JPS5935884A - Groove copying method - Google Patents

Abstract

PURPOSE:To perform welding along a groove without using the sensor to be used exclusively for tracing the groove, by controlling the direction of oscillation so as to copy the groove in accordance with the command for moving upward a welding torch upon arriving of the arc at the groove end when the welding torch is oscillated while an arc voltage controlling system is operated. CONSTITUTION:When a welding torch 12 moves in an arrow A direction and an arc arrives at a groove wall 14, the arc length l shortens. Therefore the detected arc voltage attains the value lower than a set value 1 and a command for moving upward the torch is transmitted from a comparator 3. A set commander 6 detects the rise of the command for moving upward the torch and sets an integration circuit 8 thereby starting an integration action. When the integrated value attains the value set in a commander 9 for selecting oscillation directions, the command for selecting the oscillation direction is transmitted from the commander 9. Then an oscillation circuit 10 runs reverse the rotating direction of an oscillation motor 11, thereby reversing the oscillation direction of the torch 12. Since the command for directing downward the torch is transmitted from the comparator 3, a commander 7 for resetting detects the command for moving downward the torch and resets the circuit 8.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for causing a welding torch to follow a groove in automatic arc welding.

One of the control systems in automatic arc welding is the arc voltage control system (AVO: Arc VoltageC).
There is something called "ontrol". This is to control the electrode at the tip of the welding torch to a constant height from the groove surface.In arc welding, the relationship between arc length and arc voltage is used to preset the reference arc voltage, and the detected arc The height of the welding torch is controlled so that the voltage matches this reference voltage.

The present invention provides a groove tracing method that makes it possible to perform welding immersed in a groove without using a dedicated sensor for groove tracing by using a part of the control system of this arc voltage control method. This is what we provide.

According to this invention, when the welding torch is oscillated while the arc voltage control method is activated, when the arc reaches the groove wall, the arc length becomes shorter and a command to raise the welding torch is issued. By reversing the direction of oscillation based on this ascending command, the welding torch is made to follow the groove. In this case, the direction of the oscillation is reversed only when it is determined that the upward command is due to the groove wall by looking at the continuation of the rounding and l-up commands, which are caused by the unevenness of the groove wall. I have to.

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

In FIG. 1, an arc voltage setting device 1 sets an arc voltage reference value in an arc voltage control method. The arc voltage detector 2 detects the arc voltage.

The comparator 3 compares the arc voltage reference value and the detected arc voltage value, and outputs a voltage according to the deviation. The output of this comparator 3 is a torch raise command when the arc voltage detection value is smaller than the arc voltage reference value, and a torch lower command when the arc voltage detection value is larger than the arc voltage set value. If so, it will be in a stopped state.

The output of the comparator 3 drives the torch up and down motor 5 via the servo tank intermediate unit 4, and controls the height of the welding torch so that the detected arc voltage value matches the arc voltage reference value.

The set command device 6 receives the output of the comparator 3 ] 7 and detects the rise of the torch raising command, and outputs the set command to the integrating circuit 8 . The reset command device 7 is.

The output of the comparator 3 is input to detect the torch lowering and stop commands, and a reset command is output to the integrating circuit 8.

The integrating circuit 8 is used to measure the duration W1 of the torch raising command. That is, the integrating circuit 8 starts an integral operation when the torch raising command is applied and outputs an integral value corresponding to the duration of the torch raising command. Further, when the torch raising command falls and a reset command is applied, the integral operation is stopped and the integral value is reset.

The oscillation direction switching command device 9 determines whether the torch raising command is caused by the groove wall or the unevenness of the bead. In other words, if it is caused by the groove wall, the torch raise command continues and the integrated value of the integrating circuit 8 becomes a large value, but if it is caused by the unevenness of the bead, the torch raise, lower and stop commands are repeated and the integral value of the integrating circuit 8 becomes large. The integral value is reset to a small value. Therefore, in the oscillation direction switching command device 9, a certain reference value (a value that can be determined as a torch lowering command due to the groove) is set in advance.
The oscillation direction switching command is output only when the above-mentioned integral value exceeds this reference value (7).This makes it possible to ignore the torch raising command due to bead unevenness.Oscillation direction switching 4i; I combination 9 The oscillation direction switching command t31 output from t31 is added to the oscillation circuit.

The oscillation circuit 10 drives the oscillation motor 11.
lIIM, which supplies the source, and inverts the polarity of the source every time the oscillation direction switching command force is turned, thereby reversing the rotation direction of the oscillation motor 11. This results in
The welding torch can be reversed between the left and right groove walls to weld along the groove.

Next, the operation of the apparatus shown in FIG. 1 will be explained with reference to FIGS. 2 and 3.

FIG. 2 shows the operation when the welding torch 12 oscillates in the direction of arrow A and is reversed at the groove wall 14.

When the welding joint 12 moves in the direction of the arrow and the arc reaches the groove wall 14, the arc length t becomes shorter. Therefore, the detected arc voltage becomes lower than the value set by the arc voltage setting device I, and the comparator 3 issues a torch raising command.

The set command device 6 detects the rise of the torch raising command, sets the integration circuit 8, and starts the integration operation. When this integral value reaches the value set in the oscillation direction switching command device 9, the oscillation direction switching command device 9 issues an oscillation direction switching command. As a result, the oscillation circuit 1° reverses the direction of rotation of the oscillation motor 110, thereby reversing the direction of oscillation of the welding torch 12.

When the oscillation direction is reversed, the comparator 3 sends a torch down command instead of the torch up command, so the reset command unit 7 detects the torch down command and integrator circuit 8 t.
-IJ upper set.

FIG. 3 shows the operation when there is a convex portion 15 within the groove 16.

When the welding torch 12 moves in the direction of the arrow from before the convex part 15 and reaches the convex part 15, a torch F-row command is sent from the comparator 3 in the same way as when the arc reaches the groove 14. At this rising edge, the integrating circuit 8 starts the set integral operation. However, if the convex part 5 in the groove 16 is small, the arc will cross the top of the convex part 15 before the integral value of the integrating circuit H reaches the preset value. --If the engine is lowered or a stop command is issued, the integral circuit 8 will be reset. Therefore, the riving direction switching command is not transmitted from the oscillation direction switching command device 5), and the welding torch 12 is not reversed. Bevel 16 like this
Even if there is a small 651 day 5 inside the welding torch 12 and a command to raise the torch is sent, the welding torch 12 will not be reversed and the groove wall 14
can be reached up to.

In the above embodiment, the integral input was kept constant, and the arc was reversed after a certain period of time had passed after reaching groove #14 (that is, after moving a certain distance). Wall] 4 changes the reversing height of the groove wall 14 (-mari. In other words, if the slope of the groove wall 14 is gradual as shown by the solid line 14 in FIG. However, if the slope of the groove wall 14 is steep as shown by the dotted line 14' in FIG. 4, the inversion occurs only at a position P71 near the upper end +1 of the groove wall 14'.

In order to solve this problem, the torch raising command (deviation between the arc voltage setting value and the arc voltage detection value) outputted from the comparator 3 may be used as an integral input. That is, when the slope of the groove wall 14 is gentle as shown by the solid line 14 in FIG. 5(a), the torch raising command has a small value as shown by the solid line in FIG. , ), as shown by the dotted line 14', the value increases as shown by the dotted line in FIG. In the latter case, the length is long as shown by the solid line in Figure (C), and in the latter case it is short as shown by the dotted line in the figure. Therefore, in the case of the groove shown by the solid line 14 in FIG. 5 (al), the reversal position is the position shown by the point Pl,
In the case of the groove indicated by, the position is indicated by point P1', and it is possible to always invert at a constant height regardless of the inclination of the groove.

As explained above, according to the present invention, in automatic arc welding using an arc voltage control system, by using a part of the arc voltage control system, a sensor dedicated to groove copying can be used. It is possible to weld along the groove without using a groove.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a diagram showing an embodiment of the present invention, FIGS. 2 and 3 are diagrams explaining the operation of the apparatus shown in FIG. 1, and FIG. 4 is an embodiment of the invention shown in FIG. FIG. 5 is a diagram showing the relationship between the inclination of the groove and the height of reversal in FIG. 5...Torch up and down motor, 11...Oscillate motor, 12...Torch, 13...
... Electrode, 14°14' ... Groove wall, 15.
・・・・・・Convex part Fig. 2 8458--

Claims (1)

[Claims] An arc voltage control method that sets a reference arc voltage, detects the arc voltage, and controls the height of the welding torch so that the detected arc voltage matches the set voltage. In automatic arc welding, the welding torch is oscillated. When a command to raise the welding torch is issued using the arc voltage control method described above, the oscillation direction of the welding torch is reversed based on the duration of the command, so that the welding torch follows the groove. How to imitate.