JPH01181969A - Robot for welding - Google Patents

Abstract

PURPOSE:To stabilize bead quality and to uniformize its width by detecting the temperature of base metal by a temperature detector and connecting its output to an interpolation arithmetic unit and an input-output unit and calculating the torch tip speed and welding conditions to be calculated by a function of the output of the temperature detector. CONSTITUTION:The temperature of a work is detected by a temperature sensor 21 and its output is connected to a main CUP7, the arithmetic unit 11 and the input-output unit 16 via an interface 22. The input output unit 16 changes a welding current and voltage at a predetermined ratio determined by the temperature of the work. On the other hand, the arithmetic unit 11 also changes the speed in the same way and according to the speed, the increment per unit time of a servomotor 15 is calculated and sent to an interface 12. By this method, the adaptive control of the welding conditions by the temperature of the work can be realized and the bead with the stable quality and uniform width can be obtained.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a welding robot.

BACKGROUND OF THE INVENTION Conventional robots of this type deal with the problem by adjusting the speed, current, voltage, etc. of the arm for each taught position of the arm.

Problems to be Solved by the Invention The temperature of the welding workpiece, that is, the base material, affects the quality of the welding result and the appearance such as changes in bead width.

This tendency will increase as CO2 and MAG change to TIC and MIG, but this is currently being handled using the teaching know-how.

However, the degree of temperature rise cannot be determined unless the actual workpiece is welded, and this is done using the traditional teaching method of teaching playback robots, in which the position is confirmed by partially executing the teaching content, and the welding conditions are confirmed with a test piece. This method is difficult. Furthermore, if there is another welding process in the previous process,
Since the temperature changes depending on the waiting time between processes, it becomes even more difficult to manage the conditions.

Therefore, an object of the present invention is to control a robot under optimal conditions by detecting a predetermined temperature.

Means for Solving the Problems The present invention detects the temperature of the base material with a temperature detector,
.

The output is connected to an interpolation calculation unit and an input/output unit, and the calculated torch tip speed and welding conditions are determined as a function of the temperature detector output.

The workpiece can be considered to be at approximately room temperature when teaching the action. On the other hand, in order to obtain the desired welding result, the optimum conditions for temperature are determined, so the speed is determined according to the detected temperature.

All you have to do is change the current, voltage, etc.

Example An embodiment of the present invention will be described below.

Figure 1 shows the appearance of the torch and the area around the wrist of the robot arm. 1 is a wrist, 2 is a holder for the arm to hold the torch 3, and 4 is an arc.

5 is an infrared temperature sensor fixed to holder 2;
6 indicates infrared rays emitted from parts that require temperature. At this time, the infrared temperature sensor 5 does not need to be fixed to the holder 2, and may be rotatably mounted 9 around the torch 3.

The temperature of the workpiece may be measured at an appropriate location on the workpiece before welding, rather than during welding. Until new data is input from the infrared temperature sensor 5, the speed and welding conditions are corrected based on the previous temperature data.

FIG. 2 is a block diagram of the control section. 7 is the main CPU
to integrate the whole. A ROM 8 and a RAM 9 store teaching programs and the like. 1° is a signal data bus.

Reference numeral 11 denotes an arithmetic unit, which is composed of a dedicated arithmetic element or a local CPU. Reference numeral 12 denotes a servo interface, which is comprised of various counters, digital and analog converters, and the like. 13 is a servo amplifier that rotates the motor according to a given speed command. 14 is a driver for the servo motor 15.

Reference numeral 16 denotes an input/output unit, which is composed of a dedicated local CPU. 17 is an output buffer, and 18 is an input buffer, which is composed of an optical coupling element for noise removal. 19 is a welding power source, and 20 is a jig.

21 is an infrared temperature sensor, and 22 is an interface for connection to the bus 1o.

The temperature of the workpiece is captured by the infrared temperature sensor 21 and transferred to the bus 10 via the heat exchanger 22.
Main QPU7, arithmetic unit 11. Each input/output unit 16 can know. The input/output unit 16 changes the welding current and welding voltage at a predetermined ratio determined by the temperature of the workpiece.

On the other hand, the arithmetic unit 11 similarly changes the speed, calculates the increment per unit time of the servo motor 15 according to the speed, and sends it to the interface 12.

In this way, adaptive control of welding conditions depending on the temperature of the workpiece can be realized.

There are various methods of changing the conditions depending on the temperature, but here a method using the table shown in FIG. 3 will be explained. The vertical axis is the temperature obtained by the infrared sensor, and the horizontal axis is the taught welding current. The intersection of both axes indicates the ratio by which the taught current value is multiplied to correct it by that temperature. Although not shown, similar tables exist for voltage and speed. These tables are written in the ROM 5 and, if the tables are released to the user, in the RAM 9 which is backed up by a battery.

6. When temperature data is obtained from the Hoene temperature sensor 21, the main CPU examines the data in the table above and calculates the ratio to be multiplied by the calculation unit 11. Notify the input/output unit 16.

Effects of the Invention According to the present invention, when the temperature of the workpiece influences the welding conditions, especially in TIG, MIG welding, etc., the influence of temperature is corrected, and a bead of stable quality and uniform width can be obtained.

[Brief explanation of the drawing]

Fig. 1 is an external perspective view of the wrist area of a welding robot according to an embodiment of the present invention, Fig. 2 is a block diagram of the control unit, and Fig. 3 is a table of data for correcting current according to temperature in the embodiment. shows. 3... Torch, 5-... Infrared temperature sensor, 11... Arithmetic unit. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
Figure 3

Claims (1)

[Claims] a welding torch, a robot arm that grips the welding torch, a servo that drives the robot arm, and an interpolation calculation unit that calculates the amount of movement sent to the servo;
comprising an input/output unit for controlling welding conditions and a temperature detector disposed near the torch, the temperature detector being connected to the interpolation calculation unit and the input/output unit,
A welding robot characterized in that the torch tip speed and welding conditions to be calculated are determined as a function of the output of the temperature detector.