JP2000288733A - Welding robot automatic origin check device and its check method - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a welding robot automatic origin check device and a check method thereof, in which the origin check of the welding robot can be performed easily in a short time. SOLUTION: A columnar reference bar 10 is erected at a predetermined position, and an upper end thereof is set as an origin 11. The welding wire 4 of the welding torch 3 attached to the main body 2 of the welding robot 1
When the welding wire 4 and the origin 11 come into contact with each other and are energized, it is determined that there is no positional deviation of the welding torch 3, and when not energized, it is determined that there is a positional deviation of the welding torch 3. The above operation is automatically performed by the origin check program. This makes it possible to check the origin for each predetermined welding operation in a short time and easily.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a welding robot automatic origin check device and a check method thereof.

[0002]

2. Description of the Related Art Conventionally, welding robots are often used to automate a welding line. FIG. 1 is a perspective view showing an example of the welding robot 1. In FIG. 1, a welding robot 1 includes a main body 2 having one to five rotation axes, each of which is rotatable in a predetermined direction, and an arm provided on the main body 2 (corresponding to three to five axes). And a welding torch 3 attached to the front end of the welding torch. The main body 2 drives the respective rotating shafts to move the welding torch 3. That is, each shaft rotates as shown by an arrow, and moves the welding torch 3 to a predetermined position. The welding wire 4 is fed at a predetermined feeding speed from the tip of the welding torch 3 by a feeding device (not shown).
The main body 2 is connected to a control device 6, and the control device 6 controls each rotating shaft based on the stored welding program to control the tip of the welding wire 4 projecting from the welding torch 3 by a predetermined length. Move along the trajectory and perform welding automatically.

The welding robot 1 has a welding wire contact detecting means for detecting whether or not the welding wire 4 is in contact with the work when the tip of the welding wire 4 contacts the work. Some have. When the position of the welding line of the predetermined work (welding target) is shifted, the actual position of the work is detected by the welding wire contact detecting means, and the position shift is calculated. The movement trajectory of the welding torch 3 in the program is automatically corrected based on the positional deviation, and the position of the welding torch 3 is corrected to perform correct welding. One example is disclosed in Japanese Patent Publication No. Hei 5-10189.

However, the position of the tip of the welding wire 4 often shifts due to a collision during operation or an erroneous operation. If the position of the tip of the welding wire 4 is displaced with respect to the main body 2 of the welding robot 1, correct welding may not be performed even if the above-mentioned work for correcting the work is performed. Therefore, at the start of welding, it is necessary to check whether the tip of the welding wire 4 is correctly positioned at a predetermined position with respect to the main body 2.

Normally, the position of the tip of the welding wire 4 is checked by setting an origin serving as a reference with respect to the main body 2 of the welding robot 1 in advance, setting the welding torch 3 to a predetermined posture, and setting the welding wire 4 to a predetermined position. Each rotation angle of 1 to 5 axes of the welding robot 1 when the tip is located at the origin is set in advance,
At the next check, one axis to 5
This is performed by moving the rotation axis of the shaft and checking the position of the tip of the welding torch 3. This is hereinafter referred to as origin check.

Conventionally, in the above-mentioned origin check, as shown in FIG. 5, the position and posture of the welding torch 3 (that is, the rotation angles of one to five axes) are manually set to a predetermined origin 11 as shown in FIG.
Is moved so as to come to the above set position and angle, and the operator checks whether or not the distal end of the welding wire 4 at that time is displaced from the position of the origin 11.

[0007]

However, in the above-mentioned method of checking the origin, the operator manually rotates each shaft so that the tip of the welding wire 4 of the welding torch 3 coincides with the set angle of the origin 11. Therefore, it takes a very long time for the operator to move the welding torch 3 to the set angle corresponding to the origin, and the checking operation is troublesome. For this reason, when the check frequency is increased, there is a problem that the operation rate decreases. Further, if the check frequency is reduced to, for example, about once / week, there is a problem that a positional deviation occurs during that time, and welding defects (such as welding derailment, overlap, and undercut) frequently occur. Further, when a shift occurs, many shifts having different causes are often overlapped for a long period of time, so that it takes a long time to correct the shift.

An object of the present invention is to provide an automatic welding robot origin check apparatus and a check method thereof, in which the origin can be easily checked in a short time in consideration of the above problems.

[0009]

Means for Solving the Problems, Functions and Effects In order to achieve the above object, the invention of a welding robot automatic origin check device according to the present invention comprises a welding torch and a tip of an arm to which the welding torch is attached. A welding robot that has a plurality of control axes for controlling the position and attitude, and enables the welding torch to move to a predetermined position by driving each control axis, and automatically controls the welding robot according to a stored welding program to control the welding robot. A welding robot device comprising a welding control device for welding, a welding wire protruding from the tip of the welding torch, comprising a conductive member connected to a workpiece at a predetermined position within the moving range of the welding torch at the same potential. A column-shaped reference bar having the upper end surface having a width capable of contacting the tip of the welding robot as the origin of the welding robot is erected, and the control device further moves from the tip of the welding torch. Has a touch sensor for detecting contact between the welding wire and the workpiece by energizing the welding wire and the workpiece out come, according to automatic home check program,
After the welding torch is moved to a predetermined position directly above the reference bar stored in advance and then lowered by a predetermined relative distance, when the touch sensor detects contact between the welding wire and the reference bar, the welding torch is The configuration is such that it is determined that there is no displacement, and if no contact is detected, it is determined that there is a displacement of the welding torch.

According to a second aspect of the present invention, there is provided a welding program storing a welding robot capable of moving a welding torch to a predetermined position by driving a plurality of control axes for controlling the position and posture of an arm tip to which a welding torch is attached. A welding robot device that automatically welds a work by controlling the welding torch at a predetermined position within a movement range of the welding torch, the conductive member being connected to the work at the same potential, and a tip of the welding torch. The welding torch is moved according to an automatic origin check program to a pre-stored predetermined position just above the columnar reference bar whose origin is the welding robot's origin and whose upper end surface is large enough to contact the tip of the welding wire protruding from the part. After that, when the contact between the welding wire protruding from the tip of the welding torch and the reference bar is detected during the lowering by a predetermined relative distance, the welding torch is detected. Determining positional deviation of the blood without the, if no contact is detected is a method to determine that there is positional deviation of the welding torch.

According to the present invention, even if an operator does not work, the welding torch is automatically moved to the origin position of the tip of the reference bar stored in advance, and the welding wire protruding from the tip of the welding torch and the reference wire. It automatically checks whether the tip position of the welding torch matches the origin position of the reference bar based on the presence or absence of contact with the bar. Therefore, the welding torch automatically moves to the origin position, so that the movement time is short, and the work time of the origin check by the operator is not required, and the origin check can be performed in a short time and easily. As a result, the origin can be checked for each welding operation, and the welding torch deviation can be found at an early stage, so that occurrence of welding defects can be prevented beforehand.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. In the following description,
Although an articulated robot is shown as an example of the welding robot 1 as shown in FIG. 1, the present invention is not limited to a robot type. In FIG. 1, a welding robot 1 includes a main body 2 and a welding torch 3 attached to a distal end of the main body 2. The main body 2 is provided with a turning shaft 7 a (hereinafter referred to as one axis) that can freely turn with respect to the base 8, and a first arm 7 b that is disposed on one axis and is turnable in the front-rear direction of the welding robot 1.
(Hereinafter referred to as two axes), a second arm 7c (hereinafter referred to as three axes) disposed at the tip of the two axes and rotatable in the vertical direction, and a welding robot 1 at the front end of the three axes. A first wrist shaft 7d (hereinafter referred to as four axes) rotatable about the longitudinal axis, and an axis perpendicular to the four axes. A movable second wrist shaft 7e (hereinafter, referred to as a second wrist shaft 7e)
5 axes). A welding torch 3 is attached to the tip of the five shafts. Each of these control axes is driven by an electric servomotor (not shown).

The control device 6 has a high-speed arithmetic device such as a computer device, controls the movement trajectory of the welding torch 3, and controls the setting of welding conditions for performing welding, the start and stop of welding. Is stored in a predetermined memory. Further, the control device 6 also stores an automatic origin check program as described later. Then, when these programs are executed, the electric servomotors of the respective control axes are controlled based on the stored trajectories.

As shown in FIG. 2, an origin position is provided at a predetermined position within a range in which the welding torch 3 can move, and a columnar reference bar 10 is erected and fixed at this origin position.
The leading end of 0 is the origin 11. The diameter d of the reference bar 10 is set to a predetermined size such that the distal end of the welding wire 4 of the welding torch 3 can be abutted and a positional deviation can be detected, for example, approximately 5 mm. Then, the posture of the welding torch 3 is set to a predetermined state, the tip of the welding wire 4 is brought into contact with the origin 11, and the rotation angle indicated by each of the angle control axes (1 to 5 axes) of the main body 2 at this time. The value is determined as the reference rotation angle at the origin 11 and stored in the control device 6. In this storage method, the position data may be set and stored by teaching or directly.

The control device 6 has welding wire contact detection means (not shown) (not shown) for detecting whether the welding wire 4 and the workpiece are in contact with each other or not in contact with each other based on an energized state. I have. This touch sensor
As shown in FIG. 3, when the tip of the welding wire 4 of the welding torch 3 contacts the origin 11 of the tip of the reference bar 10 as shown by a solid line within a predetermined detection timing period, the welding wire 4 Detecting the energization with the reference bar 10 (electrically connected to the workpiece at the same potential), it is determined that there is contact, and the position of the welding torch 3 shifts as shown by the broken line, and the welding wire 4 moves to the origin 11. If no contact is made, no current is detected and it is determined that there is no contact.

Next, the automatic origin check method will be described with reference to the flowchart of FIG. The control device 6 stores an automatic origin check program in advance, and causes the following operations to be performed automatically. 1) In step 101, the translation amount of the target position of each control axis with respect to the work position deviation detected when the welding program of the control device 6 is executed is canceled. The control device 6
This step is not necessary if does not have the function of moving the target position in parallel. 2) Next, in step 102, each control axis is driven to move the welding torch 3 from a welding reference position (for example, a program start position) to a position near the reference bar 10 at a high speed. At this time, even if the movement trajectory of the welding torch 3 is not strictly defined, if there is no interference between the welding torch 3 and the work or the peripheral device, each axis is independently driven to move, and there is a possibility of interference. When it is necessary to define the movement trajectory of the welding torch 3, the movement is performed by, for example, linear interpolation. 3) In step 103, the welding torch 3 is moved to a predetermined position just above the reference bar 10 at a medium speed by linear interpolation. At this time, the control axes (1 to 5 axes) of the main body 2 are set so that the attitude of the welding torch 3 at the origin 11 is substantially the same. Also, here, since it approaches the vicinity of the reference bar 10, it moves by linear interpolation to avoid interference during the movement. 4) In step 104, a touch sensor for detecting the energization between the welding wire 4 and the reference bar 10 is activated. 5) In step 105, the welding torch 3 is moved down from the predetermined position immediately above the reference bar 10 by a relative amount (a predetermined relative movement amount from the current position) at a very low speed without changing the posture of the welding torch 3, During the relative movement, it is checked that a detection signal of the energization of the welding wire 4 and the reference bar 10 is input from the touch sensor. 6) In step 106, it is determined whether or not current is applied between the welding wire 4 and the reference bar 10. 7) When the power is supplied, it is determined that there is no displacement in the position of the welding torch 3, the descent is immediately stopped in step 107, and “No welding torch position displacement” is displayed on a display (not shown) of the control device 6. . 8) Next, in step 108, the welding torch 3 is linearly moved upward by a predetermined distance. 9) Further, in step 109, the welding torch 3 is moved to the initial welding reference position according to the movement path opposite to steps 2 and 3. 10) Next, in step 110, a welding operation is started according to a predetermined welding program. 11) If the energization between the welding torch 3 and the reference bar 10 is not detected in step 106, it is determined that the welding torch 3 is misaligned. Is displayed. 12) Next, in step 112, the operation of the welding robot 1 is stopped, and the welding operation by the welding program is not started.

When the welding robot 1 does not start the welding operation due to the positional deviation as described above, the operator needs to take predetermined measures such as correcting the positional deviation of the welding torch 3 and the like. Therefore, when the operation of the welding robot 1 is stopped, a means for notifying the worker by a pilot lamp or a buzzer may be provided to prompt the worker to take an immediate action.

As described above, the automatic origin check program is stored in advance, and the positional deviation check by the origin check of the welding torch 3 is automatically performed for each predetermined welding work process, thereby preventing occurrence of welding defects and appearance. Improvements in quality can be easily achieved without the need for labor.

[Brief description of the drawings]

FIG. 1 is an external perspective view showing an example of an automatic welding robot.

FIG. 2 is a diagram showing a relationship between a welding torch and a reference bar.

FIG. 3 is an explanatory diagram of a state of energization between a welding wire of a welding torch and a reference bar.

FIG. 4 is a flowchart illustrating an automatic origin check method.

FIG. 5 is an explanatory diagram of a conventional origin check method.

[Description of Signs] 1: welding robot, 2: body, 3: welding torch, 4: welding wire, 6: control device, 10: reference bar, 11: origin.

Claims (2)

[Claims] A welding torch (3) having a plurality of control axes for controlling the position and posture of a tip end of an arm to which the welding torch (3) is attached, wherein each of the control axes is driven. A welding robot (1) that can freely move the workpiece to a predetermined position, and a control device (6) that controls the welding robot (1) according to the stored welding program and automatically welds the workpiece. At a predetermined position within the movement range of the welding torch (3), it is made of a conductive member connected to the workpiece at the same potential, and contacts the tip of the welding wire (4) projecting from the tip of the welding torch (3). A columnar reference bar (10) is set up with the upper end surface having a contactable area as the origin (11) of the welding robot (1) .The control device (6) further controls the tip of the welding torch (3). The contact between the welding wire (4) and the workpiece is detected by conducting electricity between the welding wire (4) protruding from the part and the workpiece. After the welding torch (3) is moved to a predetermined position directly above the previously stored reference bar (10) according to the automatic origin check program, the touch sensor is moved down by a predetermined relative distance. If the sensor detects contact between the welding wire (4) and the reference bar (10), it is determined that there is no displacement of the welding torch (3) .If no contact is detected, the position of the welding torch (3) is determined. A welding robot automatic origin check device, which determines that there is a deviation. 2. A welding robot capable of moving a welding torch (3) to a predetermined position by driving a plurality of control axes for controlling the position and attitude of an arm tip to which the welding torch (3) is attached.
(1) is controlled in accordance with a stored welding program and automatically welds a workpiece.In the welding robot apparatus, the welding torch (3) is erected at a predetermined position within a moving range and connected to the workpiece at the same potential. Welding wire (4) made of conductive material and protruding from the tip of welding torch (3)
Robot that welds the upper end surface with an area that can contact the tip of the
After moving the welding torch (3) to the pre-stored predetermined position just above the columnar reference bar (10) as the origin (11) of (1) according to the automatic origin check program, it descends by a predetermined relative distance. If the contact between the welding wire (4) protruding from the tip of the welding torch (3) and the reference bar (10) is detected during this time, it is determined that there is no displacement of the welding torch (3), and the contact is detected. A welding robot automatic origin check method characterized in that when no is detected, it is determined that there is a displacement of the welding torch (3).