JP2017209708A - Welding device of nut - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve weld quality by suppressing adhesion of sputter onto a screw hole of a nut, and by suppressing adhesion of sputter or soot onto a metallic member to which the nut is welded.SOLUTION: A welding device 1 includes a bottom electrode 10 abutting on a steel sheet 102, and an upper electrode 20 abutting on a nut 100. The upper electrode 20 is provided with an air supply pipe 26 through which compressed air is supplied. The downstream side of the air supply pipe 26 communicates with the opposite side to the steel sheet 102 in a screw hole 100c of the nut 100.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a nut welding apparatus for welding a nut to a metal member by projection welding that concentrates a welding current by utilizing the shape of a material to be welded, and in particular, spatter and soot generated at the time of welding cause the inner surface of the nut or metal The present invention belongs to the technical field of a structure that suppresses adhesion to members.

  For example, when welding a weld nut to a steel plate, the convex portion formed on the weld nut is brought into contact with the steel plate, the weld nut and the steel plate are sandwiched between the fixed electrode and the movable electrode, and the convex portion is energized between these electrodes. A projection welding method is used in which current is concentrated to melt the convex portion (see, for example, Patent Documents 1 and 2).

  In the fixed electrode of Patent Document 1, a pilot pin that is inserted through the screw hole of the nut is provided so as to protrude upward. The nut can be projection welded to the upper surface of the steel plate with the upper side of the pilot pin inserted through the steel plate and the screw hole. A vertical groove extending in the vertical direction is formed on the outer peripheral surface of the pilot pin. The lower side of the vertical groove is fixed to the base cylinder part. Air is supplied to the base cylinder portion. And after the air supplied to the base cylinder part flows into the lower side of the vertical groove of the pilot pin, it flows upward in the vertical groove and flows into the screw hole.

  The electrode tip holder of the upper electrode of Patent Document 2 is formed with an electrode tip attachment hole to which the electrode tip is inserted and attached, and between the inner peripheral surface of the electrode tip attachment hole and the outer peripheral surface of the electrode tip. A gap is formed. Air is supplied to the inside of the electrode tip mounting hole of the electrode tip holder, and this air passes through the gap between the inner peripheral surface of the electrode tip mounting hole and the outer peripheral surface of the electrode tip. It is designed to spout downward toward the surroundings.

JP-A-6-320288 JP 2013-111153 A

  By the way, during projection welding, spatter and soot are generated mainly from the convex portion. Since spatter and soot are scattered over a wide range, they may adhere to the inner surface of the nut or the surface of the steel plate. If spatter adheres to the inner surface of the nut, screw threading failure occurs. Therefore, after the welding process, it is necessary to perform screw sieving in order to remove the spatter adhered to the inner surface of the screw hole. Further, if spatter or soot adheres to the surface of the steel sheet, it may cause a poor appearance or cause rust due to poor coating.

  As a method for suppressing spatter from adhering to the screw hole of the nut, a method of flowing air from the lower side to the upper side of the nut as in Patent Document 1 can be considered. However, since the spatter is generated at the convex portion provided on the lower surface of the nut, when air is flowed from the lower side to the upper side as in Patent Document 1, the spatter generated near the lower surface of the nut becomes the air flow. There is a risk that it rides on the screw hole and adheres directly to the inner surface of the screw hole. In particular, in Patent Document 1, since the pilot pin is inserted into the screw hole of the nut, it is conceivable that the air flow tends to flow toward the inner surface of the screw hole, and the spatter easily adheres to the inner surface of the screw hole.

  Further, as a method for suppressing spatter and soot from adhering to the surface of the steel sheet, as in Patent Document 2, from the gap between the inner peripheral surface of the electrode tip mounting hole of the upper electrode and the outer peripheral surface of the electrode tip around the nut. A method of jetting air toward the camera can be considered. Although it may be possible to suppress spatter and soot from adhering to the surface of the steel sheet by this method, it is considered that spatter does not adhere to the inner surface of the screw hole of the nut.

  The present invention has been made in view of such a point, and an object of the present invention is to prevent spatter from adhering to the screw hole of the nut and to sputter the metal member to which the nut is welded. It is to improve welding quality by suppressing the adhesion of soot and soot.

  In order to achieve the above object, in the present invention, air is supplied from the side opposite to the welding side to the metal member in the nut to blow off the spatter and soot to the outside of the screw hole, and the spatter and soot are made of metal. Made it difficult to adhere to members.

The first invention is
In a nut welding apparatus for projection welding a nut having a screw hole with both ends opened in the center line direction to a metal member,
The welding apparatus includes: a first electrode that contacts the metal member from a side opposite to the side on which the nut is welded; and a second electrode that contacts the nut from a side opposite to the metal member. And
The second electrode is provided with an air supply pipe to which compressed air is supplied,
The downstream side of the air supply pipe communicates with the opposite side of the screw hole of the nut to the metal member.

  According to this configuration, when projection welding is performed in a state where the first electrode is in contact with the metal member and the second electrode is in contact with the nut, the compressed air supplied to the air supply pipe of the second electrode is The screw hole of the nut flows into the screw hole from the side opposite to the metal member. Since the flow of compressed air inside the screw hole is directed from the opposite side to the metal member side, the spatter generated between the nut and the metal member hardly flows into the screw hole. . Thereby, it becomes difficult for spatter to adhere to the inner surface of the screw hole of the nut. In addition, until the welding is completed, the compressed air that has flowed into the screw hole of the nut escapes from the gap formed between the nut and the metal member, so that spatter and soot get on the compressed air flow. As a result, it escapes from the surface of the metal member and becomes difficult to adhere to the metal member.

According to a second invention, in the first invention,
The second electrode has a cylindrical portion that covers the nut from the side opposite to the metal member,
A downstream side of the air supply pipe is connected to the cylindrical portion.

  According to this configuration, the cylindrical portion of the second electrode is disposed so as to cover the nut, and the compressed air supplied to the air supply pipe flows into the cylindrical portion and is supplied to the screw hole of the nut.

According to a third invention, in the second invention,
The cylindrical portion has an end wall portion arranged to cover the side of the nut opposite to the metal member,
An air inflow space is provided between the end wall portion and the nut,
The downstream side of the air supply pipe is connected to the air inflow space.

  According to this configuration, since the air inflow space is provided between the end wall portion of the cylindrical portion and the nut, the compressed air flowing into the air inflow space is screwed from the side opposite to the metal member in the nut. Smoothly flows into the hole.

4th invention is 2nd or 3rd invention,
The end of the cylindrical part is in contact with the flange formed on the nut over the entire circumference.

  According to this structure, since the edge part of a cylindrical part contact | abuts over the perimeter to the flange formed in the nut, the clearance gap between a cylindrical part and a flange is minimized. Then, the compressed air supplied to the air supply pipe flows into the cylindrical portion. At this time, since the gap between the cylindrical portion and the flange is minimized, the compressed air efficiently flows into the screw hole of the nut.

According to a fifth invention, in any one of the first to fourth inventions,
The first electrode is provided with a positioning pin that penetrates the metal member and is inserted into the nut,
A gap through which compressed air flows is formed between the outer peripheral surface of the positioning pin and the inner surface of the screw hole of the nut.

  According to this configuration, the nut is positioned at a predetermined position by the positioning pin of the first electrode. The compressed air that has flowed into the screw hole of the nut flows through the gap between the outer peripheral surface of the positioning pin and the inner surface of the screw hole of the nut, so that spatter is prevented from adhering to the outer peripheral surface of the positioning pin.

According to a sixth invention, in the fifth invention,
The proximal end side of the positioning pin is inserted into a guide hole formed in the first electrode, and supported by the inner peripheral surface of the guide hole so as to advance and retreat in the center line direction of the positioning pin.
Compressed air for biasing the positioning pin in the advance direction is supplied into the guide hole of the first electrode.

  According to this configuration, since the positioning pin is advanced by the compressed air supplied to the guide hole of the first electrode, the positioning pin is surely inserted into the screw hole of the nut and the nut is positioned. At this time, it is conceivable that the compressed air in the guide hole leaks toward the advancing direction of the positioning pin, that is, the screw hole of the nut. In this case, the spatter may ride on the compressed air flow leaking from the guide hole and flow into the nut screw hole. However, in the present invention, the compressed air supplied to the air supply pipe of the second electrode is screwed on the nut. Since the hole flows into the screw hole from the side opposite to the metal member, even if compressed air leaks from the guide hole of the first electrode, the spatter does not flow into the screw hole of the nut.

  According to the first invention, the welding apparatus includes the first electrode that contacts the metal member and the second electrode that contacts the nut, and the downstream side of the air supply pipe formed in the second electrode is a screw hole of the nut. Therefore, the flow of compressed air in the screw hole flows from the side opposite to the metal member to the metal member side. Thereby, since spatter hardly flows into the screw hole, it is possible to suppress the spatter from adhering to the inner surface of the screw hole of the nut. In addition, until the welding is completed, spatter and soot escape from the surface of the metal member riding on the flow of compressed air that escapes from the gap between the nut and the metal member, so that they adhere to the metal member. Can be suppressed.

  According to the second invention, the nut is covered with the cylindrical portion of the second electrode, and the downstream side of the air supply pipe is connected to the cylindrical portion, so that the compressed air supplied to the air supply pipe is supplied to the screw hole of the nut. It is possible to make it flow in reliably.

  According to the third invention, since the air inflow space is provided between the end wall portion of the cylindrical portion and the nut, the compressed air that has flowed into the air inflow space is threaded from the side opposite to the metal member in the nut. Can flow smoothly.

  According to the fourth invention, since the end of the cylindrical portion of the second electrode is brought into contact with the flange of the nut over the entire circumference, the compressed air supplied to the air supply pipe is efficiently supplied to the screw hole of the nut. This can further increase the spatter and soot adhesion suppressing effect.

  According to the fifth aspect, the nut can be positioned at a predetermined position by the positioning pin provided on the first electrode. And since compressed air distribute | circulates the clearance gap between the outer peripheral surface of a positioning pin, and the inner surface of the screw hole of a nut, it can also suppress that a spatter adheres to the outer peripheral surface of a positioning pin.

  According to the sixth aspect, the positioning pin can be urged in the advance direction by the compressed air supplied to the guide hole of the first electrode, so that the nut can be positioned reliably. At this time, the compressed air supplied to the guide hole may leak toward the screw hole of the nut, but the compressed air supplied to the air supply pipe of the second electrode is opposite to the metal member in the screw hole of the nut. Since the air flows into the screw hole from the side, even if compressed air leaks from the guide hole, the spatter does not flow into the screw hole of the nut, and the spatter can be prevented from adhering to the inner surface of the screw hole of the nut. .

It is a longitudinal cross-sectional view of the welding apparatus of the nut which concerns on embodiment. It is FIG. 1 equivalent view which shows the state before moving an upper electrode upwards and setting a nut and a steel plate. FIG. 2 is a view corresponding to FIG. 1 showing a state in which a nut and a steel plate are set. FIG. 2 is a view corresponding to FIG. 1 showing a state in which the upper electrode is moved downward.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. It should be noted that the following description of the preferred embodiment is merely illustrative in nature, and is not intended to limit the present invention, its application, or its use.

  FIG. 1 shows a nut welding apparatus 1 according to an embodiment of the present invention. This welding apparatus 1 is an apparatus used when projection welding various nuts 100 to a steel plate 102. The nut 100 may be a nut having screw holes 100c that are open at both ends in the center line direction, and the type thereof is not particularly limited. As shown in FIG. 3 and the like, the nut 100 may be a cap nut. The nut 100 has an opening 100a into which a bolt or the like (not shown) is inserted in a surface located at the lower end in FIG. An opening 100b smaller than the opening 100a is formed on the surface formed and positioned at the upper end. The side opposite to the steel plate 102 in the nut 100 is the upper side in FIGS. 1 to 4, and the steel plate 102 side in the nut 100 is the lower side in the figure, but the upper side and the lower side are the present embodiment. In order to facilitate the explanation, the above definition is merely made, and the orientation of the nut 100 and the steel plate 102 may be used in any orientation.

  A flange 100 d is formed on the lower side of the nut 100. A plurality of convex portions 100e protruding downward are formed on the lower surface of the flange 100d at intervals in the circumferential direction. The convex portion 100e is a portion for concentrating the current supplied during welding, and although not shown, it melts during welding and almost disappears after welding.

  Moreover, the nut 100 can also be welded to metal members other than the steel plate 102, and the metal member does not need to be plate-shaped. The steel plate 102 is formed with a through hole 102 a communicating with the opening 100 a of the nut 100.

  As shown in FIG. 1, the welding apparatus 1 includes a lower electrode (first electrode) 10, an upper electrode (second electrode) 20, a drive device 30 that moves the upper electrode 20 in the vertical direction, and the lower electrode 10. A fixed base 40 and a welding current supply unit 50 (shown only in FIG. 1) are provided. The drive device 30 can be composed of a fluid pressure cylinder that expands and contracts in the vertical direction.

(Configuration of lower electrode)
The lower electrode 10 is made of a conductive metal material, contacts the steel plate 102 from the side opposite to the side on which the nut 100 is welded, and supports the steel plate 102 from below. The upper end surface of the lower electrode 10 is in contact with the lower surface of the steel plate 102. A guide hole 11 extending in the vertical direction is formed in the lower electrode 10. The guide hole 11 is formed so as to penetrate the lower electrode 10 in the vertical direction. The lower end portion of the guide hole 11 is closed by the base 40. A coil spring 12 that expands and contracts in the vertical direction is disposed below the inside of the guide hole 11.

  The lower electrode 10 is provided with positioning pins 13 for positioning the nut 100 and the steel plate 102 at predetermined positions. The positioning pin 13 is made of a metal member extending in the vertical direction. The positioning pin 13 has a lower side (base end side) of the positioning pin 13 inserted into the guide hole 11 of the lower electrode 10. The lower side of the positioning pin 13 is formed so as to be in sliding contact with the inner peripheral surface of the guide hole 11, and the positioning pin 13 is supported by the inner peripheral surface of the guide hole 11 so as to advance and retract in the center line direction (vertical direction). Has been. The lower end surface of the positioning pin 13 comes into contact with the upper end portion of the coil spring 12.

  On the upper side of the positioning pin 13, a tapered portion 13a is formed so that the cross-sectional area in the horizontal direction becomes smaller toward the upper end. A portion of the positioning pin 13 closer to the proximal end than the tapered portion 13a is inserted into the through hole 102a of the steel plate 102 and is inserted into the screw hole 100c of the nut 100, whereby the relative positioning of the nut 100 and the steel plate 102 is achieved. And the positioning of the nut 100 and the steel plate 102 with respect to the lower electrode 10 is also performed.

  Compressed air for urging the positioning pin 13 in the advance direction is supplied into the guide hole 11 of the lower electrode 10. That is, an air supply chamber 11 a is provided below the lower end surface of the positioning pin 13 in the guide hole 11, and the air supply chamber 11 a includes the inner peripheral surface of the guide hole 11, the upper surface of the base 40, and the positioning. A compartment is formed by the lower end surface of the pin 13. A lower connection pipe 16 connected to the air supply chamber 11 a is provided on the side wall of the lower electrode 10. A supply device 17 for compressed air such as factory air is connected to the upstream side of the lower connecting pipe 16. A lower control valve 18 is provided in the middle of the lower connecting pipe 16. The lower control valve 18 can be configured by a conventionally known valve device, and adjusts the pressure of the compressed air supplied to the air supply chamber 11a to a predetermined pressure set in advance. The air supply chamber 11a can be switched between a state where it is supplied and a state where it is not supplied. The lower control valve 18 can be configured by, for example, a solenoid valve, and can be controlled by a control device (not shown), for example, to stop supplying compressed air during non-welding and to supply compressed air during welding. .

  The pressure of the compressed air supplied to the air supply chamber 11a can be set to about 0.15 MPa, for example, but is not limited to this, and the positioning pin is determined by the pressure of the compressed air supplied to the air supply chamber 11a. It is sufficient that the pressure is such that 13 can be urged in the advancing direction so that the upper side (front end side) of the positioning pin 13 protrudes from the upper end opening of the guide hole 11. The compressed air supplied to the air supply chamber 11a may leak somewhat from between the outer peripheral surface of the positioning pin 13 and the inner peripheral surface of the guide hole 11, but the amount of leakage is reduced.

  Although not shown, the positioning pin 13 is provided with a stopper for defining the amount of advancement from the guide hole 11 so that the positioning pin 13 is not detached from the guide hole 11. The positioning pin 13 is also biased upward by the coil spring 12.

  A gap through which compressed air can flow is formed between the portion of the outer peripheral surface of the positioning pin 13 inserted into the screw hole 100c of the nut 100 and the inner surface of the screw hole 100c of the nut 100. . That is, since the screw groove is formed on the inner surface of the screw hole 100c, even if the positioning pin 13 is inserted into the screw hole 100c, the compressed air flows through the inside of the screw groove, so that the vertical direction of the screw hole 100c. It is possible to pass through.

(Configuration of upper electrode)
The upper electrode 20 is made of a conductive metal material, is attached to the driving device 30, and comes into contact with the nut 100 from the side opposite to the steel plate 102. The upper electrode 20 has a substantially cylindrical tubular portion 21 that covers the nut 100 from the side opposite to the steel plate 102 (upper side). The tubular portion 21 has an end wall portion 22 that closes the upper end portion of the tubular portion 21. The end wall part 22 is arrange | positioned so that the opposite side to the steel plate 102 in the nut 100 may be covered.

  Although the inner surface 21b of the cylindrical part 21 may be formed so that it may contact the outer surface of the nut 100, it may be formed so that a clearance may be made between both. The inner diameter of the cylindrical portion 21 is set slightly larger than the upper portion and smaller than the outer diameter of the flange 100d so that only the upper portion of the nut 100 can be accommodated. In addition, the vertical dimension of the cylindrical portion 21 is set longer than the vertical dimension of the upper portion of the flange 100d of the nut 100, and the upper portion is accommodated in the cylindrical portion 21, Between the end wall portion 22 and the upper side of the nut 100, an air inflow space 20a into which compressed air described later flows is provided. In a state where the nut 100 is accommodated in the cylindrical portion 21, the air inflow space 20 a communicates with the side opposite to the steel plate 102 in the screw hole 100 c through the opening 100 b on the upper side of the nut 100. Further, the lower end portion 21a of the cylindrical portion 21 extends along the upper surface of the flange 100d formed on the nut 100, and comes into contact with the entire upper surface of the flange 100d. Thereby, the clearance gap between the cylindrical part 21 and the flange 100d is minimized.

  The upper electrode 20 is provided with an air supply pipe 26 to which compressed air is supplied. A downstream side of the air supply pipe 26 is connected to the cylindrical portion 21. Thereby, the downstream side of the air supply pipe 26 is connected to the air inflow space 20a.

  A compressed air supply device 27 such as factory air is connected to the upstream side of the air supply pipe 26. The supply device 27 may be shared with the supply device 17 on the lower electrode 10 side. An upper control valve 28 is provided in the middle of the air supply pipe 26. The upper control valve 28 can be configured by a conventionally known valve device, and adjusts the pressure of the compressed air supplied to the air inflow space 20a to a predetermined pressure set in advance. Can be switched between a state in which the air is supplied to the air inflow space 20a and a state in which the air is not supplied to the air inflow space 20a. The upper control valve 28 can be configured by, for example, an electromagnetic valve, and can be controlled by a control device (not shown) to stop the supply of compressed air when not welding and supply compressed air when welding.

  The pressure of the compressed air supplied to the air inflow space 20a is preferably set higher than the pressure of the compressed air supplied to the air supply chamber 11a of the lower electrode 10, for example, set to about 0.18 MPa. Yes, but not limited to this.

(Configuration of welding current supply unit)
The welding current supply unit 50 shown in FIG. 1 is conventionally used when performing projection welding. That is, the welding current supply unit 50 and the lower electrode 10 are connected by the electric wire 51, and the welding current supply unit 50 and the upper electrode 20 are connected by the electric wire 52. The welding current supply unit 50 is configured to energize the lower electrode 10 and the upper electrode 20 for a predetermined time at a predetermined timing. The welding current, energization time, and the like can be arbitrarily adjusted depending on the shape and size of the nut 100.

(Projection welding procedure)
Next, the procedure for projection welding the nut 100 to the steel plate 102 using the welding apparatus 1 configured as described above will be described. First, as shown in FIG. 3, after the upper electrode 20 is moved upward by the driving device 30, the nut 100 and the steel plate 102 are placed on the lower electrode 10 and set. At this time, since compressed air is supplied to the air supply chamber 11 a of the lower electrode 10, the distal end side of the positioning pin 13 protrudes upward from the upper end portion of the guide hole 11. Accordingly, the distal end side of the positioning pin 13 is inserted into the through hole 102a of the steel plate 102 and is inserted into the screw hole 100c of the nut 100, and the nut 100 and the steel plate 102 are positioned. When the distal end side of the positioning pin 13 is inserted into the through hole 102a of the steel plate 102, the tip pin 13a is formed in the positioning pin 13, so that the positioning pin 13 penetrates even if the steel plate 102 is slightly displaced in the horizontal direction. It can be made to pass through the hole 102a.

  Thereafter, as shown in FIG. 4, the upper electrode 20 is moved downward by the driving device 30 to insert the nut 100 into the cylindrical portion 21 of the upper electrode 20, and the lower end portion 21 a of the cylindrical portion 21 is connected to the flange of the nut 100. It abuts on the upper surface of 100d. At this time, since the upper electrode 20 is pressed downward by the driving device 30, the nut 100 moves downward against the urging force of the positioning pin 13, and the convex portion 100 e of the nut 100 is pressed against the upper surface of the steel plate 102. To do. Since the convex portions 100e are provided at intervals in the circumferential direction, a gap is formed between the lower surface of the flange 100d of the nut 100 and the upper surface of the steel plate 102. By lowering the upper electrode 20, the nut 100 and the steel plate 102 are sandwiched between the upper electrode 20 and the lower electrode 10 in the vertical direction.

  Compressed air is supplied from an air supply pipe 26 to the air inflow space 20 a of the upper electrode 20. The supply start timing of the compressed air may be before the welding current flows at the latest. For example, after the nut 100 and the steel plate 102 are set, or when the upper electrode 20 starts to move downward by the driving device 30, the upper electrode It may be in the middle of moving 20 downward by the drive device 30. Compressed air is continuously supplied until welding is completed.

  When compressed air is supplied to the air inflow space 20 a, there is almost no air leakage from between the upper electrode 20 and the flange 100 d of the nut 100, so the compressed air flows from the opening 100 b above the nut 100 to the screw hole 100 c. Flow into. Since the compressed air that has flowed into the screw hole 100c has a gap between the lower surface of the flange 100d of the nut 100 and the upper surface of the steel plate 102, the compressed air flows downward through the screw hole 100c and the upper surface of the flange 100d and the upper surface of the steel plate 102. It flows to the outside through.

  When a welding current is supplied by the welding current supply unit 50 in a state where compressed air is supplied to the air inflow space 20a, current concentrates on the projection 100e of the flange 100d of the nut 100 and the projection 100e is melted. At this time, spatter and soot are generated between the nut 100 and the steel plate 102, but the flow of compressed air inside the screw hole 100c is a flow from the top to the bottom. There is almost no flow into the hole 100c. Thereby, since it becomes difficult for spatter and soot to adhere to the inner surface of the screw hole 100c of the nut 100, screw sieving is unnecessary.

  In addition, until the welding is completed, the compressed air that has flowed into the screw hole 100c of the nut 100 escapes from the gap formed between the nut 100 and the steel plate 102, so that spatter and soot flow in the compressed air. And escapes from the surface of the steel plate 102 and becomes difficult to adhere to the steel plate 10. Thereby, welding quality can be improved.

  Further, since the compressed air that has flowed into the screw hole 100c of the nut 100 flows through the gap between the outer peripheral surface of the positioning pin 13 and the inner surface of the screw hole 100c of the nut 100, spatter adheres to the outer peripheral surface of the positioning pin 13. It is suppressed.

  Further, it is conceivable that the compressed air in the guide hole 11 of the lower electrode 10 leaks toward the advancing direction of the positioning pin 13, that is, toward the screw hole 100 c of the nut 100. If this happens, there is a risk that spatter will flow into the screw hole 100c of the nut 100 along the flow of compressed air leaking from the guide hole 11, but in this embodiment, the compressed air supplied to the air supply pipe 26 of the upper electrode 20 Since air flows into the screw hole 100 c from the upper side of the screw hole 100 c of the nut 100, even if compressed air leaks from the guide hole 11, spatter does not flow into the screw hole 100 c of the nut 100.

  In the above embodiment, the compressed air is supplied to the guide hole 11 of the lower electrode 10. However, the present invention is not limited to this, and the compressed air may not be supplied to the guide hole 11.

  The above-described embodiment is merely an example in all respects and should not be interpreted in a limited manner. Further, all modifications and changes belonging to the equivalent scope of the claims are within the scope of the present invention.

  As described above, the nut welding apparatus according to the present invention can be used, for example, when a nut is welded to a steel plate.

1 Nut welding device 10 Lower electrode (first electrode)
11 Guide hole 13 Positioning pin 20 Upper electrode (second electrode)
20a Air inflow space 21 Cylindrical part 22 End wall part 26 Air supply pipe 100 Nut 100c Screw hole 100d Flange 100e Convex part 102 Steel plate (metal member)

Claims (6)

In a nut welding apparatus for projection welding a nut having a screw hole with both ends opened in the center line direction to a metal member,
The welding apparatus includes: a first electrode that contacts the metal member from a side opposite to the side on which the nut is welded; and a second electrode that contacts the nut from a side opposite to the metal member. And
The second electrode is provided with an air supply pipe to which compressed air is supplied,
A nut welding apparatus, wherein a downstream side of the air supply pipe communicates with a side opposite to the metal member in a screw hole of the nut. The nut welding apparatus according to claim 1,
The second electrode has a cylindrical portion that covers the nut from the side opposite to the metal member,
A nut welding apparatus, wherein a downstream side of the air supply pipe is connected to the cylindrical portion. The nut welding apparatus according to claim 2,
The cylindrical portion has an end wall portion arranged to cover the side of the nut opposite to the metal member,
An air inflow space is provided between the end wall portion and the nut,
A nut welding apparatus, wherein a downstream side of the air supply pipe is connected to the air inflow space. The nut welding apparatus according to claim 2 or 3,
The nut welding device, wherein an end of the cylindrical portion is in contact with a flange formed on the nut over the entire circumference. The nut welding device according to any one of claims 1 to 4,
The first electrode is provided with a positioning pin that penetrates the metal member and is inserted into the nut,
A nut welding apparatus, wherein a gap through which compressed air flows is formed between an outer peripheral surface of the positioning pin and an inner surface of a screw hole of the nut. The nut welding device according to claim 5,
The proximal end side of the positioning pin is inserted into a guide hole formed in the first electrode, and supported by the inner peripheral surface of the guide hole so as to advance and retreat in the center line direction of the positioning pin.
A nut welding apparatus, wherein compressed air for urging the positioning pin in the advancing direction is supplied into the guide hole of the first electrode.

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