JP2017006982A - Electrode for electric resistance welding - Google Patents

Abstract

An object of the present invention is to reduce the amount of heat stored in a sliding portion that advances and retreats in a guide hole, to prevent abnormal wear of the outer peripheral surface of the sliding portion, and to prevent abnormal inclination of a guide pin. A guide pin 12 protruding from an electrode body 1 passes through a lower hole 14 of a steel plate part 3 and is inserted into a sliding portion 13 made of synthetic resin that slides in the guide hole 6 to slide. The thickness of the portion 13 is thin so as to reduce the amount of heat stored in the sliding portion 13, and an air passage 26 for cooling air is formed in the sliding portion 13, and the end surface 24 of the sliding portion 13 and the guide hole 6 are formed. An electrode for electric resistance welding constructed such that the inner end face 25 of the steel plate contacts or separates and the cooling air is intermittently connected. [Selection] Figure 1

Description

  The present invention relates to an electrode for electric resistance welding in which a structure portion in which a synthetic resin sliding portion is integrated with a guide pin made of a metal material or the like is improved.

  Japanese Patent No. 2903149 and Japanese Patent Application Laid-Open No. 2015-051457 describe a structure in which a sliding portion made of a synthetic resin is integrated with a guide pin made of a metal material or the like.

Japanese Patent No. 2903149 Japanese Patent Laid-Open No. 2015-051457

  The techniques described in Patent Documents 1 and 2 have a structure in which a sliding portion made of a synthetic resin is integrated with a guide pin made of a metal material or the like. Since the wall thickness is large, the amount of thermal expansion of the sliding portion becomes excessive, and there are problems such as abnormal wear on the outer peripheral surface of the sliding portion and abnormal inclination of the guide pin.

  The present invention is provided in order to solve the above-described problems, and in the electrode for electric resistance welding, the amount of heat stored in the sliding portion that advances and retreats in the guide hole is reduced, and the abnormality of the outer peripheral surface of the sliding portion is achieved. The purpose is to prevent wear and to prevent abnormal inclination of the guide pin.

The invention described in claim 1
The guide pin having a circular cross section that protrudes from the end face of the electrode body and penetrates through the pilot hole of the steel plate part is composed of a heat-resistant hard material such as a metal material or a ceramic material,
The sliding portion having a circular cross section that is fitted in the guide hole of the electrode body in a slidable state and is integrated with the guide pin in a state where the guide pin is inserted is made of a synthetic resin material,
The thickness of the sliding portion is thin so as to reduce the amount of heat stored in the sliding portion, and an air passage for cooling air is formed in the sliding portion,
An electrode for electric resistance welding, wherein the end face of the sliding portion and the inner end face of the guide hole are brought into close contact with or separated from each other to interrupt the cooling air.

  Normally, the thermal expansion amount of synthetic resin electrode parts is significantly larger than that of electrode bodies and guide pins made of metal material. However, as described above, the sliding portion made of synthetic resin is made thin to store heat. Since the amount is reduced, the amount of thermal expansion of the sliding portion itself in the diameter direction is reduced. Even if the heating cycle increases due to continuous welding and reaches the maximum value at which the temperature of the sliding part can withstand, the amount of thermal expansion is small, so the pressure applied to the inner surface of the guide hole is reduced, and the sliding part slides. Wear on the moving surface is minimized. For this reason, the service life of the sliding part that is most likely to be consumed is prolonged, which is effective in terms of component maintenance.

  Furthermore, by reducing the thermal expansion amount, the sliding gap between the outer peripheral surface of the sliding portion and the inner peripheral surface of the guide hole is kept small, and the inclination of the guide pin is suppressed. Thus, by minimizing the inclination angle of the guide pin, the positional accuracy of the projection nut and the projection bolt supported by the guide pin with respect to the pilot hole of the steel plate part is improved. That is, the deviation between the center axis of the pilot hole and the center axis of the nut or bolt can be minimized, which is effective for improving the welding accuracy.

  If the thickness of the sliding part is large, the amount of expansion of the sliding part material increases, and the increased amount expands toward the air passage space, so the flow area of the air passage is reduced, and the flow rate of the cooling air And the cooling effect is reduced. However, as described above, by reducing the thickness of the sliding portion, the amount of expansion of the sliding portion material can be minimized, and accordingly, a reduction in the flow passage area of the air passage is avoided and normal Cooling action is made.

  As the sliding portion becomes thinner, the diameter of the sliding portion becomes smaller, so the diameter of the electrode body also becomes smaller, making it easier to arrange electrodes in a narrow area.

  In addition to the above-described thinning, an air passage for cooling air is formed in the sliding portion, so that the sliding portion having a reduced volume can be effectively cooled, and the effect of reducing the thermal expansion amount can be achieved. Is further promoted.

  Overall, as described above, it is possible to reduce the thickness of the sliding portion while ensuring the contact area between the end surface of the sliding portion and the inner end surface of the guide hole to the minimum necessary. To reduce the amount of wear on the sliding part, extend the service life, improve the centering of the nut and bolt against the pilot hole of the steel plate part, and ensure a normal air passage area for cooling air, etc. In particular, an electrode for electric resistance welding that contributes to improving durability and welding accuracy is obtained.

The invention according to claim 2
The electrode for electric resistance welding according to claim 1, wherein the ratio of the diameter of the guide pin to the diameter of the sliding portion is 1.3 to 1.7.

  By setting the ratio of the diameter of the guide pin to the diameter of the sliding portion to 1.3 to 1.7, the thickness of the sliding portion is set to be thin, and the end surface of the sliding portion and the inner end surface of the guide hole are In addition to securing advantages such as thermal expansion and wear reduction due to thinning as described above, and improved accuracy of the axial center mating surface, the contact area of the cooling air can be secured. Intermittent action is reliably achieved. Further, by ensuring an appropriate thickness of the sliding portion, an air passage for cooling air is reliably formed, and the sliding portion is normally cooled.

  If the above ratio is less than 1.3, there is a problem that the thickness of the sliding portion is too thin to sufficiently secure the seating area of the sliding portion end surface with respect to the inner end surface of the guide hole. In other words, the seating width viewed in the diameter direction of the end surface of the sliding portion is insufficient, and moderation of the cooling air becomes impossible. Further, if the air passage of the cooling air is in a form in which an air groove is formed on the outer peripheral surface of the sliding portion, it is difficult to ensure a sufficient air cross-sectional area of the air groove, and proper air cooling becomes impossible. .

  On the other hand, if the ratio exceeds 1.7, the thickness of the sliding portion becomes excessive, the amount of heat stored in the sliding portion also becomes excessive, and the thermal expansion and wear caused by the above-described thinning are small. Advantages such as the improvement of the accuracy of the surface and the axis coincidence cannot be pursued. Therefore, by setting the ratio of the diameter of the guide pin to the diameter of the sliding portion to 1.3 to 1.7, an excellent and highly reliable electrode for electric resistance welding can be obtained.

It is sectional drawing of each part of an electrode. It is sectional drawing of another electrode.

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

  FIG. 1 shows a first embodiment of the present invention.

  First, the electrode body will be described.

  The electrode body 1 made of 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 coupled at a screw portion 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 at the lower portion of 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 the side of the fixed part 2.

  Next, the sliding part 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 excellent in heat resistance, for example, polytetrafluoroethylene (trade name: Teflon). The guide pin 12 is integrated in a state of being inserted into the sliding portion 13. The guide pin 12 and the sliding portion 13 are both circular in cross section, and the guide pin 12 relatively passes through the pilot hole 14 of the steel plate component 3 to perform the positioning function of the steel plate component 3 and is fitted to the tip portion thereof. An iron projection nut 15 is supported. For this purpose, a small-diameter portion 16 that matches the screw hole of the projection nut 15 is formed.

  In the following description, the projection nut may be simply expressed as a nut. The nut 15 is formed with a screw hole at the center of a square main body, and welding projections 21 are formed at the four corners of the main body. The electrode body 1 is a fixed electrode, and a movable electrode 23 is arranged coaxially therewith.

  In addition, the CC cross section of FIG. 1 (B) is the (C) figure of the same figure, and the BB cross section is the (D) figure of the same figure.

  The sliding portion 13 is fitted in a state in which there is substantially no gap in the large-diameter hole 7 and can slide. An insertion hole 17 is opened in the sliding portion 13, and the guide pin 12 is press-fitted therein. A bolt 31 is integrally formed with the end of the guide pin 12, the bolt 31 is passed through the bottom member 18 of the sliding portion 13, a washer 19 is assembled, and the lock nut 20 is tightened. The sliding portion 13 performs an insulating function so that when the movable electrode 23 is operated and a welding current is applied, the current flows only from the welding projection 21 of the nut 15 to the steel plate part 3.

  An end face 24 is formed at the 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 surface 24 and the inner end surface 25 are planar surfaces that are orthogonal to the axis of the guide pin 12 (the central axis of the electrode body 1) and that surround the axis of the guide pin 12 in an annular shape. The end surface 24 and the inner end surface 25 are in close contact with each other and are separated from each other to interrupt the cooling air, and this close 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 advancement of the movable electrode 23, the end face 24 is separated from the inner end face 25, and an air circulation gap is formed. As described above, the close contact portion between the end surface 24 and the inner end surface 25 functions as an on-off valve. The compressed air that has entered through the vent 10 cools the welded portion of the nut 15 and prevents the ingress of spatter through the air passage 26, between the end face 24 and the inner end face 25, through the gap 22 and the like.

  An air passage 26 for cooling air is formed on the outer peripheral surface of the sliding portion 13 in the direction of the central axis of the electrode body 1. Various air passages 26 can be used. Here, as shown in FIGS. 1A and 1D, the 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, as shown in FIG. 1 (E), the air passage 26 may be configured by forming a plurality of concave grooves 28 on the outer peripheral surface of the sliding portion 13 in the direction of the central axis of the electrode body 1. .

  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 surface 24 is in close contact with the inner end surface 25. Although the cooling air supplied from the vent 10 reaches the air passage 26, ventilation is prohibited by the close contact. Reference numeral 30 denotes an insulating sheet fitted into the inner bottom surface of the guide hole 6.

  Next, the combination relationship between the sliding portion and the guide pin will be described.

  The sliding portion 13 has a cylindrical shape, and a guide pin 12 is inserted therein. As described above, by inserting the guide pin 12 into the insertion hole 17, the integrity of the guide pin 12 and the sliding portion 13 is improved. The length of the portion excluding the small diameter portion 16 of the guide pin 12 is L1, and the length in which the guide pin 12 is inserted into the sliding portion 13 (insertion hole 17) is L2. Since 1/2 or more of L1 is inserted, L2 / L1 is 1/2 or more. Hereinafter, the ratio of L1 to L2 is expressed as “insertion ratio”.

  The ratio of the diameter of the guide pin 12 to the diameter of the sliding portion 13 is hereinafter expressed as “diameter ratio”. By setting the diameter of the guide pin 12 to a constant value and sequentially changing the diameter of the sliding portion 13, the state of thermal influence was observed.

  The diameter of the guide pin 12 is 10.1 mm. On the other hand, the diameter of the sliding part 13 is 15.5 mm. The diameter ratio at this time is 1.53. And the thickness of the sliding part 13 is 2.7 mm.

  By setting the dimensions of each part as described above, proper contact between the end face 24 and the inner end face 25, reduction of heat storage amount due to thinning of the sliding part 13, reduction of wear amount of the sliding face of the sliding part 13, guide It is possible to reduce the inclination of the pin 12 and improve the welding accuracy, to appropriately secure the flow passage area of the air passage 26, and to make the electrode body 1 slim.

  The diameter of the guide pin 12 is 10.1 mm. On the other hand, when the diameter of the sliding portion 13 is 13 mm, the diameter ratio is 1.29. And the thickness of the sliding part 13 will be 1.45 mm.

  Thus, if the diameter dimension of the sliding part 13 is changed with respect to the diameter dimension of the guide pin 12, the close contact between the end face 24 and the inner end face 25, the reduction of the heat storage amount due to the thinning of the sliding part 13, and the sliding The amount of wear on the sliding surface of the portion 13 can be reduced, the inclination of the guide pin 12 can be reduced and the welding accuracy can be improved, the flow passage area of the air passage 26 can be properly secured, and the electrode body 1 can be slimmed.

  However, if the diameter ratio is less than 1.3, there is a problem that the thickness of the sliding portion 13 is too thin and a sufficient seating area of the end surface 24 with respect to the inner end surface 25 cannot be secured. That is, the seating width as viewed in the diameter direction of the sliding portion end face 24 is insufficient, and moderation of the cooling air is impossible. Further, if the cooling air passage 26 is formed in the outer peripheral surface of the sliding portion to form a concave groove 28, it is difficult to ensure a sufficient ventilation cross-sectional area of the concave groove 28, and proper air cooling is not possible. It becomes possible. Therefore, it is determined that it is appropriate to set the diameter ratio to 1.3 or more. Further, when the air passage 26 is formed by the flat portion 27, the problem of the ventilation cross-sectional area similarly occurs.

  The diameter of the guide pin 12 is 10.1 mm. On the other hand, when the diameter of the sliding portion 13 is 17.3 mm, the diameter ratio is 1.72. And the thickness of the sliding part 13 will be 3.6 mm.

  Thus, if the diameter dimension of the sliding part 13 is changed with respect to the diameter dimension of the guide pin 12, the close contact between the end face 24 and the inner end face 25, the reduction of the heat storage amount due to the thinning of the sliding part 13, and the sliding The amount of wear on the sliding surface of the portion 13 can be reduced, the inclination of the guide pin 12 can be reduced and the welding accuracy can be improved, the flow passage area of the air passage 26 can be properly secured, and the electrode body 1 can be slimmed.

  However, when the diameter ratio exceeds 1.7, the thickness of the sliding portion 13 becomes excessive, the heat storage amount of the sliding portion 13 also becomes excessive, and the thermal expansion decreases and the wear amount due to the thinning as described above. Advantages such as reducing the amount of the material and improving the accuracy of the axial centering surface cannot be pursued.

  As a comparative example, the diameter ratio calculated from the dimensions of the guide pins and sliding portions illustrated in Patent Documents 1 and 2 is 2.0 to 2.6, and the results of using the electrodes having such a diameter ratio are as follows. When the thickness of the sliding part was excessive, the amount of wear on the outer peripheral surface of the sliding part was remarkably increased, and the rattling of the guide pin was found to be excessive.

  Judging comprehensively from the above considerations, it is appropriate that the diameter ratio is 1.3 to 1.7, whereby an excellent and highly reliable electric resistance welding electrode can be obtained.

  On the other hand, considering the correlation between the “diameter ratio” and the “insertion ratio”, the insertion ratio is set to 1/2 or more, so that even if the sliding portion 13 is thin, the insertion length is long. A strong unity between the sliding portion 13 and the guide pin 12 can be ensured. That is, if the sliding portion 13 is thin, the urging force of the sliding portion 13 in the diametrical direction with respect to the guide pin 12 is reduced, and the integrity with the guide pin 12 is reduced. By setting it as the above, the weak point by thickness reduction can be compensated.

  The operational effects of the first embodiment described above are as follows.

  Usually, the amount of thermal expansion of the electrode part 1 made of a synthetic resin, that is, the sliding portion 13 is significantly larger than that of the electrode body 1 and the guide pin 12 made of a metal material. Since the moving part 13 is thin and the heat storage amount is reduced, the amount of thermal expansion of the sliding part 13 itself in the diameter direction is reduced. Even if the heating cycle is increased by continuous welding and the temperature of the sliding portion 13 reaches the maximum value that can be endured, the amount of thermal expansion is small, so that the pressure applied to the inner surface of the guide hole 6 is reduced and sliding is performed. The amount of wear on the sliding surface of the portion 13 is minimized. For this reason, the service life of the sliding portion 13 that is most likely to be consumed is prolonged, which is effective in terms of component maintenance.

  Furthermore, by reducing the thermal expansion amount, the sliding gap between the outer peripheral surface of the sliding portion and the inner peripheral surface of the guide hole is kept small, and the inclination of the guide pin 12 is suppressed. By minimizing the inclination angle of the guide pin 12 in this way, the positional accuracy of the projection nut 15 supported by the guide pin 12 with respect to the pilot hole 14 of the steel plate part 3 is improved. That is, the deviation between the center axis of the lower hole 14 and the center axis of the nut 15 can be minimized, which is effective for improving the welding accuracy.

  If the thickness of the sliding portion 13 is large, the amount of expansion of the sliding portion material increases, and the increased amount expands toward the space of the air passage 26, so that the flow area of the air passage 26 is reduced and cooling is performed. The flow rate of air is reduced, and the cooling effect is reduced. However, as described above, by reducing the thickness of the sliding portion 13, the amount of expansion of the sliding portion material can be minimized, and accordingly, a reduction in the flow area of the air passage 26 is avoided. Normal cooling action is performed.

  As the sliding portion 13 becomes thinner, the diameter of the sliding portion 13 becomes smaller. Therefore, the diameter of the electrode body 1 also becomes smaller, and it becomes easier to arrange electrodes in narrow places.

  In addition to the above-described thinning, the sliding portion 13 is formed with an air passage for cooling air, so that the sliding portion 13 having a reduced volume is effectively cooled, and the amount of thermal expansion is reduced. Further promotion of the effect is achieved.

  As described above, when viewed comprehensively, it is possible to reduce the thickness of the sliding portion 13 while ensuring a tight contact area between the end surface 24 of the sliding portion 13 and the inner end surface 25 of the guide hole 6. The cooling air is reliably interrupted, the wear amount of the sliding portion 13 is reduced, the service life is prolonged, the centering of the nut 15 with respect to the pilot hole 14 of the steel plate part 3 is improved, and the normal air passage of the cooling air It correlates with the realization of the area and the like, and an electrode for electric resistance welding that contributes to the improvement of durability and welding accuracy can be obtained.

  The ratio of the diameter of the guide pin 12 to the diameter of the sliding portion 13 (“diameter ratio”) is 1.3 to 1.7.

  By setting the diameter ratio to 1.3 to 1.7, the thickness of the sliding portion 13 is set to be thin, and the contact area between the end surface 24 of the sliding portion 13 and the inner end surface 25 of the guide hole 6 is slid. It can be ensured over the entire circumference of the moving part, and in addition to ensuring advantages such as thermal expansion and wear reduction due to thinning as described above, and improved accuracy of the axis centering surface, the intermittent action of cooling air is ensured Achieved. Furthermore, by ensuring an appropriate thickness of the sliding portion 13, the air passage 26 for cooling air is reliably formed, and the sliding portion 13 is normally cooled.

  If the diameter ratio is less than 1.3, the thickness of the sliding portion 13 is too thin, and there is a problem that a sufficient seating area of the sliding portion end surface 24 with respect to the inner end surface 25 of the guide hole 6 cannot be secured. That is, the seating width as viewed in the diameter direction of the sliding portion end face 24 is insufficient, and moderation of the cooling air is impossible. Furthermore, if the air passage 26 of the cooling air is in a form in which an air groove is formed on the outer peripheral surface of the sliding portion, it is difficult to ensure a sufficient air cross-sectional area of the air groove, and proper air cooling is impossible. Become.

  On the other hand, if the diameter ratio exceeds 1.7, the thickness of the sliding portion 13 becomes excessive, the heat storage amount of the sliding portion 13 also becomes excessive, and the thermal expansion and wear amount due to the thinning as described above are increased. Advantages such as a small amount and improved accuracy of the axial centering surface cannot be pursued. Therefore, by setting the diameter ratio to 1.3 to 1.7, an excellent and highly reliable electrode for electric resistance welding can be obtained.

  FIG. 2 shows a second embodiment of the present invention.

  The second embodiment is different from the projection nut of the first embodiment in that it is a projection bolt and a method of integrating the guide pin and the sliding portion.

  The iron projection bolt 32 is obtained by integrating a circular flange 34 with a shaft portion 33 on which a male screw is formed, and three welding projections 35 are provided on the lower surface of the flange 34 at intervals of 120 degrees.

  The sliding portion 13 is formed by setting the guide pin 12 in a mold of an injection molding machine and injecting synthetic resin, and the guide pin 12 is formed with a small-diameter portion 36 for retaining. The guide pin 12 has a hollow pin shape, and a shaft portion 33 is inserted therein. The other configuration is the same as that of the previous embodiment, including a portion not shown, and the same reference numerals are given to members having similar functions.

  The operational effects of the second embodiment are the same as those of the previous embodiment.

  As described above, according to the electrode of the present invention, the amount of heat stored in the sliding portion that advances and retreats in the guide hole is reduced to prevent abnormal wear on the outer peripheral surface of the sliding portion and to prevent abnormal inclination of the guide pin. To do. Therefore, it can be used in a wide range of industrial fields such as automobile body welding processes and home appliance sheet metal welding processes.

DESCRIPTION OF SYMBOLS 1 Electrode main body 3 Steel plate components 6 Guide hole 12 Guide pin 13 Sliding part 14 Lower hole 15 Projection nut 24 End surface 25 Inner end surface 26 Air passage 32 Projection bolt

Claims (2)

The guide pin having a circular cross section that protrudes from the end face of the electrode body and penetrates through the pilot hole of the steel plate part is composed of a heat-resistant hard material such as a metal material or a ceramic material,
The sliding portion having a circular cross section that is fitted in the guide hole of the electrode body in a slidable state and is integrated with the guide pin in a state where the guide pin is inserted is made of a synthetic resin material,
The thickness of the sliding portion is thin so as to reduce the amount of heat stored in the sliding portion, and an air passage for cooling air is formed in the sliding portion,
An electrode for electric resistance welding, wherein the end face of the sliding portion and the inner end face of the guide hole are brought into close contact with each other and the cooling air is intermittently connected.   The electrode for electric resistance welding according to claim 1, wherein a ratio of the diameter of the guide pin to the diameter of the sliding portion is 1.3 to 1.7.

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