JPH049103Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The present invention relates to a welding gun unit that performs spot welding at a predetermined position of the workpiece after being moved to the position of the workpiece by a robot or the like. be.

(Prior Art) On an automobile production line, a welding gun unit is sometimes attached to a robot, and the welding gun unit is moved by the robot to an appropriate position to perform spot welding on a workpiece. Conventionally, a welding gun unit attached to a robot is shown in FIG. 5.

In this welding gun unit, a support member 2 is fixed to the upper part of a base plate 1, and a frame 4 is attached to the support member 2 via a slide mechanism 3 so as to be movable back and forth. A substantially L-shaped arm 5 and a pressure cylinder 6 are fixed to the frame 4, and one electrode 7 is attached to the tip of the substantially L-shaped arm 5, and the pressure cylinder 6 is fixed to the frame 4.
The other electrode 8 is attached to the tip of each of the two electrodes, so that one electrode 7 and the other electrode 8 face each other. When welding the workpiece W, the welding gun unit is moved by a robot (not shown) so that the welding part 9 of the workpiece W is positioned between the electrodes 7 and 8. . In this state, the pressurizing cylinder 6 is operated to bring the other electrode 8 into contact with the workpiece W to be welded, and the reaction force at this time causes the substantially L-shaped arm 5 to retreat together with the frame 4. Thereby, the welding part 9 of the workpiece W to be welded is sandwiched between the electrodes 7 and 8, and current is applied in this state.

The technology of a welding gun unit having the same basic operating principle as this welding gun unit is also disclosed in, for example, Publication No. 29195/1983.

(Problems to be Solved by the Invention) However, in the conventional welding gun unit described above, variations occur in the welding position relative to the workpiece W due to positioning errors of the workpiece W, especially at the lower end of the workpiece W. (in Figure 5)
When there is variation in the distance from to the welding part 9, the welding position of the workpiece will also be varied, resulting in poor appearance and a problem in that welding quality will deteriorate. Furthermore, if there is a bulge near the center of the welding part 9 of the workpiece W, there is no problem if the workpiece is positioned accurately as shown by W' in FIG.
As shown by W in the figure, the objects to be welded are electrodes 7 and 8.
If the electrodes 7 and 8 are positioned close to the welding point, the electrodes 7 and 8 will come into contact with the bulge of the workpiece W during welding, causing damage to the electrodes 7 and 8 and the workpiece W, or resulting in poor welding. There were also problems. Of course, a similar problem occurs when there is an error in positioning on the welding gun unit side.

The purpose of the present invention is to provide a welding gun unit that improves welding quality by eliminating problems caused by positioning errors of the workpiece or the gun unit itself, and avoids damage to the electrode or workpiece and welding defects. do.

(Means for Solving the Problems) As a means for solving the above problems, the present invention has a frame that holds a pair of welding electrodes rotatably supported on a substrate, and a frame that holds a pair of welding electrodes is supported rotatably on a substrate, and a compression spring is provided on the electrode side for applying an elastic force in a direction in which the pair of electrodes approaches the workpiece, and a stopper is provided on the substrate opposite to the pair of electrodes to suppress rotation of the frame; The present invention is characterized in that one of the pair of electrodes is integrally provided with a positioning member made of an insulating member that can come into contact with the end of the object to be welded.

(Function) The frame holding the pair of welding electrodes is rotatably supported on the substrate in this way, and the pair of electrodes is moved toward the side of the pair of electrodes across the center of rotation in a direction that brings the pair of electrodes closer to the object to be welded. Since a compression spring that imparts an elastic force is provided and a stopper that suppresses rotation of the frame is provided on the substrate opposite to the pair of electrodes, the elastic force of the compression spring is received by the stopper. The electrode will be held constant in a fixed state relative to the substrate. If the pair of electrodes is fixed and held in this way, it will be possible to maintain the frame's posture constant when moving the pair of electrodes to the welding position of the workpiece, and the pair of electrodes will be attached to the position of the workpiece. Therefore, the pair of electrodes can be reliably moved to the welding position of the workpiece without contacting the workpiece.

In addition, since a positioning member made of an insulating member that can come into contact with the end of the object to be welded is integrally provided on one of the pair of electrodes, the positioning member comes into contact with the object to be welded, compressing the compression spring and compressing the frame. Even if the electrode escapes due to rotation, the positional relationship between the welding position of the object to be welded and the electrode is maintained, and the welding position from the end of the object to be welded is always constant.

Furthermore, since one of the pair of electrodes is integrally provided with a positioning member that abuts the end of the workpiece, the electrode and positioning member do not shift, and the workpiece is reliably welded in a fixed position and has a good appearance. is obtained. Welding is then performed as follows.

First, the entire apparatus is moved to the position of the object to be welded using a robot or the like, and positioning is performed. On this occasion,
If there is a positive positioning error in the direction in which the entire device approaches the workpiece, the insulating member will come into contact with the edge of the workpiece, and this reaction force will cause the frame to rotate against the force of the biasing means. . Due to this rotation, the pair of electrodes stays at the local position, contrary to the movement of the entire device.
Once the movement has stopped, it is positioned on the workpiece. In this state, the object to be welded is pressurized and energized by a pair of electrodes to weld a predetermined position of the object. The welding position at this time is always a distance from the end of the object to be welded by the distance between the insulating member and the electrode. Furthermore, if there is no positive positioning error in the direction in which the object to be welded approaches the entire apparatus, welding is performed as is using the pair of electrodes without rotating the frame.

(Embodiment) An embodiment of the present invention will be described below with reference to FIGS. 1 to 4. The same parts as those of the conventional welding gun unit shown in FIGS. 5 and 6 will be described using the same reference numerals.

In the drawings, reference numeral 1 is a board, and the lower surface 1a of this board 1 is a moving robot (not shown).
A frame 4 holding a pair of welding electrodes 7 and 8 is supported on the upper surface 1b. Brackets 10 are fixed to both sides of the upper surface 1b, and a hinge pin 11 is rotatably supported by both brackets 10. The lower bulging portion 2a of the support member 2 is fixed to the hinge pin 11, and a pair of guide bars 12 are held on the support member 2 so as to be movable forward and backward.
A frame 4 is fixed to the front end of the guide bar 12, a substantially L-shaped arm 5 is fixed to the front side of the frame 4, and a pressure cylinder 6 is fixed to the rear side. The pressurizing cylinder 6 is provided with downward bulging portions 6a on both sides thereof, and both of the downward bulging portions 6a are fitted into the left and right guide bars 12 through notches 2b provided in the support member 2. (See Figure 3). And the support member 2 and the guide bar 12
The sliding mechanism section 3 in the front and back direction of the frame 4 is configured by the downward bulging section 6a, and the frame 4
is rotatably supported by the bracket 10 via the slide mechanism 3 and the hinge pin 11.
Furthermore, a compression spring 13 is installed inside the support member 2, and each guide bar 12 is biased forward by the compression spring 13.

Further, one electrode 7 is fixed to the tip of the approximately L-shaped arm 5, and a power supply arm 14 is connected to a piston (not shown) of the pressurizing cylinder 6, and the other is connected to the power supply arm 14 via a screw adapter 15. A shank 16 of the electrode 8 is attached. Further, the electrode 7 and the electrode 8 are arranged to face each other. A positioning member (hereinafter referred to as an insulating member) 17 is fixed near the tip of the substantially L-shaped arm 5 so as to face between the electrodes 7 and 8. This insulating member 17 can come into contact with the end of the workpiece W to be welded, and furthermore, as shown in FIG. The distance is set to match the distance to the welding part 9.

Furthermore, in the downward bulging portion 2a of the support member 2, a spring catch 18 is provided protruding from the lower surface of the front side (left side in FIG. 1) of the hinge pin 11 mounting portion. On the other hand, a spring support bracket 19 is fixed at an appropriate position on the base plate 1, and another spring clasp 20 is attached to this spring support bracket 19 so as to face the spring clasp 18 on the support member 2 side.
is fixed. Holes 21 are bored in the upper surface 1b of the base plate 1 at positions corresponding to the spring clasps 18 and 20. The compression spring 22 is locked to the spring clasp 18 and the spring clasp 20 while being loosely inserted into the hole 21.
Therefore, the support member 2 and the frame 4 are biased by the compression spring 22 in a direction to raise the electrodes 7 and 8. Further, a height-adjustable stopper 23 is installed at the rear end side of the upper surface 1b of the board 1, and this stopper 23 restricts the amount of rotation of the support member 2 by the compression spring 22. ing.

Note that the welding transformer is omitted in the drawings for convenience of illustration.

The welding gun unit configured as described above operates as follows when welding the workpiece W to be welded.

First, a welding gun unit is moved by a robot (not shown) with respect to a pre-positioned workpiece W to be welded. During this movement, if there is a positive positioning error in the direction in which the workpiece W and the welding gun unit approach (because the positioning of the welding gun unit is relatively accurately performed by a robot, there is an error in the positioning of the workpiece W). (often), the upper surface of the insulating member 17 comes into contact with the end of the workpiece W to be welded before the robot stops (see FIG. 4).
If the robot continues to move in this state, the insulating member 17 receives a reaction force from the end of the workpiece W, and this reaction force causes the support member 2 supporting the frame 4 to resist the elastic force of the compression spring 22. and rotate downward. As a result, the electrodes 7 and 8 do not move in the vertical direction after the insulating member 17 contacts the workpiece W to be welded. Of course, strictly speaking, the electrodes 7 and 8 rotate with respect to the substrate 1, so there is a slight vertical displacement (electrode 7 downward and electrode 8 upward). If a sufficient distance from 7 and 8 is ensured, the amount of displacement can be brought close to 0. Subsequently, when the robot stops moving, the pressure cylinder 6 is activated to move the electrode 8 forward. When the tip of the electrode 8 comes into contact with the workpiece W, the reaction force causes the frame 4 to move backward, and the electrode 7 at the tip of the arm 5 moves in the direction of the workpiece W. Then, when the object W to be welded is sandwiched between the electrodes 7 and 8, electricity is applied, and welding of the object W to be welded is completed. The welding part 9 of the workpiece W to be welded is always located at a distance l from the end toward the center.

Further, when the welding gun unit is moved by the robot, if there is no positive positioning error in the direction in which the workpiece W to be welded and the welding gun unit approach, the frame 4 will not rotate. Also in this case,
When the robot stops moving, the workpiece W to be welded is welded in the same manner as described above. In this case, the welding portion 9 of the workpiece W to be welded is located at a distance l from the end toward the center, or slightly shallower than that.

(Effects of the invention) As explained above, according to the invention, a frame holding a pair of welding electrodes is rotatably supported on a substrate, and the pair of welding electrodes are placed on the side of the pair of electrodes with the center of rotation sandwiched therebetween. A compression spring is provided that applies an elastic force in a direction that brings the electrode closer to the workpiece, and a stopper that suppresses rotation of the frame is provided on the substrate opposite to the pair of electrodes, so that the elastic force of the compression spring is reduced. is received by the stopper, and the pair of electrodes can be held constant in a fixed state relative to the substrate. Since the pair of electrodes is fixed and held in this way, when moving the pair of electrodes to the welding position of the object to be welded, the posture of the frame can be maintained constant, and the pair of electrodes can be moved to the position of the object to be welded. By accurately approaching the object, the pair of electrodes can be reliably moved to the welding position of the object to be welded without contacting the object. Thereby, damage to the object to be welded and the electrode can be avoided.

In addition, since a positioning member made of an insulating member that can come into contact with the end of the object to be welded is integrally provided on one of the pair of electrodes, the positioning member comes into contact with the object to be welded, compressing the compression spring and compressing the frame. Even if the electrode escapes due to rotation, the positional relationship between the welding position of the object to be welded and the electrode is maintained, and the welding position from the end of the object to be welded is always constant.

As a result, even if there are variations in the positioning of the workpiece, the workpiece will be reliably positioned and welded at a predetermined position, so the welding position of the workpiece will be constant, and the appearance will be good. Quality can be improved.

In addition, even if the workpiece has a bulge at the bottom and is positioned so that the bulge approaches the electrode, the end of the workpiece will come into contact with the positioning member and will not go down any further. Damage caused by objects coming into contact with each other can be avoided.

Furthermore, because one of the pair of electrodes is integrally provided with a positioning member that abuts the end of the workpiece, the electrode and positioning member do not shift, and the workpiece is reliably welded in a fixed position and has a good appearance. can get things.

[Brief explanation of the drawing]

Figure 1 is a front view showing one embodiment of the present invention;
The figure is the same side view, Figure 3 is the same plan view, and Figure 4 is the same side view.
FIG. 5 is a front view showing a conventional technique, and FIG. 6 is an enlarged front view corresponding to the portion shown in FIG. DESCRIPTION OF SYMBOLS 1... Board, 4... Frame, 7, 8... Electrode, 17... Insulating member, 22... Compression spring, W... Welding object.

Claims (1)

[Scope of utility model registration request] A frame holding a pair of welding electrodes is rotatably supported on a substrate, and compression is applied to the pair of electrodes across the center of rotation in a direction that brings the pair of electrodes closer to the workpiece. A spring is provided, and a stopper for suppressing rotation of the frame is provided on the substrate opposite to the pair of electrodes, and one of the pair of electrodes is made of an insulating member that can come into contact with an end of the workpiece. A welding gun unit characterized by integrally providing a positioning member.