JP2004322188A - Welding equipment for stepped welding bolts - Google Patents

Abstract

Conventionally, in the case of a stepped welding bolt, if the insertion of a small diameter thread portion of a guide pin is shallow, the lower side of a large diameter cylindrical portion floats, and the supply of the welding bolt is stable such that the welding bolt tilts and interferes with the work. There was a problem not to do.
A stepped welding bolt having a large-diameter cylindrical portion between a bolt head and a small-diameter screw portion is supplied on the same axis as a guide pin, and the guide pin is moved together with the bolt by a pressing operation of an upper electrode. Press down, insert the small diameter screw part of the welding bolt into the work positioning hole, insert the cylindrical part into the work positioning hole, sandwich the head of the welding bolt and the work between the electrodes, apply pressure, and conduct projection welding. In this case, the guide pin and the large-diameter cylindrical portion of the welding bolt have substantially the same diameter, and a concave groove for inserting a small-diameter screw portion is provided inside the guide pin. The length of the screw is longer than the length of the screw, and the pressing force applied to the large-diameter cylindrical portion by the pressing operation of the upper electrode is received at the tip end surface of the concave groove of the guide pin.
[Selection diagram] Fig. 1

Description

[0001]
Field of application belonging to the present invention
In the field of resistance welding, a guide pin (also referred to as a pilot pin) that moves up and down inside an electrode is inserted into a positioning hole of a steel part to set a work, and then a welding bolt or a similar part is placed on the guide pin. The present invention relates to a device for supplying parts and the like and performing projection welding. More specifically, the present invention relates to a projection welding apparatus for a special part in which a large-diameter cylindrical portion and a small-diameter screw portion are integrally formed below a bolt head in a welding bolt, for example, a stepped welding bolt.
[0002]
[Prior art]
Conventionally, in the case of ordinary welding bolts (straight bolts), when a welding bolt B is projection-welded to a workpiece W as shown in FIGS. 4 and 5, a compression spring is inserted into a concave groove 41 provided inside the lower electrode 40. The guide pin 43 is slightly protruded from the tip end of the chip at 42, and a concave groove 48 for inserting a bolt is provided in the guide pin 43, and the threaded portion b2 of the welding bolt B is inserted into the concave groove 48. Presses the head b1 of the welding bolt B and at the same time compresses the spring 42 with the return of the guide pin 43 to the gap n (push allowance) formed between the head and the work at the tip of the welding bolt, and presses the spring 42 into the electrode. By pushing in or using a system in which the guide pin 43 is retracted by a cylinder or the like, the tip projecting portion of the guide pin 43 is completely separated from the positioning hole 47 of the work W. , It is known a method and an electrode apparatus for projection welding (see Patent Document 1-3). These guide pins are made of a hard anodized, insulating and abrasion-resistant material such as an insulating member made of ceramic or hard synthetic resin material.
[0003]
According to such a conventional technique, with the screw portion b2 of the welding bolt B inserted into the groove 48 of the guide pin up to below the neck of the welding bolt, the projecting end of the guide pin 43 is completely inserted from the positioning hole 47 of the work. After being retracted, burrs and the like generated on the inner diameter of the positioning hole 47 during welding do not bite into the guide pins 43, and the work can be easily taken out from the lower electrode after welding.
[0004]
Further, as another conventional technique, as shown in FIG. 6, when a pilot portion 50 protrudes from the tip of the screw portion of the welding bolt B, the tip of the guide pin 51 is moved up and down by a spring force in the lower electrode. A concave groove 52 or a V-shaped groove 53 for supporting the distal end pilot portion of the welding bolt is provided in the groove, and the distal end pilot portion 50 of the welding bolt is inserted into the concave groove 48 of the guide pin 51 to support the distal end pilot portion. A method is known in which a guide pin 51 is retracted into an electrode together with a welding bolt by a pressing operation of an upper electrode, and the welding bolt is pressed into a component mounting hole to perform welding (see Patent Document 4).
[0005]
[Patent Document 1]
Japanese Patent Publication No. 7-67624 (page 2-3, FIG. 1-4)
[Patent Document 2]
Japanese Utility Model Laid-Open No. 58-134282 (pages 5-7, FIGS. 3-4)
[Patent Document 3]
Japanese Patent Application Laid-Open No. 1-278974 (page 3, FIG. 8)
[Patent Document 4]
JP-A-1-249274 (pages 1-4, FIGS. 1-5)
[0006]
[Problems to be solved by the invention]
The conventional well-known welding methods and apparatuses described above are directed to straight type welding bolts. In a system in which a guide pin is moved up and down by spring tension, the depth of the groove of the guide pin is limited to the depth of the screw portion of the bolt. If the length is not shorter than the length, the guide pin cannot be pulled in from the positioning hole when welding the welding bolt to the work. However, the stepped welding bolt B is composed of a bolt head b0 having a projection P, a large-diameter cylindrical portion b1 and a small-diameter screw portion b2, and as shown in FIG. If the insertion of the screw portion b2 of the guide pin 50 is shallow, including the method of clamping the welding bolt B between the V-shaped groove 53 of the guide pin 50 that moves up and down by the compression spring 56 and the upper electrode 54, the large-diameter cylindrical portion b1 The lower side floats, and this causes the welding bolt B to tilt or interfere with the work W, and the supply to the work positioning hole becomes unstable, which is not recommended.
[0007]
Therefore, as another method, if the electrode structure is to insert the large-diameter cylindrical portion of the welding bolt into the groove of the guide pin in order to prevent the bolt from falling, the guide pin will be lengthened by inserting the large-diameter cylindrical portion. Pressing stroke becomes longer than usual.
[0008]
Therefore, in this case, the diameter and length of the guide pin are increased by the existence of the large-diameter cylindrical portion in the welding bolt, so that the electrode device itself including the electrode tube has a very large structure. In addition, it is difficult to increase the size of the positioning hole on the work side in view of equipment and cost.
[0009]
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to stably supply a stepped welding bolt, and to solve the above-mentioned conventional problems.
[0010]
[Means for Solving the Problems]
The present invention employs the following technical means to solve the above problems. That is, according to the first aspect of the present invention, the work positioning guide pin provided inside the lower electrode slightly protrudes from the electrode surface, and the protruding guide pin is inserted into the positioning hole formed on the work side to set the work. Then, a stepped welding bolt having a large-diameter cylindrical portion between the projection head and the small-diameter screw portion is supplied on the same axis AA as the guide pin, and then the upper electrode corresponding to the lower electrode is supplied. The guide pin is pushed down together with the bolt by a pressing operation, and the small-diameter thread portion of the welding bolt is inserted into the work positioning hole. Then, the cylindrical portion is inserted into the work positioning hole, and the head of the welding bolt is inserted between the electrodes. In a welding device for sandwiching a workpiece and a workpiece and applying pressure to the workpiece to perform projection welding, the guide pin and the large-diameter cylindrical portion of the welding bolt are substantially A groove is provided inside the guide pin for inserting a small-diameter thread portion of the welding bolt, and the depth of the groove is longer than the length of the small-diameter thread portion to be inserted. Then, a pressing force applied to the large-diameter cylindrical portion by the pressing operation of the upper electrode is received by the distal end surface of the groove of the guide pin. Thus, the projection welding is performed by passing the small-diameter thread portion through the work positioning hole together with the guide pin.
[0011]
According to the apparatus of the present invention having such a configuration, the conventional welding method of welding after the guide pin is retracted from the work positioning hole together with the welding bolt by the tip of the screw portion of the bolt abutting against the bottom surface of the groove of the guide pin. In comparison with the case of the stepped welding bolt, the insertion of the small-diameter screw portion of the groove of the guide pin is deep, the tip of the screw portion is not in contact with the bottom surface of the groove, and the large-diameter cylindrical portion is not provided. The lower surface of the hole comes into flat contact with the circumferential end surface of the groove of the guide pin and pushes in. The small-diameter screw part completely penetrates the work positioning hole through the guide pin, and the large-diameter cylindrical part is inserted. You can guide until you are. As a result, the welding bolt can be prevented from interfering with the workpiece without being inclined or coming off, and the stepped welding bolt can be stably supplied.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the apparatus of the present invention is shown in FIGS. 1, 2 and 3. FIG.
In the drawing, reference numeral 1 denotes a main component of a lower electrode of a projection welding machine. Reference numeral 2 denotes a tip portion of the upper electrode. The upper electrode 2 is driven vertically by a fluid pressure or an electric actuator mounted on a welding machine corresponding to the lower electrode 1. The upper electrode 2 is an electrode necessary for welding in connection with a welding bolt supply operation from a parts feeder. The energizing operation in cooperation with the pressing operation and the welding timer is performed by sequence control. Reference numeral 3 denotes an electrode tube constituting a lower electrode, and a chip holder 4 is detachably fixed to an upper portion of the electrode tube. A cap chip 5 is detachably mounted on the upper part of the chip holder 4.
[0013]
The electrode tube 3, the tip holder 4, and the cap tip 5 are formed with hollow holes 6 communicating with each other on the same axis AA. An insulating pipe 7 is inserted into a hollow hole of the electrode tube 3, and a guide rod 8 is inserted into the insulating pipe 7. A spring 9 is arranged on the guide rod 8 so as to surround the outer periphery of the guide rod 8, and the tension of the spring 9 keeps the guide rod 8 constantly pushed up.
[0014]
A guide pin 10 is inserted into a hollow hole communicating with the tip holder 4 and the cap tip 5. The guide pin 10 has a lower base 11 separated from the flange 12 at the rod end, and is provided on an upper surface of the flange. It is built in contact. The guide pin and the rod may be connected directly or indirectly.
[0015]
The guide pin 10 is constantly pushed up by the spring force together with the guide rod 8 so that the upper wall of the lower base 11 is in contact with the lower wall of the step 13 formed between the electrode tube 3 and the tip holder 4. Thus, the protrusion e of the guide pin 10 protruding from the electrode surface is restricted, so that the guide pin 10 can be moved up and down by the spring force in the electrode.
[0016]
The diameter of the guide pin 10 is substantially the same as that of the large-diameter cylindrical portion b1 of the welding bolt B inserted into the positioning hole on the work side. A concave groove 14 into which the part b2 is inserted is formed.
[0017]
As can be seen from FIG. 2, the depth H of the concave groove 14 is formed to be longer than the length h of the small diameter screw portion b2, and the lower surface of the large diameter cylindrical portion b1 of the welding bolt and the circumferential tip of the concave groove 14 are formed. The surface is configured to abut on a plane at the position of the step portion 15. Therefore, the tip of the small-diameter screw portion b2 is inserted in a state of not contacting the bottom surface of the concave groove 14.
[0018]
An auxiliary cylinder (not shown) for return is connected to the lower end of the guide rod 9, and when the guide pin 10 retracted into the electrode is returned to the original position after welding is completed, the auxiliary cylinder is connected to the above-mentioned auxiliary cylinder. This assists the pushing force of the guide rod 9 in addition to the spring tension.
[0019]
The operation of the apparatus according to the present invention will be described below with reference to FIGS.
First, the work is set by aligning the positioning hole on the work side with the guide pin 10 of the lower electrode 1 of the projection welding machine with the electrode opened.
Next, the stepped welding bolt B sent out from the parts feeder is gripped by a chuck of the supply head (not shown), and the chuck is advanced to be supplied on the same axis AA as the guide pin 10.
[0020]
Then, the upper electrode 2 corresponding to the lower electrode 1 is pressurized, the upper electrode 2 is inserted into the chuck, the bolt is pushed out from the chuck, the welding bolt is pushed out, and the groove is formed in the groove 14 of the guide pin 10. The small diameter threaded portion b2 of the welding bolt is inserted. At this time, the large-diameter cylindrical portion b1 of the welding bolt comes into contact with the tip of the concave groove of the guide pin, and the pressing force applied to the step 15 of the cylindrical portion b1 is received by the distal end surface of the concave groove 14 of the guide pin 10. Thus, the guide pin 10 is pushed back into the electrode against the tension of the spring 9.
[0021]
With this operation, the cylindrical portion b1 is inserted into the work positioning hole 16 when the small-diameter screw portion b2 is inserted into the work positioning hole 16 together with the guide pin 10 and penetrates. In this operation, the head b0 of the welding bolt and the work W are sandwiched between the upper and lower electrodes, a predetermined pressure is applied to a welding site, and a welding current is supplied by a welding timer to perform projection welding. After welding is completed, the drive unit of the welding machine is returned, the work is replaced, the next welding preparation is started, and the same welding operation is repeated thereafter.
[0022]
In this embodiment, projection welding of stepped welding bolts has been described. However, similar effects can be obtained when welding T nuts and other similar T-shaped parts, and when using a spot welding gun and various resistance welding machines. To play.
[0023]
【The invention's effect】
As described above, according to the device of the present invention, when welding a stepped welding bolt, the small-diameter thread portion of the concave groove formed in the guide pin is different from the above-described conventional method and device. When the upper electrode is deeply inserted, the tip of the screw portion is not in contact with the bottom surface of the concave groove, and the entire length of the small-diameter screw portion is inserted into the concave groove of the guide pin, the pressing force when pressing the upper electrode Is received directly from the step of the large-diameter cylindrical portion at the circumferential end surface of the concave groove, and the large-diameter cylindrical portion formed under the neck of the welding bolt can be held in a stable state. In addition, the small-diameter thread portion can be completely penetrated from the work positioning hole via the guide pin, and can be guided until the cylindrical portion is completely inserted into the positioning hole. As a result, the conventional problems can be eliminated and a stable supply of the stepped welding bolt can be achieved.
[0024]
Further, according to the apparatus of the present invention, even when welding stepped welding bolts, there is no need to increase the size of the guide pin or change the electrode stroke, and the structure of the guide pin can be manufactured simply and at low cost.
[Brief description of the drawings]
FIG. 1 is a sectional view of a main part of a lower electrode showing an embodiment of a guide pin for implementing the device of the present invention.
FIG. 2 is a schematic sectional view illustrating an embodiment of the present invention, and is a main part sectional view showing a state before welding in which a stepped welding bolt is inserted into a lower electrode.
FIG. 3 is a schematic cross-sectional view illustrating an embodiment of the present invention, and is a main part cross-sectional view showing a state after welding by inserting a stepped welding bolt into a lower electrode and welding.
FIG. 4 is a cross-sectional view showing an example of a conventional welding device before welding in which a straight type welding bolt is inserted into a lower electrode.
FIG. 5 is a cross-sectional view after welding bolts are welded by a conventional welding device.
FIG. 6 is an enlarged cross-sectional view showing an embodiment of a concave groove and a V-shaped groove formed at a tip portion of a guide pin of a welding bolt having a pilot portion in a conventional welding method.
FIG. 7 is an explanatory view in a case where a stepped welding bolt is welded using a conventional V-cut guide pin with a conventional welding device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Lower electrode 2 Upper electrode 3 Electrode tube 4 Tip holder 5 Cap chip 6 Hollow hole 7 Insulation pipe 8 Guide rod 9 Spring 10 Guide pin 11 Base 12 Flange 13 Step 14 Depression groove 15 Step 16 Work positioning hole B Step welding Bolt W Work

Claims (1)

A work positioning guide pin provided inside the lower electrode slightly protrudes from the electrode surface, and the protruding guide pin is inserted into a positioning hole formed on the work side to set the work, and then the projection head and the small diameter A stepped welding bolt having a large-diameter cylindrical portion between the screw portion and the guide pin is supplied on the same axis AA as the guide pin, and then the guide pin is moved together with the bolt by pressing the upper electrode corresponding to the lower electrode. Is pressed down, the small-diameter screw portion of the welding bolt is inserted into the work positioning hole, and then the cylindrical portion is inserted into the work positioning hole, and the head of the welding bolt and the work are sandwiched between the electrodes. And a large-diameter cylindrical portion of the welding bolt has substantially the same diameter as that of the guide pin. A concave groove for inserting a small diameter screw portion of the welding bolt is provided in the portion, and the depth dimension of the concave groove is longer than the length of the small diameter screw portion to be inserted, and the pressure of the upper electrode is increased. A welding device for a stepped welding bolt, wherein a pressing force applied to the large-diameter cylindrical portion by an operation is received at a tip end surface of a concave groove of the guide pin.

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