JPH09277059A - Welding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a welding device which eliminates the misalignment of a weld line by adjusting the relation between the moving speed by a robot and the feed speed by an electrode roller and detecting the turning angle of objects to be welded at the time of positioning the objects to be welded. SOLUTION: The handling robot is driven prior to welding and the wrist part D of the robot is guided to an initial position suitable for welding work. A tank T is moved to a position where the flange part F of the tank T is clamped by the electrode roller r by driving the robot and welding is started in the state of clamping the flange part F by the electrode roller r. The electrode roller r is driven and the flange part F of the tank T is sent at a prescribed speed, by which the part held by the electrode roller r is welded. Simultaneously, the robot moves the tank T according to the taught coordinate values. The feed speed of the tank T by the robot is set slightly higher than the feed speed by the electrode roller r. The rotating angle of the objects to be welded is detected and the moving quantity by the robot is so adjusted that this angle enters a prescribed range.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a welding apparatus for performing welding while positioning a welding object such as a fuel tank for an automobile by a handling robot and sending it out by a pair of welding electrode rollers.

[0002]

2. Description of the Related Art FIG. 6 is a perspective view for explaining the concept of a conventional welding device. In this example, the flange portion F of the automobile fuel tank T, which is an example of a welding target, is welded along a welding line indicated by a broken line. The fuel tank T is attached to a mounting base D which is attached to a wrist D of a handling robot R and is rotatable around a vertical axis, and moves in a horizontal plane by the movement of the articulated robot R. Y is a welding machine, which sandwiches the flange F of the tank T between a pair of electrode rollers r, r while rotating the electrode rollers r, r.
By passing a welding current between r, the flange is welded out along the welding line indicated by the broken line. Regarding the movement of the tank T, the welding machine Y
Must rotate the electrode rollers r, r at a constant number of rotations without stopping, and feed the flange F at a constant speed. At this time, in order for the locus of the welding points by the electrode rollers r, r to coincide with the designed welding line along the flange portion F, the wrist portion of the handling robot R that movably supports the tank T in the horizontal plane. The tank T on D must be rotatably supported in the horizontal plane. Therefore, the conventional welding handling robot R is equipped with a joint on its wrist that can freely rotate around the vertical axis, and a tank is attached to the attachment portion on the free end side of this joint, and the tank is connected by the electrode rollers r and r. According to the amount of the flange portion F of T to be sent, the tank T is handled by the handling robot.
It is known that the position of the center of rotation is moved and the tank T is driven to rotate on the wrist D so that the loci of welding points by the electrode rollers r, r coincide with the designed welding line. However, when the tank T, which is the object to be welded as described above, freely rotates on the wrist D of the robot, the position of the tank T is not stable every moment, and the welding line is There is a problem of slippage. Therefore, it is known that the robot wrist D is provided with a drive unit for positively rotating the tank T.

[0003]

In the welding apparatus as described above, the object to be welded is substantially actively rotated by the electrode rollers r, r, and at the same time, the handling robot R
Will also be positioned positively. However, it is almost impossible to perfectly match the positioning by the electrode rollers r, r and the positioning by the handling robot R as described above, and the design along the flange portion F as shown in FIG. Even when it is desired to obtain the welding line (shown by the broken line), the welding line may actually be an inclined welding line as shown by the broken line in FIG. 7B, which is a disadvantage that the yield of the welding work is deteriorated. Therefore, an object of the present invention is to provide a welding device that can eliminate the deviation of the welding line in the welding device that positions and drives the welding object by both the electrode roller pair and the handling robot.

[0004]

To achieve the above object, the present invention comprises a welding electrode roller pair, and during welding,
By rotating the electrode roller pair at a constant speed, the welding object sandwiched between the electrode roller pair is fed out at a constant speed, while energizing the electrode roller pair to weld the portion sandwiched between the electrode roller pair. The welding machine, which has a degree of freedom of rotation in its wrist, controls the wrist of the robot so that the wrist of the robot maintains a predetermined direction with respect to the object to be welded during the welding operation. In a welding device comprising a handling robot for positioning the welding object attached to a welding part with respect to a welding machine, the welding device is mounted between the wrist part of the handling robot and the attachment part of the welding object, A rotation joint for rotatably supporting the welding target with respect to the wrist of the handling robot, and a rotation angle of the welding target with respect to the wrist are detected. And a moving speed by the handling robot is set higher than the feed speed by the electrode roller, and the angle detected by the angle detector during welding work does not deviate from the predetermined angle range. The welding device is configured to adjust the amount of movement by the robot. INDUSTRIAL APPLICABILITY The present invention is suitable for use in the case where a flange portion is welded while being rotated in a horizontal plane, such as an automobile fuel tank. In addition, by attaching an elastic member to the mounting portion of the welding object that always returns the attachment portion of the welding object in a predetermined direction with respect to the wrist portion of the handling robot, the object to be welded is welded before the welding operation. Since it can be directed in a predetermined direction, work efficiency is improved.

[0005]

In the present invention, since the moving speed of the welding object by the handling robot is set to be higher than the feeding speed by the electrode roller, when the welding work progresses, the feeding amount of the welding object by the handling robot is increased. , It will overtake the feed amount by the electrode roller. At this time, the object to be welded rotates relative to the robot wrist. This rotation is detected by the angle detector. When the deviation angle detected by the angle detector exceeds a predetermined value, the handling robot side stops the movement of the welding object. Since the opposite side of the electrode roller always sends the welding object at a constant speed during the welding work, when the handling robot stops moving the welding object, only the welding object is fed by the electrode roller and the above-mentioned deviation angle Gradually decreases, and eventually the displacement angle becomes less than the predetermined amount, the movement of the welding object by the handling robot is restarted. By repeating the above steps, the welding work is continued without the welding line of the electrode roller pair deviating significantly from the designed welding line.

[0006]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of the present invention; It should be noted that the embodiments described below are examples embodying the present invention, and do not limit the technical scope of the present invention. Here, FIG. 1 is a flowchart showing a control procedure of the handling robot during welding work, FIG. 2 is a block diagram showing a control system of the welding apparatus according to one embodiment, and FIG.
Is a detailed view of the wrist part of the handling robot used in the embodiment, FIG. 4 is an exploded perspective view of an angle detector and a rotary joint attached to the wrist part, and FIG. 5 is a welding line in welding work and welding. It is a top view which shows the sending direction of a target object. First, the configuration of the entire control system of the welding device used in the present embodiment will be described with reference to FIG. This controller is CP
A rotary encoder RE, which is an example of a rotation detector, is connected to the input side of the CPU, and the rotation speed of the driving system 1 of the handling robot 1 and the electrode rollers r and r is connected to the output side of the CPU. A welding machine drive system 2 for controlling the welding current and welding current, and a display unit 3 including a CRT are connected. The welding work program is stored in the ROM, and the target values of the robot drive system 1 obtained by the teaching work are stored in the RAM. In this embodiment, the moving speed of the object to be welded by the robot drive system 1 is determined by the electrode rollers r, r set in the welder drive system 2.
It is set to be slightly faster than the feeding speed of the welding object by. Further, as shown in FIGS. 3 and 4, the wrist D of the handling robot R has a motor 4, which is controlled by the robot drive system 1, a rotary table 5 which is rotationally driven by the motor 4, and the rotary table 5. A tank mount 6 attached to the upper rotary encoder RE is attached. Further, the tank mount 6 is freely rotatable with respect to the rotary base 5, and the rotary base 5 and the tank mount 6 are elastically connected by a spring 7. Therefore, the tank mount 6 rotates freely with respect to the rotary base 5, but is always returned to a predetermined initial position (home position) with respect to the rotary base 5, that is, the wrist D of the robot by the spring 7. Is elastically biased.

Next, the welding procedure will be described with reference to FIG. Here, S1, S2, ... Show the numbers of work procedures (steps). Further, a case where a flange portion of an automobile fuel tank is welded as a welding target will be described. Prior to the welding work, the handling robot R is driven to guide the robot wrist D to the initial position suitable for the welding work. At this time, since no force is applied to the tank T on the wrist D, the return force of the spring 7 to the initial position causes the tank T on the tank mount 6 to move to a predetermined initial position relative to the rotary table 5. It is located in. In this state, the robot R is driven to move the tank T to a position where the flange portion F of the tank T is gripped by the electrode rollers r and r, and welding work is performed with the flange portion F gripped by the electrode rollers r and r. To start. The handling robot R preliminarily teaches the roller wrist position coordinates with respect to a welding work point for controlling the robot wrist so that the wrist of the robot maintains a predetermined direction with respect to the welding object during welding work. It is taught by work, and the handling robot R moves the tank T by tracing this teaching locus. When the welding work is started,
As shown in FIG. 5, the electrode rollers r, r are driven to feed the flange portion F of the tank T at a speed V, and the portions gripped by the electrode rollers r, r are welded. At the same time, the handling robot R moves the tank T according to the coordinate values taught above. With the progress of such welding work, first, in S1, the absolute value of the delay angle θ of the rotary encoder RE, which is a rotation detector, is changed to a predetermined small angle θ.
It is determined whether it is greater than 0. At the start of work, θ is 0, so naturally it is smaller than θ 0.
The process proceeds to S2, and it is determined whether or not the end point of the welding line has been reached. At the start of welding, of course, since it is not the end point, the movement of the tank T by the handling robot R is continued in S3. As described above, the handling robot R
Since the feed speed of the tank T by the electrode robot is set to be slightly higher than the feed speed by the electrode rollers r, r, if the above-described processing of S1 to S3 is continued, the feed amount by the electrode rollers r, r will eventually occur. Is a handling robot R
Since it is later than the movement amount due to, the absolute value of the feed angle θ becomes larger than the predetermined minute angle θ0. Then the process is S
From 1 to S4, the handling robot R is temporarily stopped. If this state is continued for a while, the electrode rollers r, r continue to feed the tank T during that time, so that the absolute value of the delay angle θ soon approaches 0 and becomes less than θ0, so handling in S3. The movement of the tank T by the robot R is restarted. The above process is repeated, and the electrode rollers r, r continue the welding work following the designed welding line. Then, when the welding point reaches the end point, the process proceeds from S2 to S5 and the handling robot R
Also, the welding machine is stopped and the end is displayed on the display unit 3.

[0008]

[Embodiment] In the above embodiment, the fuel tank for automobiles is taken as an example of the object to be welded, but the present invention is not limited to this, and a fuel tank in a kerosene stove or an oil combustor, It is widely applicable to household appliances, automobile parts, etc. In the above example, an elastic member (spring) is used to regulate the angle of the object to be welded with respect to the wrist before welding work, but as another means, a magnet or the like is used to set a predetermined angular position. It is also possible to maintain.

[0009]

As described above, the welding apparatus according to the present invention includes the electrode roller pair for welding, and during welding, the electrode roller pair is rotated at a constant speed so as to be sandwiched between the electrode roller pair. A welding machine that feeds the welding object at a constant speed and energizes between the electrode roller pairs to weld the part sandwiched between the electrode roller pairs, and a wrist with a degree of freedom of rotation. A handling robot for positioning the welding target attached to the wrist with respect to the welding machine by controlling the robot wrist so that the wrist of the robot maintains a predetermined direction with respect to the welding target during work. In a welding device comprising: a wrist of the handling robot, which is mounted between a wrist of the handling robot and a mounting portion of the welding target. And a rotation joint for rotatably supporting the workpiece and an angle detector for detecting the rotation angle of the welding object with respect to the wrist. The movement speed of the handling robot is the feed speed of the electrode roller. The welding apparatus is configured to be set faster and to adjust the movement amount by the handling robot so that the angle detected by the angle detector during welding work does not deviate from a predetermined angle range. As described above, in the present invention, since the moving speed of the welding object by the handling robot is set to be higher than the feeding speed by the electrode roller, as the welding work progresses, the feeding amount of the welding object by the handling robot is increased. , The object to be welded is rotated relative to the robot wrist, overtaking the feed amount by the electrode roller. This rotation is detected by the angle detector, and if the angle exceeds the predetermined value, the handling is performed. The robot side stops moving the welding target. Since the opposite side of the electrode roller always sends the welding object at a constant speed during the welding work, when the handling robot stops moving the welding object, only the welding object is fed by the electrode roller and the above-mentioned deviation angle Gradually decreases, and eventually the displacement angle becomes less than the predetermined amount, the movement of the welding object by the handling robot is restarted. By repeating the above steps, the welding work is continued without the welding line of the electrode roller pair deviating significantly from the designed welding line. Here, if an elastic member that constantly returns the attachment part of the welding target object to the wrist part of the handling robot in the predetermined direction is attached to the rotary joint part, the orientation of the welding object is fixed before and after the welding work. So
This eliminates the need to adjust the direction of the welding object each time the electrode roller holds the welding object, thus improving work efficiency.

[Brief description of drawings]

FIG. 1 is a flowchart showing a control procedure of a handling robot during welding work.

FIG. 2 is a block diagram showing a control system of the welding device according to the embodiment.

FIG. 3 is a detailed view of a wrist portion of the handling robot used in the same embodiment.

FIG. 4 is an exploded perspective view of an angle detector and a swing joint attached to the wrist.

FIG. 5 is a plan view showing a welding line in a welding operation and a feeding direction of an object to be welded.

FIG. 6 is a perspective view showing an outline of a conventional fuel tank welding apparatus.

FIG. 7 is a plan view showing the inclination of the welding line with respect to the fuel tank.

[Explanation of symbols]

 Y ... Welding machine T ... Fuel tank F ... Flange section D ... Wrist section R ... Handling robot r ... Electrode roller 1 ... Roller drive system 2 ... Welder drive system 3 ... Display section 4 ... Motor 5 ... Rotating section 6 ... Mounting section 7 ... Spring

Claims (3)

[Claims] 1. An electrode roller pair for welding is provided, and during welding, the electrode roller pair is rotated at a constant speed to feed a welding object sandwiched between the electrode roller pair at a constant speed, while the electrode roller is being rotated. A welding machine that energizes between the pair of electrodes and welds the part sandwiched between the pair of electrode rollers, and the wrist has a degree of freedom of rotation. A welding robot comprising a handling robot for positioning the welding target attached to the wrist with respect to a welding machine by controlling the robot wrist so as to maintain a predetermined direction. A rotary joint part that is mounted between the wrist part and the attachment part of the welding object, and that rotatably supports the welding object with respect to the wrist part of the handling robot. An angle detector for detecting the rotation angle of the welding object with respect to the wrist, the moving speed of the handling robot is set higher than the feed speed of the electrode roller, and the angle detector is used during the welding operation. A welding device in which the movement amount of the handling robot is adjusted so that the detected angle does not deviate from a predetermined angle range. 2. The welding apparatus according to claim 1, wherein the object to be welded is a fuel tank of an automobile. 3. The welding according to claim 1 or 2, wherein an elastic member is attached to the rotary joint portion for constantly returning the attachment portion of the object to be welded to a wrist portion of a handling robot in a predetermined direction. apparatus.