JP5512471B2 - Resistance spot welding electrode - Google Patents

Description

  The present invention relates to an electrode for resistance spot welding that abuts against a workpiece on which plate members are superimposed to apply pressure and is energized to spot weld a plate member.

  Conventionally, for joining workpieces composed of stacked plate members, a large current is passed between the electrodes for a certain period of time while the workpiece is sandwiched between a pair of welding electrodes while applying pressure. The direct spot welding and series welding which join a plate member by forming are performed.

  On the other hand, in spot welding of a plate member in a structure such as an automobile body, direct spot welding may not have a space for arranging one welding electrode, and series welding may not have a space for arranging a back electrode.

  As a countermeasure against this, one-side resistance spot welding is performed in which welding can be performed only from one side of a workpiece on which plate members are superimposed.

  An example of this one-side resistance spot welding will be described with reference to FIG. In the one-side resistance spot welding of the workpiece 100 in which the first plate member 101 and the second plate member 102 are overlapped, the ground electrode 106 is brought into contact with the second plate member 102 so as to be energized, while the surface of the first plate member 101 is contacted. When the welding electrode 105 is brought into contact and a pressing force is applied, the pressing force causes the first plate member 101 and the second plate member 102 to come into contact with each other at the joining point a so that the first plate member can be connected from the welding electrode 105. 101, a welding energization path X reaching the ground electrode 106 through the junction point a and the second plate member 102 is formed.

  In a state where the first plate member 101 and the second plate member 102 are in contact with each other so as to be energized at the junction point a, a welding current i is passed from the welding electrode 105 to the ground electrode 106. As a result, when a part ia of the welding current i flows through the welding energization path X, the joining point a between the first plate member 101 and the second plate member 102 is heated and melted, and a nugget N is formed at the joining point a. Is done.

  Further, a part ib of the welding current i flowing from the welding electrode 105 to the ground electrode 106 does not pass through the joint point a, for example, via an energization path X1 that diverts from the first plate member 101 to the joint point b that has already been welded. Flow to the second plate member 102 side. This shunt current ib is an invalid shunt that hardly contributes to the heat generation at the junction point a. There is a concern that the current flowing through the welding current path X is reduced by the ineffective diversion ib, and the diameter of the nugget N formed at the joint point a is insufficient to obtain the required strength. Further, the current flowing through the welding energization path X is reduced by the ineffective shunt ib, so that the formation of the nugget N is delayed, and the first plate member 101 is heated in the vicinity of the welding electrode 105 having a higher current density than the formation of the nugget N. There is concern about the occurrence of melting breakage, so-called plate breakage.

  On the other hand, Patent Document 1 proposes a welding electrode that prevents the occurrence of defects such as cracks. As shown in FIG. 5, the welding electrode 111 has a substantially conical tip shape, a cone surface 112 having a cone tip angle a of 120 to 165 degrees, and a diameter b at the center of the tip of the cone. A flat portion 113 having a thickness of 1.5 to 3 mm is formed.

  According to this welding electrode 111, by reducing the diameter b of the flat portion 113 formed at the center of the conical tip to 1.5 to 3 mm, the contact area that contacts the workpiece at the initial energization is small, and the current at the initial energization The density is increased, the surface of the workpiece is heated and softened early, and the conical surface 112 with a cone tip angle of 120 to 165 degrees is provided so that cracks or the like are formed in the vicinity of the portion where the welding electrode 111 is pressed. Even when this occurs, the conical surface 112 immediately hits the crack and fills the crack immediately after the occurrence of the crack, thereby preventing defects due to the growth of the crack.

JP 2006-198676 A

  However, according to the welding electrode 111 of Patent Document 1, it is possible to suppress defects due to the generation of cracks generated in the workpiece by the pressing of the conical surface 112, but the welding current density is reduced due to the reactive current or the workpiece is damaged. There is concern about the deterioration of the welding quality due to.

  For example, as shown in FIG. 6, when one-side resistance spot welding is performed on the workpiece 100 in which the first plate member 101 and the second plate member 102 are overlapped, the ground electrode 106 is brought into contact with the second plate member 102 so as to be energized, When the welding electrode 111 is brought into contact with the surface of the first plate member 101 to apply a pressing force, the first plate member 101 and the second plate member 102 come into contact with each other at the junction point a so that energization is possible. A welding energization path X reaching the ground electrode 106 through the first plate member 101, the joint point a, and the second plate member 102 is formed. In a state where the first plate member 101 and the second plate member 102 are in contact with each other at the junction point a so as to be energized, a welding current i is passed from the welding electrode 111 to the ground electrode 106. As a result, a part ia of the welding current i flows through the welding energization path X, whereby the junction point a between the first plate member 101 and the second plate member 102 is heated and melted, and a nugget N is formed.

  On the other hand, a part ib of the welding current i flowing from the welding electrode 111 to the ground electrode 106 flows from the conical surface 112 of the welding electrode 111 that contacts the first plate member 101 in a wide range to the first plate member 101. The current flows from the plate member 101 to the second plate member 102 via the energization path X1 that diverts to the welded joint b. There is a concern that the current flowing through the welding current path X may be insufficient due to the invalid shunt ib, and the diameter of the nugget N formed at the joint a may be insufficient to obtain the required strength. Further, the current flowing through the welding energization path X is reduced by the ineffective diversion ib, and the formation of the nugget N is delayed, and the first plate member 101 is heated and melted in the vicinity of the conical surface 112 of the welding electrode 111, and the portion is damaged. There is a concern to do. In addition, there is a concern that the work 100 and the welding electrode 111 may be damaged due to welding of the welding electrode 111 and the first plate member 101.

  Accordingly, an object of the present invention made in view of such a point is to provide a resistance spot welding electrode which can avoid melting damage of a workpiece and the like and can ensure high quality welding quality.

  The electrode for resistance spot welding according to claim 1, which achieves the above object, is a shank for abutting a workpiece on which plate members are overlapped to apply pressure and energizing the plate member for resistance spot welding. In the resistance spot welding electrode attached to the tip, an energizing portion in which a base portion attached to the tip of the shank and a shaft portion having a columnar shape protruding from the base portion and contacting the workpiece is integrally formed; and the shaft portion And a cooling part having a work contact surface on the tip side from which the top end of the shaft part protrudes, and the shaft part penetrates the shaft hole and attaches the top end to the work contact. The current-carrying part and the cooling part are coupled with each other through an electrical insulator while projecting from the contact surface.

  According to this, the resistance spot welding electrode attached to the tip of the shank has a columnar shaft portion protruding from the base portion of the current-carrying portion, a cylindrical shape having a shaft hole through which the shaft portion passes, and the top end of the shaft portion is A cooling part having a workpiece contact surface is provided on the protruding tip side, and the current-carrying part and the cooling part are joined via an electrical insulator, so that the welding current during spot welding is the top end of the shaft part of the current-carrying part. The reactive current diverted from the shaft part to the work through the cooling part is extremely suppressed, so that the nugget can be formed efficiently and the work is excessively heated. Damage such as cutting of the workpiece such as melting due to overheating caused by the heating can be avoided.

  In addition, heat generation due to the reactive current that flows radially outward from the top end of the shaft portion to the work is suppressed by the cooling unit that contacts the work, and damage to the work such as a plate breakage due to overheating can be more reliably prevented.

  In addition, the reactive current diverted from the shaft to the workpiece is extremely suppressed, making it possible to bring adjacent spot positions closer, improving welding strength and facilitating the setting of spot positions and increasing design freedom. Will improve.

  According to a second aspect of the present invention, in the electrode for resistance spot welding according to the first aspect, the energizing portion is an annular shape having a base end having an opening and a cylindrical shape having an inner peripheral surface to be fitted into the tip of the shank. A cylindrical base with a bottom with the front end side of the peripheral wall closed by a partition, and a shaft having a columnar shape extending coaxially with the base from the center of the partition and having a top end contacting the workpiece The cooling portion includes a cylindrical portion having an annular base end surface facing a peripheral portion of the partition wall, a continuous diameter-reduced diameter at the distal end side of the cylindrical portion, the workpiece contact surface, and the shaft. And a top surface portion in which a shaft hole through which the portion can be inserted is formed integrally, and a base end surface of the cooling portion and a peripheral portion of the partition wall which are opposed to each other are joined via an electric insulator, The inner peripheral surface of the shaft hole is connected through an electric insulator.

  This is a specific configuration of the energization unit and the cooling unit, and the front end side of a cylindrical peripheral wall having an inner peripheral surface in which the energization unit has an opening with an opening at the base end and is fitted to the front end of the shank is a partition wall The closed bottomed cylindrical base and the shaft extending to the partition are integrally formed, and the cooling part is contracted to the cylindrical part having an annular base end face facing the peripheral part of the partition and the distal end side of the cylindrical part. Consisting of a diameter, a workpiece contact surface, and a top surface portion with a shaft hole through which a shaft portion can be inserted, are integrally formed, and the base end surface of the cooling portion and the peripheral portion of the partition wall interpose an electrical insulator. As a result, a welding electrode is formed by joining the outer periphery of the tip of the shaft portion and the inner peripheral surface of the shaft hole with an electrical insulator interposed therebetween. Ineffective while flowing through the welding current path of the workpiece from the top end, but diverting from the shaft to the workpiece via the cooling section 2. The nugget can be efficiently formed with extremely low flow, and damage such as chipping of the workpiece due to overheating caused by excessive heating of the workpiece is avoided. The action can be achieved.

  According to a third aspect of the present invention, in the resistance spot welding electrode according to the second aspect, the cooling water jacket formed by the cooperation of the partition wall, the cylindrical portion and the top surface portion of the cooling portion, and the shaft portion, and the energization A cooling water passage is provided in a partition wall that circulates and supplies the cooling water supplied into the base of the unit to the cooling water jacket.

  According to this, the cooling part is positively cooled by the cooling water circulated and supplied to the cooling water jacket, and the work piece is cut due to overheating caused by the work being heated excessively more reliably. Damage is avoided.

  The invention according to claim 4 is the resistance spot welding electrode according to any one of claims 1 to 3, wherein the electrical insulator is an adhesive having electrical insulation.

  According to this, the current-carrying part and the cooling part can be easily coupled in an electrically insulated state with an adhesive having electrical insulation.

  According to a fifth aspect of the present invention, in the resistance spot welding electrode according to any one of the first to fourth aspects, the workpiece contact surface has a conical surface shape whose diameter increases as the distance from the tip side increases. Features.

  According to this, the workpiece contact surface easily contacts the workpiece by the applied pressure, and it is possible to more reliably prevent the workpiece from being damaged due to overheating. Furthermore, local deformation of the workpiece such as indentation can be suppressed by the cooling portion in which the workpiece contact surface contacts the workpiece so as to surround the top end of the shaft portion.

  The invention according to claim 6 is the resistance spot welding electrode according to any one of claims 1 to 5, wherein the energization part and the cooling part are made of a copper alloy.

  According to this, the effect of Claims 1-5 can be achieved efficiently by comprising an energization part and a cooling part with the copper alloy excellent in electroconductivity and electrothermal property.

  According to the present invention, the welding electrode is attached to the tip of the shank, the energizing portion has a base portion and a shaft portion having a columnar shape protruding from the base portion and having a top end contacting the workpiece, and the shaft portion has a shaft hole through which the shaft portion passes. A cooling portion having a workpiece contact surface on the tip side from which the end of the shaft portion protrudes, and the current-carrying portion and the cooling portion are coupled with an electrical insulator interposed therebetween, so that the welding current during spot welding is However, while flowing through the welding energization path of the workpiece from the top end of the shaft portion of the current-carrying portion, the reactive current diverted from the shaft portion to the workpiece via the cooling portion can be extremely suppressed, and a nugget can be efficiently formed, and Damage such as cutting of the workpiece such as melting due to overheating caused by excessive heating of the workpiece is avoided.

It is explanatory drawing of the one side resistance spot welding provided with the electrode for resistance spot welding in one embodiment of this invention. It is sectional drawing of the electrode for resistance spot welding. It is an exploded sectional view of an electrode for resistance spot welding. It is explanatory drawing of the conventional electrode for resistance spot welding. It is explanatory drawing of the conventional electrode for resistance spot welding. It is explanatory drawing of the conventional electrode for resistance spot welding.

  Hereinafter, an embodiment of an electrode for resistance spot welding of the present invention will be described with reference to FIGS.

  FIG. 1 is a schematic explanatory diagram of one-side resistance spot welding to which the resistance spot welding electrode 10 of the present embodiment is applied.

  When one-side resistance spot welding is performed on the workpiece 100 on which the first plate member 101 and the second plate member 102 are overlapped, the ground electrode 1 is connected to the second plate member 102 so as to be energized. The welding electrode 10 attached to the tip of the shank 2 reciprocating in the direction of contact with and separating from the first plate member 101 is brought into contact with the surface of the first plate member 101 to apply a pressing force. The two plate members 102 are brought into contact with each other at the junction point a so that energization is possible, and a welding current i is passed between the welding electrode 10 and the ground electrode 1 to nugget the junction point a between the first plate member 101 and the second plate member 102. N is formed, and the first plate member 101 and the second plate member 102 are spot-welded.

  The welding electrode 10 will be described with reference to FIGS. FIG. 2 is a cross-sectional view of the welding electrode 10, and FIG. 3 is an exploded cross-sectional view of the welding electrode 10.

  The welding electrode 10 is mainly composed of a current-carrying part 11 attached to the tip of the shank 2 and a cooling part 21 attached to the current-carrying part 11 in an electrically insulated state.

  As shown in FIG. 3, the shank 2 to which the welding electrode 10 is attached is formed with a conical taper-shaped electrode mounting portion 4 that gradually decreases in diameter as it moves from the proximal end side to the distal end 3 side on the outer periphery of the distal end. A cooling water supply hole 5 opening at the tip 3 along the direction is formed.

  On the other hand, the current-carrying portion 11 and the cooling portion 21 of the welding electrode 10 are made of a normal welding electrode material such as a copper alloy having excellent conductivity and heat conductivity. The energizing portion 11 has an annular shape in which the base end 14 has an opening, and has an outer peripheral surface 15 and an inner peripheral surface 16 continuous to the outer edge and the inner edge of the base end 14 and extends along the central axis 11L. A base 12 formed in a bottomed cylindrical shape closed by a disc-shaped partition wall 17 having an inner surface 17a and a flat tip surface 17b on the front end side, and a central portion of the front end surface 17b of the partition wall 17 A columnar shaft portion 18 that is coaxial with the base portion 12 and extends along the central axis 11L is integrally formed. A cooling water holding portion 16 </ b> A is formed in the base portion 12 by the inner peripheral surface 16 of the peripheral wall 13 and the inner side surface 17 a of the partition wall 17.

  The inner peripheral surface 16 of the base portion 12 has a tapered hole 16a that gradually decreases in diameter as it moves from the base end 14 side that can be fitted into the conical taper-shaped electrode mounting portion 4 formed in the shank 2 to the front end side. A plurality of cooling water passages 17c that communicate the inner surface 17a side of the partition wall 17, that is, the cooling water holding portion 16A side and the tip surface 17b side adjacent to the shaft portion 18, are perforated. An annular adhesive portion 17d is formed on the distal end surface 17b of the partition wall 17 along the outer periphery.

  The shaft portion 18 protruding from the distal end surface 17b of the base portion 12 has a cylindrical shape having a peripheral surface 19 and a flat top end 20 having a diameter of 1.5 to 3 mm. An annular adhesive portion 19a is formed on the outer periphery of the distal end of the peripheral surface 19. The

  The cooling unit 21 includes an annular base end surface 23 facing the peripheral portion of the front end surface 17b and an outer peripheral edge of the base end surface 23 having an adhesive portion 23d facing the adhesive portion 17d formed on the front end surface 17b of the partition wall 17. It has an outer peripheral surface 24 and an inner peripheral surface 25 that are continuous with the inner peripheral edge, and has a cylindrical tube portion 22 that extends along the core shaft 11L. A shaft hole 29 that has the contact surface 28 and through which the shaft portion 18 can be inserted is formed, and a top surface portion 26 that reduces the diameter of the cylindrical portion 22 is formed. The workpiece contact surface 28 has a conical surface shape whose diameter increases as it moves from the distal end side to the proximal end surface 23 side around the central axis 11L. For example, the distal end angle α that can contact the workpiece 100 is set from 120 degrees to 170 degrees. The

  The energizing part 11 and the cooling part 21 are such that the tip end face 17b of the partition wall 17 formed in the energizing part 11 and the base end face 23 of the cooling part 21 face each other, and the outer periphery of the tip end of the shaft part 18 is formed in the shaft hole 29 of the top face part 26. The top end 20 is positioned so as to protrude slightly from the workpiece contact surface 28 and has excellent heat resistance and electrical insulation between the adhesive surface 17d of the opposing partition wall 17 and the adhesive portion 23d of the base end surface 23. In addition, an adhesive 31 serving as an electrical insulator, for example, a ceramic heat-resistant adhesive, is interposed in a ring shape. Similarly, an adhesive 32 that becomes an electrical insulator having excellent heat resistance and electrical insulation, for example, a ceramic heat-resistant adhesive is interposed between the inner peripheral surface 29a of the shaft hole 29 and the adhesive portion 19a of the shaft portion 18. Join. The current-carrying part 11 and the cooling part 20 can be easily coupled in an electrically insulated state by interposing the adhesives 31 and 32 having electrical insulation properties.

  The partition wall 17 and the base end surface 23 are sealed in a watertight manner by the adhesive 31, and the space between the inner peripheral surface 29 a of the shaft hole 29 and the bonding portion 19 a of the shaft portion 18 is sealed in a watertight manner by the adhesive 32. .

  As a result, the energizing portion 11 and the cooling portion 21 are electrically connected by the adhesive 31 interposed between the partition wall 17 and the base end surface 23 and the adhesive 32 interposed between the inner peripheral surface 29 a of the shaft hole 29 and the shaft portion 18. The cooling water jacket 30 is formed in the cooling portion 21 by the partition wall 17 and the shaft portion 18 of the energizing portion 11 and the cylindrical portion 22 and the top surface portion 26 of the cooling portion 21. A welding electrode 10 is configured.

  As shown in FIG. 2, the welding electrode 10 configured in this way is attached to the tip of the shank 2 with the tapered hole 16 a formed in the current-carrying portion 11 fitting into the electrode mounting portion 4 of the shank 2. The By this attachment, the energization part 11 is connected to the shank 2 so as to be energized, while the cooling water pumped from the cooling water supply means is supplied and stored in the cooling water holding part 16A through the cooling water supply hole 5 of the shank 2. In addition, the cooling water jacket 30 communicates from the cooling water passage 17c into the cooling water jacket 30 via the cooling water holding portion 16A and the cooling water passage 17c of the energizing portion 11, and is adiabatically joined to the energizing portion 11 to be cooled by the cooling portion 21. Is cooled.

  Next, the operation of the welding electrode 10 will be described with reference to FIG.

  For example, when one-side resistance spot welding is performed on the workpiece 100 in which the first plate member 101 and the second plate member 102 shown in FIG. 1 are overlapped, the ground electrode 1 is brought into contact with the second plate member 102 so as to be energized, while cooling water Cooling water from the supply means is supplied to the cooling water holding part 16A formed in the energizing part 11 of the welding electrode 10 through the cooling water supply hole 5 of the shank 2, and cooled from the cooling water channel 17c drilled in the partition wall 17. The cooling unit 21 is cooled by circulatingly supplying the water jacket 30.

  While circulating and supplying the cooling water to the cooling water jacket 30, the top end 20 of the shaft portion 18 protruding from the energizing portion 11 of the welding electrode 10 is brought into contact with the preset spot position of the first plate member 101, A pressing force is applied to the first plate member 101. The first plate member 101 and the second plate member 102 applied with pressure by the top end 20 of the shaft portion 18 of the welding electrode 10 come into contact with each other so as to be energized at the joint portion a, and the shaft portion 18 of the welding electrode 10 A welding energization path X from the top end 20 to the first plate member 101, the contact point a between the first plate member 101 and the second plate member 102, the second plate member 102, and the second plate member 102 to the ground electrode 1 is formed. The On the other hand, the workpiece contact surface 28 of the cooling unit 21 covers the periphery of the contact portion between the top end 20 of the shaft portion 18 and the first plate member 101 as the welding electrode 10 applies pressure to the first plate member 101. Thus, the first plate member 101 is contacted to cool the first plate member 101.

  The first plate member 101 and the second plate member 102 come into contact with each other so that energization is possible at the joining point a, and the workpiece contact surface 28 of the cooling unit 21 comes into contact with the first plate member 101 to cool the first plate member 101. In this state, a welding current i from the welding power source is caused to flow from the energizing portion 11 of the welding electrode 10 to the ground electrode 1 through the shank 2. Then, a part ia of the welding current i includes a contact point between the top end 20 of the shaft portion 18 and the first plate member 101, the first plate member 101, the joint portion a between the first plate member 101 and the second plate member 102, and the first plate member 101. By flowing through the welding energization path X passing through the contact portion between the two plate member 102, the second plate member 102 and the ground electrode 1, the junction point a between the first plate member 101 and the second plate member 102 is heated and melted, A nugget N is formed.

  Here, the welding current i flows through the welding energization path X from the top end 20 of the shaft portion 18 at the axial center of the welding electrode 10, and the cooling portion 21 formed on the outer periphery of the shaft portion 18 is coupled in an electrically insulated state. Therefore, the reactive current diverted from the shaft portion 18 to the first plate member 101 via the cooling portion 21 is extremely suppressed, and the welding current i is concentrated in the welding energization path X to efficiently form the nugget N. On the other hand, breakage such as cutting of the workpiece 100 such as melting due to overheating caused by excessive heating of the workpiece 100 during spot welding is avoided.

  Further, the heat generation of the first plate member 101 due to the reactive current ib that flows radially outward from the top end 20 of the shaft portion 18 to the first plate member 101 causes the work contact surface of the first plate member 101 to surround the shaft portion 18. It is suppressed by the cooling part 21 with which 28 abuts, and it is possible to prevent the workpiece 100 from being broken due to overheating more reliably.

  Further, since the periphery is held in an electrically insulating state by the adhesives 31 and 32, the ratio of the through current for welding is large, the formation efficiency of the nugget N at the joint point a is improved, and the welding quality is improved. Furthermore, local deformation of the workpiece 100 such as indentation can be suppressed by the cooling unit 21 in which the workpiece contact surface 28 contacts the first plate member 101 so as to surround the top end 20 of the shaft portion 18.

  Furthermore, since the reactive current that diverts from the shaft portion 18 to the first plate member 101 via the cooling portion 21 is extremely suppressed, it is possible to bring adjacent striking positions closer to each other. While improving the welding strength of the 1st board member 102, the setting of a hit point position becomes easy and the freedom degree of design improves.

  In the above description, the inner peripheral surface 29a of the shaft hole 29 and the shaft portion 18 are coupled with the adhesive 32 that is an electrical insulator excellent in heat resistance and electrical insulation. An electrical insulator such as a sleeve having excellent heat resistance and electrical insulation can be interposed between the inner peripheral surface 29 a of the hole 29 and the shaft portion 18.

  In the above embodiment, the welding electrode is described as an example of one-side resistance spot welding, but the reactive current is extremely suppressed by applying it to the welding electrode for direct spot welding or series welding. Adjacent hitting point positions can be brought close to each other, the setting of the hitting point positions becomes easy, and the degree of design freedom is improved.

  Moreover, although the example which supplies cooling water and cools the cooling part 21 was demonstrated in the said embodiment, active cooling with cooling water can also be abbreviate | omitted. In this case, the cooling water jacket 30 becomes a space. In the above embodiment, the tip angle α of the workpiece contact surface 28 is set from 120 degrees to 170 degrees. However, the tip angle α of the workpiece contact surface 28 is preferably set in advance by simulation or experiment.

2 Shank 5 Cooling water supply hole 10 Welding electrode 11 Current-carrying part 12 Base part 13 Perimeter wall 14 Base end 15 Outer peripheral face 16 Inner peripheral face 16a Tapered hole 17 Partition wall 17a Inner side face 17b Front end face 17c Cooling water channel 18 Shaft part 20 Top end 21 Cooling part 22 cylindrical portion 23 base end surface 24 outer peripheral surface 25 inner peripheral surface 26 top surface portion 27 inner side surface 28 work contact surface 29 shaft hole 30 cooling water jackets 31 and 32 adhesive (electrical insulator)
100 Work 101 First plate member 102 Second plate member

Claims (6)

In the resistance spot welding electrode attached to the tip of the shank that abuts the workpiece on which the plate member is overlapped to apply pressure and energizes and the plate member is resistance spot welded,
An energizing portion integrally formed with a base portion attached to the tip of the shank and a shaft portion that protrudes from the base portion and has a top end that contacts the workpiece;
A cylindrical part having a shaft hole through which the shaft part passes, and a cooling part having a workpiece contact surface on the tip side from which the top end of the shaft part protrudes,
An electrode for resistance spot welding characterized in that the shaft portion penetrates the shaft hole and causes the top end to protrude from the work contact surface, and the energizing portion and the cooling portion are coupled with an electrical insulator interposed therebetween. The current-carrying part
A bottomed cylindrical base part in which the base end is closed with a partition wall at the front end side of a cylindrical peripheral wall provided with an inner peripheral surface fitted into the tip of the shank in an annular shape having an opening;
A shaft portion having a top end in contact with the workpiece in a columnar shape extending coaxially with the base portion from the central portion of the partition wall is integrally formed,
The cooling part is
A cylindrical portion having an annular base end surface facing the peripheral portion of the partition;
The top portion of the cylindrical portion is formed integrally with the top surface portion that is continuously formed with a reduced diameter and has the work contact surface and the shaft hole into which the shaft portion can be inserted.
The opposing base end face of the cooling part and the peripheral part of the partition wall are joined via an electric insulator, and the outer periphery of the tip end of the shaft part and the inner peripheral face of the shaft hole are bonded and joined via an electric insulator. The electrode for resistance spot welding according to claim 1. A cooling water jacket formed by the cooperation of the partition wall, the cylindrical portion and the top surface portion of the cooling portion, and the shaft portion;
The resistance spot welding electrode according to claim 2, further comprising a cooling water channel formed in a partition wall that circulates and supplies the cooling water supplied into the base of the energization unit to the cooling water jacket.   The resistance spot welding electrode according to claim 1, wherein the electrical insulator is an adhesive having electrical insulation.   5. The resistance spot welding electrode according to claim 1, wherein the workpiece contact surface has a conical surface shape whose diameter increases as the distance from the tip side increases.   The resistance spot welding electrode according to any one of claims 1 to 5, wherein the energization part and the cooling part are made of a copper alloy.

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