JP6624365B2 - Cooling method of guide pin in electric resistance welding electrode - Google Patents

Description

The present invention is configured by a circular flange, a shaft formed coaxially with the flange, and a welding projection formed on a contact surface on the shaft side of the flange. An insertion guide portion having a cylindrical surface and a male screw portion continuous with the insertion guide portion are formed, and a projection bolt in which the diameter of the insertion guide portion is set to be larger than the diameter of the male screw portion is used as a welding target. The present invention relates to a method for cooling a guide pin in an electric resistance welding electrode .

  Japanese Patent Publication No. 07-067624, Japanese Patent No. 2903149, and Japanese Patent Application Laid-Open No. 2015-051457 disclose a circular flange, a male screw portion formed coaxially with the flange, and a contact surface on the male screw portion side of the flange. It describes that a projection bolt formed by the formed welding projection is inserted into a hollow guide pin protruding from a lower hole of a steel plate part and welded to the steel plate part.

Japanese Patent Publication No. 07-066764 Japanese Patent No. 2903149 JP-A-2005-051457

  Problems of the technology described in each of the above patent documents will be described with reference to FIGS. 3 (B1) and 3 (B2). In addition, these figures show the relative positional relationship between the prepared hole of the steel plate part, the hollow guide pin, the external thread portion, the flange, and the like. is there. In addition, hatching of the guide pins is not shown for easy viewing.

  The guide pin 51 of the electrode relatively penetrates the prepared hole 50 formed in the steel plate part, and the relative position of the steel plate part with respect to the electrode is set. The guide pin 51 is formed with a receiving hole 52 and has a hollow shape. A male screw portion 53 which is a shaft portion of the projection bolt is inserted into the receiving hole 52. A circular flange 54 is provided coaxially with the male screw portion 53. The central axis of the male screw portion 53 and the flange 54 is O1-O1, and the central axis of the pilot hole 50 is O2-O2. Further, three welding projections 55 are formed at intervals of 120 degrees.

  The inner diameter of the receiving hole 52 is set larger than the diameter of the male screw portion 53, and the inner diameter of the pilot hole 50 is set larger than the outer shape of the guide pin 51. Therefore, the male screw portion 53 and the guide pin 51 are eccentric to one side. When the guide pin 51 and the male screw portion 53 are shifted to the lower side in the figure as shown in FIG. 3 (B1) under the size relationship as described above, the center with respect to the center axis O2-O2. The axis O1-O1 has the largest displacement dimension. In such a case, the distance C1 between the inner edge of the pilot hole 50 and the outer shape of the flange 54, that is, the tight width of the flange 54 with respect to the steel plate part is significantly reduced as shown in the drawing, and the welding projection 55 is moved from the distance C1 toward the center from the distance C1. There is a risk of coming off. That is, the welding projection 55 does not weld to the surface of the steel plate part.

  In order to avoid this, it is necessary to set the diameter D1 of the flange 54 large so as to secure the welding of the welding projections regardless of the direction in which the guide pin 51 or the male screw part 53 is displaced. Setting it causes an increase in space due to an excessive flange and an increase in the mass of projection bolt parts, which is uneconomical in terms of miniaturization and weight reduction.

  Then, when the steel plate part to which the projection bolt is welded is removed from the electrode, as shown in FIG. 3B2, the male screw portion 53 is largely shifted with respect to the pilot hole 50, and the shifted dimension C2 becomes the maximum value. . That is, although it is best that the pilot hole 50 and the male screw portion 53 are concentric, the maximum deviation dimension C2 is formed in reverse, and the welding position of the bolt to the steel plate part is largely deviated, The welding accuracy decreases.

  More important is the problem of overheating of the guide pins 51. To smoothly insert the male screw portion 53 into the receiving hole 52, the diameter of the male screw portion 53 is set to be significantly smaller than the inner diameter of the receiving hole 52. Due to such a dimensional difference, as shown in FIG. 3 (B1), an air gap exists between the male screw portion 53 and the inner surface of the receiving hole 52, and therefore, heat is transferred from the high-temperature guide pin 51 to the male screw portion 53. Is insufficient, and the guide pin 51 is overheated, thereby lowering durability. And since the male screw part 53 has a continuous thread-shaped crest, there is a problem that even if the crest edge line is brought as close as possible to the inner surface of the receiving hole 52, sufficient heat transfer is not performed.

The method of cooling a guide pin in an electric resistance welding electrode according to the present invention is provided to solve the above-described problems, and minimizes the amount of eccentricity of a male screw portion with respect to a pilot hole of a steel plate part, thereby miniaturizing a bolt. It is an object of the present invention to reduce the weight and to prevent the guide pin from overheating and improve the durability.

The invention according to claim 1 is
A circular flange, a shaft formed coaxially with the flange, and a welding projection formed on a contact surface on the shaft side of the flange, the shaft having a cylindrical surface continuous with the flange. The provided insertion guide portion, a male screw portion that is continuous with the insertion guide portion is formed, and a projection bolt in which the diameter of the insertion guide portion is set to be larger than the diameter of the male screw portion is to be welded,
A guide pin having a circular cross section that protrudes from the end face of the electrode body and penetrates the prepared hole of the steel plate part is made of a heat-resistant hard material such as a metal material or a ceramic material, and is slidably fitted into the guide hole of the electrode body. The sliding part having a circular cross section, which is integrated with the guide pin in a state where the sliding part is inserted, is made of a synthetic resin material, an air passage for cooling air is formed on the outer peripheral surface of the sliding part, and the end face of the sliding part and the guide are formed. The inner end surface of the hole is configured so that the cooling air is intermittently brought into or out of contact with each other, and the guide pin is formed in a pipe-like hollow shape in which a receiving hole into which a shaft is inserted is formed. diameter, in the gap between the cylindrical surface of the inner surface and the insertion guide portion of the receiving-in hole is substantially absent, inserted into the inner surface of the receiving hole guide portion a cylindrical surface configured to slide the electrical resistance of Prepare the welding electrode ,
In a continuous welding heating cycle in which projection bolts are inserted one after another into the receiving hole, heat is transferred from the high-temperature guide pin to the normal temperature insertion guide portion of the projection bolt inserted into the receiving hole for each welding. The cooling method of the guide pin in the electric resistance welding electrode described above.

  By setting the dimensional difference between the inner diameter of the pilot hole of the steel plate part and the outer diameter of the guide pin as small as possible, the relative position between the steel plate part and the electrode body can be accurately obtained, By setting the dimensional difference as small as possible, it is necessary to accurately determine the relative position between the shaft portion and the pilot hole, that is, the relative position between the bolt and the steel plate component, with the eccentric amount as small as possible. It is important to improve the welding accuracy to reduce the distance between the outer cylindrical surface of the insertion guide portion and the pilot hole of the steel plate component to reduce the amount of eccentricity of the insertion guide portion in the pilot hole. Due to such a demand, it is required to make the thickness of the hollow guide pin as thin as possible.

  Under such circumstances, the gap between the inner surface of the receiving hole and the cylindrical surface of the insertion guide portion is set so that heat transfer from the inner surface of the receiving hole to the insertion guide portion is easily performed without substantially existing. Even if the heating cycle is increased by continuous welding, the heat flow from the high-temperature guide pin thin portion to the insertion guide portion inserted at room temperature is promoted, and the cooling effect of the insertion guide portion inserted one after another is improved, and the thin wall is improved. The durability of the part is improved.

  The inner surface of the prepared hole of the steel plate part is easily hit or rubbed on the outer peripheral surface of the thin portion of the guide pin at high temperatures, and such a bad effect is greatly reduced by promoting cooling. In other words, the contact between the inner surface of the receiving hole and the cylindrical surface of the insertion guide portion is a line contact geometrically, but the space between the both surfaces is set to a large area where the contact is substantially close, so that the guide pin The heat flow from the to the insertion guide portion is promoted. Even in the area other than the above-mentioned area, the gap between both surfaces is extremely small, so that a positive heat flow is also formed.

  Since the gap between the inner surface of the receiving hole and the cylindrical surface of the insertion guide portion is set so that heat transfer from the inner surface of the receiving hole to the insertion guide portion can be easily performed without substantially existing, the diametral direction of the receiving hole is inserted. The displacement of the guide is minimized. Therefore, the diameter of the flange with respect to the inner diameter of the pilot hole can be set as small as possible, which is effective in reducing the size and weight of the bolt. That is, since the dimensional difference between the inner diameter of the receiving hole 52 and the outer diameter of the external thread portion 53 in FIG. 3B1 is significantly reduced, the diameter of the flange can be reduced as described above.

  The opposing relationship between the inner surface of the receiving hole and the cylindrical surface of the insertion guide portion is not the opposing relationship between the inner surface of the receiving hole and the male screw portion, so that heat is sufficiently transferred and the guide pins are effectively cooled. You.

It is sectional drawing of each part of an electrode. It is an expanded sectional view of an important part of an electrode. It is a top view which shows the diameter dimension of each part. It is sectional drawing which shows the insertion transition period of a bolt.

Next, an embodiment for implementing the method of cooling a guide pin in the electric resistance welding electrode of the present invention will be described.

  1, 2, 3 (A1) and (A2), and FIG. 4 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 part 2 inserted into a stationary member 11 and a cap part 4 on which a steel plate part 3 is placed are connected by a screw part 5. A guide hole 6 having a circular cross section is formed in the electrode body 1, and the guide hole 6 is constituted by at least a large-diameter hole 7 and a small-diameter hole 8 opened at the center of the cap portion 4.

  A tapered portion 9 is formed below the fixed portion 2, and the tapered portion 9 is fitted into a tapered hole provided in the stationary member 11. A vent 10 for introducing compressed air into the guide hole 6 is provided on a side portion of the fixing portion 2.

  Next, the sliding portion will be described.

The guide pin 12 is made of a heat-resistant hard material such as a metal material such as stainless steel or a ceramic material. The sliding portion 13 is made of an insulating synthetic resin having excellent heat resistance, for example, polytetrafluoroethylene (trade name: Teflon.RTM .). The guide pins 12 are integrated with each other while being inserted into the sliding portions 13. The guide pin 12 and the sliding portion 13 are both circular in cross section, and the guide pin 12 relatively penetrates the prepared hole 14 of the steel plate component 3 so as to perform the positioning function of the steel plate component 3. The guide pin 12 has a pipe-like hollow shape in which a receiving hole 31 is formed.

  The iron projection bolt 32 to be welded includes a circular flange 33, a shaft portion 34 formed coaxially with the flange 33, and a welding protrusion formed on a contact surface of the flange 33 on the shaft portion 34 side. The shaft portion 34 is formed with an insertion guide portion 37 having a cylindrical surface 36 continuous with the flange 33 and a male screw portion 38 continuous with the insertion guide portion 37. Is set to be larger than the diameter of the male screw portion 38. A space between the insertion guide portion 37 and the male screw portion 38 is smoothly continued by a tapered portion 39. In the following description, the projection bolt may be simply referred to as a bolt.

  The gap between the inner surface of the receiving hole 31 and the cylindrical surface 36 of the insertion guide portion 37 is set so that heat can be easily transmitted from the inner surface of the receiving hole 31 to the insertion guide portion 37 without substantially existing. The gap is a sliding state in which the cylindrical surface 36 of the insertion guide portion 37 moves forward and backward while rubbing against the inner surface of the receiving hole 31.

  The dimensions of each part of the bolt 32 include a total length of the bolt 32 including the thickness of the flange 33 of 28 mm, a diameter of the flange 33 of 20 mm, a total length of the shaft part 34 of 25.8 mm, a length of the insertion guide part 37 and a length of the cylindrical surface 36. The diameters are 5.5 mm and 9.5 mm, respectively, and the diameter of the external thread 38 is 8 mm. On the other hand, the dimensions of each part of the guide pin 12 are such that the outer diameter of the guide pin 12 is 11.8 mm, the inner diameter of the receiving hole 31 is 9.8 mm, and the thickness of the guide pin 12 is 1 mm. The inner diameter of the prepared hole 14 of the steel plate part 3 is 12.3 mm.

  In the case where a positional displacement as shown in FIG. 3B1 occurs in the above dimensions, the distance C1 is 3.45 mm. If no displacement occurs, the interval C1 is 3.85 mm.

  The electrode body 1 is a fixed electrode, and the movable electrode 23 is arranged coaxially with the fixed electrode. 1A is a cross-sectional view taken along line BB of FIG. 1A, and a cross-sectional view taken along line CC is FIG.

  The sliding portion 13 is fitted in the large-diameter hole 7 so as to be slidable with substantially no gap. An insertion hole 17 is formed in the sliding portion 13 and the guide pin 12 is press-fitted therein. A bolt 21 is formed integrally with the end of the guide pin 12, the bolt 21 penetrates the bottom member 18 of the sliding portion 13, a washer 19 is assembled, and the bolt 21 is fastened with a lock nut 20. The sliding portion 13 has an insulating function so that when the movable electrode 23 operates and a welding current is applied, the current flows only from the welding protrusion 35 of the bolt 32 to the steel plate component 3.

  An end face 24 is formed at an end of the sliding portion 13, and the end face 24 is in close contact with the inner end face 25 of the large-diameter hole 7. The end face 24 and the inner end face 25 are in a state of a plane orthogonal to the axis of the guide pin 12 (the center axis of the electrode main body 1), and are annular surfaces surrounding the axis of the guide pin 12 in an annular manner. The end surface 24 and the inner end surface 25 come into close contact with or separate from each other to interrupt the cooling air, and the contact portion serves as an on-off valve.

A gap 22 through which compressed air passes is formed between the guide pin 12 and the small diameter hole 8. When the guide pin 12 is pushed down by the advance of the movable electrode 23, the end face 24 is separated from the inner end face 25, and a gap for air circulation is formed. As described above, the contact portion between the end face 24 and the inner end face 25 functions as an on-off valve. The compressed air that has entered through the vent 10 passes through the air passage 26, between the end face 24 and the inner end face 25, the gap 22, and the like, thereby cooling the welded portion of the bolt 32 and preventing the entry of spatter.

  An air passage 26 for cooling air is formed on the outer peripheral surface of the sliding portion 13 in the central axis direction of the electrode main body 1. Various air passages can be employed. Here, as shown in FIGS. 1A and 1B, an air passage 26 is formed by forming two flat portions 27 on the outer peripheral surface of the sliding portion 13 so as to face each other. Instead of the flat portion 27, it is also possible to form a plurality of concave grooves in the central axis direction on the outer peripheral surface of the sliding portion 13.

  A compression coil spring 29 is fitted between the washer 19 and the inner bottom surface of the guide hole 6, and the tension acts on the sliding portion 13 so that the end face 24 is in close contact with the inner end face 25. The cooling air supplied from the ventilation port 10 reaches the air passage 26, but the ventilation is prohibited due to the close contact. Reference numeral 30 denotes an insulating sheet fitted on the inner bottom surface of the guide hole 6.

  Next, the combination relationship between the receiving hole and the insertion guide will be described.

  As described above, the gap between the inner surface of the receiving hole 31 and the cylindrical surface 36 of the insertion guide portion 37 is set so that heat transfer from the inner surface of the receiving hole 31 to the insertion guide portion 37 can be easily performed without substantially existing. ing. Such a gap is realized when the diameter of the insertion guide portion 37 is 9.5 mm and the inner diameter of the receiving hole 31 is 9.8 mm. The contact between the inner surface of the receiving hole 31 and the cylindrical surface 36 of the insertion guide portion 37 is a line contact geometrically, but the space between the both surfaces is set to be large in a substantially close contact area. Such a region of substantially close contact is a range of the angle θ shown in FIG. Such a substantially close contact promotes heat flow from the guide pin 12 to the insertion guide portion 37. Even in the area other than the above-mentioned area, the gap between both surfaces is extremely small, so that a positive heat flow is also formed.

  The operation and effect of the embodiment described above are as follows.

  By setting the dimensional difference between the inner diameter of the pilot hole 14 of the steel plate part 3 and the outer diameter of the guide pin 12 as small as possible, the relative position between the steel plate part 3 and the electrode body 1 can be accurately obtained. By setting the dimensional difference of the outer diameter of the shaft portion 34 as small as possible, the relative position between the shaft portion 34 and the pilot hole 14, that is, the relative position between the bolt 32 and the steel plate part 3 can be accurately obtained by minimizing the amount of eccentricity. There is a need. It is important to reduce the amount of eccentricity of the insertion guide portion 37 in the prepared hole 14 by reducing the distance between the cylindrical surface 36 of the insertion guide portion 37 and the prepared hole 14 of the steel plate component 3 in order to improve welding accuracy. is there. Due to such a demand, it is required to make the thickness of the hollow guide pin 12 as thin as possible.

  Under such circumstances, heat is easily transmitted from the inner surface of the receiving hole 31 to the insertion guide portion 37 without substantially leaving a gap between the inner surface of the receiving hole 31 and the cylindrical surface 36 of the insertion guide portion 37. Since the setting is set, even if the heating cycle increases due to continuous welding, the heat flow from the high-temperature guide pin thin portion to the insertion guide portion 37 inserted at room temperature is promoted, and the insertion guide portion 37 inserted one after another is inserted. This improves the cooling effect and improves the durability of the thin portion.

  The inner surface of the prepared hole 14 of the steel plate part 3 is hit or rubbed on the outer peripheral surface of the thin portion of the guide pin 12 so that pain under high temperature is apt to progress. Is greatly reduced. In other words, the contact between the inner surface of the receiving hole 31 and the cylindrical surface 36 of the insertion guide portion 37 is a line contact geometrically, but the space between the both surfaces is set to be large in a substantially close contact area. Therefore, the heat flow from the guide pin 12 to the insertion guide portion 37 is promoted. Even in the area other than the above-mentioned area, the gap between both surfaces is extremely small, so that a positive heat flow is also formed.

  Since the gap between the inner surface of the receiving hole 31 and the cylindrical surface 36 of the insertion guide portion 37 is set so that heat is easily transmitted from the inner surface of the receiving hole 31 to the insertion guide portion 37 without substantially existing, The size of the displacement of the insertion guide portion 37 in the diameter direction of the hole 31 is minimized. Therefore, the diameter of the flange 33 with respect to the inner diameter of the pilot hole 14 can be set as small as possible, which is effective in reducing the size and weight of the bolt 32. That is, since the dimensional difference between the inner diameter of the receiving hole 52 and the outer diameter of the male screw portion 53 in FIG. 3B1 is significantly reduced, the diameter of the flange 33 can be reduced as described above.

  As is clear from comparison between FIGS. 3A1 and 3A2 and FIGS. 3B1 and 3B2, the diameter D1 of the flange 33 is (B1) and (B2) for (A1) and (A2). ). This is achieved by minimizing the diametrical displacement of the insertion guide portion 37 in the receiving hole 31 as described above.

  The opposing relationship between the inner surface of the receiving hole 31 and the cylindrical surface 36 of the insertion guide portion 37 is not the opposing relationship between the inner surface of the receiving hole and the male screw portion, so that heat is sufficiently transferred and the guide pin 12 is cooled. Be done effectively.

  As shown in FIG. 4, a holder 42 is provided at the tip of a supply rod 41 that advances and retreats in an oblique direction, and a bolt 32 is held by the holder 42, and the male screw portion 38 is inserted into the receiving hole 31 from an oblique direction into an arc shape. Supply while moving to. At the time of this supply, the thread of the male screw portion 38 is rubbed against the inner edge corner of the opening of the receiving hole 31, so that this portion, that is, the inside of the distal end portion of the guide pin 12, is easily worn. Since the positional relationship between the bolt 32 and the guide pin 12 is set by the close relationship between the insertion guide portion 37 and the receiving hole 31, the diameter of the male screw portion 38 is reduced to reduce the rubbing of the inside of the distal end portion, thereby reducing the guide pin. 12 can be minimized.

  As described above, according to the present invention, the amount of eccentricity of the male screw portion with respect to the prepared hole of the steel plate component is minimized, the size and weight of the bolt are reduced, and the overheating of the guide pin and the improvement in durability are realized. Therefore, it can be used in a wide range of industrial fields such as an automobile body welding process and a sheet metal welding process for home appliances.

DESCRIPTION OF SYMBOLS 1 Electrode main body 3 Steel plate component 6 Guide hole 12 Guide pin 13 Sliding part 14 Preparatory hole 24 End face 25 Inner end face 26 Air passage 31 Receiving hole 32 Projection bolt 33 Flange 34 Shaft part 35 Welding projection 36 Cylindrical surface 37 Insert guide part 38 Male thread θ Adhesion area D1 Flange diameter

Claims (1)

A circular flange, a shaft formed coaxially with the flange, and a welding projection formed on a contact surface on the shaft side of the flange, the shaft having a cylindrical surface continuous with the flange. An insertion guide portion provided, a male screw portion continuous with the insertion guide portion is formed, and a projection bolt in which the diameter of the insertion guide portion is set to be larger than the diameter of the male screw portion is to be welded,
A guide pin having a circular cross section that protrudes from the end face of the electrode body and penetrates the prepared hole of the steel plate part is made of a heat-resistant hard material such as a metal material or a ceramic material, and is slidably fitted into the guide hole of the electrode body. The sliding part having a circular cross section, which is integrated with the guide pin in a state where the sliding part is inserted, is made of a synthetic resin material, an air passage for cooling air is formed on the outer peripheral surface of the sliding part, and the end face of the sliding part and the guide are formed. The inner end surface of the hole is configured so that the cooling air is intermittently brought into or out of contact with each other, and the guide pin is formed in a pipe-like hollow shape in which a receiving hole into which a shaft is inserted is formed. diameter, in the gap between the cylindrical surface of the inner surface and the insertion guide portion of the receiving-in hole is substantially absent, inserted into the inner surface of the receiving hole guide portion a cylindrical surface configured to slide the electrical resistance of Prepare the welding electrode ,
In a continuous welding heating cycle in which projection bolts are inserted one after another into the receiving hole, heat is transferred from the high-temperature guide pin to the normal temperature insertion guide portion of the projection bolt inserted into the receiving hole for each welding. The cooling method of the guide pin in the electric resistance welding electrode.

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