JP2011000637A - Electrode with discrimination cap and welding method for electric resistance welding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrode with discrimination cap which prevents activation of welding current when posture of a projection nut is abnormal, without necessity to judge whether posture of the nut is normal or not through detecting change of stroke length of a movable electrode.SOLUTION: The discrimination cap 38 is composed of an edge plate part 39 stuck to the edge 21 of electrode body 16 and a cylindrical part 40 stuck to its outer circumferential face. The cap works as a conductive portion and its inner face is covered by an insulation layer 41. In the normal posture in which projections 4 for welding deposit of the projection nut 1 come upside, while the movable electrode 13 proceeds, a steel plate component 10 and a guide pin 20 are pressed downward together, a body part of the nut 1 is closely contacted to a conductive face 21 pressing the projections 4 for welding deposit. In this state, welding current is conducted through the movable electrode 13, the steel plate component 10, the projections 4 for welding deposit and the conductive face 21, so that the nut 1 is welded to the steel plate component 10. In the case of the abnormal posture when the projections 4 for welding deposit come downward, the current is shielded by the insulation layer 41.

Description

  In the present invention, a part to be subjected to electric resistance welding is formed with a main body part in which a through hole is formed and a protruding part that protrudes in a diameter direction and an axial direction of the through hole on one side of the main body part. The present invention relates to an electrode with a discrimination cap capable of discriminating the front and back of such parts and a welding method.

  Japanese Patent No. 2837817 describes that a recess having a shallow depth for receiving a projection nut is formed on the end face of the movable electrode, and a guide pin that enters the screw hole of the nut is provided on the fixed electrode. When the nut is supported by the guide pin in a correct posture, a part of the nut is correctly accommodated in the recessed portion of the movable electrode that has advanced. On the other hand, when the nut is supported facing away from the guide pin, the nut is not accommodated in the recess. Thus, it is described that an abnormality in the nut posture is detected based on a difference between the strokes of the movable electrodes when the nut enters the recess in a correct posture and when the nut is in an abnormal posture.

  When the technique described in this Japanese Patent No. 2837817 is observed in more detail, a steel plate part is placed on a fixed electrode provided with a guide pin, and the concave portion that receives a nut in a normal posture is formed on the end face of the movable electrode. ing. When the movable electrode advances to a position where the nut is supported by the guide pin in a normal posture, the nut correctly fits into the recess, and the stroke advance position of the movable electrode at this time is detected and the welding current is supplied. Is made.

  If the nut is positioned on the steel plate part in an abnormal posture as if it is facing down, the stroke length of the movable electrode changes compared to the normal case. Energization is stopped.

Japanese Patent No. 2837817

  Before explaining the problem, the shape of the component will be described.

  The shapes of the parts targeted in the present invention are shown in FIGS. 5 (A) and 5 (B). FIG. 5A is a perspective view of an iron projection nut 1, and the projection nut may be simply expressed as a nut in the following description. A screw hole 3 is formed in the center of the main body 2 that is a square. The welding projections 4 are formed at the four corners on one side of the main body 2. The welding protrusion 4 protrudes in the diameter direction and the axial direction of the screw hole 3, that is, in an oblique direction.

  The dimensions of each part of the nut 1 are as follows: the length of one side of the square of the main body 2 is 12 mm, the inner diameter of the screw hole 3 is 6 mm, the height of the main body 2 in the axial direction of the screw hole 3 is 7 mm, and the welding protrusion 4 is The protruding length of the screw hole 3 protruding in the diameter direction is 1.5 mm, and the protruding length of the welding protrusion 4 protruding in the axial direction of the screw hole 3 is 1.5 mm. Therefore, the form of the nut 1 is such that a main body portion in which a through hole is formed and a protruding portion that protrudes in the diameter direction and the axial direction of the through hole are formed on one side of the main body portion.

  As a part similar to the nut 1, there is an iron circular part 5 shown in FIG. The circular part 5 is also formed with a cylindrical body part 2 similar to the nut 1, a screw hole 3, and a flange part 6 corresponding to the welding protrusion 4. A welding protrusion 7 is formed on the lower surface of the flange portion 6.

  As shown in FIG. 5C, guide pins 9 are arranged on the fixed electrode 8 described in the above patent document, and a steel plate component 10 is placed on the fixed electrode 8. The movable electrode 11 corresponding to the fixed electrode 8 is arranged in a state where it can advance and retreat, and a concave portion 12 having a shallow depth is formed on its end face. FIG. 5C shows a case where the nut 1 is supported by the guide pin 9 in a normal posture (frontward). In this state, the main body 2 of the nut is housed in the recess 12, the advance position of the illustrated movable electrode 11 is detected as normal, and a welding current is applied.

  On the other hand, when the nut 1 is supplied onto the steel plate part 10 with the nut 1 facing away from the guide pin 9, the stroke length of the movable electrode 11 changes because the nut 1 does not enter the recess 12. This amount of change is detected, and the energization of the welding current is stopped in advance. That is, the detection means detects the difference between the electrode stroke length in the normal posture with the welding projection 4 on the lower side and the electrode stroke length in the abnormal posture with the welding projection 4 on the upper side, When normal, the welding current is applied, and when abnormal, the welding current is stopped.

  The problem to be solved by the invention will be described.

  In the case of detecting an abnormal state by such a difference in stroke length, the difference dimension is very small so as to be obtained from the protrusion dimension (1.5 mm) of the welding protrusion 4 described above. It is difficult to detect. The process environment in which electric resistance welding is performed usually involves scattering of impurities such as spatter at high temperatures, so it is difficult to accurately detect minute dimensions with detection means such as limit switches and optical means. is there. That is, the detection reliability of the abnormal posture cannot be ensured. At the same time, since the detection means is installed, it is structurally complicated, and further measures for protecting the detection means must be taken, which is disadvantageous in terms of structure.

  Alternatively, if the nut 1 is face down, the welding protrusion 4 may abut against the end surface of the recess 12 to damage the surface 12 of the movable electrode 11.

  The present invention is provided in order to solve the above-described problems. When the component posture is abnormal, it is impossible to energize the welding current in the electrode local area, and the electrode is not damaged. It is another object of the present invention to provide an electrode with a discrimination cap for electric resistance welding and a welding method capable of reliably energizing a welding current in an electrode local area in a normal component posture.

  The invention according to claim 1 is an invention of an electrode, and a part to be subjected to electric resistance welding includes a main body part in which a through hole is formed and a diameter direction and an axial direction of the through hole on one side of the main body part. A projecting protrusion is formed, and a guide pin that advances and retreats coaxially with the central axis of the electrode body and enters the through hole of the component is provided in a state of projecting from the end surface of the electrode body. A discriminating cap composed of an end plate portion that is in close contact with the end surface and a cylindrical portion that is in close contact with the outer peripheral surface of the electrode main body is assembled to the electrode main body while being insulated from the electrode main body, and the main body portion of the component enters. A receiving hole that is coaxial with the guide pin is formed in the end plate portion, an end surface of the electrode body that forms the bottom of the receiving hole is a conduction current conducting surface, and the receiving hole receives the body portion. Can The protrusion side is determined capped electrodes of the electric resistance welding, characterized in that there is a diameter which can not be accepted.

  When the orientation of the part is normal, with the guide pin inserted into the through hole of the part and the relative position of the main body and the receiving hole set correctly, the main body A part of enters into the receiving hole. In other words, the guide pin stands upright at the center of the receiving hole, so that the centering of the receiving hole and the parts is accurately performed, and the distance between the inner peripheral surface of the receiving hole and the outer surface of the main body is minimized. Can do. And since the end surface of the electrode main body which forms the bottom part of the said receiving hole is made into the conduction current conduction surface, the state which can supply a welding current immediately to the components of a normal attitude | position is formed. That is, since a state in which the components in the normal posture can be conducted at the local portion of the conduction surface of the electrode body is completed, reliable energization of the welding current is executed, and highly reliable electric resistance welding is realized. Since the contact between the normal posture component and the conductive surface is thus established, the welding current may be mechanically energized in conjunction with the operation stroke of the electrode, and the control structure such as the energization control circuit is simple. Is economical. Furthermore, it is not necessary to install the detection means as described above, which is effective for simplifying the structure and improving operation reliability.

  When the orientation of the component is abnormal, the guide pin is inserted into the through-hole of the component and the relative position between the protruding portion and the receiving hole is set correctly, and the diameter dimension of the receiving hole is Since the portion side is set to an unacceptable value, the protruding portion reliably hits the end plate portion of the discrimination cap. In other words, since the guide pin is erected at the center of the receiving hole, the centering of the end plate surface around the receiving hole and the projecting part of the component is accurately performed, and the projecting part is securely attached to the end plate part. The projecting portion does not contact the conductive surface. At the same time, since the discrimination cap is insulated from the electrode body, no current flows through the component even if a welding current is applied while the component is in an abnormal orientation. In this way, when the component posture is abnormal, even if the welding current is mechanically energized in conjunction with the operation stroke of the electrode, the energization is automatically blocked at the electrode local area by the insulating configuration. Therefore, energization is automatically blocked for abnormal component postures, and it is not necessary to specially install the detection means as described above.

  The invention according to claim 2 is the electrode with a discrimination cap for electric resistance welding according to claim 1, wherein the ratio of the diameter of the end face of the electrode body to the diameter of the receiving hole is 1.1 to 1.7.

  With such a configuration, the shape of the portion where the end plate portion and the end surface of the electrode body are in close contact with each other can be made annular, and the load acting on the end plate portion can be uniformly received by the annular portion, and the stable load The burden is realized. Furthermore, since the above ratio is set to 1.1 to 1.7, the area of the annular portion can be made sufficiently large, and a stable load burden is made.

  According to a third aspect of the present invention, the fixing bolt made of an insulating material is screwed into the cylindrical portion, and the outer peripheral surface of the electrode main body is pressed by the tip of the fixing bolt. It is an electrode with a discrimination cap for electrical resistance welding.

  Since the fixing bolt is made of an insulating material, it is not electrically short-circuited even if it is screwed into the discrimination cap. In other words, when the component is in an abnormal posture, the insulation state between the discrimination cap and the electrode body must be maintained. Thus, reliable insulation can be achieved by using such an insulating fixing bolt. In addition, the discrimination cap and the electrode body are integrated.

  A fourth aspect of the present invention is the electrode with a discrimination cap for electric resistance welding according to any one of the first to third aspects, wherein a magnet for attracting a component is attached in the guide pin.

  Since the component is attracted to the guide pin by the attractive force of the magnet, the component is reliably supported by the guide pin, and even if any member contacts the component, the component does not come off the guide pin. Even in the case of an electrode arrangement in which the guide pin extends downward, the component is securely held without falling from the guide pin.

  The invention according to claim 5 is the electrode with a discrimination cap for electric resistance welding according to any one of claims 1 to 4, wherein an insulating member made of an insulating material is attached to the inner surface of the discrimination cap.

  Since the insulating member made of an insulating material is attached to the inner surface of the discrimination cap in this way, the discrimination cap can be made into a two-layer structure, and an insulating state is formed by simply attaching the discrimination cap to the electrode body. And workability such as disassembly is improved.

  The invention according to claim 6 is an invention of a welding method, and a part to be subjected to electric resistance welding includes a main body portion in which a through hole is formed and a diameter direction and an axial direction of the through hole on one side of the main body portion. The electrode body is provided with a guide pin protruding from the end face of the electrode body, which is projected on the same axis as the central axis of the electrode body and advances into and retracts from the end face of the electrode body. A discriminating cap composed of an end plate portion that is in close contact with the end surface of the electrode and a cylindrical portion that is in close contact with the outer peripheral surface of the electrode body is assembled to the electrode body in a state of being insulated from the electrode body, and the main body portion of the component enters. In addition, a receiving hole that is coaxial with the guide pin is formed in the end plate portion, an end surface of the electrode main body that forms the bottom of the receiving hole is a conduction current conducting surface, and the receiving hole receives the main body portion. Can However, when the part is in a normal posture, the welding current is applied when the part is in contact with the conductive surface, and when the part is in an abnormal posture, The welding method is characterized in that the projecting portion side contacts only the end plate portion of the discrimination cap to form a state in which the energization path of the welding current is blocked in advance so that the welding current is not energized to the component.

  As the energization control of the welding current according to the part orientation, when the part is in a normal posture, the welding current is energized while the main body of the component is in contact with the conductive surface, and when the component is in an abnormal posture, the protruding side of the component is discriminated. By contacting only the end plate portion of the cap, a state in which the energization path of the welding current is interrupted in advance is formed so that the welding current is not applied to the component. Therefore, while pursuing the effect of the above-described electrode invention, the energization control of the welding current according to the component posture is automatically performed according to the state of the component posture.

It is each part sectional drawing of an electrode. It is sectional drawing which shows the discrimination state of a projection nut. It is the top view and sectional drawing which show the dimension state of a receiving hole. It is sectional drawing which shows another Example. It is sectional drawing which shows the perspective view of components, and the abnormal attitude | position of a nut.

  Next, an embodiment for carrying out an electrode with a discrimination cap for electric resistance welding and a welding method of the present invention will be described.

  1, 2 and 3 show Example 1. FIG.

  The target component in this embodiment is the projection nut 1 shown in FIG.

  Example 1 is a case where the present invention is applied to the fixed electrode 14 side. The fixed electrode 14 is inserted into the stationary member 15. The fixed electrode 14 has a guide pin structure described later incorporated in a cylindrical electrode body 16. The electrode body 16 is formed by screwing a second body 18 into a first body 17. Reference numeral 19 denotes a screw portion including a male screw and a female screw to be screwed in. The first main body 17 and the second main body 18 are made of a metal material having good conductivity and heat resistance. Here, chrome copper is used.

  A movable electrode 13 indicated by a two-dot chain line is arranged at a position coaxial with the fixed electrode 14 in a state where the movable electrode 13 can advance and retreat. The nut 1 is in a normal posture when the welding protrusion 4 is positioned on the upper side, and a guide pin 20 described later penetrates the screw hole 3 in a so-called reverse direction. On the upper side, a steel plate part 10 supported by a jig (not shown) is inserted.

  A guide pin 20 that advances and retreats coaxially with the central axis OO of the electrode body 16 and enters the screw hole 3 of the nut 1 is provided in a state of protruding from the end surface 21 of the electrode body 16. The guide pin 20 is formed of a shaft-like member that relatively enters the screw hole 3 of the nut 1, and a substantially tapered inclined portion 22 is formed to engage with the end of the screw hole 3. . A through hole 24 (see FIGS. 2 and 3B) is formed in the end member 23 of the first main body 17, and the guide pin 20 protrudes from here and enters the screw hole 3. As apparent from FIG. 3B, a gap 25 is formed between the outer peripheral surface of the guide pin 20 and the inner peripheral surface of the through hole 24, and this is an air passage described later.

  The guide pin 20 is supported by a sliding member 27 having a circular cross section made of an insulating material, and the sliding member 27 is inserted into the second main body 18 in a slidable state. The sliding member 27 is made of an insulating material such as urethane resin or polypropylene resin. The guide pin 20 is inserted into a mounting hole 28 provided at the center of the sliding member 27, and a coupling bolt 29 integral with the guide pin 20 is passed through the sliding member 27 and tightened with a fixing nut 30. 20 and the sliding member 27 are integrated.

  A spring receiver insulating member 31 is disposed on the inner end surface portion of the second main body 18, one end of the compression coil spring 32 is seated on the sliding member 27, and the other end is seated on the spring receiver insulating member 31. A compression coil spring 32 is employed as the biasing means, but it can be biased by air pressure instead.

  A flat end surface 33 formed on the sliding member 27 can be brought into close contact with the inner end surface 34 of the first main body 17. And the protrusion length of the guide pin 20 is set in this closely_contact | adhered state. As shown in FIG. 1C, an axial plane portion is formed on the outer peripheral surface of the sliding member 27, thereby forming an air passage 35. An air inlet hole 36 is provided in the lower portion of the second main body 18.

  As a method of supplying the nut 1 to the guide pin 20, various generally known methods can be adopted. For example, a supply rod that advances and retreats in an inclined posture is passed through the screw hole 3 of the nut 1, and the supply rod performs a function like a guide rod so that the nut 1 reaches the guide pin 20 in a downhill state. Alternatively, a magnet is attached to the tip of the supply rod that performs a square motion in the horizontal direction and the vertical direction, and the nut 1 attracted by the magnet reaches the guide pin 20.

  Next, the discrimination cap will be described.

  The discriminating cap 38 is composed of a circular and flat end plate portion 39 that is in close contact with the end surface 21 of the electrode main body 16 and a cylindrical portion 40 that is in close contact with the outer peripheral surface of the electrode main body 16. Yes. This conducting portion has a cup shape as described above, and is made of a material that does not have a problem in strength even when the welding protrusion 4 of the nut 1 is pressed. Here, the conducting portion is made of stainless steel.

  An insulating layer 41 made of an insulating material is attached to the inner surface of the conducting portion. This insulating layer 41 is obtained by bonding polyamide resin to the inner surfaces of the end plate portion 39 and the cylindrical portion 40 and finishing the thickness of the layer to a predetermined value by machining. A circular receiving hole 42 is formed at the center of the end plate portion 39, and the guide pin 20 protrudes coaxially therewith. The receiving hole 42 is formed so as to penetrate both the end plate portion 39 and the insulating layer 41. As is clear from FIG. 1A, the electrode main body 16 is inserted inside the cylindrical portion 40 without a gap.

  In this embodiment, the cylindrical member in which the end plate portion 39, the cylindrical portion 40, and the insulating layer 41 are integrated is collectively referred to as a “discriminating cap 38”. However, only the insulating material having high strength and rigidity is used. A layer structure discrimination cap may be formed.

  As shown in FIG. 4D, a fixing bolt 43 made of an insulating material is screwed into the cylindrical portion 40 and the insulating layer 41, and the outer peripheral surface of the electrode body 16 is pressurized with the tip of the fixing bolt 43. By doing so, it is possible to prevent the discrimination cap 38 from coming out of the electrode body 16 and to ensure insulation. The fixing bolt 43 is made of various synthetic resins, and here a polyamide resin is employed.

  An end surface 21 of the electrode body 16 forming the bottom of the receiving hole 42 is a conduction surface 21 for welding current (the same reference numeral 21 is also given to the conduction surface). Although the receiving hole 42 can receive the main-body part 2, it is set as the diameter dimension which cannot accept the said protrusion part side, ie, the welding protrusion 4 side.

  Although not shown in FIGS. 1 to 3, a magnet can be embedded in the guide pin 20 to improve the holding stability of the nut 1 with respect to the guide pin 20.

  As shown in FIG. 3B, the diameter D1 of the receiving hole 42 is 17.5 mm, the diameter D2 of the end surface 21 of the electrode body 16 is 20.0 mm, and the diameter of the portion where the end surface 21 is in close contact with the end plate portion 39. The width dimension W1 in the direction is 1.25 mm. That is, the portion where the end surface 21 is in close contact with the end plate portion 39 is an annular area portion having a width dimension W1 of 1.25 mm. Here, the ratio of the diameter D2 of the end face 21 of the electrode body 16 to the diameter D1 of the receiving hole 42 is 1.14. Note that the length of W1 of 3 (B) is shown enlarged for easy understanding.

  The above ratio is desirably set to 1.1 to 1.7. If this ratio is less than 1.1, the width dimension W1 becomes too narrow, the pressure receiving area becomes insufficient, and the load of the movable electrode 13 acting on the component in the abnormal posture cannot be sufficiently received. If the ratio exceeds 1.7, the diameter of the receiving hole 42 may not be sufficiently large, or the diameter of the electrode body 16 may be excessive, making it difficult to arrange the electrodes in a narrow place.

  Next, the operation of this embodiment will be described.

  The nut 1 shown in FIG. 1A is in a normal posture with the welding protrusion 4 on the upper side. When the movable electrode 13 advances in such a state, the steel plate part 10 and the guide pin 20 are pushed down together. At this time, the sliding member 27 compresses the compression coil spring 32 while sliding in the second main body 18. When the movable electrode 13 further advances, as shown in FIGS. 2 (A) and 3 (A), the nut 1 accurately enters the receiving hole 42 while being centered by the guide pin 20, and the main body 2 is conducted. Close contact with the surface 21. When the movable electrode 13 further advances, the guide pin 20 is pushed down to pressurize the welding projection 4 as indicated by the two-dot chain line in the steel plate part 10. When an energization signal of the welding current is output from the control device (not shown) in this stroke state, the welding current is energized through the movable electrode 13, the steel plate component 10, the welding protrusion 4, and the conduction surface 21, and the steel plate The nut 1 is welded to the component 10.

  As described above, when the movable electrode 13 advances most and starts to retract from the position where the welding is completed, the main body 2 is separated from the conductive surface 21. With this separated state, the cooling air passes through the air passage 35 and the gap 25 from the inlet hole 36 to cool the upper portion of the fixed electrode 14.

  The nut 1 shown in FIG. 2 (B) has an abnormal posture in which the welding protrusion 4 is on the lower side. When the movable electrode 13 advances in such a state, the steel plate part 10 and the guide pin 20 are pushed down together. At this time, the sliding member 27 compresses the compression coil spring 32 while sliding in the second main body 18. When the movable electrode 13 further advances, as shown in FIG. 2B, the welding projection 4 contacts the end plate 39 around the receiving hole 42 while the nut 1 is centered by the guide pin 20. This contact is made at a position on the circumference that is concentric with the receiving hole 42 by the centering. At this time, the welding protrusion 4 does not contact the conductive surface 21. When the movable electrode 13 further advances, the guide pin 20 is pushed down to pressurize the main body 2 as indicated by the two-dot chain line in the steel plate part 10. When an energization signal of the welding current is output from the control device (not shown) in this stroke state, the welding current flows to the movable electrode 13, the steel plate component 10, the welding protrusion 4, and the end plate portion 39. Insulation is prevented by the insulating layer 41. Therefore, even if the welding current is applied, the nut 1 is automatically cut off by the insulating layer 41 without contacting the conduction surface 21.

  In the above description, the electrode to which the discrimination cap 38 is attached is in a stationary state. Instead, the electrode to which the discrimination cap 38 is attached is advanced upward so that the electrode 13 is in close contact with the electrode 13 in a stationary state. It is also possible to perform nut welding on the steel plate part 10 that is provided.

  In the above-described embodiment, the rectangular projection nut shown in FIG. 5 (A) is targeted. However, even in the case of the circular part 5 as shown in FIG. It can be.

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

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

  When the welding protrusion 4 of the nut 1 is facing upward and is normal, the relative position between the main body 2 and the receiving hole 42 is set correctly while the guide pin 20 is inserted into the screw hole 3 that is a through hole of the component. In this state, a part of the main body 2 enters the receiving hole 42 when the movable electrode 13 advances or the electrode main body 16 advances. In other words, since the guide pin 20 is erected at the center of the receiving hole 42, the receiving hole 42 and the nut 1 are accurately centered, and the inner peripheral surface of the receiving hole 42 and the outer surface of the main body 2 are separated. The interval can be minimized. And since the end surface 21 of the electrode main body 16 which forms the bottom part of the said receiving hole 42 is made into the conduction surface 21 of a welding current, the state which can immediately apply a welding current with respect to the nut 1 of a normal attitude | position is formed. . That is, since the nut 1 in the normal posture is in a conductive state at the local portion of the conductive surface 21 of the electrode body 16, reliable energization of the welding current is executed, and highly reliable electric resistance welding is realized. . Since the contact between the nut 1 in the normal posture and the conductive surface 21 is established as described above, the welding current may be mechanically energized in conjunction with the operation stroke of the electrode. Can be simplified and economical. Furthermore, it is not necessary to install the detection means as described above, which is effective for simplifying the structure and improving operation reliability.

  When the welding protrusion 4 of the nut 1 is facing downward and is abnormal, the guide pin 20 is inserted into the screw hole 3 that is a through hole of the component, and the portion on the welding protrusion 4 side that is the protruding portion side is received. Since the relative position of the hole 42 is set correctly, and the diameter dimension of the receiving hole 42 is a value that the welding protrusion 4 cannot accept, the welding protrusion 4 is the end plate of the discrimination cap 38. It hits part 39 reliably. In other words, since the guide pin 20 is erected at the center of the receiving hole 42, the centering of the surface of the end plate 39 around the receiving hole 42 and the welding protrusion 4 is accurately performed, and the welding protrusion 4 reliably hits the end plate portion 39 and the welding projection 4 does not contact the conductive surface 21. At the same time, since the discrimination cap 38 is insulated from the electrode main body 16, no current flows through the nut 1 even if a welding current is applied while the nut 1 is in an abnormal direction. In this way, when the nut posture is abnormal, even if the welding current is mechanically energized in conjunction with the operation stroke of the electrode, the energization is automatically blocked at the electrode local area by the insulating configuration. Therefore, energization is automatically blocked for abnormalities in the nut front and back posture, and there is no need to specially install the detection means as described above.

  The ratio of the diameter D2 of the end face 21 of the electrode body 16 to the diameter D1 of the receiving hole 42 is 1.14.

  With such a configuration, the shape of the portion where the end plate portion 39 and the end surface 21 of the electrode body 16 are in close contact with each other can be made annular, and the contact width dimension W1 can be an appropriate value of 1.25 mm. it can. Therefore, the load acting on the end plate portion 39 can be uniformly received by the annular portion, and a stable load load is realized. Furthermore, since the above ratio is set to 1.1 to 1.7, the area of the annular portion can be made sufficiently large, and a stable load burden is made. The above ratio is desirably set to 1.1 to 1.7. If this ratio is less than 1.1, the width dimension W1 becomes too narrow and the pressure receiving area becomes insufficient, which acts on a component in an abnormal posture. The load of the movable electrode 13 to be received cannot be sufficiently received. If the ratio exceeds 1.7, the diameter of the receiving hole 42 may not be sufficiently large, or the diameter of the electrode body 16 may be excessive, making it difficult to arrange the electrodes in a narrow place.

  A fixing bolt 43 made of an insulating material is screwed into the cylindrical portion 40, and the outer peripheral surface of the electrode body 16 is pressurized with the tip portion of the fixing bolt 43.

  Since the fixing bolt 43 is made of an insulating material, it is not electrically short-circuited even if it is screwed into the discrimination cap 38. That is, when the nut 1 is in an abnormal posture, the insulating state between the conductive portion of the discrimination cap 38 and the electrode body 16 must be maintained. By using it, reliable insulation can be ensured, and the discrimination cap 38 and the electrode body 16 are integrated.

  A magnet for attracting parts is mounted in the guide pin 20.

  Since the nut 1 is attracted to the guide pin 20 by the attractive force of the magnet, the nut 1 is reliably supported by the guide pin 20, and the nut 1 is detached from the guide pin 20 even if any member contacts the nut 1. Do not do. Even when the electrode arrangement is such that the guide pin 20 extends downward, the nut 1 is securely held without dropping from the guide pin 20.

  An insulating layer 41 made of an insulating material is disposed on the inner surfaces of the end plate portion 39 and the tube portion 40.

  Since the insulating layer 41 made of an insulating material is attached to the inner surface of the conductive portion of the discrimination cap 38 in this way, the discrimination cap 38 can be made into a two-layer structure, and the discrimination cap 38 is simply assembled to the electrode body 16. As a result, an insulating state is formed, and workability such as assembly and disassembly is improved.

  As an invention of the welding method, a projection nut 1 to be subjected to electric resistance welding includes a main body portion 2 in which a screw hole 3 as a through hole is formed, and a diameter direction of the screw hole 3 on one side of the main body portion 2. A welding protrusion 4 protruding in the axial direction is formed, and a guide pin 20 that advances and retreats coaxially with the central axis OO of the electrode body 16 and enters the screw hole 3 of the nut 1 is provided on the electrode body 16. A discriminating cap 38 that is provided in a state of protruding from the end surface 21 and is composed of an end plate portion 39 that is in close contact with the end surface 21 of the electrode main body 16 and a cylindrical portion 40 that is in close contact with the outer peripheral surface of the electrode main body 16. The end plate 39 is formed with a receiving hole 42 which is assembled to the electrode body 16 in an insulated state, and the body 2 of the nut 1 enters and is coaxial with the guide pin 20. The end surface 21 of the electrode body 16 that forms the bottom of the receiving hole 42 is a welding current conducting surface 21, and the receiving hole 42 can receive the body 2, but the welding projection 4 side that is the protruding portion side. This diameter is unacceptable, and when the nut 1 is in a normal posture, a welding current is applied with the main body 2 of the nut 1 in contact with the conducting surface 21, and when the nut 1 is in an abnormal posture, the nut 1 1, the welding projection 4 side contacts only the end plate portion 39 of the discrimination cap 38, thereby forming a state in which the energization path of the welding current is interrupted in advance so that the welding current is not energized to the nut 1. It is what.

  As the energization control of the welding current according to the nut posture, when the nut 1 is in the normal posture, the welding current is energized with the main body portion 2 of the nut 1 in contact with the conduction surface 21, and when the nut 1 is in the abnormal posture, the nut The welding projection 4 side of 1 contacts only the end plate portion 39 of the conducting portion of the discrimination cap 38 to form a state in which the energization path of the welding current is interrupted in advance, so that the welding current is not energized to the nut 1. Is. Therefore, while pursuing the effect of the embodiment of the electrode described above, the energization control of the welding current accompanying the nut posture is automatically performed according to the state of the component posture.

  FIG. 4 shows a second embodiment.

  In the first embodiment, the guide pin 20 stands up and the nut 1 is placed on the guide pin 20. In the second embodiment, the guide pin 20 extends downward. Thus, the vertical relationship of neighboring members is opposite to that of the first embodiment.

  In order to prevent the nut 1 from falling, a magnet (permanent magnet) 44 is embedded in the guide pin 20, and thereby the nut 1 is attracted to the guide pin 20. Other configurations are the same as those of the first embodiment including the portions not shown, and members having the same functions are denoted by the same reference numerals. The operational effects are the same as in the previous embodiment.

  As described above, according to the present invention, when the component posture is abnormal, it is impossible to energize the welding current at the electrode local area, the electrode is not damaged, and the normal component posture is maintained. Sometimes, an electrode with a discrimination cap for electric resistance welding and a welding method capable of reliably energizing the welding current in the electrode local area. 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 Projection nut, components 2 Main body part 3 Screw hole 4 Welding protrusion 10 Steel plate part 13 Movable electrode 14 Fixed electrode 16 Electrode main body OO Center axis 20 Guide pin 21 End surface, Conductive surface 38 Discriminating cap 39 End plate part 40 Tube part 41 Insulating layer 42 Receiving hole D1 Receiving hole diameter D2 Diameter of electrode body end face W1 Contact width

Claims (6)

  A part to be subjected to electric resistance welding is a body part in which a through-hole is formed and a projecting part that projects in the diameter direction and the axial direction of the through-hole on one side of the body part. A guide pin that advances and retreats coaxially with the central axis of the main body and enters the through-hole of the component is provided in a state of protruding from the end surface of the electrode main body, and is provided on the end plate portion that is in close contact with the end surface of the electrode main body and the outer peripheral surface of the electrode main body. A discriminating cap composed of an intimate cylindrical portion is assembled to the electrode body in an insulated state with respect to the electrode body, and a receiving hole that is coaxial with the guide pin while the body portion of the component enters the end The end surface of the electrode body that is formed in the plate portion and forms the bottom of the receiving hole is a conduction current conducting surface, and the receiving hole can receive the main body portion but cannot receive the protruding portion side. Electric resistance welding of discriminated capped electrode, characterized in that there is a diameter.   2. The electrode with a discrimination cap for electrical resistance welding according to claim 1, wherein a ratio of a diameter of an end face of the electrode body to a diameter of the receiving hole is 1.1 to 1.7.   The electrode with a discrimination cap for electric resistance welding according to claim 1 or 2, wherein a fixing bolt made of an insulating material is screwed into the cylindrical portion, and an outer peripheral surface of the electrode body is pressurized by a tip portion of the fixing bolt. .   The electrode with a discrimination cap for electrical resistance welding according to any one of claims 1 to 3, wherein a magnet for attracting a component is attached in the guide pin.   The electrode with a discrimination cap for electric resistance welding according to claim 1, wherein an insulating member made of an insulating material is attached to an inner surface of the discrimination cap.   A part to be subjected to electric resistance welding is a body part in which a through-hole is formed and a projecting part that projects in the diameter direction and the axial direction of the through-hole on one side of the body part. A guide pin that advances and retreats coaxially with the central axis of the main body and enters the through-hole of the component is provided in a state of protruding from the end face of the electrode main body, and is attached to the end plate portion that is in close contact with the end face of the electrode main body A discriminating cap composed of an intimate cylindrical portion is assembled to the electrode body in an insulated state with respect to the electrode body, and a receiving hole that is coaxial with the guide pin while the body portion of the component enters the end The end surface of the electrode body that is formed in the plate portion and forms the bottom of the receiving hole is a conduction current conducting surface, and the receiving hole can receive the main body portion but cannot receive the protruding portion side. When the part is in a normal position and the part is in a normal posture, the welding current is applied with the main part of the part in contact with the conductive surface. When the part is in an abnormal position, the protruding part of the part is only on the end plate of the discrimination cap. A welding method characterized by forming a state in which an energization circuit of a welding current is interrupted in advance by contact so that the welding current is not energized to a component.

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