JPH0815659B2 - Arc start mistake automatic recovery method in arc welding robot - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an arc welding robot, and relates to a countermeasure when an arc does not occur at the start of an arc.

Conventional technology In arc welding, a welding current is passed between the work and wire of the base material to be welded to generate an arc between the work and the wire, but at the start of welding, slag and dust on the work In some cases, an arc may not occur.
In such a case, in the conventional arc welding robot, a voltage is applied between the work and the wire for a predetermined time, and when the arc is not generated even after the lapse of the predetermined time, an alarm is issued and the work is stopped. Therefore, every time such an alarm occurs, a worker needs to perform manual recovery work such as cleaning the work and the tip of the wire, removing slag and dust, and making the welding robot work again.

Problems to be Solved by the Invention If an arc does not occur at the time of arc start, the welding work is interrupted, and it takes manpower to restore it, the work efficiency of the welding robot that automates welding cannot be improved, and the arc start A mistake was one of the obstacles to improving automation efficiency.

Therefore, an object of the present invention is to provide an automatic recovery method for improving automation efficiency by automatically performing an arc start by automatically performing a process of eliminating the cause of an arc start error when an arc does not occur at the time of arc start. To provide.

Means for Solving Problems When the arc does not occur at the start of the arc, the torch is moved by a set predetermined amount, and when the arc is generated while moving the predetermined amount, the torch is returned to the start position and welding is performed. When the arc does not occur even when the torch moves by the predetermined amount, an alarm is generated and the welding work of the robot is stopped to solve the above problem.

Even if the work and wire are insulated by the slag and dust adhering to the work, and the arc is not generated at the start of the arc, moving the torch changes the wire tip position relative to the work, causing slag and dust. Will move to a position where is not attached and an arc will be generated. In addition, since the wire is projected from the torch and slidably contacts the work surface to move, the work surface is cleaned by the wire, so that slag and dust are eliminated and an arc is generated. When an arc is generated, the torch is returned to the start position and welding is performed along the taught welding line.

If the arc does not occur even if the torch is moved by a predetermined amount, an alarm is given and the welding work of the robot is stopped.

Embodiment FIG. 2 is a block diagram of essential parts of an embodiment of a welding robot for realizing the automatic start-miss recovery method of the present invention.

In the figure, reference numeral 1 is a control device for controlling the robot main body 2 and the welding machine 3. The control device 1 has a central processing unit (hereinafter referred to as CPU) 10, and the CPU 10 has a memory composed of a ROM.
11, a memory 12 composed of RAM, a teaching operation panel 13, a main data input device with a CRT display device (hereinafter referred to as CRT / MDI) 14, a tape reader 15 are connected by a bus 20, and an input / output circuit 1
6, the axis control circuit 17, and the welder interface 19 are connected to the bus.

The memory 11 stores various control programs to be executed by the CPU 10. The memory 12 has a teaching operation panel 13, CRT / M
Teaching data input from the DI 14, the tape reader 15 and the like, and data such as various parameters input from the CRT / MDI 14 are input, and the results and data of calculations performed by the CPU 10 are stored. The input / output circuit 16 is connected to various sensors and actuators provided in the robot body 2, and the axis control circuit 17 is connected to a servo circuit 18 that controls a servo motor that drives each axis of the robot. Further, the welding machine 3 and the control device 1 are connected via the welding machine interface 19 to control the welding machine 3, and these configurations are the same as those of the conventional arc welding robot.

FIG. 1 shows a flowchart at the time of arc start of one embodiment performed by the welding robot, and the arc start miss automatic recovery operation will be described together with the flowchart.

First, the CRT / MDI 14 sets the torch movement amount when an arc start error occurs as a parameter and stores it in the memory 12. And CPU10 is welder interface 1
An arc start command is output to the welding machine 3 via 9 and the timer T is started (step S1). The welding machine 3 receives the arc start command, applies a voltage between the work and the wire, and tries to flow the welding current. When the welding current flows, the welding machine 3 transmits an arc generation signal to the control device 1. on the other hand,
The CPU 10 of the controller 1 monitors whether or not an arc generation signal is transmitted from the welder 3 via the welder interface 19 until the timer T times out (steps S2, S3), and the timer T times out. If the arc generation signal is sent before the welding, the welding work is started according to the teaching data stored in the memory 12, that is, the teaching program. However, if the arc generation signal is not sent before the timer T times up, the servo motor for each axis of the robot 2 is driven through the axis control circuit 17 and the servo circuit 18 according to the teaching program to move the torch. Allow (step S4). This torch moving direction may be specified by a program along the welding line taught by the teaching program, or a new torch moving direction for this arc start mistake may be specified by the program (in the conventional welding robot, When timer T timed up in S3, an alarm was issued and welding work was stopped). After the torch starts moving, the CPU 10 determines whether or not an arc generation signal is sent from the welding machine 3 (step S5).
It is judged whether or not the torch movement has moved by a predetermined amount set by the parameter (step S6), and if the arc generation signal is sent from the welding machine 3 before the torch moves by the set predetermined amount, the torch is moved to the start position. (Step S7), the robot is driven according to the taught program, and the welding work is disclosed (Step S7).

On the other hand, if the arc generation signal is not sent from the welding machine 3 even if the torch is moved by the set amount, the CPU 10 outputs an alarm signal and displays an alarm on the CRT screen of the CRT / MDI 14 and the robot 2 Stop the drive and stop the welding work.

In arc / spot welding, the torch does not move during arc welding.In this case, teach a dummy point on the program so that the arc does not occur within the predetermined time at arc start. (Step S
2, S3), move the torch to the dummy point, and if an arc occurs during this time, return to the spot point to perform welding, and when the torch reaches the dummy point without arcing while moving the torch The alarm should be issued for the first time and the welding operation should be stopped.

EFFECTS OF THE INVENTION According to the present invention, when the arc does not occur at the start of the arc, the torch is moved by the set predetermined amount and waits for the arc to occur, so that the movement of the torch does not cause slag or dust to be attached to the wire tip. It is easy to generate an arc when facing the work position,
Further, since the tip of the wire makes sliding contact with the surface of the work and rubs against it, slag and dust adhering to the surface of the work are eliminated, which facilitates arc generation and increases the probability of arc generation. Further, even if an arc is generated during the movement of the torch by a predetermined amount, the welding is performed by returning to the start position, so that the welding can be accurately performed from the welding start position and no unwelded portion is generated. Then, only when the arc does not occur even if the torch is moved by a predetermined amount, the alarm is issued for the first time and the welding work is interrupted, so the work interruption due to the arc start mistake is reduced,
The efficiency of automation can be improved.

[Brief description of drawings]

FIG. 1 is a flow chart of an operation process of an embodiment of the present invention, and FIG. 2 is a block diagram of essential parts of an example of a welding robot adopting the method of the present invention. 1 ... Control device, 2 ... Robot body, 3 ... Welding machine.

Claims (1)

[Claims] 1. In an arc welding robot, when no arc is generated at a welding start position at the time of arc start, the torch is moved by a set predetermined amount, and when the arc is generated during the predetermined amount of movement, the torch is moved. When the welding is started after returning to the start position and the arc does not occur even if the torch moves by the above specified amount, an alarm is output and the robot welding operation is stopped. How to return.