JP7441434B1 - Electrode for electric resistance welding - Google Patents

Abstract

An object of the present invention is to prevent a reciprocating member from tilting easily and to cause elastic deformation in a steel plate between a guide pin and a chuck mechanism of a robot device. A guide pin 20 is integrated with a sliding member 22 inserted into a guide hole 15 of a main cylindrical part 8 to constitute a reciprocating member 23, and the end of the steel plate part 2 is chucked by a robot device 44. The guide pin 20 is configured to be firmly held by a mechanism 45, the slope portion 21 is formed on the guide pin 20, and the support plate 16 made of a synthetic resin material arranged on the cap portion 9 has a through hole 17 through which the guide pin 20 passes. The outer diameter of the guide pin 20 and the inner diameter of the through hole 17 are set so that the guide pin 20 can advance and retreat while its outer peripheral surface rubs against the inner peripheral surface of the through hole 17. The member 23 is configured so as not to be substantially tilted with respect to the central axis OO of the electrode, and elastic deformation in the bending direction or stretching direction is generated in the steel plate component 2 between the guide pin 20 and the chuck mechanism 45. It was configured as follows. [Selection diagram] Figure 3

Description

In this invention, a reciprocating member is formed by a guide pin protruding from an electrode body and a sliding member that slides inside the electrode main body, and the positional state of the reciprocating member is improved to cause a required elastic deformation of a steel plate component. It relates to electrodes for electric resistance welding.

JP-A-10-118775 describes an electric resistance welding electrode for welding a projection nut to a steel plate component, in which a reciprocating member in which a guide pin and a sliding member are integrated is inserted into the electrode body of the electric resistance welding electrode. It is described that the guide pin is housed in the electrode body, and that a part of the guide pin protrudes from the electrode body.

Japanese Patent Application Publication No. 10-118775

In such electrodes, a steel plate part such as an automobile floor panel held by a robot device is usually placed on the top of the electrode body, and the central axis of the pilot hole drilled in the steel plate part and the electrode guide pin It is necessary to move the steel plate part toward the electrode body with the central axes of the guide pins relatively passing through the pilot hole, and by achieving this, the projection nut can be placed concentrically with the pilot hole or It is welded to steel plate parts in the same condition.

However, as shown in FIG. 5, it is difficult to make the pilot hole 51 of, for example, a diameter of about 5 mm in the floor panel 50 coaxial with the guide pin 52 from the viewpoint of controlling the operation of the robot device 53. . The reason for this difficulty is thought to be that when a large steel plate component such as the floor panel 50 is used, bending deformation occurs due to its own weight, causing a shift in the position of the pilot hole 51 relative to the guide pin 52. . When the steel plate component 50 is moved toward the end face of the electrode in a state where the pilot hole 51 and the guide pin 52 are eccentric, the inner peripheral surface of the pilot hole 51 is strongly rubbed against the guide pin 52, causing the guide pin 52 to be tilted. The steel plate component 50 is then placed on the mounting surface 54 of the electrode body (see FIG. 5(A)). In the structure described in Patent Document 1, the reciprocating member consisting of the guide pin 52 and the sliding member has a structure in which only the sliding member slides in the guide hole of the electrode. There is a problem in that the guide pin 52 tilts when an external force is applied.

When welding a projection nut to a steel plate component, if the guide pin is tilted and eccentric with respect to the pilot hole as described above, the screw hole of the projection nut will be lowered as shown in Figure 5 (B). Welding will be performed at an eccentric position offset from the hole 51. Hereinafter, in this specification, a projection nut may be simply expressed as a nut.

The present invention was provided in order to solve the above-mentioned problems, and in an electric resistance welding electrode that accommodates a reciprocating member consisting of a guide pin and a sliding member, a part of a steel plate component comes into contact with the guide pin. The purpose of this invention is to prevent the reciprocating member from tilting easily even when the robot device is moved, and to cause elastic deformation to occur in the steel plate between the guide pin and the chuck mechanism of the robot device.

The invention according to claim 1 is
The electrode body on which the steel plate component is placed is constituted by at least a main cylindrical part and a cap part integrated therein,
The cap portion includes a cylindrical portion with a circular cross section that is integrated with the main cylindrical portion, and an end member that functions as a lid member for the electrode body and on which the steel plate component is placed,
A guide pin having a circular cross section protruding from the end member is integrated with a sliding member slidably inserted into a guide hole formed in the main cylindrical portion to constitute a reciprocating member;
configured to firmly hold the end of the steel plate component with a chuck mechanism of a robot device,
A pilot hole is formed in the steel plate component, through which the guide pin relatively passes through when the steel plate component is placed on the electrode body,
A sloped portion whose diameter gradually decreases toward the tip of the guide pin is formed at the tip of the guide pin,
A through hole having a circular cross section through which the guide pin passes is provided in a support plate which is disposed in the inner part of the cap part and is made of a synthetic resin material,
The outer diameter of the guide pin and the inner diameter of the through hole are set so that the guide pin can advance and retreat while its outer peripheral surface rubs against the inner peripheral surface of the through hole, so that the reciprocating member can move forward and backward. , configured so as not to be substantially tilted with respect to the central axis of the electrode,
After the inner periphery of the pilot hole of the steel plate component comes into contact with the inclined portion due to the operation of the robot device, the inner periphery of the pilot hole rubs the inclined portion due to the weight of the steel plate component, and the steel plate component is moved onto the end member. When the guide pin is placed, the steel plate component between the guide pin and the chuck mechanism is elastically deformed in the bending direction or the elongation direction without substantially tilting, so that the guide pin is relatively The electrode for electric resistance welding is characterized in that the steel plate component is placed on the end member by penetrating the pilot hole.

The invention according to claim 2 is:
A vent hole for feeding cooling air into the guide hole is provided in the main cylindrical portion, an air passage is formed in the sliding member, and the outer circumferential surface of the guide pin advances and retreats while rubbing against the inner circumferential surface of the through hole. A ventilation gap is present in the
The support plate has a disc-shaped shape, and its outer diameter is set smaller than the inner diameter of the cylindrical part of the cap, so that a part of the support plate fills the space inside the cap. The electric resistance welding electrode according to claim 1, wherein the electrode is exposed in a protruding state.

In the invention according to claim 1,
The reciprocating member is configured by integrating a guide pin with a circular cross section that protrudes from the end member of the cap portion, and a sliding member that is slidably inserted into a guide hole formed in the main cylindrical portion. The outer diameter of the guide pin and the inner diameter of the through hole are set so that the outer circumferential surface of the guide pin can move forward and backward while rubbing against the inner peripheral surface of the through hole in the support plate inside the cap. The member is configured such that there is no substantially oblique displacement with respect to the central axis of the electrode. The difference between the outer diameter of the guide pin and the inner diameter of the through hole is narrowed to such a level that even when the guide pin rattles in the diametrical direction, no rattling or gaping sensation is felt. In other words, there is substantially no gap between the outer circumferential surface of the guide pin and the inner circumferential surface of the through hole, allowing the guide pin to slide.

The reciprocating member in which the guide pin and sliding member are integrated has two parts: one where the sliding member slides on the guide hole, and the other where the outer circumferential surface of the guide pin rubs against the inner circumferential surface of the through hole. Supported in places. When fitting a steel plate component onto a guide pin, if the center axis of the guide pin and the center axis of the pilot hole of the steel plate component are eccentric, the inner periphery of the pilot hole of the steel plate component will be attached to the inclined part of the guide pin. A phenomenon such as rubbing against the guide pin occurs, and a force that tries to topple the guide pin is applied. Even if such a force acts, the central axis of the reciprocating member will not easily tilt due to the support at the two locations.

On the other hand, since the steel plate component is firmly held by the chuck mechanism of the robot device, positional displacement such as the steel plate component slipping out from the chuck mechanism does not occur.

In this way, the guide pin is not easily inclined, and the steel plate part is not easily pulled out of the chuck mechanism, so when the inner circumference of the prepared hole slides on the slope, there is a gap between the guide pin and the chuck mechanism. Elastic deformation occurs in the steel plate. After such elastic deformation, when the steel plate component is placed on the end member, the pilot hole of the steel plate component becomes substantially concentric with the guide pin, or the amount of eccentricity is at a level that does not cause any actual damage.

The above-mentioned elastic deformation on the steel plate component side is performed by elastic deformation such as bending deformation or elongation deformation that occurs in the steel plate component. The end of the steel plate part is firmly held by the chuck mechanism of the robot device, so if the pilot hole of the steel plate part is misaligned from the guide pin, the steel plate part will slip or become misaligned at the chuck mechanism. In addition, since the guide pin does not easily tilt, bending deformation and stretching deformation occur on the side of the steel plate component.

Normally, for example, when welding a nut, the tip of a guide pin has an inclined shape, such as a tapered shape, where the diameter gradually decreases toward the tip. When moving toward the member side, the inner circumferential portion of the prepared hole is moved in the direction of the center axis of the electrode and rubbed against the tapered portion. At this time, a force in the diametrical direction of the guide pin, that is, a force that tends to overturn the guide pin, acts on the guide pin, but the above-mentioned two-point support prevents the guide pin from substantially tilting. In addition, since there is no slippage or other misalignment of the steel plate part at the chuck mechanism, elastic displacement of the guide pin in the diametrical direction occurs on the side of the steel plate part, and the center axis of the guide pin and the pilot hole are aligned. The eccentricity with respect to the central axis is reduced to a level that does not substantially pose a problem. In other words, the inner periphery of the pilot hole of the steel plate component, which is firmly held by the chuck mechanism, rubs against the strong guide pin where tilting displacement is virtually no problem, causing elastic deformation toward the steel plate component side. It is possible to do so.

The elastic displacement in the guide pin diameter direction on the steel plate component side as described above is ensured by causing the steel plate component to undergo bending direction deformation and elongation direction deformation. In the present invention, for example, the elastic deformation of a steel plate component that is thin and much larger than the pilot hole size, such as the floor panel or door panel described above, is intentionally utilized. In other words, the amount of eccentricity between the center axis of the prepared hole and the center axis of the guide pin is absorbed by elastic deformation of the steel plate component. As a mode of this elastic deformation, when the distance between the guide pin and the chuck mechanism is about to be shortened, bending deformation occurs in the steel plate between the guide pin and the chuck mechanism. Furthermore, when the distance between the guide pin and the chuck mechanism is about to increase, elongation deformation occurs in the steel plate between the guide pin and the chuck mechanism.

When holding a steel plate component with the aforementioned robot device, the steel plate component is held in its mouth by a chuck mechanism of the robot device, or by a chuck mechanism provided on a conveyance jig for the steel plate component. Since the positional deviation of the prepared hole is absorbed by the elastic deformation of the steel plate parts, it becomes easier to employ robot equipment, conveyance jigs, etc. In other words, since the guide pin is not easily tilted and the chuck mechanism firmly holds the steel plate component, elastic deformation can occur on the steel plate component side.

In the invention according to claim 2,
Cooling air flowing into the electrode body from the inlet passes through the air passage of the sliding member and the ventilation gap of the guide pin part, and a part of the support plate is exposed to protrude into the space inside the cap part. By doing so, the support plate made of synthetic resin material can be effectively cooled, which is effective for improving the durability of the support plate. In particular, since the support plate is disposed in the inner part of the cap portion, that is, in a position close to the location where welding heat is generated, the cooling effect as described above is important.

Furthermore, since a part of the support plate is exposed and protrudes into the space inside the cap, if the support plate expands due to welding heat. The exposed portion bulges into the space within the cap portion. This expansion and deformation toward the space alleviates the abnormally strong contact between the inner circumferential surface of the through hole and the outer circumferential surface of the guide pin, thereby reducing the progress of wear on the inner surface of the through hole to zero or substantially reducing it. This is effective in improving the durability of the support plate. It is thought that such a phenomenon occurs because the internal stress within the support plate caused by thermal expansion is reduced by the dispersive expansion toward space.

The present invention improves the electric resistance welding electrode in terms of tilt displacement of the guide pin, and can be utilized for welding floor panels and door panels that are firmly held by a chuck mechanism of a robot device. In addition, it can be used as a welding method that intentionally utilizes the elastic deformation of a steel plate component that is thin like the panel and is much larger than the pilot hole size. In other words, it is possible to provide a welding method based on the idea that the amount of eccentricity between the central axis of the prepared hole and the central axis of the guide pin is absorbed by elastic deformation of the steel plate component.

FIG. 2 is a cross-sectional view of the entire electrode and a cross-sectional view of a partial portion thereof. FIG. 3 is an external view showing an inclined portion of a guide pin. It is a sectional view when a steel plate component shifts to the right side of a guide pin. It is a sectional view when a steel plate component shifts to the left side of a guide pin. FIG. 6 is an exaggerated cross-sectional view showing a case where the guide pin is abnormally tilted.

EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing the electric resistance welding electrode of this invention is demonstrated.

1 to 4 show embodiments of the invention.

First, the parts to be welded will be explained.

The parts to be welded are often perforated parts such as nuts and washers to steel plate parts, but here we will weld a projection nut to a large steel plate part 2 such as an automobile floor panel or door panel. This is the case when welding 3.

The nut 3 has a screw hole 5 drilled in the center of a square nut body 4, and welding protrusions 6 are provided at the four lower corners. A pilot hole 7 is formed in the steel plate component 2, through which a guide pin, which will be described later, passes through.

Next, the electrode body will be explained.

The cylindrical electrode main body 1 includes at least a main cylindrical portion 8 and a cap portion 9 integrated therein. The main cylindrical portion 8 is preferably made of a copper alloy such as chromium copper, and the cap portion 9 is preferably made of a copper alloy such as beryllium copper, which has superior heat resistance and wear resistance.

The cap portion 9 includes a cylindrical portion 11 with a circular cross section that is integrated with the main cylindrical portion 8 via a threaded portion 10, and an end that serves as a lid member for the electrode body 1 and on which the steel plate component 2 is placed. It is composed of a member 13. The main cylindrical portion 8 is made of a cylindrical member, and has a guide hole 15 having a circular cross section.

The electrodes such as the electrode main body 1 in this embodiment are fixed electrodes, and are fixed to a stationary member 42 such as a machine frame. A reciprocating movable electrode 41 corresponding to the fixed electrode is arranged on the central axis OO.

Next, the support plate will be explained.

The diameter of the disk-shaped support plate 16 is smaller than the inner diameter of the cylindrical portion 11, and a through hole 17 is provided in the center. An insertion hole 18 is formed in the end member 13 from the inside of the cap portion 9, and a support plate 16 is press-fitted therein. This press-fitting is performed to the middle of the thickness of the support plate 16, so that a part of the support plate 16 is exposed in a protruding state into the space 31 within the cap portion 9. As shown in FIG. 1C, the dimension obtained by subtracting the diameter dimension of the support plate 16 from the inner diameter dimension of the cylindrical portion 11 is indicated by the symbol D1, and the corner portion 19 of the support plate 16 is measured from the ceiling surface in the cap portion 9. The protruding dimension is indicated by L1. The support plate 16 is made of a synthetic resin material such as polyamide resin, and polytetrafluoroethylene (trade name: Teflon, registered trademark), which has excellent heat resistance and abrasion resistance, is used here.

Next, the reciprocating member will be explained.

The guide pin 20 made of a ceramic material or stainless steel is constituted by a rod-shaped member having a circular cross section, and has an inclined portion 21 formed at its distal end, the diameter of which gradually decreases toward the distal end. The opposite side of the inclined portion 21 is a threaded structure. The sliding member 22 slidably inserted into the guide hole 15 is made of a synthetic resin material such as polytetrafluoroethylene (trade name: Teflon, registered trademark). Therefore, the guide pin 20 and the sliding member 22 are integrated to form the advancing/retracting member 23 (see FIG. 1(C)).

As a structure for integrating the guide pin 20 and the sliding member 22, a method such as casting the end of the guide pin 20 during injection molding of the sliding member 22 can be considered, but a screw structure is adopted here. There is.

A bolt 25 is formed at the end of the guide pin 20, passes through a bottom member 26 of the sliding member 22, fits a washer 27, and is tightened with a nut 28.

The guide pin 20 protrudes from the end member 13, and the opening corner of the threaded hole 5 of the nut 3 matches the inclined part 21, so that the nut 3 is held by the guide pin 20. Further, the pilot hole 7 of the steel plate component 2 is concentric with the guide pin 20.

FIG. 2 shows a modification of the guide pin 20. FIG. 1A shows a case where the outer shape of the inclined portion 21 is curved, and the embodiment shown in FIG. 1 is of this type. In addition, FIG. 2B shows a case where the outer shape of the inclined portion 21 is linear. Moreover, the same figure (C) is a case where the inclined part 21 is arrange|positioned at the intermediate part. In FIG. 2 , the steel plate component 2 is illustrated by two-dot chain lines, and each pilot hole 7 is shown shifted to the right, with the inner peripheral portion of one side of the pilot hole 7 hooked on the inclined portion 21 .

Next, the ventilation structure will be explained.

The ventilation structure includes an inlet 29 provided in the main cylindrical portion 8, a guide hole 15, an air passage 30 provided in the sliding member 22, a space 31 in the cylindrical portion 11, and a through hole 17 in the support plate 16. and the guide pin 20 (see FIG. 1(C)), the exhaust passage 33 opened in the diametrical direction of the end member 13, the ventilation hole 24, and the pilot hole 7 of the steel plate component 2. There is. The area where the guide pin 20 passes through the through hole 17 may be insufficient in flow path area necessary for ventilation. As a countermeasure against this, it is desirable to provide a ventilation groove 35 on the inner peripheral surface of the through hole 17, as shown in FIG. 1(D).

An air passage 30 is provided between the sliding member 22 and the guide hole 15, and its structure is such that a concave groove is provided on the outer peripheral surface of the sliding member 22 in the same direction as the central axis OO of the electrode, Various methods can be used, such as scraping off the outer peripheral surface of the sliding member 22. Here, it is the latter type of scraping. That is, the outer circumferential surface of the sliding member 22 has four flat portions 36 extending in the direction of the central axis OO, and the flat portions 36 and the arcuate inner surface of the guide hole 15 form an air passage 30 .

When the movable end surface 38 provided on the upper surface of the sliding member 22 comes into close contact with the stationary inner end surface 37 of the support plate 16, the airflow is interrupted and the cooling air sent from the inflow port 29 is interrupted. When the movable end face 38 is released, air flow is initiated. The stationary inner end surface 37 and the movable end surface 38 exist on a virtual plane in which the central axis OO is perpendicular. The force that presses the movable end surface 38 against the stationary inner end surface 37 is obtained by the tension of a compression coil spring 39 disposed within the guide hole 15. One end of the compression coil spring 39 is pressed against the washer 27, and the other end is pressed against the insulating sheet 34 fitted into the inner bottom surface of the guide hole 15.

After the support plate 16 is press-fitted into the insertion hole 18, an exhaust passage 33 in the electrode diameter direction is formed by drilling. Therefore, as shown in FIG. 1(E), a concave groove 40 having an arc-shaped cross section and forming a part of the exhaust passage 33 is formed.

Next, a description will be given of carrying in steel plate parts using a robot device.

Although the robot device 44 is only partially shown, it is a normal six-axis type device. Various types are employed as the chuck mechanism 45 that firmly holds the end of the steel plate component 2. Although the illustration is simplified here, a pair of open/close type clamping pieces are made of a metal material with excellent wear resistance, and the clamping pieces are opened and closed by an air cylinder. Therefore, if the clamping pieces strongly clamp the steel plate component 2 with the air cylinder, even if a force is applied to the steel plate component 2 to try to pull it out of the chuck mechanism 45, the steel plate component 2 will not come out easily.

In the case shown in FIG. 3, the pilot hole 7 is shifted to the right with respect to the central axis O-O of the guide pin 20, and the left inner circumference of the pilot hole 7 is caught in the middle of the inclined portion 21. ing. From this state, the steel plate part 2 descends and seats on the upper surface of the end member 13 while the left inner peripheral part of the pilot hole 7 rubs against the inclined part 21 due to its own weight. When the steel plate component 2 descends in this manner, the guide pin 20 hardly tilts, so elastic elongation occurs in the steel plate between the guide pin 20 and the chuck mechanism 45, allowing the steel plate component 2 to descend. Elastic elongation is indicated by arrow 46.

Therefore, as shown in FIG. 3(C), the threaded hole 5 of the nut 3 and the lower hole 7 of the steel plate component 2 are slightly eccentric, and the movable electrode 41 moves forward and welds while compressing the compression coil spring 39. The welding projection 6 is pressed against the steel plate part 2, and then welding current is applied to complete welding. When the guide pin 20, that is, the reciprocating member 23 descends due to the advance of the movable electrode 41, the movable end surface 38 separates from the stationary inner end surface 37, and a so-called valve opening action is performed.

As a result, the inlet 29 provided in the main cylindrical portion 8, the guide hole 15, the air passage 30 provided in the sliding member 22, the space 31 in the cylindrical portion 11, the through hole 17 of the support plate 16, and the guide The above-mentioned structure is formed by the slight gap 32 between the pins 20 (see FIG. 1(C)), the exhaust passage 33 opened in the diametrical direction of the lid member 13, the ventilation hole 24, and the pilot hole 7 of the steel plate component 2. Cooling air is circulated through the ventilation structure. Further, spatter scattered from the melted portion is discharged to the outside from the exhaust passage 33 via the lower hole 7 and the ventilation hole 24.

Therefore, as shown in FIG. 3(C), the screw hole 5 of the nut 3 and the pilot hole 7 of the steel plate component 2 have a slight eccentricity that causes no actual damage, and the compression coil spring 39 is compressed by the advance of the movable electrode 41. Meanwhile, the welding protrusion 6 is pressed against the steel plate component 2, and then welding current is applied to complete the welding. When the guide pin 20, that is, the reciprocating member 23 descends due to the advance of the movable electrode 41, the movable end surface 38 separates from the stationary inner end surface 37, and a so-called valve opening action is performed.

In the case shown in FIG. 4, the pilot hole 7 is shifted to the left with respect to the center axis O-O of the guide pin 20, and the inner circumference on the right side of the pilot hole 7 is caught in the middle of the inclined portion 21. ing. From this state, the steel plate part 2 descends and seats on the upper surface of the end member 13 while the right inner peripheral part of the prepared hole 7 rubs against the inclined part 21 due to its own weight. When the steel plate component 2 descends in this manner, the guide pin 20 hardly tilts, so that the steel plate between the guide pin 20 and the chuck mechanism 45 undergoes elastic bending deformation in the direction of expansion, allowing the steel plate component 2 to descend. . The bending deformation in the bulging direction causes elastic deformation in the direction of the arrow 48, as shown in the image deformation indicated by the two-dot chain line 47 in FIG.

As shown in FIG. 4(C), the amount of eccentricity between the screw hole 5 and the pilot hole 7 of the steel plate component 2 is a small value that does not cause any actual damage. The circulation of cooling air in the ventilation structure and the discharge of spatter are performed in the same manner as in the case of FIG.

Although FIG. 5 is a cross-sectional view showing the problems of the prior art, the symbols used in the above embodiment are written in FIG. 5 to make it easier to understand.

The effects of the embodiment described above are as follows.

The reciprocating member 23 includes a guide pin 20 having a circular cross section protruding from the end member 13 of the cap portion 9 and a sliding member 22 slidably inserted into the guide hole 15 formed in the main cylindrical portion 8. The guide pin 20 has an outer diameter dimension so that the guide pin 20 can advance and retreat while its outer circumferential surface rubs the inner circumferential surface of the through hole 17 formed in the support plate 16 in the cap part 9. By setting the inner diameter of the through hole 17, the reciprocating member 23 is configured not to be substantially tilted relative to the central axis OO of the electrode. The difference between the outer diameter of the guide pin 20 and the inner diameter of the through hole 17 is narrowed to such a level that even if the guide pin 20 rattles in the diametrical direction, no rattling or gap feeling is felt. That is, there is substantially no gap between the outer circumferential surface of the guide pin 20 and the inner circumferential surface of the through hole 17, so that the guide pin 20 can slide.

The reciprocating member 23 in which the guide pin 20 and the sliding member 22 are integrated has a portion where the sliding member 22 slides on the guide hole 15 and a portion where the outer circumferential surface of the guide pin 20 is on the inner circumferential surface of the through hole 17. It is supported at two places where it is being rubbed. When fitting the steel plate component 2 to the guide pin 20, if the center axis OO of the guide pin 20 and the center axis of the pilot hole 7 of the steel plate component 2 are eccentric, the pilot hole of the steel plate component 2 A phenomenon occurs in which the inner circumferential portion rubs against the inclined portion 21 of the guide pin 20, and a force that tends to topple the guide pin 20 acts. Even if such a force acts, the central axis OO of the reciprocating member 23 will not easily tilt due to the support at the two locations.

On the other hand, since the steel plate component 2 is firmly held by the chuck mechanism 45 of the robot device 44, positional displacement such as the steel plate component 2 slipping out from the chuck mechanism 45 does not occur.

In this way, the guide pin 20 is not easily inclined, and the steel plate component 2 is not easily removed from the chuck mechanism 45, so when the inner peripheral part of the pilot hole 7 slides on the inclined part 21, Elastic deformation occurs in the steel plate between the guide pin 20 and the chuck mechanism 45. After such elastic deformation, when the steel plate part 2 is placed on the end member 13, the pilot hole 7 of the steel plate part 2 becomes substantially concentric with the guide pin 20, or the eccentricity is at a level that does not cause any actual damage. It becomes. Comparing FIGS. 3A and 3B, it is found that there is a large difference in the spatial clearance of the prepared hole 7, and (B) is the amount of eccentricity at a level that does not cause any actual damage. The same applies to FIG. 4 as well.

The above-mentioned elastic deformation on the side of the steel plate component 2 is performed by elastic deformation such as bending deformation or elongation deformation that occurs in the steel plate component 2. Since the end of the steel plate component 2 is firmly held by the chuck mechanism 45 of the robot device 44, if the pilot hole 7 of the steel plate component 2 deviates from the guide pin 20, the steel plate component 20 will be damaged at the location of the chuck mechanism 45. Since positional displacement such as slipping does not occur, and the guide pin 20 does not easily tilt, bending deformation and elongation deformation occur on the side of the steel plate component 2.

Normally, for example, when welding a nut 3, the tip of the guide pin 20 has an inclined shape, such as a tapered shape, whose diameter gradually decreases toward the tip. When the electrode is moved toward the end member 13, the inner peripheral portion of the prepared hole is moved in the direction of the central axis OO of the electrode and rubbed against the tapered portion. At this time, a force in the diametrical direction of the guide pin 20, that is, a force that tends to overturn the guide pin 20, acts on the guide pin 20, but the above-mentioned support at two locations substantially prevents the tilting movement of the guide pin 20. In addition, since there is no slippage or other misalignment of the steel plate part 2 at the chuck mechanism 45, elastic displacement of the guide pin 20 in the diametrical direction occurs on the side of the steel plate part 2, and the guide The eccentricity between the central axis OO of the pin 20 and the central axis O1-O1 of the prepared hole 7 is reduced to a level that does not pose a substantial problem. In other words, the inner periphery of the pilot hole 7 of the steel plate component 2, which is firmly held by the chuck mechanism 45, rubs against the strong guide pin 20 where tilting displacement is not a substantial problem. can be caused to undergo elastic deformation.

The elastic displacement in the guide pin diameter direction on the steel plate component 2 side as described above is ensured by causing the steel plate component 2 to undergo bending direction deformation and elongation direction deformation. In this embodiment, the elastic deformation of the steel plate component 2, which is thin and much larger than the pilot hole size, such as the above-mentioned floor panel or door panel, is intentionally utilized. In other words, the amount of eccentricity between the center axis O1-O1 of the prepared hole 7 and the center axis O-O of the guide pin 20 is absorbed by the elastic deformation of the steel plate component 2. As a mode of this elastic deformation, when the distance between the guide pin 20 and the chuck mechanism 45 is about to be shortened, bending deformation occurs in the steel plate between the guide pin 20 and the chuck mechanism 45. Moreover, when the distance between the guide pin 20 and the chuck mechanism 45 is about to increase, the steel plate between the guide pin 20 and the chuck mechanism 45 undergoes elongation deformation.

When the steel plate part 2 is held by the robot device 44 described above, the steel plate part 2 is held by the chuck mechanism 45 of the robot device 44, or by the chuck mechanism 45 provided on the conveyance jig for the steel plate part 2. However, since the positional deviation between the guide pin 20 and the pilot hole 7 is absorbed by the elastic deformation of the steel plate component 2, it becomes easier to employ a robot device 44, a conveyance jig, etc. In other words, since the guide pin 20 is not easily tilted and the chuck mechanism 45 firmly holds the steel plate component 2, elastic deformation can occur on the steel plate component 2 side.

The cooling air that has flowed into the electrode body 1 from the inlet 29 passes through the air passage 30 of the sliding member 22 and the ventilation gap 32 of the guide pin part, and a part of the support plate 16 is connected to the space 31 in the cap part 9. By exposing the support plate 16 in a protruding state, the support plate 16 made of synthetic resin material can be effectively cooled, which is effective for improving the durability of the support plate 16. In particular, since the support plate 16 is disposed at the inner part of the cap portion 9, that is, at a position close to the location where welding heat is generated, the cooling effect as described above is important.

Further, since a part of the support plate 16 is exposed and protrudes into the space 31 within the cap portion 9, the support plate 16 expands due to welding heat. The exposed portion bulges into the space 31 within the cap portion 9 as shown by the two-dot chain line. Such expansion and deformation toward the space 31 alleviates the abnormally strong contact between the inner circumferential surface of the through hole 17 and the outer circumferential surface of the guide pin 20, thereby reducing the progress of wear on the inner surface of the through hole to zero, or Alternatively, the abrasion level can be reduced to a level that causes no actual damage, which is effective for improving the durability of the support plate 16. It is thought that such a phenomenon occurs because the internal stress within the support plate 16 caused by thermal expansion is reduced by the dispersive expansion toward space.

As described above, according to the electrode of the present invention, in an electric resistance welding electrode that accommodates a reciprocating member consisting of a guide pin and a sliding member, even if a part of a steel plate component comes into contact with the guide pin, the retracting member does not move. This prevents the steel plate from tilting easily and causes elastic deformation of the steel plate between the guide pin and the chuck mechanism of the robot device. Therefore, it can be used in a wide range of industrial fields, such as automobile body welding processes and sheet metal welding processes for home appliances.

1 Electrode body 2 Steel plate parts 3 Projection nut 5 Screw hole 7 Pilot hole 8 Main cylindrical part 9 Cap part 11 Cylindrical part 13 End member 15 Guide hole 16 Support plate 17 Through hole 19 Corner part 20 Guide pin 21 Inclined part 22 Sliding Member 23 Reciprocating member 24 Ventilation hole 29 Inflow port 30 Air passage 31 Space 32 Gap 33 Exhaust passage 37 Stationary inner end surface 38 Movable end surface 39 Compression coil spring 44 Robot device 45 Chuck mechanism OO Center axis of electrode O1-O1 of lower hole center axis

Claims (2)

The electrode body on which the steel plate component is placed is constituted by at least a main cylindrical part and a cap part integrated therein,
The cap portion includes a cylindrical portion with a circular cross section that is integrated with the main cylindrical portion, and an end member that functions as a lid member for the electrode body and on which the steel plate component is placed,
A guide pin having a circular cross section protruding from the end member is integrated with a sliding member slidably inserted into a guide hole formed in the main cylindrical portion to constitute a reciprocating member;
configured to firmly hold the end of the steel plate component with a chuck mechanism of a robot device,
A pilot hole is formed in the steel plate component, through which the guide pin relatively passes through when the steel plate component is placed on the electrode body,
A sloped portion whose diameter gradually decreases toward the tip of the guide pin is formed at the tip of the guide pin,
A through hole having a circular cross section through which the guide pin passes is provided in a support plate which is disposed in the inner part of the cap part and is made of a synthetic resin material,
The outer diameter of the guide pin and the inner diameter of the through hole are set so that the guide pin can advance and retreat while its outer peripheral surface rubs against the inner peripheral surface of the through hole, so that the reciprocating member can move forward and backward. , configured so as not to be substantially tilted with respect to the central axis of the electrode,
After the inner periphery of the pilot hole of the steel plate component comes into contact with the inclined portion due to the operation of the robot device, the inner periphery of the pilot hole rubs the inclined portion due to the weight of the steel plate component, and the steel plate component is moved onto the end member. When the guide pin is placed, the steel plate component between the guide pin and the chuck mechanism is elastically deformed in the bending direction or the elongation direction without substantially tilting, so that the guide pin is relatively An electrode for electric resistance welding, characterized in that the steel plate component is placed on the end member by penetrating the pilot hole. A vent hole for feeding cooling air into the guide hole is provided in the main cylindrical portion, an air passage is formed in the sliding member, and the outer circumferential surface of the guide pin advances and retreats while rubbing against the inner circumferential surface of the through hole. A ventilation gap is present in the
The support plate has a disc-shaped shape, and its outer diameter is set smaller than the inner diameter of the cylindrical part of the cap, so that a part of the support plate fills the space inside the cap. The electric resistance welding electrode according to claim 1, wherein the electrode is exposed in a protruding state.

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