JP2020127967A - Electric resistance welding electrode and cooling method thereof - Google Patents

Abstract

To excellently execute heat radiation to the hollow space side of a guide pin and heat radiation to the electrode body side.SOLUTION: A projection bolt 19 including a shaft part 20, a circular flange 21 and a plurality of deposition projections 22 is an object of welding; a guide pin 12 projecting from an end surface of an electrode body 1 and penetrating a prepared hole 10 of a steel plate part 3 is formed in a hollow shape of including a receiving hole 35 of the shaft part 20; a cross-sectional circular sliding member 13 is constituted by being integrated into the guide pin 12 and being fitted in a slidable state to a guide hole 6 of the electrode body 1; hot air in the receiving hole 35 is pushed out, heat is absorbed by the shaft part 20 in a normal temperature state, and cold air of an external part is sucked in the receiving hole 35; and welding heat is transmitted to the electrode body 1 to radiate heat to outside air, setting the ratio of a thickness T2 of the guide pin 12 to a thickness T1 of the sliding member 13 as 0.15 or more and less than 0.32.SELECTED DRAWING: Figure 3

Description

The present invention relates to an electric resistance welding electrode having a hollow guide pin made of a heat-resistant hard material and a sliding member made of an insulating synthetic resin material, and a cooling method thereof.

In Japanese Patent No. 6395068, a guide pin having a circular cross-section that projects from the end face of the electrode body and penetrates a pilot hole of a steel plate component is formed into a hollow shape having a receiving hole for a projection bolt and is made of a heat-resistant hard material. It is described that the sliding member having a circular cross section which is integrated with the guide pin and is slidably fitted in the guide hole of the electrode body is made of an insulating synthetic resin material.

Japanese Patent No. 6395068

Since the integrated member composed of the guide pin made of the heat-resistant hard material and the sliding member made of the insulating synthetic resin material is housed in the electrode body, in order to radiate the welding heat transmitted to the integrated member, It is necessary to satisfactorily dissipate heat to the hollow space side of the guide pin and to the electrode body side. In the technique described in Patent Document 1, nothing about heat dissipation of welding heat is described, and regarding heat flow toward both the inside and outside of heat dissipation to the hollow space side and heat dissipation to the electrode body side, Nothing is disclosed.

The present invention is provided to solve the above problems, and an object thereof is to satisfactorily perform heat dissipation to the hollow space side of the guide pin and heat dissipation to the electrode body side.

The invention according to claim 1 is an invention of an electric resistance welding electrode,
A shaft portion on which a male screw is formed, a circular flange integrally provided on the shaft portion, and a projection bolt having a plurality of welding projections provided on the flange surface of the shaft portion are targets for welding,
Projecting from the end surface of the electrode body having a circular cross section, a guide pin having a circular cross section that penetrates the pilot hole of the steel plate component is a hollow shape having a shaft receiving hole, and is made of a heat-resistant hard material,
The sliding member having a circular cross section which is integrated with the guide pin and is slidably fitted in the guide hole of the electrode body is made of an insulating synthetic resin material,
When inserting the shaft into the receiving hole, the hot air in the receiving hole is pushed out, and the welding heat stored in the guide pin and the sliding member is absorbed by the shaft at room temperature. When pulling out the part from the receiving hole, it is configured to suck outside cool air into the receiving hole,
By setting the ratio of the thickness of the guide pin to the thickness of the sliding member to 0.15 or more and less than 0.32, the welding heat accumulated in the guide pin and the sliding member is transmitted to the electrode body and radiated to the outside air. It is characterized by doing.

In the following description, the projection bolt may be simply expressed as a bolt.

When inserting the projection bolt into the receiving hole, push out the hot air in the receiving hole and absorb the welding heat stored in the guide pin and the sliding member with the bolt at room temperature. When extracting, cool air outside is sucked into the receiving hole. The hot air is discharged and the cool air is sucked in through the gap between the bolt and the inner surface of the receiving hole.

As described above, when the bolt is pushed into the receiving hole, hot air is discharged and at the same time, the residual heat of the guide pin and the sliding member is absorbed by the low temperature bolt at room temperature. The air pressure inside the hole is lowered, and cold air outside is sucked into the receiving hole. Therefore, the integrated member of the guide pin and the sliding member is cooled from the inside. The bolt plays a role as if it were a piston to supply/discharge the inside of the guide pin, and the cooling of the integrated member proceeds from the inside.

The ratio of the thickness of the guide pin to the thickness of the sliding member is 0.15 or more and less than 0.32. The above ratio means that when the thickness of the sliding member is increased, the thickness of the guide pin is also increased.

When the wall thickness of the guide pin becomes thick, the wall thickness of the sliding member also becomes thick and the amount of heat storage increases, and moreover, the difference between the shaft portion diameter and the prepared hole inner diameter of the steel plate component becomes large. Therefore, the amount of eccentricity of the shaft portion with respect to the prepared hole may be excessive, which causes a decrease in welding accuracy. If the guide pin is too thick, the inner diameter of the pilot hole will increase, and the weld will be located near the opening edge of the pilot hole. May cause a decrease in In addition, since the dimensions of each part of the bolt are generally standardized, the wall thickness of the guide pin becomes too large with respect to the distance between the welding projection and the shaft, and it is necessary to manufacture a nonstandard bolt. Occurs and is not preferable in terms of promoting standardization.

Further, when the wall thickness of the guide pin becomes thin, the strength as a hollow guide pin decreases. When the inner surface of the pilot hole collides with the guide pin when the steel plate component is set on the electrode, the circular hollow shape of the guide pin is deformed into an abnormal shape. At the same time, since the thickness of the sliding member is also reduced, the overall strength of the integrated member is reduced.

Under the above various conditions, if the ratio of the thickness of the guide pin to the thickness of the sliding member is less than 0.15, the guide pin is too thin and the hollow guide pin lacks strength. Or the strength as an integrated member of the guide pin and the sliding member is insufficient. Further, when the thermal capacity of the integrated member becomes small, the heating temperature of the guide pin and the sliding member due to welding heat becomes extremely high, which is not good in terms of thermal durability.

When the above ratio is 0.32 or more, the following problems occur. That is, the wall thickness of the guide pin becomes thicker, and the wall thickness of the sliding member becomes thicker at the same time, and the heat storage amount increases. Moreover, since the difference between the shaft diameter and the inner diameter of the pilot hole of the steel plate component becomes large, the amount of eccentricity of the shaft portion with respect to the pilot hole may become excessive, which causes a decrease in welding accuracy. If the guide pin is too thick, the inner diameter of the pilot hole will increase, and the weld will be located near the opening edge of the pilot hole. It may cause a drop. In addition, since the dimensions of each part of the bolt are generally standardized, the wall thickness of the guide pin becomes too large with respect to the distance between the welding projection and the shaft, and it is necessary to manufacture a nonstandard bolt. Occurs and is not preferable in terms of promoting standardization.

When the ratio is 0.15 or more and less than 0.32, the above problems are solved. That is, the strength of the hollow guide pin and the integrated member can be sufficiently ensured. The thermal capacity as an integrated member is optimized, and the thermal durability is improved. Since the difference between the outer diameter of the guide pin and the inner diameter of the pilot hole does not become excessive, the amount of eccentricity of the shaft portion with respect to the pilot hole decreases. The welded portion becomes a proper portion with respect to the opening edge of the prepared hole, and the problem of the abnormal welded portion described above is solved. The distance between the welding protrusion of the bolt and the shaft portion has an appropriate value for the wall thickness of the hollow guide pin, and it is possible to properly implement the standardized bolt.

The welding heat stored in the integrated member of the guide pin and the sliding member is radiated to the outside air through the space of the receiving hole, or is absorbed by the low temperature shaft portion toward the receiving hole. In addition to such an inward heat dissipation path, an outward heat dissipation path toward the electrode body side is also important.

Regarding heat dissipation to the electrode body, it is important to select the heat quantity of the entire integrated member formed by the guide pin and the sliding member and the thickness of the guide pin itself. The wall thickness of the guide pin is positioned as having a deep relationship with the distance between the welding projection and the shaft portion and the strength when the steel plate component collides. If the guide pin is too thick, the inner diameter of the pilot hole of the steel plate part will also be large, so the welded part of the welding projection will be near the opening edge of the pilot hole, or it will stick out from the opening edge and cause welding. There is a risk of insufficient strength. Further, as the thickness of the guide pin increases, the thickness of the sliding member also increases, so the heat capacity of the integrated member becomes excessive, and the heat dissipation to the electrode body side is sufficient for the heat dissipation via the receiving hole. This cannot be ensured, and as a result, insufficient cooling is brought about and the thermal durability of the entire electrode is reduced.

The optimization of heat dissipation to the electrode body side is that the amount of heat of the integrated member does not become excessive. If the amount of heat of the integrated member becomes too large, that is, if the thickness of the guide pin or the thickness of the sliding member becomes too large, the amount of heat accumulated in the integrated member will become excessive and the amount of heat released to the electrode body side will be insufficient. It will be. Compared to the case of thick integrated member and the case of thin integrated member within a certain heat radiation time, the thick one tends to accumulate residual heat, but the thin one has a low residual heat accumulation property, so short Can radiate heat in time. From this point of view, the relationship between the thickness of the guide pin and the thickness of the sliding member is important.

Since the thickness of the integrated member is reduced, the inner diameter of the prepared hole can be reduced as much as possible, and the reduction in rigidity of the steel plate component can be minimized.

As described above, since the ratio is less than 0.32, the outer diameter of the integrated member does not become excessively large, and accordingly, the diameter of the electrode body can be reduced, and the electrode installation in a narrow place or It is also effective for saving electrode materials.

Each of the above effects is based on the diameter of the shaft of the bolt. That is, by correlating with the inner diameter of the pilot hole with respect to the diameter of the bolt shaft portion, the appropriate distance from the opening edge of this inner diameter to the welding portion, the wall thickness value of the guide pin with respect to the distance between the shaft portion and the welding protrusion, etc. The effect of the present invention is derived from the fact that the ratio of the thickness of the guide pin to the thickness of the sliding member is set to 0.15 or more and less than 0.32.

The invention according to claim 2 is an invention of a method for cooling an electric resistance welding electrode,
A shaft portion on which a male screw is formed, a circular flange integrally provided on the shaft portion, and a projection bolt having a plurality of welding projections provided on the flange surface of the shaft portion are targets for welding,
Projecting from the end surface of the electrode body having a circular cross section, a guide pin having a circular cross section that penetrates the pilot hole of the steel plate component is a hollow shape having a shaft receiving hole, and is made of a heat-resistant hard material,
A sliding member having a circular cross section which is integrated with the guide pin and fitted in a guide hole of the electrode body in a slidable state prepares an electric resistance welding electrode composed of an insulating synthetic resin material,
When inserting the shaft into the receiving hole, the hot air in the receiving hole is pushed out, and the welding heat stored in the guide pin and the sliding member is absorbed by the shaft at room temperature, and after the welding to the steel plate parts is completed, When removing the part from the receiving hole, by sucking outside cool air into the receiving hole, the welding heat is radiated from the inside of the receiving hole to the outside air,
By setting the ratio of the thickness of the guide pin to the thickness of the sliding member to 0.15 or more and less than 0.32, the welding heat accumulated in the guide pin and the sliding member is transmitted to the electrode body and radiated to the outside air. It is characterized by doing.

The effect of the invention of the cooling method according to the second aspect is the same as the effect of the invention of the electric resistance welding electrode.

It is sectional drawing of the whole electrode. It is sectional drawing which shows the state in which a bolt is inserted in an electrode one by one. It is sectional drawing which shows a wall thickness dimension. It is sectional drawing which shows the abnormal state of the thickness of a guide pin and a sliding member.

Next, modes for carrying out the electric resistance welding electrode and the cooling method thereof according to the present invention will be described.

1 to 4 show an embodiment of the present invention.

First, the projection bolt will be described.

As shown in FIG. 1, the bolt 19 is provided on a shaft portion 20 formed with a male screw, a circular flat plate-shaped flange 21 integrally provided on the shaft portion 20, and a flange surface on the shaft portion 20 side. It is composed of a plurality of welding projections 22. Two welding protrusions 22 are provided on the same circle at intervals of 120 degrees. As shown in FIG. 2(A), the welding protrusions 22 and the shaft portion 20 are connected by a flat surface. The interval L is set.

Regarding the dimensions of each part of the bolt 19, the diameter and the length of the shaft part 20 are 8 mm and 30 mm, the thickness and the diameter of the flange are 3.2 mm and 20 mm, respectively, and the interval L is 2.3 mm.

The electrode body 1 made of a conductive material made of a copper alloy such as chrome copper has a cylindrical shape and a circular cross section, on which the fixing portion 2 to be inserted into the stationary member 11 and the steel plate component 3 are placed. The cap portion 4 is coupled with the screw portion 5 to form the electrode body 1 having a circular cross section. A guide hole 6 having a circular cross section is formed in the electrode body 1. The guide hole 6 is formed in the cap portion 4 with a large diameter hole 7 formed in the fixed portion 2 and a diameter smaller than the large diameter hole 7. A medium-diameter hole 8 and a small-diameter hole 9 having a smaller diameter than the medium-diameter hole 8 are formed, and the large-diameter hole 7, the medium-diameter hole 8 and the small-diameter hole 9 are coaxial with each other and aligned on the central axis O-O of the electrode body 1. It is arranged in a state.

The guide pin 12 having a circular cross-section that protrudes from the end surface of the electrode body 1 on which the steel plate component 3 is placed and penetrates the prepared hole 10 of the steel plate component 3 is made of a heat-resistant hard material such as a metal material such as stainless steel or a ceramic material. It is configured. The guide pin 12 is provided with a receiving hole 35 into which the shaft portion 20 is inserted, and the depth dimension thereof is set shorter than the length of the shaft portion 20 as shown in FIG. 2(B).

A sliding member 13 having a circular cross section, which is integrated with the guide pin 12 and is slidably fitted in the guide hole 6 of the electrode body 1, is made of an insulating synthetic resin material such as polytetrafluoroethylene (trade name: Teflon).・Registered trademark). As another material, a resin having excellent heat resistance and abrasion resistance can be adopted from polyamide resins.

Next, an integrated member of the guide pin and the sliding member will be described.

The guide pin 12 is inserted into the center of the sliding member 13 so that the guide pin 12 and the sliding member 13 are integrated. As the structure for integrating the guide pin 12 with the sliding member 13, a method of molding the guide pin 12 together during injection molding of the sliding member 13, a method of providing a coupling bolt structure portion on the guide pin 12, and the like, Various types can be adopted.

Here, it is the latter type of connecting bolt structure.

That is, the bolt 14 is formed integrally with the lower end portion of the guide pin 12, the bolt 14 penetrates the bottom member 15 of the sliding member 13, the washer 16 is assembled, and the lock nut 17 is tightened. The sliding member 13 has an insulating function so that when the movable electrode paired with the electrode body 1 operates and a welding current is applied, the current flows only from the welding projection 22 of the flange 21 to the steel plate component 3. Is playing.

The compression coil spring 23 is fitted between the washer 16 and the inner bottom surface of the guide hole 6, and the tension thereof acts on the sliding member 13. Note that reference numeral 24 indicates an insulating sheet fitted on the inner bottom surface of the guide hole 6. The tension of the compression coil spring 23 establishes pressure contact of the movable end face with the stationary inner end face, which will be described later. The compression coil spring 23 is a pressurizing unit, and instead of this, the pressure of compressed air can be used.

Next, the correspondence between each part of the sliding member and each part of the guide hole will be described.

It will be described with reference to FIG. 3 in which hatching is not entered for the sake of easy viewing.

A large diameter portion 26 and a medium diameter portion 27 are formed in the sliding member 13, and the guide pin 12 having a diameter smaller than that of the medium diameter portion 27 is integrated. The large-diameter portion 26 is fitted into the large-diameter hole 7 in a state where the large-diameter portion 26 can slide without any substantial gap between the large-diameter portion 7 and the inner surface of the large-diameter hole 7. And a ventilation gap 28 for cooling air is left between them. The above-mentioned "... state in which sliding is possible with substantially no gap" means that the sliding member 13 has a rattling sensation of a gap even when a force in the diametrical direction of the electrode body 1 is applied. This means a state in which there is no feeling of sticking and sliding in the direction of the central axis O--O is possible. A guide pin 12 projects from the upper surface of the electrode body 1 through the small diameter hole 9. A ventilation gap 29 through which cooling air passes when the guide pin 12 is pushed down is formed between the small diameter hole 9 and the guide pin 12.

Next, the intermittent structure of the cooling air will be described.

A vent 30 is formed to guide the cooling air to the guide hole 6. In order to secure an air passage for the sliding portion of the large diameter portion 26 and the large diameter hole 7, a concave groove in the direction of the central axis O--O can be formed on the outer peripheral surface of the large diameter portion 26. As shown in FIG. 1(B), an air passage formed by forming a flat surface portion 31 in the direction of the central axis O--O on the outer peripheral surface of the large diameter portion 26 and by the flat surface portion 31 and the arc-shaped inner surface of the large diameter hole 7. 32 is formed. Such flat portions 31 are formed at intervals of 180 degrees, and air passages are provided at two locations.

An annular stationary inner end surface 33 is formed at the boundary between the medium diameter hole 8 and the large diameter hole 7 of the guide hole 6. An annular movable end surface 34 is formed at the boundary between the medium diameter portion 27 and the large diameter portion 26 of the sliding member 13. The stationary inner end surface 33 and the movable end surface 34 are arranged on a virtual plane where the central axis O-O of the electrode body 1 intersects perpendicularly, and the movable end surface 34 is annular with respect to the stationary inner end surface 33 due to the tension of the compression coil spring 23. In close contact with each other, cooling air is sealed by this close contact.

Next, a projection bolt supply mechanism will be described.

As the above-mentioned supply mechanism, a type in which a bolt is held at the tip of a supply rod that moves forward and backward in an oblique direction and is supplied to a receiving hole of a guide pin, a supply rod having a bolt at the tip is subjected to a square motion in the lateral direction. Various types such as a type and a type in which a worker manually inserts a bolt can be adopted. Here it is of the laterally actuated square motion type.

The supply pipe 36 of the bolt 19 is fixed to a predetermined position of the stationary member 11 such as a machine frame, and its pipe end is open upward. The bolts 19 sent from a parts supply source such as a parts feeder (not shown) are sent to the supply pipe 36 by the jetted carrier air. The flange 21 of the bolt 19 is attracted to the lower surface of the tip of the supply rod 37 that moves in the horizontal direction, and the bolt 19 is held in a suspended state. In this holding, a permanent magnet 39 is attached to the operating rod 38 that moves forward and backward in the supply rod 37, and the operating rod 38 is moved forward and backward to switch the permanent magnet 39 between the attraction position and the open position. The supply pipe 36 is provided with a split groove 41 through which the shaft portion 20 passes.

Next, the bolt supply operation and the heat flow at that time will be described.

As shown in FIG. 1, the advancing of the supply rod 37 is stopped at a position where the shaft portion 20 is coaxial with the central axis line OO. Then, when the entire supply rod 37 descends, the shaft portion 20 is inserted into the receiving hole 35. At the time of this insertion, as shown in FIG. 2(A), the hot air in the receiving hole 35 is pushed out through the gap between the shaft portion 20 and the inner surface of the receiving hole 35. At the time of this extrusion, the welding heat stored in the integrated member 25 including the guide pin 12 and the sliding member 13 is also radiated.

When the insertion of the shaft portion 20 into the receiving hole 35 progresses, the operating rod 38 retracts in the middle thereof, so that the attractive force of the permanent magnet 39 disappears, the bolt 19 falls by its own weight, and the tip portion of the shaft portion 20. Is seated on the bottom of the receiving hole 35, the insertion of the bolt 1 is completed (see FIG. 2B). Even in the transitional period of falling by its own weight, the discharge of hot air shown by the arrow in FIG. 1A continues. The inserted bolt 19 is at room temperature, and the welding heat remaining on the guide pin 12 and the sliding member 13 is absorbed by the bolt 19. In this way, the temperature of the integrated member 25 is reduced by the guide pin 12 and the sliding member 13.

After that, the supply rod 37 is retracted, the movable electrode is advanced, and pressurization and energization are performed, and the welding projection 22 is welded to the steel plate component 3 as shown in black in FIG. 2(C). This welded portion is indicated by reference numeral 40.

After the welding, as shown in FIG. 2C, the bolt 19 welded to the steel plate component 3 is extracted from the receiving hole 35 by utilizing the attractive force of the permanent magnet 39 in the supply rod 37. At this time, since the inside of the receiving hole 35 has a negative pressure, the external cool air is sucked into the receiving hole 35 and the temperature of the integrated member 25 is lowered, as shown in FIG. 2C. This bolt extraction can be performed by holding the steel plate component 3 with a robot device or manually by an operator.

Next, the thickness of the guide pin and the sliding member will be described.

In the integrated member 25, the ratio of the wall thickness T2 of the guide pin 12 to the wall thickness T1 of the sliding member 13 is 0.15 or more and less than 0.32. As shown in FIG. 4, when the wall thickness T2 becomes excessively large, the difference between the distance L between the flange portions and the wall thickness T2 decreases, so that the diameter of the pilot hole 10 increases as shown in FIG. The weld 40 is located just before the opening edge 10A. Further, due to a slight deviation in the diametrical direction, the welded portion 40 may protrude from the opening edge 10A toward the center side, as shown in FIG. Such a problem is solved as described above by setting the ratio of the thickness T2 of the guide pin 12 to the thickness T1 of the sliding member 13 to be 0.15 or more and less than 0.32.

When the ratio is 0.32 or more, a defect occurs in the welded portion 40, and when the ratio is less than 0.15, the thickness of the guide pin 12 is too small, and the guide pin 12 shown in FIG. As shown in B2), when the inner surface of the pilot hole 10 collides with the guide pin 12, the circular hollow shape is abnormally deformed, and the shaft portion 20 cannot be inserted.

Further, if the ratio is less than 0.15, the circular hollow shape of the guide pin 12 causes abnormal deformation, but the wall thickness of the entire integrated member 25 is too thin and the heat capacity becomes too small. The temperature rises rapidly, and the thermal durability of the integrated member 25 cannot be sufficiently maintained. On the other hand, when the ratio is 0.32 or more, the thickness of the integrated member 25 becomes too thick and the heat storage amount becomes excessive, and even if heat is radiated to the electrode body 1 side, the heat radiation amount is not sufficient. Eventually, the amount of residual heat in the integrated member 25 becomes large, and the cooling of the entire electrode becomes insufficient.

Therefore, by setting the ratio of the wall thickness T2 of the guide pin 12 to the wall thickness T1 of the sliding member 13 to be 0.15 or more and less than 0.32, the heat quantity of the integrated member 25 is optimized and the electrode body 1 side. It is possible to effectively radiate heat to the. Then, by optimizing the thickness of the guide pin 12, the position of the welded portion 40 with respect to the opening edge 10A of the pilot hole 10 becomes favorable.

The movable electrode is arranged coaxially with the fixed electrode, and its illustration is omitted.

It is also possible to replace the permanent magnet with an electromagnet.

The above-described advancing/retreating operation and elevating operation of the supply rod can be easily performed by a generally adopted control method. A predetermined operation can be ensured by combining an air switching valve that operates with a signal from the control device or the sequence circuit, a sensor that emits a signal at a predetermined position of the air cylinder, and transmits the signal to the control device.

The effects of the embodiment described above are as follows.

When the projection bolt 19 is inserted into the receiving hole 35, the hot air in the receiving hole 35 is pushed out, and the welding heat accumulated in the guide pin 12 and the sliding member 13 is absorbed by the bolt 19 in the room temperature state, so that the steel plate part 3 When the bolt 19 is pulled out after the completion of the welding to the outside, cold air outside is sucked into the receiving hole 35. The hot air is discharged and the cool air is sucked in through a gap between the bolt 19 and the inner surface of the receiving hole 35.

As described above, when the bolt 19 is pushed into the receiving hole 35, hot air is discharged, and at the same time, the residual heat of the guide pin 12 and the sliding member 13 is absorbed by the low-temperature bolt 19 at room temperature. When 19 is taken out, the atmospheric pressure inside the receiving hole 35 is lowered and the outside cool air is sucked into the receiving hole 35. Therefore, the integrated member 25 of the guide pin 12 and the sliding member 13 is cooled from the inside. The bolt 19 plays a role as if it were a piston, so that the supply and discharge to and from the inside of the guide pin 12 are performed, and the cooling of the integrated member 25 proceeds.

The ratio of the wall thickness T2 of the guide pin 12 to the wall thickness T1 of the sliding member 13 is 0.15 or more and less than 0.32. The above ratio means that when the wall thickness T1 of the sliding member 13 is increased, the wall thickness T2 of the guide pin 12 is also increased.

When the wall thickness T2 of the guide pin 12 becomes thicker, the wall thickness T1 of the sliding member 13 also becomes thicker and the amount of accumulated heat increases, and moreover, the difference between the diameter of the shaft portion 20 and the inner diameter of the prepared hole 10 of the steel plate component 3 becomes large. .. Therefore, the amount of eccentricity of the shaft portion 20 with respect to the prepared hole 10 may be excessive, which causes a decrease in welding accuracy. When the wall thickness T2 of the guide pin 12 becomes excessively large, the inner diameter of the pilot hole 10 becomes large, and the welded portion 40 is positioned just before the opening edge 10A of the pilot hole 10, or the welded portion 40 is opened by the pilot hole. It may protrude from the edge 10A and cause a decrease in welding strength. In addition, since the dimensions of each part of the bolt 19 are generally standardized, the wall thickness T2 of the guide pin 12 becomes excessively large with respect to the distance L between the welding projection 22 and the shaft part 20, which is outside the standard. Since it is necessary to manufacture the bolt 19, it is not preferable in terms of promoting standardization.

Further, when the wall thickness T2 of the guide pin 12 becomes thin, the strength of the hollow guide pin 12 decreases. When the inner surface of the pilot hole 10 collides with the guide pin 12 when the steel plate component 3 is set on the electrode, the circular hollow shape of the guide pin 12 is deformed into an abnormal shape. At the same time, the thickness T1 of the sliding member 13 is also reduced, so that the overall strength of the integrated member 25 is reduced.

Under the above various conditions, when the ratio of the wall thickness T2 of the guide pin 12 to the wall thickness T1 of the sliding member 13 is set to less than 0.15, the wall thickness T2 of the guide pin 12 is too thin, and the hollow The strength of the guide pin 12 may be insufficient, or the strength of the integrated member 25 of the guide pin 12 and the sliding member 13 may be insufficient. Further, when the thermal capacity of the integrated member 25 becomes small, the heating temperature of the guide pin 12 and the sliding member 13 due to welding heat becomes abnormally high, which is not good in terms of thermal durability.

When the above ratio is 0.32 or more, the following problems occur. That is, the wall thickness T2 of the guide pin 12 becomes thicker, and the wall thickness T1 of the sliding member 13 also becomes thicker, so that the heat storage amount increases. Moreover, since the difference between the diameter of the shaft portion 20 and the inner diameter of the pilot hole 10 of the steel plate component 3 becomes large, the eccentric amount of the shaft portion 20 with respect to the pilot hole 10 may become excessive, which causes a decrease in welding accuracy. When the thickness of the guide pin 12 becomes excessively large, the inner diameter of the pilot hole 10 becomes large, and the welded portion 40 is positioned just before the opening edge 10A of the pilot hole 10, or the welded portion 40 is positioned at the pilot hole opening edge. It may protrude from 10 A and cause a decrease in welding strength. In addition, since the dimensions of each portion of the bolt 19 are generally standardized, the wall thickness T2 of the guide pin 12 becomes excessive with respect to the distance L between the welding projection 22 and the shaft portion 20, which is outside the standard. It is necessary to manufacture the bolt 19, which is not preferable in terms of promoting standardization.

When the ratio is 0.15 or more and less than 0.32, the above problems are solved. That is, the strength of the hollow guide pin 12 and the integrated member 25 can be sufficiently ensured. The thermal capacity of the integrated member 25 is optimized, and the thermal durability is improved. Since the difference between the outer diameter of the guide pin 12 and the inner diameter of the pilot hole 10 does not become excessive, the amount of eccentricity of the shaft portion 20 with respect to the pilot hole 10 decreases. The welded portion becomes a proper portion with respect to the opening edge 10A of the pilot hole 10, and the problem of the abnormal welded portion described above is solved. The distance L between the welding projection 22 of the bolt 19 and the shaft portion 20 has an appropriate value for the wall thickness T2 of the hollow guide pin 12, and thus the standardized bolt 19 can be properly handled.

The welding heat accumulated in the integrated member 25 of the guide pin 12 and the sliding member 13 is radiated to the outside air through the space of the receiving hole 35, or is absorbed by the low temperature shaft portion 20 to the receiving hole 35 side. In addition to such an inward heat dissipation path, an outward heat dissipation path toward the electrode body 1 side is also important.

Regarding heat dissipation to the electrode body 1, it is important to select the amount of heat of the entire integrated member 25 by the guide pin 12 and the sliding member 13 and the thickness T2 of the guide pin 12 itself. The wall thickness T2 of the guide pin 12 is positioned as having a deep relationship with the space L between the welding projection 22 and the shaft portion 20 and the strength when the steel plate component 3 collides. When the wall thickness T2 of the guide pin 12 is excessively large, the inner diameter of the pilot hole 10 of the steel plate component 3 also becomes large, so that the welded portion 40 of the welding projection 22 is located near the opening edge 10A of the pilot hole 10 or the opening. There is a possibility that the welding strength may be insufficient due to the protrusion from the edge 10A. Furthermore, since the thickness T1 of the sliding member 13 increases as the thickness of the guide pin 12 increases, the heat capacity of the integrated member 25 becomes excessive, and the electrode body 1 side with respect to the heat radiation through the receiving hole 35. Heat cannot be sufficiently radiated to the electrode, resulting in insufficient cooling, resulting in a decrease in thermal durability of the entire electrode.

The optimization of heat dissipation to the electrode body 1 side is that the amount of heat of the integrated member 25 does not become excessive. If the amount of heat of the integrated member 25 becomes excessively large, that is, if the thickness T2 of the guide pin 12 or the thickness T1 of the sliding member 13 becomes excessively large, the amount of heat accumulated in the integrated member 25 becomes excessive and the electrode body 1 side There will be a shortage of heat radiation. When the thick integrated member 25 and the thin integrated member 25 are compared within a certain heat radiation time, the thick one easily accumulates residual heat, but the thin one has low residual heat storage property. , Can radiate heat in a short time. From such a viewpoint, the relationship between the wall thickness T2 of the guide pin 12 and the wall thickness T1 of the sliding member 13 becomes important.

Since the thickness of the integrated member 25 is reduced, the inner diameter of the prepared hole 10 can be reduced as much as possible, and the reduction in rigidity of the steel plate component 3 can be minimized.

Since the above-mentioned ratio is less than 0.32, the outer diameter of the integrated member 25 does not become excessively large, so that the diameter of the electrode body 1 can be made thin accordingly, and the electrode can be installed in a narrow place or the electrode can be installed. It is also effective in saving material.

The effect of the embodiment of the cooling method is the same as the effect of the embodiment of the electric resistance welding electrode.

As described above, according to the electrode and the cooling method thereof of the present invention, heat dissipation to the hollow space side of the guide pin and heat dissipation to the electrode body side can be favorably performed. Therefore, it can be used in a wide range of industrial fields such as car body welding processes and sheet metal welding processes for home appliances.

DESCRIPTION OF SYMBOLS 1 Electrode main body 3 Steel plate component 10 Lower hole 10A Opening edge 12 Guide pin 13 Sliding member 19 Projection bolt 20 Shaft portion 21 Flange 22 Welding projection 25 Integrated member 35 Receiving hole 40 Welding portion OO Center axis T1 Sliding member Thickness of T2 Guide pin thickness L Distance between welding protrusion and shaft

Claims (2)

A shaft portion on which a male screw is formed, a circular flange integrally provided on the shaft portion, and a projection bolt having a plurality of welding projections provided on the flange surface of the shaft portion are targets for welding,
Projecting from the end surface of the electrode body having a circular cross section, a guide pin having a circular cross section that penetrates the pilot hole of the steel plate component is a hollow shape having a shaft receiving hole, and is made of a heat-resistant hard material,
The sliding member having a circular cross section which is integrated with the guide pin and is slidably fitted in the guide hole of the electrode body is made of an insulating synthetic resin material,
When inserting the shaft into the receiving hole, the hot air in the receiving hole is pushed out, and the welding heat stored in the guide pin and the sliding member is absorbed by the shaft at room temperature, and after the welding to the steel plate parts is completed, When pulling out the part from the receiving hole, it is configured to suck the outside cool air into the receiving hole.
By setting the ratio of the thickness of the guide pin to the thickness of the sliding member to 0.15 or more and less than 0.32, the welding heat accumulated in the guide pin and the sliding member is transmitted to the electrode body and radiated to the outside air. An electric resistance welding electrode characterized by being. A shaft portion on which a male screw is formed, a circular flange integrally provided on the shaft portion, and a projection bolt having a plurality of welding projections provided on the flange surface of the shaft portion are targets for welding,
Projecting from the end surface of the electrode body having a circular cross section, a guide pin having a circular cross section that penetrates the pilot hole of the steel plate component is a hollow shape having a shaft receiving hole, and is made of a heat-resistant hard material,
A sliding member having a circular cross section which is integrated with the guide pin and fitted in a guide hole of the electrode body in a slidable state prepares an electric resistance welding electrode composed of an insulating synthetic resin material,
When inserting the shaft into the receiving hole, the hot air in the receiving hole is pushed out, and the welding heat stored in the guide pin and the sliding member is absorbed by the shaft at room temperature, and after the welding to the steel plate parts is completed, When removing the part from the receiving hole, by sucking outside cool air into the receiving hole, the welding heat is radiated from the inside of the receiving hole to the outside air,
By setting the ratio of the thickness of the guide pin to the thickness of the sliding member to 0.15 or more and less than 0.32, the welding heat accumulated in the guide pin and the sliding member is transmitted to the electrode body and radiated to the outside air. A method for cooling an electric resistance welding electrode, comprising:

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