JPH049102Y2 - - 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. As a welding gun unit attached to a robot, the one shown in FIG. 6 has conventionally been adopted.

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. 62-29195.

(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. If there is variation in the distance from the welding part 9 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. If the workpiece is positioned close to the electrodes 7 and 8, 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. There was also the problem that the welding process could lead to poor welding. 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 provides a frame for holding a pair of welding electrodes.
The slide mechanism member is supported by a slide mechanism member, and the slide mechanism member is supported so as to be able to approach and leave the substrate via a constant posture maintaining member consisting of a guide holder and a guide pin, and between the slide mechanism member and the substrate, the A compression spring is provided that applies an elastic force in a direction in which the pair of electrodes approaches the workpiece, and a positioning member made of an insulating member that can come into contact with an end of the workpiece is attached to one of the pair of electrodes. It is characterized by this.

(Function) The frame holding the pair of welding electrodes is supported by a slide mechanism member, and the slide mechanism member approaches and leaves the substrate via a constant posture maintaining member consisting of a guide holder and a guide pin. Since a compression spring is provided between the slide mechanism member and the substrate to apply an elastic force in a direction in which the pair of electrodes approaches the workpiece, the electrodes are supported by the slide mechanism member. In addition, the frame that holds the pair of electrodes has a constant posture maintaining member that is provided between the slide mechanism member and the substrate and consists of a guide holder and a guide pin, and provides an elastic force in the direction of moving the electrodes closer to the workpiece. A compression spring keeps it in a fixed position at all times without shifting. If the frame is held in a fixed position in this way, when moving the pair of electrodes to the welding position of the object to be welded, it becomes possible to maintain the frame's posture constant, and the position of the frame can be maintained constant when moving the pair of electrodes to the welding position of the object to be welded. The object to be welded can be approached accurately, and the pair of electrodes can be reliably moved to the welding position of the object without coming into contact with the object.

In addition, since a positioning member made of an insulating member that can come into contact with the end of the workpiece is attached to one of the pair of electrodes, the positioning member comes into contact with the workpiece, compressing the compression spring and causing the frame to swing. Even if the electrode escapes, the positional relationship between the swinging position of the object to be welded and the electrode is maintained, making it possible to always keep the welding position from the end of the object to be constant. Welding is then performed as follows.

First, the entire installation 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 positioning member will come into contact with the end of the workpiece, and the frame will receive a reaction force in the direction opposite to the direction of the compression spring force. Become. Due to this reaction force, the frame moves relative to the substrate while maintaining a fixed posture, and actually stays at a fixed position contrary to the movement of the substrate. Therefore, the pair of electrodes is positioned while maintaining a constant positional relationship with 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 positioning member and the electrode. Furthermore, if there is no positive positioning error in the direction in which the welding gun unit and the object to be welded approach, welding is performed as is using the pair of electrodes without moving the frame relative to the substrate.

(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. 6 and 7 will be described using the same reference numerals.

In the figure, 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. A plurality of through holes 11 are bored at appropriate positions on the upper surface 1b, and a cylindrical guide holder 12 is fixed so as to be coaxial with these through holes 11. A flange 12a is formed at the base of this guide holder 12.

On the other hand, reference numeral 2 denotes a support member that supports the frame 4, and this support member 2 includes a pair of guide bars 1.
3 is held so that it can move forward and backward. Guide bar 13
A frame 4 is fixed to the front end of the frame 4, 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 these downward bulging portions 6a are fitted into the left and right guide bars 13 through notches 2a provided in the support member 2. (See Figure 3). Furthermore, a compression spring 14 is installed inside the support member 2, and the compression spring 14 pushes the pair of guide bars 13 and the frame 4 forward. These support members 2, guide bars 1
3. The compression spring 14 and the downward bulging portion 6a of the cylinder 6 constitute a slide mechanism member 3 that slides the frame 4 in the front and back direction.

Further, a plurality of guide pins 15 are protruded from the lower surface of the support member 2, and the tips of the guide pins 15 are slidably fitted into the guide holder 12 on the substrate 1 side and the through hole 11. In this example,
The guide pin 15 and guide holder 12 are attached to the frame 4
It is a constant posture maintaining member that moves the robot in a constant posture. Further, a guide pin 15 is provided between the lower surface of the support member 2 and the flange 12a of the guide holder 12.
A compression spring 16 as a biasing means is interposed so as to surround the. Therefore, the support member 12 and the frame 4 supported by it are always urged upward (in the direction of bringing the electrodes 7 and 8 closer to the workpiece W) by the compression spring 16 while being maintained in a fixed position. It is becoming more and more popular. still,
In this embodiment, the compression spring 16 as a biasing means is arranged so as to surround the guide pin 15, but the compression spring 16 can also be provided at a different position from the guide pin 15.

One electrode 7 is fixed to the tip of a substantially L-shaped arm 5 fixed to the frame 4, a power supply arm 17 is connected to a piston (not shown) of the pressurizing cylinder 6, and a screw adapter 18 is connected to the power supply arm 17.
The shank 19 of the other electrode 8 is attached via the shank 19 of the other electrode 8. The electrode 7 and the electrode 8 are arranged to face each other. Almost L-shaped arm 5
A positioning member (hereinafter referred to as an insulating member) 20 made of an insulating member is fixed near the tip of the insulating member so as to face between the electrodes 7 and 8. This insulating member 20 can come into contact with the lower end of the workpiece W, and further, as shown in FIG. The distance is set to match the distance to the welding part 9.

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

The welding gun unit constructed 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 20 comes into contact with the lower 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 20 receives a reaction force from the end of the object to be welded W, and this reaction force causes the support member 2 supporting the frame 4 to descend in a fixed position against the elastic force of the compression spring 16. . This lowering is relative to the substrate 1 and is actually
Contrary to the rise of the support member 2, the support member 2 remains in a fixed position. As a result, the pair of electrodes 7 and 8 supported by the frame 4 do not move while maintaining a constant positional relationship with the workpiece W to be welded.

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.

Furthermore, when the welding gun unit is moved by the robot, if there is no positive positioning error in the direction in which the object W to be welded and the welding gun unit approach, that is, if the welding gun unit does not protrude in the direction in which they approach, the frame 4 will not move relative to the substrate 1. It will no longer occur. In this case as well, welding of the workpiece W is performed in the same manner as described above when the robot stops moving. 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.

The embodiments of the present invention are not limited to those described above, and there are other embodiments as shown in FIG. 5, for example. In this embodiment, a threaded portion 21 is provided at the tip of the guide pin 15 in the fixed posture maintenance mechanism, and a nut 22 is screwed into the threaded portion 21 of the guide pin 15 that passes through the guide holder 12 and the through hole 11 of the substrate 1. The elastic force of the compression spring 16 can be adjusted by adjusting the tightness of the nut 22. Furthermore, reference numeral 23 in Fig. 5
indicates a washer, and 24 indicates a lock nut.

(Effect of the invention) Since the present invention is configured as explained above,
A frame holding a pair of electrodes supported by a slide mechanism member includes a constant posture maintaining member consisting of a guide holder and a guide pin provided between the slide mechanism member and the substrate, and a frame that holds a pair of electrodes between the electrodes and an object to be welded. A compression spring that applies an elastic force in a direction that causes the robot to approach the target is always held in a fixed position without shifting. If the frame is held in a fixed position in this way, when moving the pair of electrodes to the welding position of the object to be welded, the frame can be held in a constant position at all times, and the pair of electrodes will be positioned. Therefore, the pair of electrodes can be reliably moved to the welding position of the welding object without making the pair of electrodes come into contact with the welding object. This makes it possible to avoid damage to the object to be welded and the electrode, and to always perform welding in an optimal posture.

In addition, since a positioning member made of an insulating member that can come into contact with the end of the workpiece is attached to one of the pair of electrodes, the positioning member comes into contact with the workpiece, compressing the compression spring and causing the frame to swing. Even if the electrode escapes, 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,
Since the workpiece is reliably positioned at a predetermined position and welded in an optimal posture, the welding position of the workpiece becomes constant, the appearance is good, and the quality of welding can be improved.

Also, even if the workpiece has a bulge at the bottom and is positioned so that the bulge approaches the electrode,
Since the end of the object to be welded contacts the positioning member and does not move down any further, damage caused by contact between the electrodes and the object to be welded can be avoided.

[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 sectional view showing another embodiment, FIG. 6 is a front view showing the conventional technique, and FIG.
The figure is an enlarged front view corresponding to the part shown in FIG. 6. 1...Substrate, 4...Frame, 7, 8...Electrode, 11...Through hole, 12...Guide holder, 1
5... Guide pin, 16... Compression spring, 2
0...Insulating member, W...Object to be welded.

Claims (1)

[Scope of utility model registration request] A frame holding a pair of welding electrodes is supported by a slide mechanism member, and the slide mechanism member is supported so as to be able to approach and leave the substrate via a constant posture maintaining member consisting of a guide holder and a guide pin. A compression spring is provided between the slide mechanism member and the substrate to apply an elastic force in a direction that causes the pair of electrodes to approach the workpiece, and one of the pair of electrodes is provided with a compression spring that applies an elastic force to the end of the workpiece. A welding gun unit characterized by being equipped with a positioning member made of an insulating member that can be contacted.