JPH0340667B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD The present invention relates to a control device for a dual welding gun that is attached to the tip of a robot.

BACKGROUND OF THE INVENTION For example, a dual welding gun having two welding guns that operate independently of each other is configured as shown in the first example.

That is, the dual welding gun 2 attached to the tip of the robot arm 1 consists of welding guns 4, 5, etc., which are arranged at a predetermined interval on the bracket 3 and operate independently of each other. It is composed of a pair of tips 8, 8 provided on the gun arm 6 and the adapter 7, respectively, and a pressurizing cylinder 9 that moves the adapter 7 forward and backward with respect to the gun arm 6 in order to open and close the pair of tips 8, 8. The welding gun 5 is similarly composed of a pair of tips 12, 12 provided on a gun arm 10 and an adapter 11, respectively, a pressurizing cylinder 13, and the like.

The control device for this dual welding gun 2 includes, for example, as shown in FIG. 15
and thyristor switch circuits 16 and 17 inserted in the primary sides of welding transformers 15 and 15, respectively, to control the current value and energization time of the welding current flowing between chips 8 and 8 and between chips 12 and 12. At the same time, an air source 18 is connected to the pressurizing cylinders 9 and 13.
Pressurizing valves 19, 20 that supply compressed air from
a welding control device (timer) 21 that controls the opening and closing of the
22 etc.

However, in the case of such a conventional dual welding gun control device, two relatively large and heavy welding transformers are prepared depending on the number of welding guns, so the space for the welding transformer is limited. This is disadvantageous in terms of layout as it requires a large area, and since they are suspended from a ceiling monorail and each secondary cable is routed from there to the tip of the robot arm, these two secondary cables are used to connect the robot itself. There was a problem in that there were more restrictions on the movement of the welding point, and the welding spot speed deteriorated accordingly.

As a solution to this problem, one welding transformer is used, and the chips 8 and 12 on the gun arms 6 and 10 sides of the welding guns 4 and 5 shown in FIG. 1 are electrically connected to both ends of the secondary side of the transformer. At the same time, the chips 8 and 12 on the adapters 7 and 11 side are also electrically connected to each other, and furthermore, the pressure cylinders 9 and 13 can be driven simultaneously, so that two points can be connected with one energization by one welding control device. It is conceivable to use a so-called series welding specification that performs welding of 2 sheets, but in this case, welding can only be performed in areas with good welding conditions such as 2 sheets stacked, and it is difficult to weld 3 sheets stacked or with 2 welding guns. There was a problem in that it became impossible to weld parts where the conditions of the parts to be welded were different, for example, where one part was made of two layers and the other part was made of three pieces.

Purpose This invention was made in view of the above background, and it reduces the restrictions on the movement of the robot by reducing the space of the welding transformer and reducing the number of two cables routed by the robot. The purpose is to improve welding point speed.

Configuration Therefore, in the dual welding gun control device according to the present invention, the first chips of each of the plurality of welding guns are connected in parallel to one output terminal on the secondary side of a welding transformer that is appropriately controlled from the primary side. and the second chips of each of the plurality of welding guns are connected in parallel to the other output terminal, and each pressurizing cylinder independently opens and closes each pair of chips of the plurality of welding guns. The welding apparatus has a driving means that is driven simultaneously only when an external command is given to selectively perform a simultaneous welding operation by all of the plurality of welding guns and a welding operation with a time difference.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to FIGS. 3 and 4 of the drawings.

FIG. 3 is a block diagram showing an embodiment of the present invention, and parts corresponding to those in FIG. 2 are given the same reference numerals.

In the same figure, the secondary side of a welding transformer 23 whose primary side is appropriately controlled by the welding control device 21 or 22 has one output terminal connected to the first output terminal of the welding gun 4 in the dual welding gun 2 of FIG. The chip and the first chip 12 of the welding gun 5 are connected in parallel and wired, and the second chip of the welding gun 4 and the second chip 12 of the welding gun 5 are connected in parallel and wired to the other output terminal. ing.

In this embodiment, thyristor switch circuits 16 and 17 are connected in parallel and inserted into the primary side of a welding transformer 23, and a welding control device 2 drives these thyristor switch circuits 16 and 17, respectively.
1 and 22 are, for example, this dual welding gun 2, respectively.
Based on external command signals Sx and Sy from the control device (not shown) of the robot to which the robot is attached, the current value and energization time of the welding current are controlled in order to perform optimal welding that matches the conditions of the welded part. It's becoming like that.

The gate valve 24 includes pressurizing cylinders 9, 13 (FIG. 1) that independently open and close each pair of chips 8, 8, 12, 12 in the welding guns 4, 5.
It functions as a driving means that simultaneously drives the robots only when an external command signal SG is applied, for example, from the aforementioned robot control device.

That is, this gate valve 24 opens only when an external command signal SG is applied, and supplies compressed air from the air source 18 to the pressurizing cylinder 9 of the welding gun 4 via the pressurizing valve 19, for example, to the welding gun. The pressure is also fed to the pressure cylinder 13 of No. 5, thereby pressurizing the welding guns 4 and 5 at the same time.

Note that the pressurizing valves 19 and 20 are configured to open at a predetermined timing when the welding control devices 21 and 22 are activated by external command signals Sx and Sy, respectively.

Next, the effects will be explained by case.

(A) As shown in Fig. 4 A, when the parts to be welded by welding guns 4 and 5 are both two-layered. First, the robot equipped with dual welding gun 2 shown in Fig. 1 moves up to the taught dot point. Move and stop.

Next, an external command signal is sent from the robot control device.
Sx is output to the welding control device 21, and an external command signal SG is output to the gate valve 24, respectively.

As a result, the welding guns 4 and 5 of the dual welding gun 2 are simultaneously pressurized and energized, and the 2
A spot series weld is made. In other words, simultaneous welding operations (series welding) are performed using all the chips of the plurality of welding guns 4 and 5.

After welding is completed, the robot control device receives a completion signal from the welding control device 21 and moves the robot to the next welding point.

(B) As shown in Fig. 4B, when the area to be welded by welding gun 4 is three layers, and the area to be welded by welding gun 5 is two layers, First, the robot moves to the welding point and stops. do.

Next, for example, an external command signal Sx is output from the robot control device to the welding control device 21.
Only the welding gun 4 is energized under pressure, thereby welding the three welded parts. At this time, the pressurizing valve 20 of the welding gun 5 is not operated, its tips 12, 12 remain open, and no welding current flows.

Next, after the welding by the welding gun 4 is completed, an external command signal Sy is output from the robot control device to the welding control device 22, and only the welding gun 5 is energized under pressure, thereby controlling the welding area of the two stacked sheets. Welding is performed, and then the robot control device receives a completion signal from the welding control device 22 and moves the robot to the next welding point. In other words,
Welding operation by the first and second chips 3, 12 forming a pair of one welding gun 4, followed by welding by the first and second chips 3, 12 forming a pair of another welding gun 5 with a time difference. Each operation results in direct welding.

(C) As shown in FIG. 4C, the area to be welded by the welding gun 4 is two layers, and the area to be welded by the welding gun 5 is three layers.Although it is almost the same as in case (B), In order to weld the three welded parts first, the welding gun 5 is pressurized and energized, and then the welding gun 4 is pressurized and energized.

(D) Although not shown, when the parts to be welded by the welding guns 4 and 5 are three or two sheets, but the plates are relatively thick and welding conditions are poor. Simultaneous pressurization. Do not perform two-point series welding with simultaneous energization, but perform direct welding one point at a time as in (B) or (C).

In addition, in each welding mentioned above, there are two types of welding: series welding of two layers, direct welding of two layers, three types of welding.
It is assumed that welding conditions (current value, energization time, pressure force) are different for direct welding of sheets, etc.

In this way, according to this embodiment, not only can a wide range of welding conditions be handled as described above, but only one welding transformer is required, which is advantageous in terms of space, and the restrictions placed on robot movement are reduced compared to conventional ones. As a result, the welding spot speed is improved compared to the conventional method.

Note that if the welding control device is made programmable by, for example, a microcomputer, the welding control devices 21 and 22 shown in FIG. 3 can be replaced with one device, and the thyristor switch circuit 16, One of 17 can be omitted.

Further, instead of the gate valve 24 for simultaneous pressurization, a timing device that starts the pressurization valves 19 and 20 at the same time may be used.

Further, although the above embodiments have been explained using a dual welding gun as an example, the present invention can be similarly applied to a dual welding gun having three or four welding guns.

Effects As explained above, according to this invention,
The first chips of each of the plurality of welding guns are connected in parallel to one output terminal of the secondary side of a welding transformer that is appropriately controlled from the primary side, and each of the plurality of welding guns is connected to the other output terminal. The second chips of the plurality of welding guns are connected in parallel and wired, and the pressure cylinders for independently opening and closing each pair of chips of the plurality of welding guns are driven simultaneously only when an external command is given, thereby producing the plurality of welding guns. Since we have provided a drive means that selectively performs simultaneous welding operations by all of Welding point speed can be improved by reducing restrictions on movement.

Therefore, if the present invention is applied to, for example, a welding robot that performs additional welding on an automobile manufacturing line, work efficiency will be significantly improved.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an outline of a dual welding gun as a dual welding gun which is the background of this invention;
FIG. 2 is a block diagram showing a conventional example of a control device for a dual welding gun, FIG. 3 is a block diagram showing an embodiment of the present invention, and FIG. 4 is a diagram for explaining the operation of FIG. be. 1... Robot arm, 2... Dual welding gun, 4, 5... Welding gun, 8, 12... Chip,
9, 13...pressure cylinder, 14, 15, 23
... Welding transformer, 16, 17 ... Thyristor switch circuit, 18 ... Air source, 19, 20 ... Pressure valve, 21, 22 ... Welding control device, 24 ...
...Gate valve (driving means).

Claims (1)

[Claims] 1. In a control device for a multiple welding gun having a plurality of welding guns that are attached to the tip of a robot and have a pair of first and second chips that operate independently of each other, The first chips of each of the plurality of welding guns are connected in parallel to one output terminal of the secondary side of the welding transformer which is controlled as appropriate, and the first chip of each of the plurality of welding guns is connected to the other output terminal. Two chips are connected in parallel and wired, and each pressure cylinder that independently opens and closes each pair of chips of the plurality of welding guns is driven simultaneously only when an external command is given, so that all of the plurality of welding guns are connected. A control device for a dual welding gun comprising a driving means for selectively performing simultaneous welding operations and time-differentiated welding operations.