JPS58112661A - Arc welding method - Google Patents

Abstract

PURPOSE:To form an offset bead and perform profile control in a weld line direction at the same time, by performing welding while oscillating a welding electrode so that the difference in waveform area value of one of a welding current, arc voltage, and displacement of torch height obtained in every half period of the oscillation of the welding electrode. CONSTITUTION:In oscillating a torch 4 in groove width directions of materials 3 and 3' to be welded, when the feeding speed of a wire as a consumable electrode for welding which uses a welding power source with constant voltage characteristics is specified, an arc current increases at a right end R and decreases below R at a left end L. At this time, the arc voltage is low at the right end R and higher than R at the left end L. Assuming that neither the current nor the current has variation, the displacement value Y of the height direction of the torch 4 under profile control at the groove of the material 3 to be welded is as shown by A and B. Therefore, a waveform in a half period C-C is integrated to obtain sectional area values A and B, so the oscillation of the torch 4 is controlled so that A is greater than B.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an arc welding method in which a biased bead is formed while a welding electrode is oscillated in the width direction of the groove, and welding images are performed.

A weaving welding method is known in which multi-layer welding is performed by swinging a welding electrode such as a consumable electrode or a non-consumable electrode in the direction of the groove width, but when the groove width is wider than the limit of the weaving mechanism, As shown in the cross-sectional view of a multilayer bead in Figure 1, the first layer bead 1 is connected to one of the welded materials 3
Place the second layer bead 2 on the right side of the other workpiece 3.
It is necessary to perform multi-layer welding to the left on the '' side.

However, a technique for tracing the groove of a welding electrode in such multilayer welding has not yet been established.

From the above-mentioned viewpoints, the present invention provides an arc welding method that can simultaneously perform the formation of a biased bead necessary for multilayer welding and the tracing control in the weld line direction. In an arc welding method in which welding is performed while swinging the welding electrode in the width direction of the groove using a power source with current characteristics, welding current, arc voltage, or torch height obtained every half cycle of swinging of the welding electrode. The welding is performed while the welding electrode is oscillated so that the difference in the waveform area of each waveform area of the displacement is always a constant value, and while forming the offset bead that is the basis of multilayer welding, This method is characterized in that welding is performed while the center of swing of the electrode is always placed at a predetermined position in the width direction of the groove.

Next, the present invention will be explained with reference to the drawings, using an example in which a consumable electrode fed at a constant speed is used as a welding electrode. Fig. 2 is a front view showing the principle of this invention, Fig. 3 is a current waveform used in this invention, Fig. 4 is a voltage waveform, and Fig. 5 is a diagram showing a displacement waveform of the torch height. be.

In Figures 2 to 5, the torch 4 is connected to the workpiece 3.3'
In welding using a welding power source with constant voltage characteristics, if the feeding speed of the wire, which is a consumable electrode, is kept constant, the arc current will be oscillated in the groove width direction as shown in Figure 3. It becomes a dog at the R part, and the value is smaller at the left end R than at the right end R.

Further, the arc voltage at that time is lower at the right end R, and higher at the left end than at the right end R. Furthermore, when the torch 4 is made to follow the groove 5 of the workpiece 3 so that the change in the current or voltage described above is 0, the displacement value Y of the torch 4 in the height direction becomes as shown in FIG. expressed.

Therefore, when the waveforms of each half period (C, C) shown in FIGS. 3 to 5 are integrated, they are expressed by cross-sectional areas A and B, so the cross-sectional area AfJ''-B shows a certain relationship of dog, that is, A- B=△
If you control the swing of the torch 4 so that the relationship is normal,
The torch 4 can always follow the inside of the groove 5 in the direction of the welding line while forming the offset bead 1.

FIG. 6 is a block diagram when the present invention is implemented using the displacement value Y in the height direction of the torch 4 shown in FIG. The material to be welded, 4 is a torch, and 5 is a groove.

A wire 6 is fed to the torch 4 at a constant speed, and the torch 4 is swung in the groove width direction by a groove width direction drive motor (hereinafter referred to as an X-axis motor) 7 and a screw shaft 8 .

Further, the X-axis support block 9 that supports the X-axis motor 7 and the screw shaft 8 is connected to the support block 1 in the height direction (Y-axis).
0, and the screw shaft 11 is driven by a height direction drive motor (hereinafter referred to as Y-axis motor) 12. 13, the X-axis support block 9 is connected to the Y-axis motor 1.
This is a potentiometer that detects the amount of displacement in the Y-axis direction when driven by 2.

When the wire 6 is fed at a constant speed and the torch 4 swings in the groove width direction while emitting an arc, the voltage detector 14
The arc voltage is detected by

The detected arc voltage is compared with the reference value of the reference voltage generator 15 by the comparator 16, and Y is set such that the deviation is O.
The axis motor controller 17 operates and sends a control signal to the Y-axis motor 12.

Therefore, the torch 4 follows the groove bottom shape while maintaining a constant arc voltage. At this time, the X-axis support block 9 is
Since it is moved in the height direction, a waveform as shown in FIG. The above-mentioned cross-sectional areas A and B are calculated. The calculated cross-sectional areas A and B are calculated by a subtracter 20.
-B is calculated, and its value ΔSo is stored in the memory 21 and compared with ΔS1 during the next reciprocation of the torch 4 by the comparator 22.

Therefore, if the deviation between △So and △S1...△Sn is O, the torch 4 always follows the welding line inside the groove.
The bead 1 is also formed with a biased bead as shown. If a deviation occurs between ΔSo and ΔS,
The deviation signal acts on the X-axis motor controller 23, and the reverse switching position of the torch 40 is controlled.

In addition, 24 is a reference value generator for providing ΔSo as a reference signal in place of the memory 21, and its value can be known in advance experimentally.Furthermore, 25 is a reference value generator for supplying ΔSo as a reference signal. It is a reference signal generator for control.

In addition, in this invention, when the change in arc voltage shown in FIG. 4 is used for control, the output of the arc voltage detector 14 shown in FIG. When using the change in arc current shown in for control,
The arc current value may be detected by a known detector and input to the switch 18.

After welding by the bead 1 shown in FIG. 1 is completed by the method described above, next, B) A, that is, B-A=ΔS.

Welding of the bead 2 is performed by controlling it so that

Furthermore, the present invention can also be applied to lap welding of irregularly shaped grooves as shown in FIG.

As explained above, according to the present invention, the direction of the welding line is controlled by providing a difference in the value of the half-cycle of the torch oscillation in advance and using the oscillation of the torch so that the difference remains constant. Therefore, the formation of a biased bead necessary for multilayer welding and the tracing control in the welding line direction can be performed at the same time, resulting in extremely excellent industrial effects.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing a multilayer bead, Fig. 2 is a front view showing the principle of the invention, Fig. 3 is a current waveform diagram used in this invention, Fig. 4 is a voltage waveform diagram, and Fig. 4 is a voltage waveform diagram. FIG. 5 is a waveform diagram of displacement in the torch height direction, FIG. 6 is a control block diagram showing an embodiment of the present invention, and FIG. 7 is a sectional view showing another example of a welded joint to which the present invention is applied. . In the drawings, 1.2... Offset bead, 3, 3'... Material to be welded, 4... Torch, 5... Bevel, 6
...Wire, 7...X-axis motor, 8
．． 11... Screw shaft, 9... X-axis support block, 10... X-axis support block, 12...
Y-axis motor, 13...potentiometer 14
... arc voltage detector, 15 ... reference voltage generator,
16... Comparator, 17... Y-axis motor controller, 18... Switching device, 19, 19'...
- Integrator with memory, 2o... Subtractor, 21... Memory, 22... Comparator, 23... X-axis motor controller, 24... Reference signal generator, 2
5...X-axis motor reference signal generator. Applicant Nippon Kokan Co., Ltd. Agent Keitabe Tsutsumi and 1 other person

Claims (1)

[Claims] In an arc welding method in which welding is performed while a welding electrode is oscillated in the groove width direction using a power source with constant voltage or constant current characteristics, every half period of oscillation of the welding electrode Welding is performed while the welding electrode is oscillated so that the difference in the waveform area of any one of the welding current, arc voltage, or torch height displacement obtained during the welding process is always a constant value. Characteristic arc welding method.