923. The four slits 923 are aligned in the central axis X direction. The number of slits 923 formed in the holder 92 is not limited to four. A base is formed between the slits 923 adjacent to each other in the central axis X direction. The holder 92 has three bases. Each of the three bases is annular and surrounds the inner hole 922 that forms the refrigerant passage 93, and has a thickness that allows elastic deformation so as to bend in the central axis X direction.

Although detailed illustration is omitted in FIG. 12, multiple columns are formed in each slit 923. Each of the multiple columns extends in the direction of the central axis X and is connected to the base. The second electrode 9 is elastically deformable in the holder 92 between the tip surface 913 of the cap tip 91 and the base end of the second electrode 9. By elastically deforming the holder 92, the tip surface 913 of the cap tip 91 can apply a uniform load to the second welded material 1020. The four protrusions 1022 of the second welded material 1020 are uniformly welded to the first welded material 1010.

The second electrode 9 has a refrigerant passage 93, so the refrigerant leaks through the slits 923. The second electrode 9 has a suppression portion that suppresses the leakage of the refrigerant. The suppression portion is a cover 60 attached to the outer peripheral surface of the holder 92, as shown in FIG. 12.

The cover 60 covers the openings of each of the four slits 923 formed on the outer peripheral surface of the holder 92. An O-ring 601 is interposed between the holder 92 and the cover 60. The O-ring 601 prevents the refrigerant from leaking from the gap between the holder 92 and the cover 60.

In this way, the second electrode 9 having a cooling structure can be elastically deformed by the slits 923 while preventing leakage of the refrigerant.

Other Embodiments
The technology disclosed herein is not limited to application to the spot welding device 1, 10 or the projection welding device 7. As described above, the technology disclosed herein can apply a load uniformly to a workpiece through the first electrode and the second electrode. By utilizing this feature, the workpiece to be treated by the resistance welding device may be, for example, a workpiece in which cylindrical workpieces are butted together in the axial direction. The resistance welding device can apply a load uniformly through the first electrode and the second electrode around the entire circumference of the joint of the workpieces. The resistance welding device can improve welding quality.

The technology disclosed herein can also be applied to ring mash welding. In ring mash welding, which welds a hole formed in a first workpiece to a second workpiece having an outer shape slightly larger than the hole, the resistance welding device can apply a uniform load to the weld points around the hole. The resistance welding device improves the welding quality of ring mash welding.

Furthermore, the features described in the above-mentioned embodiments can be combined to the extent possible.

100 Workpiece 101 Welding material 102 Welding material 1000 Workpiece 1010 First welding material 1020 Second welding material 2 First electrode 20 Second electrode 21 Cap tip 22 Shank 220 Shank 221 First hole 222 Inner tube 23 Holder 24 Feed path 25 Return path 251 Return path 252 Return path 26 Coolant path 31 First column 32 Second column 33 Third column 34 Fourth column 4 Slit 41 First slit 42 Second slit 43 Third slit 44 Fourth slit 45 First base 46 Second base 47 Third base 6 Cover 60 Cover 61 O-ring 610 O-ring 8 First electrode 81 Cap tip 84 Holder 851 Slit 9 Second electrode 91 Cap tip 92 Holder 922 Inner hole 923 Slit 93 Coolant path

Claims (6)

A resistance welding apparatus for welding a workpiece including a plurality of stacked weld materials by applying pressure to the workpiece and supplying power to the workpiece,
An electrode is provided which is in contact with the workpiece and applies pressure to and supplies electricity to the workpiece,
The electrodes include
A coolant passage extending in a radial center portion in a direction of a central axis of the electrode;
a slit communicating with the coolant passage and opening in an outer peripheral surface of the electrode, the slit extending in a circumferential direction on a plane intersecting the central axis direction,
The electrode has a suppression portion that suppresses leakage of the refrigerant through the slit. 2. The resistance welding apparatus according to claim 1,
The slit is formed in at least one of a first electrode located on a first side of the workpiece and a second electrode located on a second side of the workpiece,
A resistance welding apparatus, wherein the suppression portion is attached to the electrode in which the slit is formed. 2. The resistance welding apparatus according to claim 1,
A resistance welding apparatus, wherein the suppression portion is a cover attached to an outer peripheral surface of the electrode and covering the opening of the slit. 2. The resistance welding apparatus according to claim 1,
the coolant passage has an inner tube that extends to a tip end of the electrode and forms a coolant passage;
the refrigerant passage has a double structure in which a refrigerant return passage is formed on the outside of the inner tube,
The slit communicates with the return path. 2. The resistance welding apparatus according to claim 1,
The slit extends in a circumferential direction on a plane perpendicular to the central axis direction,
The electrode is
A plurality of slits arranged in the central axis direction;
a base that is formed by a first slit and a second slit that are adjacent to each other in the central axis direction, that is annular and surrounds the refrigerant passage, and that has a thickness that allows the base to be elastically deformed so as to bend in the central axis direction;
a column formed in each of the first slit and the second slit, extending in the central axis direction and connected to the base. The resistance welding apparatus according to any one of claims 1 to 5,
The electrode has a cap tip that contacts the workpiece, a shank to which the cap tip is attached, and a holder that holds the shank,
The slit is formed in the shank or the holder,
A resistance welding device, wherein the suppression portion is attached to the shank or the holder in which the slit is formed.