JPS6130788Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a spot welding electrode welding detection device for detecting welding of each electrode to a workpiece in a spot welding machine.

In general, a spot welding machine is a welding machine that welds the workpiece by pressurizing the workpiece between a pair of opposing copper electrodes in a welding gun and passing welding current between the two electrodes. It is. In such a spot welding machine, when the electrode is overheated due to fluctuations in welding current or other changes in welding conditions, a phenomenon occurs in which the electrode is welded to the workpiece.

By the way, when detecting the above-mentioned electrode welding in a multi-point spot welding machine that automatically performs spot welding at a large number of welding point positions one after another by sequence control, conventionally, for example, when the welding gun is turned on after welding is completed, A method has been adopted in which the welding state is detected by detecting with a limit switch, etc., that the welding gun is held back by the object to be welded and does not move to the predetermined shift position when shifting to the next welding point position. has been done.

However, with this method, welding is not detected at the welded dot position, but instead is detected by shifting the welding gun, so it takes time to detect welding, and it takes time to detect welding. If the stop position when stopping the welding gun is not constant and the welding gun is restarted after removing the welding, the welding gun will not return to the welding point position where the welding is incomplete due to sequence control and will continue to the next welding point. Spot welding was restarted from the dot position,
Therefore, after the automatic feed of the welding gun is once canceled, it is necessary to re-weld the welding point position by manual operation, and there is a problem that re-welding the welding point position is extremely troublesome.

The present invention has been devised in view of this point, and the welding of each electrode of a spot welding gun is detected by determining whether or not each electrode returns to its non-welding position at the welded dot position. ,
Welding can be detected in a short time, and
It is an object of the present invention to provide a welding detection device for spot welding electrodes, in which a welding gun stops operating at a welding point position when welding is detected, and re-welding at the welding point position can be easily performed.

That is, the present invention provides a spot welding electrode welding detection device that detects the welding state of an electrode of a spot welding machine that spot-welds a workpiece fixed to a welding jig. A spot welding gun having a movable electrode disposed opposite to the movable electrode and moved by a cylinder device,
Elasticity supported on a base so as to be movable in the same direction as the moving direction of the movable electrode, and constantly biasing the movable electrode in the backward direction so as to bring the spot welding gun to a welding position where the supporting electrode contacts the workpiece. While the member is provided, the spot welding gun is normally movable in synchronization with the retreat of the movable electrode and against the urging force of the elastic member to a retracted position in which the supporting electrode is separated from the workpiece to be welded. A cylinder device is provided, and the position detects the retracted position of the welding gun and the retracted position of the movable electrode after welding is completed, and generates a welding signal when the welding gun or the movable electrode does not return to the retracted position or the retracted position, respectively. This device is characterized by being equipped with a detection device.

Hereinafter, the present invention will be explained in detail based on an embodiment shown in the drawings.

In the drawings, reference numeral 1 denotes a welding gun of a spot welding machine, and the welding gun 1 has a pair of movable electrodes 2 and a support electrode 3 located above and below, sandwiching a workpiece W fixedly held on a welding jig A. , the moving electrode 2 has a piston rod 4 whose both ends protrude from the cylinder 4a.
The piston rod 4b is attached to one end (lower end) of the first air cylinder device 4 equipped with a piston rod 4b, and is reciprocated in the vertical direction by the first air cylinder device 4. On the other hand, the supporting electrode 3 is attached to the distal end of a substantially U-shaped arm member 5 fixed to the cylinder 4a of the first air cylinder device 4.
are installed opposite to each other below. Each cylinder chamber (not shown) of the first air cylinder device 4 is supplied with compressed air through air passages 6 and 7 each having a 3-port switching valve 8 having two flow passage switching positions a and b. The workpiece W is pressurized between the electrodes 2 and 3 by the biasing force of the elastic member 12 (to be described later) and the expansion operation of the first air cylinder device 4. The workpiece W to be welded is spot welded by applying current to the workpiece W.

Reference numeral 9 denotes a base formed by connecting and fixing an upper plate 9a and a lower plate 9b together through a guide member 9c, and a bracket 1 is attached to the guide member 9c of the base 9.
The welding gun 1 is supported so as to be movable in the same direction as the moving direction of the movable electrode 2 (up and down in the figure).

An arm portion 11 extending horizontally between the upper and lower plates 9a and 9b of the base 9 is integrally attached to the bracket 10, which is integrated with the welding gun 1. An elastic member 12 made of a coil spring is installed in between, and the elastic member 12 constantly urges the welding gun 1 in the backward direction of the movable electrode 2 (upward in the figure), so that the supporting electrode 3 It is configured to bring the welding position into pressure contact with the workpiece W to be welded.

On the other hand, a second air cylinder device 13 is attached to the upper surface of the upper plate 9a of the base 9 in an upright state, and a piston rod 13 of the second air cylinder device 13 is attached to the upper surface of the upper plate 9a of the base 9.
The tip part a passes through the upper plate 9a and connects to the bracket 1.
It is connected to the arm part 11 of 0. Further, the expansion cylinder chamber (not shown) of the second air cylinder device 13 is connected to an air passage 6 for supplying and discharging air to and from the contraction cylinder chamber of the first air cylinder device 4.
are connected via an air passage 14 in the middle of the
During normal operation, by the extension operation of the second air cylinder device 13, the welding gun 1 is synchronized with the retreat of the movable electrode 2, and the support electrode 3 is moved against the biasing force of the elastic member 12 to be welded. It is configured to be movable to a retreat position where it is away from the object W.

Furthermore, a movable electrode position detecting device 16 consisting of a micro switch is attached to the upper surface of the upper plate 9a of the base 9 via a pole 15, and a movable lever portion 16a of the position detecting device 16 is connected to the first movable electrode in the welding gun 1. Piston rod 4 of air cylinder device 4
b is engaged with a cam 17 fixed to the other end. Further, a welding gun position detection device 19 consisting of a micro switch is attached to the upper surface of the lower plate 9b of the base 9 via a pole 18.
The movable lever portion 19a of 9 engages with the arm portion 11 of the bracket 10. Therefore, both the position detection devices 16 and 19 detect the retracted position of the movable electrode 2 and the retracted position of the welding gun 1 after welding is completed, so that the movable electrode 2 or the welding gun 1 is in the retracted position or the retracted position, respectively. The device is configured to generate a welding signal if the welding signal does not return to normal.

Next, the operation of the above embodiment will be explained.
When the switching valve 8 is switched to the flow path switching position A during spot welding, compressed air is not introduced into the expansion cylinder chamber of the second air cylinder device 13, and the second air cylinder device 13 becomes inactive. , the welding gun 1 is moved by the urging force of the elastic member 12, and the support electrode 3 is placed on one side (lower side) of the workpiece W to be welded.
The welding position is reached by pressing into contact with the At the same time, compressed air is introduced into the expansion cylinder chamber of the first air cylinder device 4 of the welding gun 1, so that the first air cylinder device 4 is expanded, and the piston rod 4b provided at one end of the piston rod 4b is expanded. The movable electrode 2 descends and presses into contact with the other surface side (upper surface side) of the object W to be welded, whereby the object W to be welded is held between the electrodes 2 and 3 under pressure. Thereafter, spot welding of the workpiece W is performed by passing a welding current between the electrodes 2 and 3.

After welding is completed, when the switching valve 8 is switched to the flow path switching position B, compressed air is introduced into the expansion cylinder chamber of the second air cylinder device 13, and the second
The air cylinder device 13 is extended and the welding gun 1 is activated.
is pushed down in the figure against the biasing force of the elastic member 12. In addition, in synchronization with this operation, compressed air is also introduced into the contraction cylinder chamber of the first air cylinder device 4 of the welding gun 1, so that the movable electrode 2 is moved back due to the contraction operation of the first air cylinder device 4. pulled up to the side.

At that time, if the above spot welding is performed normally and the electrodes 2 and 3 are not welded to the workpiece W, the support electrode 3 separates from the workpiece W and the welding gun 1 continues to descend. Return to the evacuation position, and
The moving electrode 2 leaves the workpiece W to be welded and returns to the retracted position. As a result, each position detection device 16, 19 does not generate a welding signal, and the welding gun 1
is slid to the next welding point position on the workpiece W, and spot welding is continued.

On the other hand, if the support electrode 3 or the movable electrode 2 is welded to the workpiece W due to an increase in the amount of melting of the workpiece W during welding, the welding gun 1 is moved downward or the welding gun is moved downward, respectively. Since the upward movement of the piston rod 4b of the first air cylinder device 4 is prevented, the welding gun 1 will not return to the retracted position, and the movable electrode 2 will not return to the retracted position. As a result, each position detection device 1
6 and 19 detect and generate a welding signal, thereby stopping the operation of the welding gun 1 and notifying the welding by an alarm device or the like.

Therefore, in the above embodiment, the welding of each electrode 2, 3 of the welding gun 1 to the workpiece W is determined by whether or not the welding gun 1 returns to the retracted position or the movable electrode 2 returns to the retracted position. Since welding can be detected at the welding point position of the workpiece W, welding detection time can be shortened, and the welding gun 1 can immediately and stably stop operating at that position. As a result, when the welding gun 1 is restarted after the welding is removed, it becomes possible to resume spot welding from the welding point position where the welding is incomplete, while keeping the welding gun 1 in automatic feed mode.
Re-welding work at welding point positions can be easily performed.

In addition, in the above embodiment, the moving electrode 2 and the supporting electrode 3
We have described the case where the above two electrodes 2 and 2 are applied to a vertical spot welding machine in which the
Needless to say, the present invention can be similarly applied to a horizontal spot welding machine in which the parts No. 3 are arranged in the left and right direction.

As explained above, according to the present invention, a welding signal is generated when the welding gun of a spot welding machine does not return to the retracted position or when the movable electrode of the welding gun does not return to the retracted position. As a result, it is possible to quickly detect welding of the electrode to the workpiece, which is a practical advantage in that it can stabilize the stopping position of the welding gun during welding and facilitate re-welding at the welding point position. Accordingly, it is possible to provide a spot welding electrode welding detection device that has the following effects.

[Brief explanation of the drawing]

The drawing is a schematic front view illustrating an embodiment of the invention. DESCRIPTION OF SYMBOLS 1... Welding gun, 2... Moving electrode, 3... Support electrode, 4... First air cylinder device, 8... Switching valve, 9... Base, 12... Elastic member, 13... Second Air cylinder device, 16, 19... position detection device, A... welding jig, W... object to be welded.

Claims (1)

[Scope of utility model registration request] A spot welding electrode welding detection device configured to detect the welding state of an electrode of a spot welding machine that spot-welds a workpiece fixed to a welding jig, comprising: a supporting electrode; and a spot welding electrode disposed opposite the supporting electrode. A spot welding gun having a movable electrode moved by a cylinder device is supported on a base so as to be movable in the same direction as the moving direction of the movable electrode, and the spot welding gun is welded with the support electrode in contact with the workpiece. An elastic member is provided that constantly biases the movable electrode in a backward direction so as to bring the movable electrode into position, while supporting the spot welding gun in synchronization with the retreat of the movable electrode and against the biasing force of the elastic member under normal conditions. A cylinder device is provided that allows the electrode to move to a retracted position away from the workpiece, and the retracted position of the spot welding gun and the retracted position of the movable electrode are detected after welding is completed, and the welding gun or the retracted position is detected. A welding detection device for a spot welding electrode, comprising a position detection device that generates a welding signal when the electrode does not return to a retracted position or a retracted position.