JP6720458B2 - Guide member for electric resistance welding electrode - Google Patents

Description

The present invention relates to a guide member for an electric resistance welding electrode, in which a guide pin made of a heat resistant hard material such as a metal material or a ceramic material and a sliding member made of an insulating synthetic resin material are integrated.

Japanese Patent No. 3326491 describes the structure shown in FIG. Explaining this, the metal guide pin 50 having a circular cross section is composed of a small diameter portion 51 having a uniform diameter over the entire length and a large diameter portion 52 integrated with the small diameter portion 51. A sliding member 53 made of synthetic resin having a circular cross section is formed by injection molding, and the guide pin 50 is integrated with the sliding member 53 by insert molding during this molding. The sliding member 53 has a uniform diameter over its entire length.

Japanese Patent No. 3326491

In the structure described in Patent Document 1, since the guide pin 50 is composed of the small diameter portion 51 and the large diameter portion 52, the wall thickness of the sliding member 53 in the diametrical direction can be made different in magnitude, and by cooling after insert molding , A difference in contraction is formed. As is apparent from the outer diameter line 54 shown by the two-dot chain line in FIG. 3, there is a difference in the outer diameter of the sliding member 53 after cooling. Such a size difference occurs because the shrinkage amount is large on the outer peripheral side of the small diameter portion 51 and is small on the outer peripheral side of the large diameter portion 52.

When such a difference in size is formed, there is a problem that it takes time to finish by machining. If the difference in size becomes large, the amount of cutting becomes large, which is uneconomical in terms of material and the processing time becomes long. Therefore, it is important to minimize such a difference in the diametrical direction.

The present invention is provided to solve the above problems, and an object of the present invention is to minimize the difference in size in the diameter direction of a sliding member made of synthetic resin by injection molding in an electric resistance welding electrode.

The invention according to claim 1 is
A guide pin having a circular cross section that protrudes from the end surface of the electrode body and penetrates the pilot hole of the steel plate component is made of a heat-resistant hard material such as a metal material or a ceramic material,
The sliding member having a circular cross section, which is slidably fitted in the guide hole of the electrode body, is made of an insulating synthetic resin material,
The guide member is formed by integrating the guide pin and the sliding member,
The integration is performed by insert molding when injection molding the sliding member,
On the surface of the guide pin that is inserted into the sliding member, a fine uneven portion is formed,
The diameter of the guide pin and the diameter of the sliding member are set uniformly over the entire length , and the sliding member is opposite to the projecting direction of the guide pin from the position of the end surface of the sliding member that closely contacts the inner end surface of the guide hole. It is a guide member in an electric resistance welding electrode characterized in that it is a length portion up to the end of the sliding member on the side .

The diameter of the guide pin made of the heat-resistant hard material and the diameter of the sliding member made of the insulating synthetic resin material are set uniformly over the entire length. Its to the sliding member, from the point of the end face of the sliding member in close contact with the inner end face of the guide hole, and the projecting direction of the guide pin is the length of the up sliding member end opposite ing. Therefore, the amount of expansion and contraction of the guide pin itself in the diametrical direction due to heating during injection molding changes uniformly over the entire length of the guide pin. At the same time, the amount of expansion and contraction in the diametrical direction of the sliding member itself due to melting and heating during injection molding also changes uniformly over the entire length of the sliding member.

As described above, since the heat expansion and contraction states of the guide pin and the sliding member are uniform as described above, the guide member taken out from the injection molding apparatus has a straight cylindrical shape. Therefore, the final finishing process of the sliding member becomes unnecessary, which is effective in reducing the number of manufacturing steps. Further, even if the guide member expands in the diametrical direction by transmitting the heat of fusion to the guide pin or the sliding member, the expansion deformation causes a uniform increase in diameter in the diametrical direction. The movement angle can be minimized, and the misalignment of the guide pin with respect to the central axis of the electrode can be set to a value that does not substantially pose a problem, and the welding position of the component with respect to the steel plate component can be accurately ensured.

When an air passage is formed on the outer peripheral surface of the sliding member, a flat surface portion or a concave groove is formed on the outer peripheral surface of the sliding member. Further, it can be obtained at a time at the time of injection molding of the sliding member without forming it by machining, which is convenient in manufacturing. Further, since the flat portion and the passage space of the concave groove are accurately obtained under the thermal expansion and contraction conditions of the sliding member as described above, stable ventilation of cooling air can be secured.

A fine uneven portion is formed on the surface of the guide pin that is inserted into the sliding member. Since the insulating synthetic resin material in a molten state flows into the projections and valleys of the concave-convex shape without any gaps, the guide pin and the sliding member can be firmly integrated, and the guide pin and the sliding member can be secured. Does not easily shift in either the circumferential direction or the axial direction. Further, since the uneven portion is made minute, a uniform thickness can be secured without changing the thickness of the synthetic resin portion of the sliding member, and the thermal expansion and contraction of the sliding member is uniform over the entire length. Done.

It is sectional drawing of each part of an electrode. It is sectional drawing of another guide member. It is sectional drawing which shows the conventional guide member.

Next, a mode for carrying out the guide member in the electric resistance welding electrode according to the present invention will be described.

1 and 2 show an embodiment of the present invention.

First, the electrode body will be described.

The electrode body 1 made of a copper alloy has a cylindrical shape, and a fixing portion 2 to be inserted into the stationary member 11 and a cap portion 4 on which the steel plate component 3 is placed are connected by a screw portion 5. The central axis of the electrode body 1 is indicated by the symbol O-O. A guide hole 6 having a circular cross section is formed in the electrode body 1.

A taper portion 12 is formed below the fixed portion 2, and the taper portion 12 is fitted in a taper hole provided in the stationary member 11. A ventilation port 13 for introducing compressed air for cooling into the guide hole 6 is provided on a side portion of the fixed portion 2.

The electrode body 1 is a fixed electrode, to which the movable electrode is designated by 24.

Next, the sliding member will be described.

The guide pin 15 is made of a heat resistant hard material such as a metal material such as stainless steel or a ceramic material. The sliding member 16 is excellent in heat resistance insulating synthetic resin, for example, polytetrafluoroethylene: is constituted by (tradename Teflon ®). The guide pin 15 is integrated in a state of being inserted in the sliding member 16. Each of the guide pin 15 and the sliding member 16 has a circular cross section, and the guide pin 15 relatively penetrates the through hole 8 and the pilot hole 17 of the steel plate component 3 to perform the positioning function of the steel plate component 3. It supports an iron projection nut 18 fitted to the tip. Therefore, a small diameter portion 19 that matches the screw hole of the projection nut 18 is formed. In the following description, the projection nut may be simply referred to as a nut.

A space 9 is formed between the through hole 8 and the guide pin 15 at a position where the guide pin 15 penetrates the through hole 8 and serves as an air passage for cooling air.

The guide pin 15 is integrated in a state of being inserted in the sliding member 16, penetrates the through hole 8 and the lower hole 17, and projects to the upper side of the steel plate component 3.

Next, the guide member will be described.

The guide member 10 is a composite structure in which the guide pin 15 is integrated with the sliding member 16 inserted therein. This integration is performed when the sliding member 16 is molded by injection molding. The guide pin 15 is held in a state of protruding into the mold space of the injection molding machine, and the molten synthetic resin is injected into the mold space, so that the guide pin 15 is cast. That is, it is insert molding which is generally adopted.

In order to further strengthen the integrity of the cast guide pin 15 and the sliding member 16, a fine uneven portion 14 is formed on the surface of the guide pin 15 inserted into the sliding member 16. Has been done. The uneven portion 14 can be obtained by chemically treating the surface of the guide pin 15 or imparting plastic deformation. Here, the latter is plastic deformation and is knurling. Fine irregularities are formed on the surface of the rotary mold, and the irregularities are formed by plastic deformation by pressing the fine irregularities on the surface of the guide pin 15 and rotating. This uneven shape has a rough feel to the touch. When the injection molding is completed, as shown in FIG. 1(D), the synthetic resin is spread over the projections and the valleys of the concave and convex portions, and the guide pin 15 and the sliding member 16 are integrated. ..

When setting the guide pin 15 in the mold, the concave-convex portion 14 is exposed in the mold space, whereby the concave-convex portion 14 is cast with synthetic resin.

The sliding member 16 is fitted in the guide hole 6 in a state where it can slide with substantially no gap. An air passage 20 is formed to allow the cooling air to flow along the sliding member 16. The air passage 20 is formed in the central axis O-O direction by forming a flat surface portion 21 on the outer peripheral surface of the sliding member 16. Instead of the flat surface portion 21, the air passage 20 may be configured by a plurality of concave grooves in the central axis O-O direction. Mold shapes corresponding to the flat surface portion 21 and the concave groove are defined, and the flat surface portion 21 and the concave groove are obtained by mold molding at the time of injection molding. Note that reference numeral 22 is a large-diameter space portion formed by increasing the inner diameter of the cap portion 4.

As shown in FIG. 1(C), since the air passages 20 are formed at four locations of the sliding member 16, the cylindrical surfaces 23 are placed at four locations other than the air passages 20, and this is the inner surface of the guide hole 6. On the other hand, it slides with almost no gap. The sliding member 16 performs an insulating function so that when the movable electrode 24 advances and the welding current is applied, the current flows only from the welding projection 25 of the nut 18 to the steel plate component 3. There is.

A compression coil spring 27 is fitted between the sliding member 16 and the inner bottom surface of the guide hole 6, and the tension thereof acts on the sliding member 16. A circular opening 29 for receiving the compression coil spring 27 is formed on the lower side of the sliding member 16. A bottom member 30 is formed between the opening 29 and the guide pin 15. The cross-sectional shape of the synthetic resin portion where the bottom member 29 is formed is the same as the cross-sectional shape of the CC cross-sectional portion. Reference numeral 28 is an insulating sheet fitted on the inner bottom surface of the guide hole 6. Further, instead of the tension of the compression coil spring 27, the air pressure introduced from the ventilation port 13 can be used.

The diameter of the guide pin 15 and the diameter of the sliding member 16 are set uniformly over the entire length, which means that the sliding member has a guide hole when viewed in the longitudinal direction of the guide member 10 (center axis O--O direction). It is premised that the length is from the position of the end surface of the sliding member that comes into close contact with the inner end surface of the guide member to the end of the sliding member on the side opposite to the protruding direction of the guide pin.

The cross section C-C of FIG. 1B is the view of FIG.

Next, the on-off valve structure section will be described.

The on-off valve structure part 31 performs whether to allow the cooling air introduced from the vent 13 to flow into the void 9 or to block the flow to the void 9, and has an on-off valve function. In the on-off valve structure portion 31, the end surface 33 of the sliding member 16 is in close contact with the inner end surface 32 of the guide hole 6 to block the cooling air flow, or the end surface 33 separates from the inner end surface 32 and allows the cooling air to flow. I am. As described above, in order to ensure the close contact between the both surfaces 32 and 33 and maintain the airtightness, the both surfaces 32 and 33 are present on an imaginary plane where the central axes OO intersect perpendicularly.

The upper end surface of the sliding member 16 constitutes a contact surface (end surface 33) on the sliding member 16 side, and as described above, this contact surface lies on a virtual plane where the central axes OO intersect perpendicularly. Existing.

The close contact between the both surfaces 32, 33 is performed by the tension of the compression coil spring 27, and in the close contact state, a gap L is provided between the welding projection 25 and the steel plate component 3.

When the guide pin 15 is pushed down while the compression coil spring 27 is being compressed by the advancing of the movable electrode 24, the on-off valve structure portion 31 is opened and an air circulation gap is formed. At the same time, the welding projection 25 is pressed against the steel plate component 3 and a welding current is applied. By pushing down the guide pin 15 as described above, the cooling air sent from the ventilation port 13 flows through the guide hole 6, the air passage 20, the open/close valve structure portion 31, the gap 9, and the prepared hole 17, and the nut 18 The welded part is cooled and spatter is prevented from entering.

Next, a modified example will be described.

In the modification shown in FIG. 2, the guide pin 15 corresponds to the projection bolt 35. The projection bolt 35 includes a shaft portion 36 having an external thread, a circular flange 37 formed integrally with the shaft portion 36, and a welding projection 38 formed on the lower surface of the flange 37. The guide pin 15 has the shape of a hollow pin in which a receiving hole 39 is formed for inserting the shaft portion 36. In the following description, the projection bolt may be simply expressed as a bolt. The rest of the configuration is the same as the previous case, including parts not shown, and members with similar functions are given the same reference numerals.

The effects of the embodiment described above are as follows.

The diameter of the guide pin 15 made of a heat resistant hard material and the diameter of the sliding member 16 made of an insulating synthetic resin material are set uniformly over the entire length. The sliding member 16 has a length from the position of the end surface 33 of the sliding member 16 that is in close contact with the inner end surface 32 of the guide hole 6 to the end of the sliding member on the side opposite to the protruding direction of the guide pin 15. It is said that. Therefore, the amount of expansion and contraction of the guide pin itself in the diametrical direction due to heating during injection molding changes uniformly over the entire length of the guide pin. At the same time, the amount of expansion and contraction in the diametrical direction of the sliding member 16 itself due to melting and heating during injection molding also changes uniformly over the entire length of the sliding member.

As described above, the thermal expansion and contraction states of the guide pin 15 and the sliding member 16 are uniform as described above, so that the sliding member 16 of the guide member 10 taken out from the injection molding apparatus has a straight cylindrical shape. .. Therefore, the final finishing process of the sliding member 16 becomes unnecessary, which is effective in reducing the number of manufacturing steps. Further, even if the guide member 10 expands in the diametrical direction by transmitting the heat of fusion to the guide pin 15 and the sliding member 16, the expansion and deformation of the guide member 10 cause a uniform increase in diameter in the diametrical direction. The tilting swing angle of 10 can be minimized, and the misalignment of the guide pin 15 with respect to the central axis OO of the electrode can be set to a value that does not substantially cause a problem, and the nut 18 for the steel plate component 3 can be obtained. It is possible to accurately secure the welding position of the bolt 35.

In other words, if the amount of expansion of the outer surface of the sliding member 16 is partially large, the locally large portion comes into contact with the inner surface of the guide hole 6, and the other portion is between the inner surface of the guide hole and the other portion. Since there is a gap, the tilting swing angle of the guide member 10 appears to be large, and the tilt core deviation amount at the tip of the guide pin 15 increases. Due to such a deviation, the relative positions of the parts such as the nuts 18 and the bolts 35 and the steel plate parts 3 are greatly displaced. The amount of deviation of such relative position is minimized.

When the air passage 20 is formed on the outer peripheral surface of the sliding member 16, the flat portion 21 or the concave groove is formed on the outer peripheral surface of the sliding member 16. 21 and the concave groove can be obtained at a time at the time of injection molding of the sliding member 16 without forming by machining, which is convenient in manufacturing. Further, since the flat portion 21 and the passage space of the concave groove are also accurately obtained under the thermal expansion and contraction condition of the sliding member 16 as described above, stable ventilation of cooling air can be secured.

A fine uneven portion 14 is formed on the surface of a guide pin 15 inserted into the sliding member 16. Since the insulating synthetic resin material in a molten state flows into the projections and valleys of the concave-convex shape portion 14 without any gaps, the guide pin 15 and the sliding member 16 can be firmly integrated and the guide can be secured. The relative position of the pin 15 and the sliding member 16 does not easily shift in either the circumferential direction or the axial direction. Further, since the uneven portion 14 is made fine, a uniform thickness can be secured without changing the thickness of the synthetic resin portion of the sliding member 16, and the thermal expansion and contraction of the sliding member 16 can be performed over the entire length. Made evenly over.

When viewed in the longitudinal direction of the sliding member 16 (direction of the central axis O-O), the uneven portion 14 is cast on the upper side and the opening 29 is formed on the lower side, so that the entire length of the sliding member 16 is formed. Can be set longer. As a result, the length of the sliding member 16 in the central axis O-O direction can be increased, and the sliding area between the sliding member 16 and the inner surface of the guide hole 6 can be increased, and the sliding direction in the tilt direction can be increased. The sliding movement of the smooth guide member 10 with little center deviation can be achieved.

As described above, according to the present invention, in the electric resistance welding electrode, the size difference in the diameter direction of the synthetic resin sliding member formed by injection molding is minimized. Therefore, an electric resistance welding electrode having good operation reliability can be obtained regardless of thermal expansion, and can be used in a wide range of industrial fields such as a car body welding process of automobiles and a sheet metal welding process of household appliances.

DESCRIPTION OF SYMBOLS 1 Electrode main body 6 Guide hole 9 Void 10 Guide member 14 Concavo-convex shaped portion 15 Guide pin 16 Sliding member 18 Projection nut, part 20 Air passage 23 Cylindrical surface 31 Open/close valve structure part 32 Inner end surface 33 End surface 35 Projection bolt, part 39 Receiving Hole OO Central axis

Claims (1)

A guide pin having a circular cross section that protrudes from the end surface of the electrode body and penetrates the pilot hole of the steel plate component is made of a heat-resistant hard material such as a metal material or a ceramic material,
The sliding member having a circular cross section, which is slidably fitted in the guide hole of the electrode body, is made of an insulating synthetic resin material,
The guide member is formed by integrating the guide pin and the sliding member,
The integration is performed by insert molding when injection molding the sliding member,
On the surface of the guide pin that is inserted into the sliding member, a fine uneven portion is formed,
The diameter of the guide pin and the diameter of the sliding member are set uniformly over the entire length , and the sliding member is opposite to the projecting direction of the guide pin from the position of the end surface of the sliding member that closely contacts the inner end surface of the guide hole. A guide member in an electric resistance welding electrode, wherein the guide member has a length up to the end of the sliding member on the side .

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