WO2010143294A1 - Electrode of spot welding machine - Google Patents

Abstract

Provided is the electrode of a spot welding machine wherein a capped tip does not fall off from a holder and faulty power supply to a capped tip can be eliminated. Since a capped tip (12) is fixed to a holder (11) by forming a planar abutting portion (11b) on the periphery of the fixing portion (11a) of the holder (11), by forming a planar receiving portion (12b) on the periphery of a fixing recess (12a) at the proximal end of the cap tip (12), and by making the receiving portion (12b) abut on the abutting portion (11b), the fixing recess (12a) is not stretched by the fixing portion (11a) at the time of pressurization, the fitting state of the fixing recess (12a) and the fixing portion (11a) is maintained and thereby the capped tip (12) is prevented from falling off from the holder (11).  Furthermore, poor welding due to faulty power supply is prevented because the planar receiving portion (12b) and the abutting portion (11b) contact closely and a welding current is supplied surely to between the holder (11) and the capped tip (12).

Description

Spot welder electrode

The present invention relates to the structure of an electrode part of a spot welder.

Conventionally, as shown in Patent Document 1, spot welding is widely used as one of means for welding metal members, in which an electric current is applied while the metal members are crimped and the metals are melted and joined by the electric resistance heat. . As shown in FIG. 12, a spot welder for performing such spot welding is attached to a pair of cylindrical shanks 91 arranged so as to be separable from each other and to the tips of the pair of shanks 91. In addition, an electrode portion 90 including the cap chip 95 is provided. Spot welding is performed by passing an electric current while pressing the metal member with a pair of cap tips 95. At the tip of the shank 91, an attachment portion 91a having a diameter reduced in a tapered shape toward the tip is formed. The cap chip 95 is formed with a mounting recess 95a having a tapered diameter toward the back. The cap chip 95 is attached to the shank 91 by fitting the attachment recess 95a to the attachment portion 91a. Inside the shank 91, a water conduit 92 facing the bottom of the mounting recess 95a is disposed. By supplying cooling water into the water conduit 92, the cap chip 95 is cooled, and overheating of the cap chip 95 is prevented. ing.

In recent years, the use of high-tensile materials has been increasing for the purpose of reducing the weight of passenger cars and improving safety. When spot-welding a high-tensile material, it is necessary to press the high-tensile material with high pressure because it is necessary to closely adhere the high-tensile material that is difficult to deform. For this reason, the taper-shaped attachment part 91a will gradually expand the attachment recessed part 95a with spot welding. When the tip of the mounting portion 91a comes into contact with the bottom of the mounting recess 95a, the cap chip 95 falls off the mounting portion 91a of the shank 91 due to the reaction. In order to attach the dropped cap chip 95 to the mounting portion 91a again, the cap chip 95 is squeezed by passing the cap chip 95 through the hole of the die, and the expanded mounting recess 95a is returned to the original shape. Therefore, it was very troublesome.

Further, since the taper-shaped mounting recess 91a is fitted into the taper-shaped mounting portion 91a and the cap chip 95 is mounted on the shank 91, the contact between the mounting portion 91a and the mounting recess 95a becomes insufficient, and the cap chip 95 is moved to the cap chip 95. There were many welding defects due to poor power supply.

JP-A-8-197262

An object of the present invention is to provide an electrode portion of a spot welder that solves the above-described problems and that can solve a power feeding failure to the cap chip without the cap chip falling off the holder.

The invention according to claim 1, which has been made to solve the above problems,
A mounting part protruding from the tip, a holder to which a welding current is supplied,
A mounting recess is formed at the base end, and the cap tip pressurizes the member to be welded at the contact portion formed at the tip.
In the electrode part of the spot welder with the mounting recess attached to the mounting part and the cap chip attached to the holder,
Form a flat contact part around the holder mounting part,
Around the mounting recess at the base end of the cap chip, a contacted portion that is a flat surface is formed,
The cap chip is attached to the holder by bringing the abutted part into contact with the abutting part.

The invention according to claim 2 is the invention according to claim 1,
The mounting part is a tapered shape with the outer diameter gradually decreasing toward the tip,
The mounting recess is a tapered shape whose inner diameter gradually decreases toward the back,
The cap recess is fitted to the holder by fitting the mounting recess into the mounting portion.

The invention according to claim 3 is the invention according to claim 2,
A slit is formed in the mounting portion along the protruding direction.

The invention according to claim 4 is the invention according to claim 1,
The mounting portion is a columnar shape or a cylindrical shape,
The mounting recess is a shape corresponding to the mounting portion,
Forming a first O-ring groove in the mounting portion;
Forming a second O-ring groove in the mounting recess,
The cap chip is attached to the holder by inserting the attachment portion into the attachment recess and fitting the O-ring into the first O-ring groove and the second O-ring groove.

According to the first aspect of the present invention, a flat contact portion is formed around the mounting portion of the holder, and a flat contacted portion is formed around the mounting recess at the base end of the cap chip. The cap chip is attached to the holder by bringing the abutted part into contact with the abutting part.
For this reason, since the pressing force when the member to be welded is pressed with a pair of opposing cap tips acts on the flat contacted portion and the contact portion, the cap tip and the holder are not deformed. The chip is prevented from falling off the holder.
In addition, since the cap tip and the holder are in contact at the abutted portion and the abutting portion, which are flat surfaces, a welding current is surely passed between the holder and the cap tip, preventing welding failure due to power feeding failure. Is done.
Furthermore, since the cap chip and the holder are in contact with each other at the abutted portion and the abutting portion which are flat, heat is efficiently transferred from the cap chip to the holder, the cap chip is prevented from overheating, and deformation due to softening of the cap chip is prevented. Deterred, extending the life of the cap chip.

The invention according to claim 2 is the invention according to claim 1,
The mounting part is a tapered shape with the outer diameter gradually decreasing toward the tip,
The mounting recess is a tapered shape whose inner diameter gradually decreases toward the back,
The cap recess is fitted to the holder by fitting the mounting recess into the mounting portion.
For this reason, even if a member to be welded is pressurized with a pair of opposing cap tips, the mounting recess is not expanded by the mounting portion, so that the fitting state between the mounting recess and the mounting portion is maintained, and the cap chip Dropping from the holder is prevented.

The invention according to claim 3 is the invention according to claim 2,
A slit is formed in the mounting portion along the protruding direction.
For this reason, when fitting the mounting recess of the cap chip into the mounting portion, each piece of the mounting portion is bent and elastically deformed, and plastic deformation of the mounting recess and the mounting portion is suppressed. And the cap chip are prevented from falling off the holder.
In addition, since plastic deformation of the mounting recess and the mounting portion is suppressed, even if the cap chip is detached from the holder multiple times for dressing, the fitting state between the mounting portion and the mounting recess is maintained, and the cap chip holder Dropping from is prevented.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the attachment portion has a columnar shape or a cylindrical shape, the attachment concave portion has a shape corresponding to the attachment portion, and the attachment portion has a first O-ring. Forming a groove, forming a second O-ring groove in the mounting recess, inserting the mounting portion into the mounting recess, fitting the O-ring into the first O-ring groove and the second O-ring groove, The cap chip is attached to the holder.
For this reason, since the O-ring is fitted in the first O-ring groove and the second O-ring groove, the cap chip is prevented from falling off the holder.

It is explanatory drawing of the electrode part of the spot welder of 1st Embodiment. It is explanatory drawing which showed the procedure which attaches a cap chip | tip to a holder. It is explanatory drawing of a removal recessed part. It is explanatory drawing of the removal state of a cap chip | tip. It is explanatory drawing of another example of 1st Embodiment. It is explanatory drawing of the holder of 2nd Embodiment. It is explanatory drawing of another example of the holder of 2nd Embodiment. It is explanatory drawing of the electrode part of the spot welder of 3rd Embodiment. It is explanatory drawing of another example of 3rd Embodiment. It is explanatory drawing of the electrode part of the spot welder of 4th Embodiment. It is explanatory drawing of another example of the electrode part of the spot welder of 4th Embodiment. It is explanatory drawing of the electrode part of the conventional spot welder.

(First embodiment)
A preferred embodiment (first embodiment) of the present invention will be described below with reference to the drawings. As shown in FIG. 1, the electrode portion 10 of the spot welder according to the first embodiment includes a cylindrical holder 11 and a cap chip 12 attached to the tip of the holder 11. The cylindrical holder 11 as shown in FIG. 1 is generally called a shank. The holder 11 is attached to a power feeding unit of a spot welder, and a welding current is fed from the power feeding unit. The holder 11 is made of a tough copper alloy having good electrical conductivity, such as beryllium copper or chromium copper.

At the tip of the holder 11, a cylindrical mounting portion 11a is formed to protrude. The outer peripheral surface of the attachment portion 11a is tapered so that the outer diameter gradually decreases toward the tip. A flat contact portion 11b is formed around the attachment portion 11a at the tip of the holder 11. The surface of the contact part 11b is orthogonal to the forming direction of the attachment part 11a.

A contact portion 12 c is formed at the tip of the cap chip 12. The contact portion 12c is a portion that contacts the member to be welded and pressurizes the member to be welded. The shape of the contact portion 12c is appropriately selected depending on welding conditions, and includes a spherical shape, a truncated cone shape, a planar shape, and the like. An attachment recess 12 a is formed in the base end of the cap chip 12. The inner peripheral surface of the mounting recess 12a has a tapered shape that gradually decreases in diameter toward the back. The taper angle of the mounting recess 12a is the same as the taper angle of the mounting portion 11a, and the mounting recess 12a has a shape corresponding to the mounting portion 11a. A flat contacted portion 12b is formed around the mounting recess 12a at the base end of the cap chip 12. The surface of the contacted portion 12b is orthogonal to the protruding direction of the mounting recess 12a.

The procedure for attaching the cap chip 12 to the holder 11 will be described with reference to FIG. As shown in FIG. 2A, the mounting recess 12 a of the cap chip 12 is inserted into each mounting portion 11 a of the pair of holders 11. In this state, the contact portion 11b and the contacted portion 12b are separated by a predetermined dimension a. That is, when the mounting recess 12a of the cap chip 12 is inserted into the mounting portion 11a, the mounting portion 11a and the mounting recess 12a are formed so that the contact portion 11b and the contacted portion 12b are separated by a predetermined dimension a. ing. The predetermined dimension a is 0.3 to 1.5 mm.

As shown in FIG. 2B, the cap chips 12 attached to the tips of the pair of holders 11 are brought into contact with each other and further pressurized. Then, as shown in FIG. 2C, the mounting recess 12a is fitted into the mounting portion 11a, and the mounting recess 12a is attached to the mounting portion 11a. In this state, the contacted part 12b is in contact with the contact part 11b.

As shown in FIG. 1, in the present invention, the contacted part 12 b formed on the cap chip 12 is in contact with the contact part 11 b formed on the holder 11. Even if the member to be welded is pressurized, the applied pressure acts on the abutted portion 12b and the abutting portion 11b, which are flat surfaces, so that the attaching recess 12a is not expanded by the attaching portion 11a. For this reason, since the fitting state of the mounting recess 12a and the mounting portion 11a is maintained, the cap chip 12 does not fall off the holder 11.

A cooling water passage 11 e is formed in the holder 11 along the longitudinal direction of the holder 11. A water conduit 13 is disposed in the cooling water passage 11e. The tip of the water conduit 13 faces the mounting recess 12 a of the cap chip 12. The cap chip 12 is cooled by the cooling water supplied into the water conduit 13. The cooling water that has cooled the cap chip 12 flows through the flow path inside the holder 11 and outside the water conduit 13 and is discharged from the holder 11.

In the present invention, the abutted portion 12b and the abutting portion 11b, which are flat surfaces, are in close contact with each other, so that heat is transferred from the cap chip 12 to the holder 11, the cap chip 12 is efficiently cooled, and the cap chip 12 is overheated. Is prevented. For this reason, softening of the cap chip 12 due to overheating of the cap chip 12 is prevented, and deformation of the cap chip 12 is suppressed, so that the cap chip 12 has a long life.

Further, in the present invention, the abutted portion 12b and the abutting portion 11b, which are flat surfaces, are in contact with each other. Since power is supplied to the cap chip 12, poor welding due to power supply failure to the cap chip 12 is prevented.

A removal recess 11 c is formed in the outer peripheral surface of the tip of the holder 11. As shown in FIG. 3A, a removal recess 11c may be formed on a part of the outer peripheral surface of the tip of the holder 11, and as shown in FIG. The removal recess 11c may be formed all around the outer peripheral surface. As described above, since the recess 11c for removal is formed on the outer peripheral surface of the tip of the holder 11, the fixed claw 81 and the movable claw 82 of the electrode removing device 80 as shown in FIG. The cap chip 12 can be removed from the holder 11 by opening the claw 82. Alternatively, the cap chip 12 can be removed from the holder 11 by inserting the electrode removal tool into the recess 11c for removal.

In the embodiment shown in FIG. 1, the attachment portion 11a has a cylindrical shape, but the attachment portion 11a may be a column. In the case of this configuration, the end of the cooling water passage 11e is sealed by the mounting portion 11a, but in the present invention, the abutted portion 12b and the abutting portion 11b which are flat surfaces are in close contact, Heat is transferred from the cap chip 12 to the holder 11 side, and overheating of the cap chip 12 is prevented.

As shown in FIG. 5, the holder 11 may be bent in a substantially J shape or the like.

(Second Embodiment)
FIGS. 6 and 7 are explanatory views of the holder 11 of the second embodiment, and the difference between the second embodiment and the first embodiment will be described below. As shown in FIG. 6 and FIG. 7, a slit 11 d is formed in the attachment portion 11 a of the holder 11 of the second embodiment along the protruding direction of the attachment portion 11 a. The slit 11d reaches the tip of the mounting portion 11a. As shown in FIG. 6, one slit 11d may be formed in the attachment portion 11a, or as shown in FIG. 7, a cross-shaped slit 11d may be formed in the attachment portion 11a. Alternatively, three or more slits 11d may be formed in the attachment portion 11a.

In the second embodiment, since the slit 11d is formed in the mounting portion 11a, when the mounting recess 12a of the cap chip 12 is fitted into the mounting portion 11a of the holder 11, each piece of the mounting portion 11a is bent and elastic. It deform | transforms and the plastic deformation of the attachment recessed part 12a and the attachment part 11a is suppressed. For this reason, the fitting state of the attachment part 11a and the attachment recessed part 12a is maintained, and the drop of the cap chip 12 from the holder 11 is prevented. In addition, since the plastic deformation of the mounting recess 12a and the mounting portion 11a is suppressed, even when the cap chip 12 is detached from the holder 11 a plurality of times for dressing, the fitting state between the mounting portion 11a and the mounting recess 12a is maintained. As a result, the cap chip 12 does not fall off the holder 11. Note that the holder 11 is preferably made of beryllium copper or phosphor bronze, which is an elastic material, so that each piece of the attachment portion 11a is bent and elastically deformed. The beryllium copper is 0.2 to 3.0% beryllium (Be), 0.15 to 2.5% cobalt (Co), and the balance is copper (Cu) and inevitable impurities. It is a copper alloy. Phosphor bronze has a mass ratio of tin (Sn) of 3.5 to 9.0%, phosphorus (P) of 0.03 to 0.35%, and the balance of copper (Cu) and inevitable impurities. It is a copper alloy.

As shown in FIGS. 6 and 7, in the second embodiment, in order to prevent water leakage, the cooling water channel 11e of the holder 11 does not reach the tip of the mounting portion 11a, and the cooling water channel 11e is sealed. It is preferably stopped. Even in such a structure, in the present invention, the abutted portion 12b of the cap chip 12 is in close contact with the abutting portion 11b of the holder 11, so that heat is transferred from the cap chip 12 to the holder 11, and the cap chip. 12 is not overheated.

(Third embodiment)
FIG. 8 shows an explanatory diagram of the holder 31 of the third embodiment, and the difference between the third embodiment and the first embodiment will be described below. At the tip of the holder 31 of the third embodiment, a cylindrical mounting portion 31a is formed to project. A flat contact portion 31 b is formed around the attachment portion 31 a at the tip of the holder 31. The surface of the contact part 31b is orthogonal to the formation direction of the attachment part 31a. A first O-ring groove 31d is formed in the outer peripheral surface of the attachment portion 31a so as to be recessed over the entire periphery.

A mounting recess 32a having a circular cross-sectional shape is formed in the base end of the cap chip 32 of the third embodiment. The shape of the mounting recess 32a is a shape corresponding to the shape of the mounting portion 31a, and the inner diameter of the mounting recess 32a is slightly larger than the outer diameter of the mounting portion 11a. A flat contacted portion 32b is formed around the mounting recess 32a at the base end of the cap chip 32. A second O-ring groove 32d is formed in the inner circumferential surface of the mounting recess 32a so as to be recessed over the entire circumference.

The O-ring 34 is fitted and attached to the first O-ring groove 31d. The material of the O-ring 34 includes nitrile rubber, hydrogenated nitrile rubber, fluorine rubber, silicon rubber, and urethane rubber. The mounting portion 31a is inserted into the mounting recess 32a, the O-ring 34 is fitted into the second O-ring groove 32d, the mounting recess 32a is crowned on the mounting portion 31a, and the cap chip 32 is mounted on the holder 31. ing. In this state, the contacted part 32b is in contact with the contact part 31d.

A cooling water passage 31e is formed in communication with the holder 31 along the longitudinal direction of the holder 31. A water conduit 33 is disposed in the cooling water passage 31e. The tip of the water conduit 33 faces the mounting recess 32 a of the cap chip 32. The cap chip 32 is cooled by the cooling water supplied into the water conduit 33. The cooling water that has cooled the cap chip 32 flows through the flow path 30 a between the cooling water passage 31 e and the water conduit 33 and is discharged from the holder 31. The O-ring 34 disposed between the mounting recess 32a and the mounting portion 31a prevents the cooling water supplied into the mounting recess 32a from leaking.

In addition, as shown in FIG. 9, the attachment portion 31a may be a cylindrical shape, and the holder 31 in which the end of the cooling water passage 31e is sealed may be used.

As shown in FIGS. 8 to 9, the first O-ring groove 31d formed in the attachment portion 31a is formed deep so as to receive the O-ring 34, and the O-ring 34 is removed when the cap chip 32 is removed. Does not fall off from the first O-ring groove 31d. On the other hand, the second O-ring groove 32d formed in the mounting recess 32a is recessed in a V shape, so that the cap chip 32 can be removed with a small force, and when removing the cap chip 32, the O-ring 34 The first O-ring groove 31d does not fall off.

(Fourth embodiment)
FIG. 10 is an explanatory diagram of the electrode section 40 of the spot welder according to the fourth embodiment, and hereinafter, the fourth embodiment will be described with respect to differences from the first embodiment. The holder 41 of the fourth embodiment is plate-shaped. A cylindrical or columnar mounting portion 41 a is formed on the front surface of the holder 41 so as to protrude. The outer peripheral surface of the mounting portion 41a has a tapered shape with the outer diameter gradually decreasing toward the tip. A flat contact portion 41b is formed around the attachment portion 41a. The surface of the contact part 41b is orthogonal to the formation direction of the attachment part 41a.

The cap chip 12 is mounted on the holder 41 by fitting the mounting recess 12a to the mounting portion 41a. In this state, the member to be welded 12b is in contact with the contact portion 41b. The holder 41 is formed with cooling water passages 41e and 41f communicating with the tip of the mounting portion 41a. The cooling water flowing through the cooling water channel 41e cools the cap chip 12, then flows through the cooling water channel 41f, and is discharged to the outside.

Similarly to the first embodiment, the electrode portion 40 of the spot welder of the fourth embodiment is also in contact with the contact portion 41b, so that the pair of cap chips 12 facing each other is in contact with the contact portion 41b. Even if the member to be welded is pressurized, the mounting recess 12a is not expanded by the mounting portion 41a. For this reason, since the fitting state of the mounting recess 12a and the mounting portion 41a is maintained, the cap chip 12 does not fall off the holder 41. Note that, as in the second embodiment, a slit may be formed in the attachment portion 41a.

Further, as in the third embodiment, the first O-ring groove is formed in the column-shaped or cylindrical mounting portion 41a, and the O-ring 34 is fitted into the first O-ring groove to be mounted, and the mounting recess. A structure may be adopted in which the cap chip 32 is attached to the holder 41 by inserting the attachment portion 41a into the 32a and fitting the O-ring 34 into the second O-ring groove 32d (shown in FIG. 11).

When the cooling water is supplied to the cooling water passage 41e, the water pressure in the mounting recess 32a increases, and the cap chip 32 is pushed up by the water pressure as shown in FIG. It separates from the contact part 41b. Since the O-ring 34 is fitted in the first O-ring groove 41d and the second O-ring groove 32d, even if the cap chip 32 is pushed up by the water pressure, the cap chip 32 falls off the mounting portion 41a. There is nothing.

As shown in FIG. 3B, when the welded members 98 and 99 are pressure-bonded with the cap chip 32 and the cap chip 97 opposed thereto, the contacted part 32b comes into contact with the contact part 41b. When a welding current is passed between the cap chip 32 and the cap chip 97 in this state, the welded member 98 and the welded member 99 are melted by the electric resistance heat and welded. Since the contacted part 32b and the contacted part 41b are flat, a welding current is reliably conducted between the contacted part 41b and the contacted part 32b during welding. At the time of welding, the electrical resistance heat generated in the welded members 98 and 99 is transferred to the contact portion 32c of the cap chip 32. When the welding is completed, as shown in FIG. The cap chip 32 is pushed up by the water pressure acting inside, so that the abutted portion 32b is separated from the abutting portion 41b and hardly transfers heat from the cap chip 32 to the holder 41 side. Further, the holder 41 is cooled by the cooling water flowing through the cooling water channel 10g. For this reason, since the plate-shaped holder 41 is not softened and deformed by heat, the accuracy of welding is ensured.

Except during welding, the abutted portion 32b is separated from the abutting portion 41b, so that the abutted portion 32b comes into contact with air and is cooled. At the time of welding, the abutted portion 32b and the abutting portion 41b come into contact with each other, and the air deprived of the heat of the abutted portion 32b is discharged from the space between the abutted portion 32b and the abutting portion 41b. Further, since the abutting portion 41b is also cooled by air, the abutted portion 32b and the abutting portion 41b are not oxidized and the current is reliably supplied between the abutted portion 32b and the abutting portion 41b. ing. Even if the contacted part 32b is separated from the contact part 41b and hardly transfers heat from the cap chip 32 to the holder 41 side, the cap chip 32 is always cooled by the cooling water supplied from the water conduit 33. The cap chip 32 is not overheated and softened.

Although the present invention has been described above in connection with the most practical and preferred embodiments at the present time, the present invention is not limited to the embodiments disclosed herein. However, it can be appropriately changed without departing from the gist or concept of the invention that can be read from the claims and the entire specification, and the electrode part of a spot welder with such a change is also included in the technical scope. Must be understood.

10 Electrode part of spot welder (first embodiment, second embodiment)
11 Holder (first embodiment, second embodiment)
11a Attaching part 11b Abutting part 11c Detachment recess 11d Slit 11e Cooling water passage 12 Cap chip (first embodiment, second embodiment)
12a mounting recess 12b contacted part 12c contact part 13 water conduit (first embodiment, second embodiment)
30 Electrode part of spot welder (third embodiment)
30a channel 31 holder (third embodiment)
31a Attaching part 31b Abutting part 31c Detachment recess 31d First O-ring groove 31e Cooling water passage 32 Cap chip (third embodiment)
32a Mounting recess 32b Contacted part
32c Contact part 32d 2nd O-ring groove 33 Water conduit (3rd Embodiment)
34 O-ring 40 Electrode part of spot welder (fourth embodiment)
41 Holder (fourth embodiment)
41a mounting portion 41b contact portion 41c removal recess 41d first O-ring groove 41e cooling water passage 41f cooling water passage 80 electrode removal device 81 fixed claw 82 movable claw 90 electrode portion 91 of conventional spot welder 91 shank 91a attachment Portion 92 Water conduit 95 Cap tip 95a Mounting recess 97 Cap tip 98 Welded member 99 Welded member

Claims (4)

A mounting part (11a) is formed to protrude at the tip, and a holder (11) to which a welding current is supplied,
A mounting recess (12a) is formed at the proximal end, and the cap tip (12) pressurizes the member to be welded by the contact portion (12c) formed at the distal end.
In the electrode part (10) of the spot welder in which the mounting recess (12a) is attached to the mounting part (11a) and the cap chip (12) is mounted on the holder (11),
A flat contact portion (11b) is formed around the mounting portion (11a) of the holder (11),
Around the mounting recess (12a) at the base end of the cap chip (12), a contacted portion (12b) that is a plane is formed,
An electrode part of a spot welder, wherein the abutted part (12b) is brought into contact with the abutting part (11b) and the cap chip (12) is attached to the holder (11). The attachment portion (11a) has a tapered shape in which the outer diameter gradually decreases toward the tip,
The mounting recess (12a) has a tapered shape in which the inner diameter gradually decreases toward the back,
The electrode part of the spot welder according to claim 1, wherein the cap recess (12) is mounted on the holder (11) by fitting the mounting recess (12a) to the mounting part (11a). The electrode part of the spot welder according to claim 2, wherein a slit (11d) is formed in the mounting part (11a) along the protruding direction. The attachment portion (31a) has a columnar shape or a cylindrical shape,
The mounting recess (32a) has a shape corresponding to the mounting portion (31a),
Forming a first O-ring groove (31d) in the attachment portion (31a);
Forming a second O-ring groove (32d) in the mounting recess (32a);
A cap chip is formed by inserting the mounting portion (31a) into the mounting recess (32a) and fitting the O-ring (34) into the first O-ring groove (31d) and the second O-ring groove (32d). The electrode part of the spot welder according to claim 1, wherein (32) is attached to a holder (31).

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