(19)
(11)EP 3 670 065 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
12.10.2022 Bulletin 2022/41

(21)Application number: 18846518.1

(22)Date of filing:  10.08.2018
(51)International Patent Classification (IPC): 
B23K 35/04(2006.01)
B23K 11/14(2006.01)
B23K 11/30(2006.01)
B23K 35/02(2006.01)
(52)Cooperative Patent Classification (CPC):
B23K 11/14; B23K 11/3018; B23K 35/0205
(86)International application number:
PCT/JP2018/030085
(87)International publication number:
WO 2019/035423 (21.02.2019 Gazette  2019/08)

(54)

ELECTRIC RESISTANCE WELDING ELECTRODE AND METHOD OF MAINTAINING AIRTIGHTNESS

ELEKTRISCHE WIDERSTANDSSCHWEISSELEKTRODE UND VERFAHREN ZUR AUFRECHTERHALTUNG DER LUFTDICHTHEIT

ÉLECTRODE DE SOUDAGE PAR RÉSISTANCE ÉLECTRIQUE ET PROCÉDÉ DE MAINTIEN DE L'ÉTANCHÉITÉ À L'AIR


(84)Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

(30)Priority: 17.08.2017 JP 2017170664

(43)Date of publication of application:
24.06.2020 Bulletin 2020/26

(73)Proprietor: Aoyama Shoji
Sakai-shi, Osaka 590-0116 (JP)

(72)Inventors:
  • AOYAMA Yoshitaka
    Sakai-shi Osaka 590-0114 (JP)
  • AOYAMA Shoji
    Sakai-shi Osaka 590-0116 (JP)

(74)Representative: Grünecker Patent- und Rechtsanwälte PartG mbB 
Leopoldstraße 4
80802 München
80802 München (DE)


(56)References cited: : 
JP-A- H 106 033
JP-A- 2002 248 578
JP-A- 2017 047 469
JP-A- 2017 136 639
JP-A- H10 118 774
JP-A- 2015 147 246
JP-A- 2017 136 639
US-A- 6 008 463
  
      
    Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


    Description

    TECHNICAL FIELD



    [0001] The present invention relates to an electric resistance welding electrode and a method for maintaining airtightness in which an end surface of a sliding part made of a synthetic resin material is brought into close contact with or separated from an inner end surface formed on an electrode main body, thereby ventilating and blocking cooling air.

    BACKGROUND ART



    [0002] In an electric resistance welding electrode described in JP 2002-248578 A, JP 2017-006982 A, JP 2017-047469 A, JP 2017-136639 A, a guide hole constituted of a large-diameter hole, a medium-diameter hole, and a small-diameter hole is formed in an electrode main body, a sliding part made of a synthetic resin material and having a guide pin is fitted into the guide hole, an end surface formed on the sliding part is brought into close contact with an inner end surface formed in a portion of the guide hole to block flow of cooling air, and the end surface is separated from the inner end surface to allow flow of the cooling air.
    US 6 008 463 A discloses the preamble of the independent claims 1 and 2.

    CITATIONS LIST


    PATENT LITERATURE



    [0003] 

    Patent Literature 1: JP 2002-248578 A

    Patent Literature 2: JP 2017-006982 A

    Patent Literature 3: JP 2017-047469 A

    Patent Literature 4: JP 2017-136639 A

    Patent Literature 5: US 6 008 463 A


    SUMMARY OF INVENTION


    TECHNICAL PROBLEMS



    [0004] In the technique described in the above-mentioned patent literatures, regarding a close-contact area of the end surface formed in the sliding part made of the synthetic resin material, no consideration is given to the size of the area and handling of a minute metal piece that has entered the close-contact area. Further, no consideration is given also to minimize misalignment and inclination of the guide pin by a sliding state of the sliding part. Due to these matters, in the electrode described in the above-mentioned patent literature, service life in which airtightness of cooling air can be reliably maintained is shortened.

    [0005] The present invention is provided in order to solve the above-described problems, and it is an object thereof to eliminate adverse effects associated with intervention of a minute metal piece by increasing a surface pressure of a movable end surface formed on a sliding part made of a synthetic resin material, and to substantially eliminate misalignment and tilting of the guide pin by selecting a sliding state of the sliding part.

    SOLUTIONS TO PROBLEMS



    [0006] The present invention, solving the above problem, is defined in independent claims 1 and 2.

    ADVANTAGEOUS EFFECTS OF INVENTION



    [0007] A width dimension of a movable end surface seen in a diametrical direction of an electrode main body is set to be less than half of a thickness dimension of a large-diameter portion at a position where a guide pin is inserted. For this reason, an area of the movable end surface is reduced to increase a pressurizing force of the movable end surface against a stationary inner end surface, and a minute metal piece that has entered a close-contact area between the movable end surface and the stationary inner end surface is pushed from the movable end surface into a base material of a sliding part.

    [0008] Since a close-contact area of the movable end surface with respect to the stationary inner end surface is reduced, a pressurizing force per unit area, that is, surface pressure is increased. Therefore, a minute metal piece that has reached a close-contact position is sandwiched between the stationary inner end surface that is a metal surface and the movable end surface that is a surface made of a synthetic resin material, and the metal piece is brought to a state of being embedded in a soft base material of the sliding part, and no gap is formed between the stationary inner end surface and the movable end surface.

    [0009] When the guide pin is pushed down and the movable end surface is separated from the stationary inner end surface and a gap is formed between both the end surfaces, cooling air circulates energetically, and minute metal pieces and carbides, and the like are sent out from a melting local area to an outside of the electrode by airflow. Normally, the sending out is in this manner, but when metal is melted, minute metal pieces that have scattered energetically from a melted portion due to rapid air expansion may collide with an outer peripheral surface of the guide pin and bounce back, move against the airflow, and reach the movable end surface. In such a phenomenon, it is conceivable that movement against the airflow becomes possible because dynamic pressure of airflow acting on a metal piece is low when the metal piece is minute. When such a metal piece adheres to the surface of the movable end surface, a gap is formed between the stationary inner end surface and the movable end surface when the guide pin returns to the standby position, and sealing for circulation of the cooling air is no longer possible. An abnormal behavior of a metal piece as described above does not normally occur if circulation of the cooling air is maintained in good condition, but may occur with a low probability due to some kind of cause as described above.

    [0010] However, in the present invention, as described above, the metal piece is brought to a state of being embedded in the soft base material of the sliding part, and no gap is formed between the stationary inner end surface and the movable end surface. Thus, it is possible to ensure complete airtightness and avoid economic loss due to air leakage. Furthermore, when air leakage continues, noise accompanying air ejection is generated and working environment for the operator is deteriorated. However, the environment is improved by maintaining airtightness as described above.

    [0011] In other words, by synergizing increasing of the surface pressure by reducing the area of the movable end surface made of a synthetic resin material and pressing of the minute metal piece strongly against the movable end surface, the metal piece is embedded from the movable end surface into the base material of the sliding part.

    [0012] The width dimension of the movable end surface seen in the diametrical direction of the electrode main body is set to be less than half of the thickness dimension of the large-diameter portion at the position where the guide pin is inserted. Thus, a thickness dimension of a medium-diameter portion is set large to operate so as to receive an external force acting on the guide pin in the diametrical direction of the electrode main body.

    [0013] Since the sliding part slides with a large-diameter hole and a medium-diameter hole at two portions of the large-diameter portion and the medium-diameter portion, the sliding part with which the guide pin is integrated is in a two-point support state. Therefore, even if an external force acts in the diametrical direction of the electrode main body against the guide pin projecting from the end surface of the electrode main body due to a collision of a steel plate component, or the like, the amounts of tilt displacement of the guide pin and the sliding part are not substantially a problem. Therefore, the close contact between the stationary inner end surface and the movable end surface is not impaired, and reliable airtightness maintenance can be ensured.

    [0014] Furthermore, a diameter of the medium-diameter portion becomes close to a diameter of the large-diameter portion, and thus the diameter of the medium-diameter portion can be set large. At the same time, the thickness of the medium-diameter portion can be increased as much as possible. Accordingly, since an external force in the diametrical direction is received by the medium-diameter portion with an increased diameter and an increased thickness, elastic deformation in the medium-diameter portion can be reduced, and the amounts of tilt displacement of the guide pin and the sliding part can be set to a level that is substantially free of problems. It is particularly effective to reduce the amount of elastic deformation by increasing the diameter. Such increase in thickness and increase in diameter of the medium-diameter portion are achieved in correlation with reduction in the width dimension of the movable end surface. That is, increase in thickness and increase in diameter of the medium-diameter portion and increase in surface pressure of the movable end surface are compatible.

    [0015] Although minute protrusions and recesses remain on the surface of the movable end surface by cutting-finish processing or injection molding, protruding portions of protruding and recessed portions pressed against the stationary inner end surface are in a crushed state due to the above-described improvement in surface pressure, and thus improvement in close contact of the synthetic resin end surface and the metal end surface can be ensured.

    [0016] According to the present invention, a ratio of a width dimension of the movable end surface to the thickness dimension of the large-diameter portion at the position where the guide pin is inserted is less than 0.5 and more than or equal to 0.3.

    [0017] When the width dimension of the movable end surface is more than or equal to half of the thickness dimension of the large-diameter portion where the guide pin is inserted, that is, the ratio is 0.5 or more, the close-contact area of the annular movable end surface becomes excessive, and the increase in surface pressure and the pushing of the metal piece as described above are not achieved satisfactorily. On the other hand, when the ratio is less than 0.3, the close-contact area of the movable end surface becomes too small, the sealing area of cooling air becomes insufficient, and the sealing action becomes slow, which is not preferable in terms of maintaining airtightness.

    [0018] Effects of the invention of the method for maintaining airtightness are the same as the effects of the electric resistance welding electrode.

    BRIEF DESCRIPTION OF DRAWINGS



    [0019] 

    FIG. 1A is a longitudinal sectional view of an entire electrode.

    FIG. 1B is a cross-sectional view taken along a line B-B in FIG. 1A.

    FIG. 1C is a cross-sectional view taken along a line C-C in FIG. 1A.

    FIG. 2A is a cross-sectional view taken along the line B-B in FIG. 1A illustrating a dimensional relationship of W1 to W3.

    FIG. 2B is a local longitudinal sectional view illustrating a dimensional relationship of W1 to W3.

    FIG. 3A is a cross-sectional view illustrating a pushing state of a metal piece. FIG. 3B is a partial plan view of a movable end surface illustrating presence of metal pieces.

    FIG. 3C is a cross-sectional view illustrating a state before the metal pieces are pushed in.

    FIG. 3D is a cross-sectional view illustrating a state after the metal pieces are pushed in.

    FIG. 4 is a cross-sectional view of a projection bolt.


    DESCRIPTION OF EMBODIMENT



    [0020] Next, an embodiment for implementing an electric resistance welding electrode and a method for maintaining airtightness according to the present invention will be described.

    [Embodiment]



    [0021] FIGs. 1A to 4 illustrate an embodiment of the present invention.

    [0022] First, an electrode main body will be described.

    [0023] An electrode main body 1 made of a conductive metal material made of a copper alloy such as chrome copper has a cylindrical shape and a circular cross section, and a fixed part 2 to be inserted into a stationary member 11 and a cap part 4 on which a steel plate component 3 is placed are coupled at a screw portion 5 to form the electrode main body 1 having a circular cross section. A guide hole 6 having a circular cross section is formed in the electrode main body 1, and this guide hole 6 is formed of a large-diameter hole 7 formed in the fixed part 2, a medium-diameter hole 8 smaller in diameter than the large-diameter hole 7 and formed in the cap part 4, and a small-diameter hole 9 smaller in diameter than the medium-diameter hole 8. The large-diameter hole 7, the medium-diameter hole 8, and the small-diameter hole 9 are disposed in a coaxial state of being aligned on a central axis O-O of the electrode main body 1. The small-diameter hole 9 smaller in diameter than the medium-diameter hole 8 is provided on the central axis O-O.

    [0024] A guide pin 12 that has a circular cross section, projects from an end surface of the electrode main body 1 on which the steel plate component 3 is placed, and penetrates a pilot hole 10 of the steel plate component 3 is formed of a metal material such as stainless steel or a heat-resistant hard material such as a ceramic material.

    [0025] Further, as will be described later, a sliding part 13 having a circular cross section that advances and retreats in a sliding state with respect to the guide hole 6 is formed of an insulating synthetic resin material having excellent heat resistance, for example, polytetrafluoroethylene (trade name: Teflon (registered trademark)). As another material, from polyamide resins, a resin excellent in heat resistance and wear resistance can be employed.

    [0026] Next, an integrated part of the guide pin and the sliding part will be described.

    [0027] The guide pin 12 is inserted into a center portion of the sliding part 13 to thereby integrate the guide pin 12 and the sliding part 13. For a structure in which the guide pin 12 is integrated with the sliding part 13, one of various methods such as a method of molding the guide pin 12 together at the time of injection molding of the sliding part 13, a method of providing a connecting bolt structure portion on the guide pin 12, and the like can be employed.

    [0028] Here, the latter type of the connecting bolt structure portion is employed.

    [0029] Specifically, a bolt 14 is formed integrally with a lower end portion of the guide pin 12, the bolt 14 is passed through a bottom member 15 of the sliding part 13, and a washer 16 is fitted therewith and tightened with a lock nut 17. The sliding part 13 has an insulating function such that when a movable electrode 18 paired with the electrode main body 1 is operated and welding current is applied, current flows from a welding projection 20 of a nut 19 to the steel plate component 3 only.

    [0030] Note that the nut 19 is used for projection welding, a screw hole 28 is formed in a center of a square body, and welding projections 20 are provided in four corners. An open end of the screw hole 28 is engaged with a tapered portion 21 of the guide pin 12. Since the nut 19 is in a state of floating from the steel plate component 3 in this manner, a length L1 is left by which the guide pin 12 retracts during welding in which the movable electrode 18 advances.

    [0031]  A compression coil spring 22 is fitted between the washer 16 and an inner bottom surface of the guide hole 6, and a tension thereof acts on the sliding part 13. Note that reference numeral 23 indicates an insulating sheet fitted into the inner bottom surface of the guide hole 6. The tension of the compression coil spring 22 establishes pressurized close contact of a movable end surface with a stationary inner end surface, which will be described later. The compression coil spring 22 is a pressurizing unit, and instead of this, it is also possible to use a pressure of compressed air.

    [0032] Next, a fitting correspondence between respective portions of the sliding part and respective portions of the guide hole will be described.

    [0033] The sliding part 13 is formed with a large-diameter portion 24 and a medium-diameter portion 25, and the guide pin 12 having a smaller diameter than the medium-diameter portion 25 is integrated with the sliding part 13. The large-diameter portion 24 is fitted into the large-diameter hole 7 in a slidable state with substantially no gap with an inner surface of the large-diameter hole 7, and the medium-diameter portion 25 is fitted into the medium-diameter hole 8 in a slidable state with substantially no gap with an inner surface of the medium-diameter hole 8. Such "a slidable state with substantially no gap" means a state that when a force in a diametrical direction of the electrode main body 1 acts on the sliding part 13, there is no feeling of rattling such as clattering that gives a feeling of gap, and moreover, sliding is possible in a central axis O-O direction. By the guide pin 12 that penetrates the small-diameter hole 9 and projects from the end surface of the electrode main body 1, a ventilation gap 26 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.

    [0034] A length in the central axis O-O direction of the electrode main body in which the medium-diameter portion 25 is fitted in the medium-diameter hole 8 is set to be shorter than a length in which the guide pin 12 retracts during welding. In this embodiment, a tapered portion 27 is formed on an upper portion of the medium-diameter portion 25, and a length in the central axis O-O direction in which the medium-diameter portion 25 is fitted in the medium-diameter hole 8 is a length L2 that does not include the tapered portion 27. Accordingly, the length L2 in the central axis O-O direction of the electrode main body in which the medium-diameter portion 25 is fitted in the medium-diameter hole 8 is set to be shorter than the length L1 in which the guide pin 12 retracts during welding. When the guide pin 12 is pushed down, first, the ventilation gap is formed between the tapered portion 27 and the medium-diameter hole 8.

    [0035] Next, an intermittent structure of cooling air will be described.

    [0036] A vent hole 29 is formed for guiding cooling air to the guide hole 6. In order to secure an air passage at a sliding position of the large-diameter portion 24 and the large-diameter hole 7, a concave groove in the central axis O-O direction can be formed on an outer peripheral surface of the large-diameter portion 24, but as illustrated in FIG. 1B here, a flat surface portion 30 in the central axis O-O direction is formed on an outer peripheral surface of the large-diameter portion 24, and an air passage 31 constituted of the flat surface portion 30 and an arc-shaped inner surface of the large-diameter hole 7 is formed. Such flat portions 30 are formed at intervals of 90 degrees, and air passages are provided at four locations.

    [0037] An annular stationary inner end surface 32 is formed at a boundary portion between the medium-diameter hole 8 and the large-diameter hole 7 of the guide hole 6. Further, an annular movable end surface 33 is formed at a boundary between the medium-diameter portion 25 and the large-diameter portion 24 of the sliding part 13. The stationary inner end surface 32 and the movable end surface 33 are disposed on a virtual plane where the central axis O-O of the electrode main body 1 perpendicularly intersects, and the movable end surface 33 is in close contact in an annular state with the stationary inner end surface 32 by tension of the compression coil spring 22, and cooling air is sealed by close contact.

    [0038] As illustrated in FIG. 2B, a width of the stationary inner end surface 32 as seen in a diametrical direction of the electrode main body 1 is large, but a width of the portion where the movable end surface 33 is in close contact is narrow, and a close-contact area of the movable end surface 33 is small. This close-contact width is W1 described later.

    [0039] Next, a width dimension of the movable end surface will be described.

    [0040] A width dimension W1 of the movable end surface 33 seen in the diametrical direction of the electrode main body 1 is a dimension obtained by subtracting a thickness dimension W2 of the medium-diameter portion 25 from a thickness dimension W3 of the large-diameter portion 24 as seen in FIG. 2A. A thickness dimension of the large-diameter portion 24 at a position where the guide pin 12 is inserted is W3. Then, a thickness dimension of the medium-diameter portion 25 at the position where the guide pin 12 is inserted is W2. Since the sliding part 13 is fitted into the large-diameter hole 7 and the medium-diameter hole 8, a thickness of the sliding part 13 is sectioned into the thickness dimension W3 of the large-diameter portion 24 at the position where the guide pin 12 is inserted, and the thickness dimension W2 of the medium-diameter portion 25 seen in the diametrical direction of the electrode main body 1.

    [0041] Note that, as is clear from FIG. 2A, the close-contact area of the movable end surface 33 is reduced by a cross-sectional area of the air passage 31. This reduction in the width dimension W1 of the movable end surface 33 caused by formation of the air passage 31 is determined so as not to impair sealing of cooling air. Further, in FIG. 2A, hatchings of a metal cross section and satin finish of the synthetic resin portion are not illustrated for easiness of viewing.

    [0042] Next, dimensions of respective parts will be described.

    [0043] Sizes of respective parts vary depending on a size of the electrode. Here, a square projection nut 19 having a length and a width of 12 mm each and a thickness of 7.2 mm is electrically welded to a steel plate component 3 having a thickness of 0.7 mm.

    [0044] An example of dimensions of the electrode to which the projection nut 19 is welded is as follows.
    • Diameter dimension of the guide pin 12 = 9.4 mm
    • Outer dimension of the large-diameter portion 24 = 17.8 mm
    • Thickness dimension W3 = 4.2 mm of the large-diameter portion at the position where the guide pin is inserted
    • Outer dimension = 14.3 mm of the medium-diameter portion 25
    • Width dimension W1 = 1.8 mm of the movable end surface seen in the diametrical direction of the electrode main body
    • Ratio = 0.43 of the width dimension W1 of the movable end surface to the thickness dimension W3 of the large-diameter portion
    • Length L2 = 2.4 mm that the medium-diameter portion 25 is fitted in the medium-diameter hole 8
    • Length L1 = 4.4 mm that the guide pin retracts during welding


    [0045] The width dimension W1 of the movable end surface 33 seen in the diametrical direction of the electrode main body 1 is less than half of the thickness dimension W3 of the large-diameter portion 24 at the position where the guide pin 12 is inserted, and here the ratio of W1 to W3 is 0.43.

    [0046] Next, a behavior of a minute metal piece will be described.

    [0047] When the guide pin is pushed down, and the movable end surface is separated from the stationary inner end surface and a gap is formed between both end surfaces, cooling air circulates energetically, and minute metal pieces and carbides, and the like are sent out from a melting local area to the outside of the electrode by airflow. Normally, the sending out is in this manner, but when metal is melted, minute metal pieces that have scattered energetically from a melted portion due to rapid air expansion may collide with an outer peripheral surface of the guide pin and bounce back, move against airflow, and reach the movable end surface. In such a phenomenon, it is conceivable that movement against airflow becomes possible because dynamic pressure of the airflow acting on a metal piece is low when the metal piece is minute. When such a metal piece adheres to the surface of the movable end surface, a gap is formed between the stationary inner end surface and the movable end surface when the guide pin returns to the standby position, and sealing for circulation of the cooling air is no longer possible. The abnormal behavior of a metal piece as described above does not normally occur if circulation of the cooling air is maintained in good condition, but may occur with a low probability due to some kind of cause as described above.

    [0048] Fine metal pieces 34 scattered from the melted portion are usually round particles or particles having angular portions, each of which has a diameter of about 0.1 to 0.2 mm. When such a metal piece 34 reaches the movable end surface 33 for some reason as described above, the metal piece 34 stops in a state of adhering to the surface of the movable end surface 33. Although the flow of cooling air continues even at the time of this stop, the metal piece 34 stops on the surface of the movable end surface 33 conceivably because the metal piece 34 is partially buried or stuck in and projecting from the end surface 33 made of synthetic resin material as illustrated in FIG. 3C.

    [0049] When the sliding part 13 is pushed up in such a state of FIG. 3C, the movable end surface 33 is pressed against the stationary inner end surface 32 having a metal surface, and the metal piece 34 projecting from the movable end surface 33 is pushed into a base material of the movable end surface 33. That is, since the movable end surface 33 side is made of synthetic resin, the metal piece 34 is relatively buried in the base material of the sliding part 13. Such a buried state is illustrated in FIG. 3D.

    [0050] A seating area of the movable end surface 33 is a close-contact area with respect to the stationary inner end surface 32. This area has a width dimension of the movable end surface 33 seen in the diametrical direction of the electrode main body 1 that is less than half of a thickness of the large-diameter portion 24 at the position where the guide pin 12 is inserted, and W1/W3 is 0.43 as a specific numerical value in the present embodiment. By setting 0.43 in this manner, the width dimension of the movable end surface 33 is reduced, and the total close-contact area of the movable end surface 33 is set small. Along with this, a pressurizing force per unit area, that is, surface pressure increases, and the minute metal piece 34 having reached the close-contact position is sandwiched between the stationary inner end surface 32 that is a metal surface and the movable end surface 33 that is a surface made of a synthetic resin material. The metal piece 34 is brought to a state of being embedded in the soft base material of the sliding part 13, and no gap is formed between the stationary inner end surface 32 and the movable end surface 33, thereby reliably maintaining airtightness and preventing cooling air leakage.

    [0051] As a result of performing a test of welding nuts to the steel plate component 3 with W1/W3 set to 0.43, there was no air leakage even after 100,000 times of welding, that is, welding of 100,000 nuts. Thus, it is judged that the electrode can withstand use in an automobile body assembly process or the like. Further, similar test results were obtained when W1/W3 was set to 0.45 or 0.48.

    [0052] When W1/W3 is 0.5 or more, the close-contact area of the movable end surface 33 becomes excessive, and due to accompanying decrease in surface pressure, the force that presses the metal piece 34 from the surface of the movable end surface 33 into the base material of the sliding part 13 becomes insufficient. When such insufficiency occurred, a gap was formed between the movable end surface 33 and the stationary inner end surface 32 when the guide pin 12 was in a projecting state, and air leakage occurred. Therefore, it is appropriate to set W1/W3 to less than 0.5.

    [0053] Conversely, by setting W1/W3 to 0.26 as a lower limit value, the width dimension of the movable end surface 33 is remarkably reduced, and the total contact area of the movable end surface 33 is set to be significantly smaller. Along with this, the pressurizing force per unit area, that is, the surface pressure increases, and the minute metal piece 34 having reached the close-contact position is sandwiched between the stationary inner end surface 32 that is a metal surface and the movable end surface 33 that is a surface made of a synthetic resin material. The metal piece 34 is brought to a state of being embedded in the soft base material of the sliding part 13.

    [0054] However, since the width direction dimension of the movable end surface 33 becomes short, the close-contact width W1 of the movable end surface 33 becomes excessively short, and it is difficult to ensure a sufficient sealing action. Further, when the dimension in the width direction of the movable end surface 33 became short, when a phenomenon occurred such that a large metal piece 34 adheres in a state of crossing the width W1 of the movable end surface 33, there was a metal piece 34 that was not completely buried in the surface of the movable end surface 33. Further, even when the metal piece was buried, it was recognized that a groove-like void was formed in the width direction of the movable end surface 33 due to deformation of the synthetic resin material at the time of being buried. Due to these phenomena, it was recognized that even when the movable end surface 33 was in close contact with the stationary inner end surface 32, air leakage occurred and airtightness maintenance could not be achieved.

    [0055] As a result of performing the nut welding test as described above with W1/W3 set to 0.26, air leakage occurred from the number of weldings around 25,000 times. The cause of this is conceivably the above-described phenomenon of excessively short W1. Further, when W1/W3 was set to 0.28, an unfavorable test result was obtained.

    [0056] On the other hand, when W1/W3 is 0.3 or more, it is judged that the close-contact area of the movable end surface 33 is appropriately reduced, and due to accompanying increase in surface pressure, the force that presses the metal piece 34 from the surface of the movable end surface 33 into the base material of the sliding part 13 is sufficiently obtained as an appropriate value. Together with this, air leakage accompanying the above-described phenomenon of excessively short W1 could be avoided. Therefore, it is appropriate to set W1/W3 to 0.3 or more.

    [0057] Next, a buffer function of the medium-diameter portion will be described.

    [0058] In order to receive an external force in the diametrical direction that acts on the guide pin 12, it is advantageous to increase the diameter of the medium-diameter portion 25 as much as possible and increase the thickness as much as possible. The thickness increase and the diameter increase of the medium-diameter portion 25 are achieved by setting the width dimension W1 of the movable end surface 33 to less than half of the thickness dimension W3 of the large-diameter portion 24.

    [0059]  When an operator fails in handling and the steel plate component 3 collides with the guide pin 12 from the diametrical direction of the electrode main body 1, the guide pin 12 tends to tilt, but since the width dimension W1 of the movable end surface 33 is set so that the diameter of the medium-diameter portion 25 becomes large, a force per unit area acting on the cylindrical surface of the medium-diameter portion 25 is reduced, and the inclination angle does not become a substantial problem. Furthermore, the amount of compressive deformation of the medium-diameter portion 25 is reduced by reducing the force, which is effective for reducing the tilt angle.

    [0060] Next, another case example will be described.

    [0061] The above example is a case of a projection nut, but an example illustrated in FIG. 4 is a case of a projection bolt. A projection bolt 36 is constituted of a shaft portion 37 in which a male screw is formed, a circular flange 38 integrated with the shaft portion 37, and a welding projection 39 provided on a lower surface of the flange 38. The guide pin 12 has a tubular hollow shape and is provided with a receiving hole 40 into which the shaft portion 37 is inserted. The other configuration is the same as that of the previous example including any portion that is not illustrated, and the same reference numerals are used for members having similar functions.

    [0062] Next, operation of the electrode will be described.

    [0063] FIG. 1A illustrates a state that the movable end surface 33 is in close contact with the stationary inner end surface 32 due to tension of the compression coil spring 22 and seals flow of cooling air. At this time, if a minute metal piece 34 is interposed between the movable end surface 33 and the stationary inner end surface 32, airtightness is maintained by the pushing operation described with reference to FIGs. 3.

    [0064] When the movable electrode 18 advances and the interval L1 disappears, the medium-diameter portion 25 having entered the medium-diameter hole 8 comes out of the medium-diameter hole 8, and a passage for cooling air is formed. The cooling air diverges to the outside through the vent hole 29, the air passage 31, the medium-diameter hole 8, and the ventilation gap 26, and through the gap between the lower surface of the nut 19 and the steel plate component 3. By this airflow, impurities such as spatter are removed in a direction to separate from the electrode. When the guide pin 12 is pushed down, an air passage is first formed by the tapered portion 27. An air passage having a large flow path area is formed in an initial stage due to a slope of the tapered portion 27, which is preferable for reliable cooling air circulation. Further, when the guide pin 12 returns, the medium-diameter portion 25 smoothly enters the medium-diameter hole 8 by a guide function of the tapered portion 27. The operation is the same in a case of the projection bolt 36 illustrated in FIG. 4.

    [0065] Operations and effects of the embodiment described above are as follows.

    [0066] The width dimension W1 of the movable end surface 33 seen in the diametrical direction of the electrode main body 1 is set to be less than half of the thickness dimension W3 of the large-diameter portion 24 at the position where the guide pin 12 is inserted. For this reason, the area of the movable end surface 33 is reduced to increase a pressurizing force of the movable end surface 33 against the stationary inner end surface 32, and a minute metal piece 34 that has entered the close-contact area between the movable end surface 33 and the stationary inner end surface 32 is pushed from the movable end surface 33 into the base material of the sliding part 13.

    [0067] Since the close-contact area of the movable end surface 33 with respect to the stationary inner end surface 32 is reduced, the pressurizing force per unit area, that is, the surface pressure is increased. Therefore, the minute metal piece 34 that has reached the close-contact position is sandwiched between the stationary inner end surface 32 that is a metal surface and the movable end surface 33 that is a surface made of the synthetic resin material, and the metal piece 34 is brought to a state of being embedded in the soft base material of the sliding part 13, and no gap is formed between the stationary inner end surface 32 and the movable end surface 33.

    [0068] When the guide pin 12 is pushed down and the movable end surface 33 is separated from the stationary inner end surface 32 and a gap is formed between both the end surfaces, cooling air circulates energetically, and minute metal pieces 34 and carbides, and the like are sent out from a melting local area to the outside of the electrode by airflow. Normally, the sending out is in this manner, but when metal is melted, minute metal pieces 34 that have scattered energetically from a melted portion due to rapid air expansion may collide with an outer peripheral surface of the guide pin 12 and bounce back, move against airflow, and reach the movable end surface 33. In such a phenomenon, it is conceivable that movement against airflow becomes possible because dynamic pressure of the airflow acting on a metal piece 34 is low when the metal piece 34 is minute. When such a metal piece 34 adheres to the surface of the movable end surface 33, a gap is formed between the stationary inner end surface 32 and the movable end surface 33 when the guide pin 12 returns to the standby position, and sealing for circulation of the cooling air is no longer possible. The abnormal behavior of a metal piece 34 as described above does not normally occur if circulation of the cooling air is maintained in good condition, but may occur with a low probability due to some kind of cause as described above.

    [0069] However, in the present embodiment, as described above, the metal piece 34 is brought to a state of being embedded in the soft base material of the sliding part 13, and no gap is formed between the stationary inner end surface 32 and the movable end surface 33. Thus, it is possible to ensure complete airtightness and avoid economic loss due to air leakage. Furthermore, when air leakage continues, noise accompanying air ejection is generated and working environment for the operator is deteriorated. However, the environment is improved by maintaining airtightness as described above.

    [0070] In other words, by synergizing increasing of the surface pressure by reducing the area of the movable end surface 33 made of a synthetic resin material and pressing of the minute metal piece 34 strongly against the movable end surface 33, the metal piece 34 is embedded from the movable end surface 33 into the base material of the sliding part 13.

    [0071] The width dimension W1 of the movable end surface 33 seen in the diametrical direction of the electrode main body 1 is set to be less than half of the thickness dimension W3 of the large-diameter portion 24 at the position where the guide pin 12 is inserted. Thus, the thickness dimension of the medium-diameter portion 25 is set large to operate so as to receive an external force acting on the guide pin 12 in the diametrical direction of the electrode main body 1.

    [0072] Since the sliding part 13 slides with the large-diameter hole 7 and the medium-diameter hole 8 at two portions of the large-diameter portion 24 and the medium-diameter portion 25, the sliding part 13 with which the guide pin 12 is integrated is in a two-point support state. Therefore, even if an external force acts in the diametrical direction of the electrode main body 1 on the guide pin 12 projecting from the end surface of the electrode main body 1 due to a collision of the steel plate component 3, or the like, the amounts of tilt displacement of the guide pin 12 and the sliding part 13 are not substantially a problem. Therefore, the close contact between the stationary inner end surface 32 and the movable end surface 33 is not impaired, and reliable airtightness maintenance can be ensured.

    [0073] Furthermore, the diameter of the medium-diameter portion 25 becomes close to the diameter of the large-diameter portion 24, and thus the diameter of the medium-diameter portion 25 can be set large. At the same time, the thickness of the medium-diameter portion 25 can be increased as much as possible. Accordingly, since an external force in the diametrical direction is received by the medium-diameter portion 25 with an increased diameter and an increased thickness, elastic deformation in the medium-diameter portion 25 can be reduced, and the amounts of tilt displacement of the guide pin 12 and the sliding part 13 can be set to a level that is substantially free of problems. It is particularly effective to reduce the amount of elastic deformation by increasing the diameter. Such increase in thickness and increase in diameter of the medium-diameter portion 25 are achieved in correlation with reduction in the width dimension W1 of the movable end surface 33. That is, increase in thickness and increase in diameter of the medium-diameter portion 25 and increase in surface pressure of the movable end surface 33 are compatible.

    [0074] Although minute protrusions and recesses remain on the surface of the movable end surface 33 by cutting-finish processing or injection molding, protruding portions of protruding and recessed portions pressed against the stationary inner end surface 32 are in a crushed state due to the above-described improvement in surface pressure, and thus improvement in close contact of the synthetic resin end surface and the metal end surface can be ensured.

    [0075] The ratio of the width dimension W1 of the movable end surface 33 to the thickness dimension W3 of the large-diameter portion 24 at the position where the guide pin 12 is inserted is less than 0.5 and more than or equal to 0.3.

    [0076] When the width dimension W1 of the movable end surface 33 is more than or equal to half of the thickness dimension W3 of the large-diameter portion 24 at the position where the guide pin 12 is inserted, that is, the ratio is 0.5 or more, the close-contact area of the annular movable end surface 33 becomes excessive, and the increase in surface pressure and the pushing of the metal piece 34 as described above are not achieved satisfactorily. Preferably, the upper limit side is less than 0.5. On the other hand, when the ratio is less than 0.3, the close-contact area of the movable end surface 33 becomes too small, the sealing area of cooling air becomes insufficient, and the sealing action becomes slow, which is not preferable in terms of maintaining airtightness. Preferably, the lower limit side is more than or equal to 0.3.

    [0077] Effects of the embodiment of the method for maintaining airtightness according to the present invention as defined in claim 2 are the same as the effects of the electric resistance welding electrode.

    INDUSTRIAL APPLICABILITY



    [0078] As described above, in an electrode and a method for maintaining airtightness of the present invention, adverse effects associated with intervention of a minute metal piece are eliminated by increasing a surface pressure of a movable end surface formed on a sliding part made of a synthetic resin material, and misalignment and tilting of a guide pin is substantially eliminated by selecting a sliding state of the sliding part. Therefore, the invention can be used in a wide range of industrial fields such as automobile body welding processes and sheet metal welding processes of home appliances.

    REFERENCE SIGNS LIST



    [0079] 
    1
    electrode main body
    6
    guide hole
    7
    large-diameter hole
    8
    medium-diameter hole
    9
    small-diameter hole
    12
    guide pin
    13
    sliding part
    18
    movable electrode
    19
    projection nut
    24
    large-diameter portion
    25
    medium-diameter portion
    26
    ventilation gap
    29
    vent hole
    31
    air passage
    32
    stationary inner end surface
    33
    movable end surface
    34
    metal piece
    36
    projection bolt
    40
    receiving hole
    W1
    width dimension of movable end surface
    W2
    thickness dimension of medium-diameter portion
    W3
    thickness dimension of large-diameter portion
    L1
    retraction length of guide pin
    L2
    insertion length of medium-diameter portion



    Claims

    1. An electric resistance welding electrode comprising:

    an electrode main body (1) that has a circular cross section and is constituted of a metal material such as a copper material;

    a guide pin (12) that has a circular cross section, projects from an end surface of the electrode main body (1) on which a steel plate component (3) is placed, penetrates a pilot hole (10) of the steel plate component (3), and is constituted of a heat-resistant hard material such as a metal material or a ceramic material; and

    a sliding part (13) that has a circular cross section, is fitted into a guide hole (6) formed in the electrode main body (1) in a slidable state, has a central portion in which the guide pin (12) is inserted, and is constituted of a synthetic resin material, wherein

    the guide hole (6) is constituted of a large-diameter hole (7), a medium-diameter hole (8), and a small-diameter hole (9),

    a large-diameter portion (24) formed in the sliding part (13) is fitted into the large-diameter hole (7) in a slidable state with substantially no gap,

    a medium-diameter portion (25) formed in the sliding part (13) is fitted into the medium-diameter hole (8) in a slidable state with substantially no gap,

    a ventilation gap (26) through which cooling air passes is formed between the small-diameter hole (9) and the guide pin (12) when the guide pin (12) is pushed down by the guide pin (12) that penetrates the small-diameter hole (9),

    a movable end surface (33) formed at a boundary portion between the medium-diameter portion (25) and the large-diameter portion (24) of the sliding part (13) is configured to be in close-contact with a stationary inner end surface (32) formed at a boundary portion between the medium-diameter hole (8) and the large-diameter hole (7) of the guide hole (6), and the stationary inner end surface (32) and the movable end surface (33) are disposed on a virtual plane where a central axis of the electrode main body (1) perpendicularly intersects,

    a length (L2) in the central axis direction of the electrode main body (1) in which the medium-diameter portion (25) is fitted in the medium-diameter hole (8) is set to be shorter than a length (L1) in which the guide pin (12) moves backward during welding,

    a pressurizing unit that presses the movable end surface (33) against the stationary inner end surface (32) is disposed in the guide hole (6),

    and being characterised in that:

    a width dimension (W1) of the movable end surface (33) seen in a diametrical direction of the electrode main body (1) is a dimension obtained by subtracting a thickness direction (W2) of the medium-diameter portion (25) at a position where the guide pin (12) is inserted from a thickness dimension (W3) of the large-diameter portion (24) at the position where the guide pin (12) is inserted, and

    by the width dimension (W1) of the movable end surface (33) seen in the diametrical direction of the electrode main body (1) being less than half of the thickness dimension (W3) of the large-diameter portion (24) at the position where the guide pin (12) is inserted, an area of the movable end surface (33) is configured to be small to increase a pressurizing force of the movable end surface (33) against the stationary inner end surface (32), such that a minute metal piece (34) entering a close-contact position of the movable end surface (33) and the stationary inner end surface (32) is pushed from the movable end surface (33) into a base material of the sliding part (13), and

    by the width dimension (W1) of the movable end surface (33) seen in the diametrical direction of the electrode main body (1) being less than half of the thickness dimension (W3) of the large-diameter portion (24) at the position where the guide pin (12) is inserted, the thickness dimension (W2) of the medium-diameter portion (25) is configured to be set large so as to receive an external force that acts on the guide pin (12) in the diametrical direction of the electrode main body (1),

    and in that a ratio of the width dimension (W1) of the movable end surface (33) to the thickness dimension (W3) of the large-diameter portion (24) at the position where the guide pin (12) is inserted is less than 0.5 and more than or equal to 0.3.


     
    2. A method for maintaining airtightness of an electric resistance welding electrode, the method comprising:

    forming an electrode main body (1) that has a circular cross section by a metal material such as a copper material;

    forming a guide pin (12) that has a circular cross section, projects from an end surface of the electrode main body (1) on which a steel plate component (3) is placed, and penetrates a pilot hole (10) of the steel plate component (3) by a heat-resistant hard material such as a metal material or a ceramic material; and

    forming a sliding part (13) that has a circular cross section, is fitted into a guide hole (6) formed in the electrode main body (1) in a slidable state, and has a central portion in which the guide pin (12) is inserted, by a synthetic resin material, wherein

    the guide hole (6) is constituted of a large-diameter hole (7), a medium-diameter hole (8), and a small-diameter hole (9),

    a large-diameter portion (24) formed in the sliding part (13) is fitted into the large-diameter hole (7) in a slidable state with substantially no gap,

    a medium-diameter portion (25) formed in the sliding part (13) is fitted into the medium-diameter hole (8) in a slidable state with substantially no gap,

    a ventilation gap (26) through which cooling air passes is formed between the small-diameter hole (9) and the guide pin (12) when the guide pin (12) is pushed down by the guide pin (12) that penetrates the small-diameter hole (9),

    a movable end surface (33) formed at a boundary portion between the medium-diameter portion (25) and the large-diameter portion (24) of the sliding part (13) is configured to be in close-contact with a stationary inner end surface (32) formed at a boundary portion between the medium-diameter hole (8) and the large-diameter hole (7) of the guide hole (6), and the stationary inner end surface (32) and the movable end surface (33) are disposed on a virtual plane where a central axis of the electrode main body (1) perpendicularly intersects,

    a length (L2) in the central axis direction of the electrode main body (1) in which the medium-diameter portion (25) is fitted in the medium-diameter hole (8) is set to be shorter than a length (L1) in which the guide pin (12) moves backward during welding,

    a pressurizing unit that presses the movable end surface (33) against the stationary inner end surface (32) is disposed in the guide hole (6),

    and being characterised in that:

    a width dimension (W1) of the movable end surface (33) seen in a diametrical direction of the electrode main body (1) is a dimension obtained by subtracting a thickness direction (W2) of the medium-diameter portion (25) at a position where the guide pin (12) is inserted from a thickness dimension (W3) of the large-diameter portion (24) at the position where the guide pin (12) is inserted, and

    by the width dimension (W1) of the movable end surface (33) seen in the diametrical direction of the electrode main body (1) being less than half of the thickness dimension (W3) of the large-diameter portion (24) at the position where the guide pin (12) is inserted, an area of the movable end surface (33) is configured to be small to increase a pressurizing force of the movable end surface (33) against the stationary inner end surface (32), such that minute metal piece (34) entering a close-contact position of the movable end surface (33) and the stationary inner end surface (32) is pushed from the movable end surface (33) into a base material of the sliding part (13), and

    and by the width dimension (W1) of the movable end surface (33) seen in the diametrical direction of the electrode main body (1) being less than half of the thickness dimension (W3) of the large-diameter portion (24) at the position where the guide pin (12) is inserted, the thickness dimension (W2) of the medium-diameter portion (25) is configured to be set large so as to receive an external force that acts on the guide pin (12) in the diametrical direction of the electrode main body (1) by the medium-diameter portion (25),

    and in that a ratio of the width dimension (W1) of the movable end surface (33) to the thickness dimension (W3) of the large-diameter portion (24) at the position where the guide pin (12) is inserted is less than 0.5 and more than or equal to 0.3.


     


    Ansprüche

    1. Elektrische Widerstandsschweißelektrode, welche umfasst:

    einen Elektrodenhauptkörper (1), der einen kreisförmigen Querschnitt aufweist und aus einem Metallmaterial, wie Kupfermaterial, gebildet ist;

    einen Führungsstift (12), der einen kreisförmigen Querschnitt aufweist, von einer Endfläche des Elektrodenhauptkörpers (1) vorsteht, auf welcher ein Stahlplattenbauteil (3) angeordnet wird, ein Führungsloch (10) des Stahlplattenbauteils (3) durchdringt und aus einem hitzeresistenten harten Material, wie einem Metallmaterial oder einem Keramikmaterial, gebildet ist; und

    einen gleitenden Teil (13), der einen kreisförmigen Querschnitt aufweist, in einem verschiebbaren Zustand in ein Führungsloch (6) gepasst ist, das in dem Elektronenhauptkörper (1) gebildet ist, einen zentralen Abschnitt aufweist, in welchem der Führungsstift (12) eingesetzt ist und aus einem Kunstharzmaterial gebildet ist, wobei

    das Führungsloch (6) von einem Loch (7) mit großem Durchmesser, einem Loch (8) mit mittlerem Durchmesser und einem Loch (9) mit kleinem Durchmesser gebildet wird,

    ein Abschnitt (24) mit großem Durchmesser, der in dem gleitenden Teil (13) ausgebildet ist, in das Loch (7) mit großem Durchmesser in einem verschiebbaren Zustand mit im Wesentlichen keinem Spalt gepasst ist,

    ein Abschnitt (25) mit mittlerem Durchmesser, der in dem gleitenden Teil (13) ausgebildet ist, in einem verschiebbaren Zustand mit im Wesentlichen keinem Spalt in das Loch (8) mit mittlerem Durchmesser gepasst ist,

    ein Belüftungsspalt (26), durch welchen Kühlluft strömt, zwischen dem Loch (9) mit kleinem Durchmesser und dem Führungsstift (12) gebildet wird, wenn der Führungsstift (12) von dem Führungsstift (12), der das Loch (9) mit kleinem Durchmesser durchdringt, heruntergedrückt wird,

    eine bewegliche Endfläche (33), die an einem Grenzabschnitt zwischen dem Abschnitt (25) mit mittlerem Durchmesser und dem Abschnitt (24) mit großem Durchmesser des gleitenden Teils (13) ausgebildet ist, konfiguriert ist, um in engem Kontakt mit einer stationären inneren Endfläche (32) zu sein, die an einem Grenzabschnitt zwischen dem Loch (8) mit mittlerem Durchmesser und dem Loch (7) mit großem Durchmesser des Führungslochs (6) ausgebildet ist, und die stationäre innere Endfläche (32) und die bewegliche Endfläche (33) auf einen virtuellen Ebene angeordnet sind, wo eine zentrale Achse des Elektrodenhauptkörpers (1) senkrecht kreuzt,

    eine Länge (L2) in der Richtung der zentralen Achse des Elektrodenhauptkörpers (1), in welcher der Abschnitt (25) mit mittlerem Durchmesser in das Loch (8) mit mittlerem Durchmesser eingepasst ist, kürzer festgelegt ist als eine Länge (L1), in welcher sich der Führungsstift (12) während eines Schweißens zurückbewegt,

    eine drückende Einheit, die die bewegliche Endfläche (33) gegen die stationäre innere Endfläche (32) drückt, in dem Führungsloch (6) angeordnet ist,

    und dadurch gekennzeichnet ist, dass

    eine Breitenabmessung (W1) der beweglichen Endfläche (33), in einer diametralen Richtung des Elektrodenhauptkörpers (1) gesehen, eine Abmessung ist, die durch Subtrahieren einer Dickenrichtung (W2) des Abschnitts (25) mit mittlerem Durchmesser an einer Position, wo der Führungsstift (12) eingesetzt ist, von einer Dickenabmessung (W3) des Abschnitts (24) mit großem Durchmesser an der Position, wo der Führungsstift (12) eingesetzt ist, erhalten wird, und

    indem die Breitenabmessung (W1) der beweglichen Endfläche (33), in der diametralen Richtung des Elektrodenhauptkörpers (1) gesehen, geringer ist als die Hälfte der Dickenabmessung (W3) des Abschnitts (24) mit großem Durchmesser an der Position, wo der Führungsstift (12) eingesetzt ist, eine Fläche der beweglichen Endfläche (33) so konfiguriert ist, dass sie klein ist, um eine drückende Kraft der beweglichen Endfläche (33) gegen die stationäre innere Endfläche (32) zu erhöhen, so dass ein winziges Metallstück (34), das in eine Position mit engem Kontakt der beweglichen Endfläche (33) und der stationären Endfläche (32) eindringt, von der beweglichen Endfläche (33) in ein Basismaterial des gleitenden Teils (13) gedrückt wird, und

    indem die Breitenabmessung (W1) der beweglichen Endfläche (33), in der diametralen Richtung des Elektrodenhauptkörpers (1) gesehen, geringer ist als die Hälfte der Dickenabmessung (W3) des Abschnitts (24) mit großem Durchmesser an der Position, wo der Führungsstift (12) eingesetzt ist, die Dickenabmessung (W2) des Abschnitts (25) mit mittlerem Durchmesser so konfiguriert ist, dass sie groß festgelegt ist, um eine äußere Kraft aufzunehmen, die auf den Führungsstift (12) in der diametralen Richtung des Elektrodenhauptkörpers (1) einwirkt,

    und dass ein Verhältnis der Breitenabmessung (W1) der beweglichen Endfläche (33) zu der Dickenabmessung (W3) des Abschnitts (24) mit großem Durchmesser an der Position, wo der Führungsstift (12) eingesetzt ist, kleiner als 0,5 und größer oder gleich 0,3 beträgt.


     
    2. Verfahren zur Aufrechterhaltung der Luftdichtheit einer elektrischen Widerstandsschweißelektrode, wobei das Verfahren umfasst:

    Ausbilden eines Elektrodenhauptkörpers (1), der einen kreisförmigen Querschnitt aufweist, mit einem Metallmaterial, wie einem Kupfermaterial;

    Ausbilden eines Führungsstifts (12), der einen kreisförmigen Querschnitt aufweist, von einer Endfläche des Elektrodenhauptkörpers (1) vorsteht, auf welcher ein Stahlplattenbauteil (3) angeordnet wird, und ein Führungsloch (10) des Stahlplattenbauteils (3) durchdringt, mit einem hitzeresistenten harten Material, wie einem Metallmaterial oder einem Keramikmaterial; und

    Ausbilden eines gleitenden Teils (13), der einen kreisförmigen Querschnitt aufweist, in ein Führungsloch (6), das in dem Elektrodenhauptkörper (1) ausgebildet ist, in einem verschiebbaren Zustand eingepasst ist und einen zentralen Abschnitt aufweist, in welchen der Führungsstift (12) eingesetzt ist, mit einem Kunstharzmaterial, wobei

    das Führungsloch (6) von einem Loch (7) mit großem Durchmesser, einem Loch (8) mit mittlerem Durchmesser und einem Loch (9) mit kleinem Durchmesser gebildet wird,

    ein Abschnitt (24) mit großem Durchmesser, der in dem gleitenden Teil (13) ausgebildet ist, in das Loch (7) mit großem Durchmesser in einem verschiebbaren Zustand mit im Wesentlichen keinem Spalt eingepasst ist,

    ein Abschnitt (25) mit mittlerem Durchmesser, der in dem gleitenden Teil (13) ausgebildet ist, in das Loch (8) mit mittlerem Durchmesser in einem verschiebbaren Zustand mit im Wesentlichen keinem Spalt eingepasst ist,

    ein Belüftungsspalt (26), durch welchen Kühlluft strömt, zwischen dem Loch (9) mit kleinem Durchmesser und dem Führungsstift (12) gebildet wird, wenn der Führungsstift (12) von dem Führungsstift (12), der das Loch (9) mit kleinem Durchmesser durchdringt, nach unten gedrückt wird,

    eine bewegliche Endfläche (33), die an einem Grenzabschnitt zwischen dem Abschnitt (25) mit mittlerem Durchmesser und dem Abschnitt (24) mit großem Durchmesser des gleitenden Teils (13) ausgebildet ist, konfiguriert ist, um in engem Kontakt mit einer stationären inneren Endfläche (32) zu sein, die an einem Grenzabschnitt zwischen dem Loch (8) mit mittlerem Durchmesser und dem Loch (7) mit großem Durchmesser des Führungslochs (6) ausgebildet ist, und die stationäre innere Endfläche (32) und die bewegliche Endfläche (33) auf einer virtuellen Ebene angeordnet sind, wo eine zentrale Achse der Elektrodenhauptkörpers (1) senkrecht kreuzt,

    eine Länge (L2) in der Richtung der zentralen Achse des Elektrodenhauptkörpers (1), in welcher der Abschnitt (25) mit mittlerem Durchmesser in das Loch (8) mit mittlerem Durchmesser eingepasst ist, kürzer festgelegt ist als eine Länge (L1), in welcher sich der Führungsstift (12) während eines Schweißens zurückbewegt,

    eine drückende Einheit, die die bewegliche Endfläche (33) gegen die stationäre innere Endfläche (32) drückt, in dem Führungsloch (6) angeordnet ist,

    und dadurch gekennzeichnet ist, dass:

    eine Breitenabmessung (W1) der beweglichen Endfläche (33), in einer diametralen Richtung des Elektrodenhauptkörpers (1) gesehen, eine Abmessung ist, die durch Subtrahieren einer Dickenrichtung (W2) des Abschnitts (25) mit mittlerem Durchmesser an einer Position, wo der Führungsstift (12) eingesetzt ist, von einer Dickenabmessung (W3) des Abschnitts (24) mit großem Durchmesser an der Position, wo der Führungsstift (12) eingesetzt ist, erhalten wird, und

    indem die Breitenabmessung (W1) der beweglichen Endfläche (33), in der diametralen Richtung des Elektrodenhauptkörpers (1) gesehen, geringer ist als die Hälfte der Dickenabmessung (W3) des Abschnitts (24) mit großem Durchmesser an der Position, wo der Führungsstift (12) eingesetzt ist, eine Fläche der beweglichen Endfläche (33) so konfiguriert ist, dass sie klein ist, um eine drückende Kraft der beweglichen Endfläche (33) gegen die stationäre innere Endfläche (32) zu erhöhen, so dass ein winziges Metallstück (34), das in eine Position mit engem Kontakt der beweglichen Endfläche (33) und der stationären Endfläche (32) eindringt, von der beweglichen Endfläche (33) in ein Basismaterial des gleitenden Teils (13) gedrückt wird, und

    indem die Breitenabmessung (W1) der beweglichen Endfläche (33), in der diametralen Richtung des Elektrodenhauptkörpers (1) gesehen, geringer ist als die Hälfte der Dickenabmessung (W3) des Abschnitts (24) mit großem Durchmesser an der Position, wo der Führungsstift (12) eingesetzt ist, die Dickenabmessung (W2) des Abschnitts (25) mit mittlerem Durchmesser so konfiguriert ist, dass sie groß festgelegt ist, um eine äußere Kraft aufzunehmen, die auf den Führungsstift (12) in der diametralen Richtung des Elektrodenhauptkörpers (1) einwirkt,

    und dass ein Verhältnis der Breitenabmessung (W1) der beweglichen Endfläche (33) zu der Dickenabmessung (W3) des Abschnitts (24) mit großem Durchmesser an der Position, wo der Führungsstift (12) eingesetzt ist, kleiner als 0,5 und größer oder gleich 0,3 beträgt.


     


    Revendications

    1. Électrode de soudage par résistance électrique, comprenant :

    un corps principal d'électrode (1) qui présente une section transversale circulaire et est constitué à partir d'un matériau métallique tel que le cuivre ;

    une broche de guidage (12) qui présente une section transversale circulaire, se projette depuis une surface terminale du corps principal d'électrode (1) sur laquelle est placé un composant de plaque en acier (3), pénètre dans un trou pilote (10) du composant de plaque en acier (3), et est constituée en un matériau dur résistant à la chaleur, tel qu'un matériau métallique ou un matériau céramique ; et

    une partie coulissante (13) qui présente une section transversale circulaire, est insérée dans un trou de guidage (6) formé dans le corps principal d'électrode (1) dans un état coulissant, comporte une portion centrale dans laquelle est insérée la broche de guidage (12), et est constituée d'un matériau en résine synthétique, dans laquelle

    le trou de guidage (6) est constitué d'un trou de grand diamètre (7), d'un trou de diamètre moyen (8) et d'un trou de petit diamètre (9),

    une portion de grand diamètre (24) formée dans la partie coulissante (13) est insérée dans le trou de grand diamètre (7) dans un état coulissant substantiellement sans intervalle,

    une portion de diamètre moyen (25) formée dans la partie coulissante (13) est insérée dans le trou de diamètre moyen (8) dans un état coulissant substantiellement sans intervalle,

    un intervalle de ventilation (26) à travers lequel passe de l'air de refroidissement est formé entre le trou de petit diamètre (9) et la broche de guidage (12) quand la broche de guidage (12) est poussée vers le bas par la broche de guidage (12) qui pénètre dans le trou de petit diamètre (9),

    une surface terminale mobile (33) formée à une portion de délimitation entre la portion de diamètre moyen (25) et la portion de grand diamètre (24) de la partie coulissante (13) est configurée pour être en contact étroit avec une surface terminale interne stationnaire (32) formée à une portion de délimitation entre le trou de diamètre moyen (8) et le trou de grand diamètre (7) du trou de guidage (6), et la surface terminale interne stationnaire (32) et la surface terminale mobile (33) sont disposées dans un plan virtuel intersecté perpendiculairement par un axe central du corps principal d'électrode (1),

    la longueur (L2) en direction de l'axe central du corps principal d'électrode (1) sur laquelle la portion de diamètre moyen (25) est insérée dans le trou de diamètre moyen (8) est configurée pour être plus petite que la longueur (L1) sur laquelle la broche de guidage (12) se déplace vers l'arrière durant le soudage,

    une unité de pressurisation qui presse la surface terminale mobile (33) contre la surface terminale interne stationnaire (32) est disposée dans le trou de guidage (6),

    et caractérisée en ce que :

    la dimension de la largeur (W1) de la surface terminale mobile (33) vue en direction du diamètre du corps principal d'électrode (1) est une dimension obtenue en soustrayant la dimension de l'épaisseur (W2) de la portion de diamètre moyen (25) à une position où la broche de guidage (12) est insérée de la dimension de l'épaisseur (W3) de la portion de grand diamètre (24) à la position où la broche de guidage (12) est insérée, et

    la dimension de la largeur (W1) de la surface terminale mobile (33) vue en direction du diamètre du corps principal d'électrode (1) est inférieure à la moitié de la dimension de l'épaisseur (W3) de la portion de grand diamètre (24) à la position où la broche de guidage (12) est insérée, et la superficie de la surface terminale mobile (33) est configurée pour être petite afin d'augmenter la force de pressurisation de la surface terminale mobile (33) contre la surface terminale interne stationnaire (32), de telle sorte qu'une pièce métallique minuscule (34) entrant dans une position de contact étroit entre la surface terminale mobile (33) et la surface terminale interne stationnaire (32) est poussée de la surface terminale mobile (33) dans un matériau de base de la partie coulissante (13), et

    la dimension de la largeur (W1) de la surface terminale mobile (33) vue en direction du diamètre du corps principal d'électrode (1) est inférieure à la moitié de la dimension de l'épaisseur (W3) de la portion de grand diamètre (24) à la position où la broche de guidage (12) est insérée, et la dimension de l'épaisseur (W2) de la portion de diamètre moyen (25) est configurée pour être plus grande de manière à recevoir une force externe exercée sur la broche de guidage (12) en direction du diamètre du corps principal d'électrode (1), et

    le ratio de la dimension de la largeur (W1) de la surface terminale mobile (33) par la dimension de l'épaisseur (W3) de la portion de grand diamètre (24) à la position où la broche de guidage (12) est insérée est inférieur à 0,5 et supérieur ou égal à 0,3.


     
    2. Procédé pour maintenir l'étanchéité à l'air d'une électrode de soudage par résistance électrique, le procédé comprenant :

    la formation d'un corps principal d'électrode (1) qui présente une section transversale circulaire à partir d'un matériau métallique tel que le cuivre ;

    la formation d'une broche de guidage (12) qui présente une section transversale circulaire, se projette depuis une surface terminale du corps principal d'électrode (1) sur laquelle est placé un composant de plaque en acier (3), et pénètre dans un trou pilote (10) du composant de plaque en acier (3) à l'aide d'un matériau dur résistant à la chaleur tel qu'un matériau métallique ou un matériau céramique ; et

    la formation d'une partie coulissante (13) qui présente une section transversale circulaire, est insérée dans un trou de guidage (6) formé dans le corps principal d'électrode (1) dans un état coulissant, et comporte une portion centrale dans laquelle la broche de guidage (12) est insérée, à partir d'un matériau en résine synthétique, dans lequel

    le trou de guidage (6) est constitué d'un trou de grand diamètre (7), d'un trou de diamètre moyen (8) et d'un trou de petit diamètre (9),

    une portion de grand diamètre (24) formée dans la partie coulissante (13) est insérée dans le trou de grand diamètre (7) dans un état coulissant substantiellement sans intervalle,

    une portion de diamètre moyen (25) formée dans la partie coulissante (13) est insérée dans le trou de diamètre moyen (8) dans un état coulissant substantiellement sans intervalle,

    un intervalle de ventilation (26) à travers lequel passe de l'air de refroidissement est formé entre le trou de petit diamètre (9) et la broche de guidage (12) quand la broche de guidage (12) est poussée vers le bas par la broche de guidage (12) qui pénètre dans le trou de petit diamètre (9),

    une surface terminale mobile (33) formée à une portion de délimitation entre la portion de diamètre moyen (25) et la portion de grand diamètre (24) de la partie coulissante (13) est configurée pour être en contact étroit avec une surface terminale interne stationnaire (32) formée à une portion de délimitation entre le trou de diamètre moyen (8) et le trou de grand diamètre (7) du trou de guidage (6), et la surface terminale interne stationnaire (32) et la surface terminale mobile (33) sont disposées dans un plan virtuel intersecté perpendiculairement par un axe central du corps principal d'électrode (1),

    la longueur (L2) en direction de l'axe central du corps principal d'électrode (1) sur laquelle la portion de diamètre moyen (25) est insérée dans le trou de diamètre moyen (8) est configurée pour être plus petite que la longueur (L1) sur laquelle la broche de guidage (12) se déplace vers l'arrière durant le soudage,

    une unité de pressurisation qui presse la surface terminale mobile (33) contre la surface terminale interne stationnaire (32) est disposée dans le trou de guidage (6),

    et caractérisé en ce que :

    la dimension de la largeur (W1) de la surface terminale mobile (33) vue en direction du diamètre du corps principal d'électrode (1) est une dimension obtenue en soustrayant la dimension de l'épaisseur (W2) de la portion de diamètre moyen (25) à une position où la broche de guidage (12) est insérée de la dimension de l'épaisseur (W3) de la portion de grand diamètre (24) à la position où la broche de guidage (12) est insérée, et

    la dimension de la largeur (W1) de la surface terminale mobile (33) vue en direction du diamètre du corps principal d'électrode (1) est inférieure à la moitié de la dimension de l'épaisseur (W3) de la portion de grand diamètre (24) à la position où la broche de guidage (12) est insérée, et la superficie de la surface terminale mobile (33) est configurée pour être petite afin d'augmenter la force de pressurisation de la surface terminale mobile (33) contre la surface terminale interne stationnaire (32), de telle sorte qu'une pièce métallique minuscule (34) entrant dans une position de contact étroit entre la surface terminale mobile (33) et la surface terminale interne stationnaire (32) est poussée de la surface terminale mobile (33) dans un matériau de base de la partie coulissante (13), et

    la dimension de la largeur (W1) de la surface terminale mobile (33) vue en direction du diamètre du corps principal d'électrode (1) est inférieure à la moitié de la dimension de l'épaisseur (W3) de la portion de grand diamètre (24) à la position où la broche de guidage (12) est insérée, et la dimension de l'épaisseur (W2) de la portion de diamètre moyen (25) est configurée pour être plus grande de manière à recevoir une force externe exercée sur la broche de guidage (12) en direction du diamètre du corps principal d'électrode (1) par la portion de diamètre moyen (25), et

    le ratio de la dimension de la largeur (W1) de la surface terminale mobile (33) par la dimension de l'épaisseur (W3) de la portion de grand diamètre (24) à la position où la broche de guidage (12) est insérée est inférieur à 0,5 et supérieur ou égal à 0,3.


     




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    Cited references

    REFERENCES CITED IN THE DESCRIPTION



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    Patent documents cited in the description