JPH05200551A - Controller for welding robot - Google Patents

Abstract

PURPOSE:To perform welding without positional deviation by providing a touch sensor to detect materials to be welded being set on the specified position on a welding torch of an articulated robot. CONSTITUTION:The touch sensor 44 is provided on a third casing 28 of the tip of the welding robot 2 and an electrically conductive pin 46 connected electrically to the welding torch 30 is provided on the tip thereof with extension thereof adjustable. The extension of the pin 46 is adjusted in accordance with a shape of materials 38 to be welded and an accurate welding starting point is marked on the materials 38 to be welded. The pin 46 is driven so as to approach a marking point. When the pin 46 comes into contact with marking point, the pin 46 and the materials 38 to be welded are energized and the touch sensor 44 outputs a reference position detection signal. Based on this, welding can be performed without the positional deviation according to the data inputted in advance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a welding robot controller for reproducing a welding operation taught in advance by a teaching playback method or a program input method.

[0002]

2. Description of the Related Art In this type of welding robot, generally, a deviation occurs between a welding start point of a movement trajectory taught in advance and a welding start point of a material to be actually welded, and it is necessary to correct this deviation. is there. As a means to correct this deviation,
A method by image processing using a television camera or the like arranged around the robot can be considered.

[0003]

However, since fumes (smoke) are usually generated together with a light flame during welding, a clear view is often not obtained in a room (place) where welding is performed. Further, in the method using image processing, since the operator's visual observation is used, there is a problem in that accuracy varies. The present invention aims to solve the above problems.

[0004]

According to the present invention, there is provided a welding robot control device in which a welding torch is arranged at a tip of an articulated robot, wherein the welding torch is set at a predetermined position with respect to a material to be welded. A touch sensor that detects that the welding torch is in a predetermined position, a storage unit that stores the position data of each movable element of the articulated robot when the welding torch is in a predetermined position, and the welding torch is preset based on the position data. And a shift amount calculating means for calculating a deviation from the reference position.

[0005]

The welding robot is displaced by being drive-controlled based on the position data obtained by adding the shift amount obtained by the shift amount calculating means to the position data of the movement trajectory taught in advance. Weld exactly.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. First, the schematic configuration of the welding robot to be controlled will be described with reference to FIG.

In the figure, reference numeral 2 is a welding robot main body, and a cylindrical pedestal 4 below the main body is placed on the floor. A servomotor is incorporated in the pedestal 4, and the rotation of the output shaft of the motor causes the cylindrical rotation seat 6 disposed on the pedestal 4 to rotate in the forward and reverse directions about the axis. It is controlled. A support seat 8 having a built-in servo motor is fixedly mounted on the upper surface of the rotary seat 6, and the output shaft of the servo motor is connected to a drive lever 10.

The upper end of the support seat 8 is rotatably supported by the other end of a main shaft 14 having one end fixed to a first arm 12, and the end of the drive lever 10 has a first end. The other end of a link 16 whose one end is rotatably supported by the arm 12 is rotatably connected. And the support seat 8
Drive lever 1 to control the servo motor built in
By controlling the rotational movement of 0, the swinging movement of the first arm 12 can be controlled.

The second arm 1 is attached to the tip of the first arm 12.
8 is rotatably inserted around its axis, and the first arm 1
A servo motor for rotating the second arm 18 around the axis is provided inside the unit 2.

A first casing 20 is fixed to the end of the second arm 18, and a servomotor is built in the first casing 20. The output shaft 22 of the servomotor is connected to the second casing 24, so that the second casing 24 can rotate around the shaft 22.

A small servomotor is incorporated inside the second casing 24, and the output shaft 26 of this motor is provided.
Is connected to the third casing 28, and the third casing 28
Rotational movements in the forward and reverse directions about the axis 26 are controlled by the motor. MIG is provided on one end side of the third casing 28.
A welding torch 30 for welding is fixed.

On the other hand, a wire reel 34 around which a wire 32 serving as a filler material is wound is arranged on the first arm 12, and the tip of the wire 32 is also on the first arm 12. The wire feeding device 36 is guided to the line-in portion thereof, comes out of the line-out portion of the device 36, and is guided to the other end side of the third casing 28.

A mounting table 40 for mounting the material 38 to be welded is provided on the floor facing the welding robot main body 2. The platform 40 is mounted in a direction in which the rail 42 is brought into contact with or separated from the robot body 2 (arrow α or arrow β in FIG.
It is arranged so as to be movable in the same direction) and is driven in the same direction by a hydraulic cylinder (not shown).

A touch sensor 44 is provided on the third casing 28. This touch sensor 4
A conductive pin 46, which is electrically connected to the welding torch 30, is provided at the tip of 4 so that the protruding length thereof can be adjusted. Further, inside the touch sensor 44, a small circuit for detecting the current flow of the pin 46 is incorporated.

Each of the servo motors provided in the welding robot and the hydraulic cylinders for driving the mounting table 40 have a pulse encoder at the output thereof, and are connected to a controller (not shown). The movement is controlled. A wire feeding device 36 is also connected to the same controller and is configured to feed the wire 32 to the welding torch 30 in cooperation with each servo motor. Further, the output part of the circuit for detecting the current flow of the pin 46 is also connected to the same controller, so that the energization of the pin 46 can be detected by the controller.

A pipe for gas supply (not shown) is connected to the torch 30 from an inert gas supply device (not shown) used for preventing the generation of slag, and the torch 30 and the material to be welded are connected. One of the wires from a direct current welding machine (not shown), which is used to generate an arc between the two and 38, is led (not shown). The other side of the wiring from the DC welding machine is the welded material 38.
(Not shown). Further, the supply of the inert gas and the supply of the welding current are performed in conjunction with the feeding of the wire 32.

In the above welding robot, the welding torch 30 is controlled so as to perform welding while drawing a predetermined locus at a predetermined speed on the basis of a program input in advance to perform welding on the material 38 to be welded. It has become.

Next, the operation of this embodiment having the above structure will be described with reference to FIGS. Here, FIG.
Above, reference numerals 48, 52, 56, 60, 64 are respectively
The welding robot body 2 includes a pedestal 4, a support seat 8, a first arm 12, a first casing 20, and a second casing 24.
Reference numerals 54, 58, 62 and 66 are pulse encoders which are position detectors of the servo motors 48, 52, 60 and 64, respectively. Reference numeral 68 is a hydraulic cylinder that drives the platform 40, and reference numeral 70 is a pulse encoder that is a position detector of the hydraulic cylinder 68. Reference numeral 72 is a controller for driving and controlling these servomotors 48, 52, 56, 60, 64 and the hydraulic cylinder 68, and constitutes robot operation control means 74, storage means 76, and shift amount calculation means 78, which will be described later. is doing.

When the controller of this welding robot is used to correct the deviation between the welding start point of the movement trajectory taught in advance and the welding start point of the material 38 to be actually welded,
First, the protruding length of the pin 46 is adjusted according to the shape of the material to be welded 38, and the tip of the pin 46 is set on the material to be welded 38 when the tip of the welding torch 30 is set at an accurate welding start point. The position of contact is marked on the material to be welded 38.

Next, the touch sensor 44 is turned on (step SP1), and a predetermined voltage is applied between the pin 46 and the material 38 to be welded. The relative position of the robot with respect to the workpiece 38, that is, the servo motors 48, 52,
The rotation (movement) positions of 56, 60, 64 and the hydraulic cylinder 68 are set to the respective pulse encoders 50, 54, 58, 62, 6
While detecting by the robot operation control means 74 via 6, 70, the robot approaches the point where the tip of the pin 46 is marked on the above-mentioned welded material 38 manually or by inputting the movement amount from the keyboard. It is gradually driven so as to move (step SP2).

When the tip of the pin 46 contacts the marking point of the material to be welded 38, the pin 46 and the material to be welded 38 are energized, and the touch sensor 44 outputs a reference position detection signal to the robot operation control means 74 (step SP3). ). The robot operation control means 74, when outputting the reference position detection signal from the touch sensor 44, the servo motors 48, 52, 56, 6
0, 64 and rotational (moving) position data of the hydraulic cylinder 68 are detected and output to the storage means 76 (step SP4), and the touch sensor 44 is turned off (step SP5). The shift amount calculation means 78 includes servo motors 48, 52, 56,
After receiving the previously input position data of 60 and 64 and the hydraulic cylinder 68 and the position data detected at the time of outputting the reference position detection signal from the storage means 76, after calculating the position amount (shift amount) to be corrected ( In step SP6), the shift amount data is output to the robot operation control means 74.

The robot operation control means 74 corrects the position data of the welding start point based on the shift amount data obtained from the shift amount calculating means 78, and then performs welding by drawing a predetermined locus to thereby shift the position. It is possible to perform accurate welding.

Although the MIG welding robot is used as the welding robot in the above-mentioned embodiment, this is, for example, TIG.
It may be a welding robot. In the case of a TIG welding robot, the position of each movable element (servo motor, hydraulic cylinder, etc.) of the robot when a current flows between the tungsten electrode and the welding start point of the material to be welded is the criterion for creating the shift amount. As a result, the tungsten electrode can be used as a touch sensor in a range that does not cause electrode consumption.

Further, as described above, the touch sensor is not limited to the one using the electric current, but may be a pressure sensitive type such as a strain gauge or a micro switch.

Further, in the above embodiment, the storage means 76 and the shift amount calculation means 78 are realized by the controller 72, but it goes without saying that an equivalent logic circuit may be provided.

[0026]

As described above, according to the present invention,
In a welding robot control device in which a welding torch is arranged at a tip of an articulated robot, a touch sensor for detecting that the welding torch is set at a predetermined position with respect to a material to be welded, and the welding torch are provided. A storage means for storing the position data of each movable element of the multi-joint robot at a predetermined position, and a shift amount calculation means for calculating a deviation between the welding torch and a preset reference position based on the position data. Since it is configured to include, it is possible to correct the deviation between the welding start point of the movement trajectory taught in advance and the welding start point of the material to be actually welded, and perform welding without positional deviation. There are effects that can be achieved.

[Brief description of drawings]

FIG. 1 is a block diagram according to an embodiment of the present invention.

FIG. 2 is a side view of a welding robot according to an embodiment.

FIG. 3 is a flowchart according to one embodiment.

[Explanation of symbols]

 30 welding torch 44 touch sensor 76 storage means 78 shift amount calculation means

Claims (1)

[Claims] 1. A controller for a welding robot, wherein a welding torch is provided at the tip of an articulated robot, and a touch for detecting that the welding torch is set at a predetermined position with respect to a material to be welded. A sensor, a storage means for storing the position data of each movable element of the articulated robot when the welding torch is at a predetermined position, and a deviation from a preset reference position of the welding torch based on the position data. A control device for a welding robot, comprising: a shift amount calculating means for calculating