JPS58176078A - Weld line detecting method - Google Patents

Abstract

PURPOSE:To easily detect a welding position by a simple sensor, and to instruct it to a welding robot, by providing the sensor in a welding torch, making a welding core wire contact with a welding work, and detecting the generated couple or axial force. CONSTITUTION:A sensor 3 is provided on a part of the outside circumference of a welding torch from which a welding core wire 1 is led out. The sensor 3 is constituted by installing the first - the fourth gauges 5-8 consisting of four strain gauges at intervals of 90 degrees each, to a coil spring 4 whose element is a band plate wound round the torch 2. Also, each gauge is constituted of the first element A which coincides with the center axis direction of the coil spring 4, and the second and the third elements B, C making + or -45 degrees against it. The core wire 1 is made to press-cotact with a welding work against a fillet welding position P, bending moments Md, Mu generated in the core wire 1, or axial force Fn are detected by said elements A-C, and the welding position P is instructed to a welding robot and is stored before the welding work is started.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a welding line detection method for teaching a welding position to a welding robot as a pre-work for fillet welding. With the goal.

Conventionally, as a method for a welding robot to detect a welding position on a welding workpiece, a method using a contact type or non-contact type displacement meter has been adopted.

However, with this method, it is necessary to install the sensor separately from the welding torch, which is undesirable as it increases unnecessary countermeasures, such as retracting operations during welding so as not to disturb the welding operation, and countermeasures for increasing the weight of the tip of the robot arm. .

This invention was made with the above points in mind,
It is possible to detect the welding f device with only a slight modification such as installing a simple sensor in a part of the welding torch.

That is, the present invention provides a weld line detection method for teaching a welding position to a welding robot as a pre-work for fillet welding.
A welding core derived from a welding torch is pressed against a welding workpiece, and a sensor provided in the torch detects a couple or axial force generated by the angle formed between the corewire and the workpiece at the time of the pressing, The method is characterized in that the relationship between the fillet welding position and the current position is determined from the type and direction of the couple or axial force, and the position to be welded is detected. In order to detect the couple force or axial force generated by the motor, a sensor with a simple configuration may be sufficient.

Next, the present invention will be explained in detail with reference to the drawings showing one embodiment of the invention.

As shown in FIG. 1, a sensor (3) is provided on a part of the outer periphery of the welding torch (2) from which the welding core wire (1) is derived.

As shown in Fig. 2, this sensor (3) consists of a coil spring (4) whose strip plate is a bare wire wound around a torch (2), and four strain gauges attached to this coil spring (4). Karana 6
1st. Second. Third. 4th gauge (5), (6),
(7), (8) are installed at positions 90 degrees apart, and each cage has eight first... Second. Third
Element (3), (B).

+C), the first element (A) is provided in alignment with the central axis direction of the coil spring (4), and the second element (B) and the third cable j'-(C)Vi first Mo 45 degrees for child prisoners, -4
It is provided so as to take a 5 degree direction.

Now, from the state shown in Fig. 2, when the coil bar (4) is bent upward in a convex shape with respect to the plane of the paper with its longitudinal direction as an axis, the second element (8) of the second cage (6) will undergo tensile strain. , the eighth element (C) receives compressive strain, and as shown in Fig. 8, when the second element Q3) and the eighth element C) are assembled into a bridge circuit (9), the output of the bridge circuit (9) Assume that a positive output is obtained. On the contrary, when the coil flange (4) is bent downward from the state shown in FIG. C) is subjected to tensile strain and a negative output is obtained at the output of the bridge circuit (9). Therefore, the positive and negative signs of the output of the bridge circuit (9) and the direction of bending of the coil spring (4) directly correspond to each other. direction can be detected.

On the other hand, the first element (A) of the second gauge (6) receives strain due to the bending, but also due to the axial force in the same direction as the axis of the coil deflection (4). Then, the $1 element (4) of the first gauge (5) and the third one located 180 degrees apart.
The wJ1 elements (3) of the gauge (7) are connected in series, and the fourth
When assembled into the bridge circuit 00 as shown in the figure, the first element (A) of each of the first gauge (5) and the third gauge (7)
are subjected to strains in opposite directions with respect to bending, so they are canceled out, and the effects of bending are canceled out in the bridge circuit 00 of FIG. 4. However, for axial force, both gauges (5
) and (7), each of the first elements (A) receives a strain of the same sign, so the output from the bridge circuit 01 is only for the axial force, and the axial force can be detected by the bridge circuit 00 in Fig. 4. I can do it.

As shown in Fig. 5(a), assume that the welding torch (2) comes to the fillet welding position P on the Y-Z plane, and move the torch (2) to the welding core line (1). When the torch (2) is pushed in the direction of
The relationship with the sign of the output of 01 is set to 3 in advance to the robot.
3, the robot moves in the direction of the welding position P and finally reaches the state shown in FIG. 5(g).

In this state, no bending moment is generated in the torch (2), and only the axial force Fn is applied. Therefore, the robot judges from the relationship between the outputs of the bridge circuit (9) and OO,
Operation will be stopped within the range of axial force that does not cause any problems.

If the core wire (1) hits as shown in Figure 5 Ω, the bending moment will be in the opposite direction to that in Figure 5 (a)) M
u is generated, the robot moves in the opposite direction to that shown in FIG. 5(a), and reaches the welding position P.

The behavior described above is on the YZ plane, but the welding workpiece has a three-dimensional structure as shown in FIG. 6, and posture alignment on the XY plane is also required.

Now, as shown in Fig. 7(a), when the core wire (1) hits the workpiece, the torch (2) has a bending moment) M
t occurs, but at this time, the sensor (
3) is bent upward or downward in the plane of the drawing ÷+. Then, if the fourth gauge (8) is bent upward,
When the shape becomes convex, it is assumed that there is a positive output from the pinched bridge circuit as shown in Figure 8.The robot moves to the left based on the information of this output, and the bending moment (Mt) is When the output from the bridge circuit for detecting axial force, which is set up in the same way as shown in Fig. 4, reaches a certain value pn 7 or more, it is determined that the attitude shown in Fig. 7 (b) has been taken, and the movement is stopped. Stop.

Furthermore, as shown in Fig. 7 (Q), when the core wire (1) hits the workpiece in the opposite direction, a bending moment (Mr) is generated, but the output from the bridge circuit becomes negative, and in contrast to the above-mentioned melting, the robot moves to the right side. The robot moves to the position shown in FIG. 7(C).

Therefore, by the above operation, the torch (2) faces the welding line at right angles, and the core wire (1) is placed at the corner to be welded.
are in contact, and the coordinates at this time are read as the coordinates of the welding point.

The above explanation has been given using the detection of a corner to be fillet welded as an example, but since this invention has a function of vertically facing a torch (2) to a certain target surface, this function can be used to It also becomes possible to measure the distance to a surface.

However, it is assumed that the welding rod has its own origin, that all movements and rotations thereafter are integrated, and that the coordinates of the tip position of the torch (2) at each point in time are constantly detected.

Further, in this example, a coil spring in which the strip plate is a wire is used as an example of the structure of the sensor, but a cantilever or other structure may be used.

[Brief explanation of drawings]

The drawings show one embodiment of the welding line detection method of the present invention, in which Fig. 1 is a front view of a welding torch, Fig. 2 is an enlarged view of a part of Fig. 1, and Figs. 3 and 4 are bridge circuits. Figure, Figure 5 (
a), (b), (C) are explanatory diagrams of the movement of the welding torch, Fig. 6 is an explanatory diagram of the welding workpiece, Fig. 7 (a),
(b) and (C) are explanatory diagrams of movement of the welding torch. +11...Welding core wire, (2)...Welding torch, (3
)...Sensor, (4)...Coil spring, (5)j
(61# (71? +81...Gauge, (5). (G), (Q...Element, +91, elG...Bridge circuit. Agent: Patent attorney Ryotabe Fujita

Claims (1)

[Claims] ■ In a welding line detection method in which a welding position device is taught to a welding robot as a pre-work for fillet welding, a welding core wire derived from a welding torch is pressed against a welding workpiece, and at the time of the pressing, the core wire and the workpiece are A sensor installed in the torch detects the couple or axial force generated by the angle formed by the angle, and determines the relationship between the fillet welding position and the current position from the type and direction of the couple or axial force, and determines the relationship between the fillet welding position and the current position. A welding line detection method characterized by detecting a position.