JPS60170572A - Multi-electrode welding method - Google Patents

Abstract

PURPOSE:To enable easy regulation of the welding current and voltage of the entire electrode by detecting and processing the welding current and voltage of only the reference electrode among the multiple electrodes of a multi-electrode welding machine. CONSTITUTION:The current and voltage of a reference electrode 1 of a multi- electrode welding machine are set by a welding control device 2 and are outputted from a reference electrode 1 via a welding power source 3 for the reference electrode and a wire feeder 4. The signals from a current detecting part 5 and voltage detecting part 6 for the electrode 1 enter a calculator 7. The calculator 7 emits a command to a welding control device 9 for subsidiary electrodes so that the current and voltage values of a subsidiary electrode 8 attain the specified relation determined preliminarily with the current and voltage values of the electrode 1. The device 9 controls a welding power source 10 for subsidiary electrodes and a wire feeder 11 so as to attain the target current and voltage values.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method of controlling the welding conditions of each electrode in multi-polar welding.

(Prior art) Conventionally, when setting welding conditions for multi-electrode welding, in order to set the current and voltage of each electrode individually, variable resistors or switches were used to control the current and voltage of each electrode. It was necessary to operate the control panel. Therefore, in order to maintain the welding conditions at appropriate values, the welding conditions for each electrode must be set by the operator in advance before welding starts, or the welding conditions for each electrode must be set immediately after welding starts so that each electrode moves on the tab plate. I'm making adjustments while I'm at it.

However, as the number of electrodes increases, when modifying welding conditions during welding, it takes time to adjust the current and voltage values of the entire multi-electrode welding machine, which burdens the welder. Because the timing may be off, the monitoring work that should normally be performed by welders has been neglected.

If such a timing shift occurs, the parts welded at this time may be affected by a deviation from the appropriate current and voltage conditions, insufficient monitoring of the welding status, insufficient seepage, poor fusion, overlap, undercut, etc. There is a large possibility that welding defects will occur, and the occurrence of welding defects results in a large amount of time being spent on rework. In order to prevent welding defects caused by causes specific to multi-electrode welding, it is possible to increase the number of welders and divide the work, but this method has the disadvantage of increased labor costs. have.

(Objective of the Invention) In view of the above-mentioned circumstances, the present invention simplifies the operation of changing one or both of the welding current and voltage of multiple electrodes in multi-electrode welding, lightens the burden on the welder, and furthermore, makes it possible to change the welding conditions. The purpose is to shorten the time required for welding and prevent the occurrence of welding defects, thereby achieving a remarkable effect on quality improvement and labor saving. , a reference electrode is determined, and one of the welding current and voltage of the reference electrode is adjusted so that the current and voltage of the reference electrode and one or both of the welding current and voltage of the other electrodes maintain a constant relationship. Alternatively, one or both of the welding current, frost, and pressure of the other electrodes can be controlled using the signals processed by the arithmetic unit.

Further, in the present invention, a reference electrode is determined in multi-electrode welding, one or both of the welding current and voltage of the reference electrode and the subordinate electrode are detected, both signals are processed by a comparator, and the signals are used to to control one or both of the welding current voltages of the subordinate electrodes.

Thus, a method is provided in which the above objectives are achieved.

(Structure of the invention) Hereinafter, an explanation will be given based on an example and with reference to FIG.

The current and voltage of the base electrode 1 are set by the welding control device 2 and outputted to the reference electrode 1 through the welding power source 3 for the reference electrode and the wire feeding device 4. At this time, the current and voltage of the reference electrode may be set automatically or manually. Signals from the current detection terminal 5 and voltage detection terminal 6 of the reference electrode 1 enter a computing unit 7. This calculator 7 issues a command to the welding control device 9 for the dependent electrode 8 so that the current and voltage value of the dependent electrode 8 has a predetermined constant relationship with the current and voltage value of the base ring electrode 1. The welding control device 9 for the subordinate electrode controls the welding power source 1 for the subordinate electrode so that the target current and voltage value given from the calculator 7 is achieved.
0 and the wire feeding device 11.

In addition, in order to improve the accuracy of controlling the current and voltage values of the dependent electrodes,
As shown in FIG. 2, the specified value of the current and voltage of the dependent electrode calculated from the current and voltage value of the reference electrode 1 and the current detection n: 14
A comparator 16 may also be provided which is taken out from the voltage detection terminal 15 for comparison and correction, and in this case, the signal after comparison and computation is used as the reference value for the current and voltage of the dependent electrode.

Furthermore, if the distance between the base electrode and the dependent electrode is μ and the time lag accompanying the progress of welding cannot be ignored, a delay device 12 shown in FIGS. 1 and 2 is installed, and the current voltage of the reference electrode is In response to the change, the change in the current and voltage output of the dependent electrode may be delayed in accordance with the electrode spacing and welding speed.

Although these have been described for the case of two-electrode welding, they can be implemented similarly in a multi-electrode welding machine with three or more electrodes. Ma'
In addition, regarding the purpose of control and power supply characteristics, it is not necessary to control the current and voltage of the reference electrode and the current and voltage of the subordinate electrode at the same time, and it is not possible to obtain the same result by controlling only the current or voltage so that they have a constant relationship. can.

Here the reference electrode and subordinate! An example is given for a constant relationship between current and voltage for each of the poles. For example, when performing Uranami welding at the same speed with the electrodes of a two-electrode welding machine arranged in series in the welding direction in a V-shaped groove, the welding conditions and groove conditions that can obtain an appropriate Uranami are determined. The range is narrow, and when welding large structures, it is often difficult to keep the groove conditions, especially the root spacing, within a narrow range that allows welding under constant welding conditions.

Therefore, in order to obtain an appropriate uranami peed, when the root spacing is large, the current and voltage of the leading electrode is lowered to prevent the molten metal from dripping, and when the root spacing is small, the uranami peed is lowered. It is well known that it is necessary to increase the current and voltage of the leading electrode to ensure this.

Even though the groove cross-sectional area becomes wider in areas where the root spacing is large, the current and voltage of the leading electrode is lowered to weld.
The weld cross section obtained by the leading electrode is reduced. For this reason, the trailing electrode has an increase in the groove cross-sectional area due to the widening of the root spacing of the remaining welds to be welded during trailing electric welding, and an increase in the groove in the remaining groove due to the narrowing of the welding cross-sectional area of the leading electrode. An increase in current and voltage is required to correspond to an increase in the weld cross-sectional area given by the sum of the increases in cross-sectional area. This results in a stacked layer as shown in FIG. 3(a). On the other hand, if the root spacing is narrow, the current and voltage will be increased at the leading electrode in order to secure the Uranami bead, and the current and voltage will need to be lowered at the trailing electrode because the groove cross-sectional area of the remaining groove will become smaller. There are 8 layers as shown in Figure 3).

To control the amount of welding, between the leading current and voltage and the trailing current and voltage, use Figure 4 (a) if the welding power source has constant voltage characteristics, or Figure 4 if the welding power source has droop characteristics. The relationship shown in (b) may be sufficient, and the calculation unit may be used to set the current of the trailing electrode to the relationship shown in FIG. 4 with reference to the current voltage of the leading electrode.

Next, FIG. 5 shows a case where the plate thickness of the welded part changes during welding. When welding a welded part where the plate thickness increases during welding using a two-electrode welder with electrodes arranged in series with the weld line, with each electrode advancing at the same speed, the groove cross-sectional area In order to cope with the increase in the current and voltage of each electrode, the current and voltage of each electrode are increased. In this case, the current-voltage relationship between the leading and trailing electrodes may be proportional. Therefore, the relationship between the current and voltage of the leading electrode and the trailing electrode is the condition shown in FIG.

Furthermore, a case will be described in which sideways welding of an upright plate-shaped base material is carried out using a double-sided welding device with the electrodes on both surfaces aligned in the same position in the welding direction. In this welding method, in order to obtain a good bead shape as shown in Figure 6(a),
It is necessary to make the current and voltage of opposing electrodes on both sides almost the same. There is no problem even if there is a difference of 10 inches in current, but if there is a difference in voltage of 2% or more, the molten metal will be blown to one side and the bead will be formed unevenly, as shown in Figure 6 Φ). Ru. For this reason, it is impossible to finish both sides at the same time, and the meaning of double-sided horizontal welding is diminished. In order to match the voltage values within 0.5 layers, it is difficult to accurately set the voltage values by adjusting the voltage meter reading υ at the welded part because the error is too large. In addition, even if a device that allows accurate current and voltage settings is used, the voltage balance between opposing electrodes cannot be achieved when starting an arc or when disturbances occur due to voltage fluctuations, resulting in the formation of a biased bead and a stable bead. Until this happens, a weld bead will occur that requires rework. In such a horizontal double-sided welding device, the above problem can be solved by using the electrode on one side as a reference electrode, the opposing electrode as a dependent electrode, and controlling the current and voltage of both to match.

Furthermore, the control in this case is simplified as follows. When a welding power source with constant voltage characteristics is used for current/voltage control, the current is determined only by the wire feed speed, which is fed at a constant speed when the wire protrusion length and arc length are constant. Since the aiming position accuracy is good in horizontal welding, the sum of the wire protrusion length and the arc length is constant. Since the wire feed speed can be set with an accuracy of within 5%, in order to balance the weld bead, it is not necessary to control the reference electrode and slave electrode currents to be the same, and only the voltage at the reference electrode is required. Control may be performed so that the and subordinate electrodes are the same. As described above, depending on the purpose of control and the power supply characteristics, it is not necessary to control the current and voltage of the reference electrode and the dependent electrode at the same time, and the same result can be obtained by controlling only the current or voltage to have a constant relationship.

(Effect of the invention) As described above, if the present invention is used, even in multi-electrode welding, it is possible to adjust the welding current and voltage of all electrodes by simply adjusting the welding current and voltage of only the reference electrode. The load is very light, and since the current and voltage of each electrode are adjusted accurately and in a timely manner, welding defects can be prevented, and a remarkable effect is recognized in improving quality and efficiency.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention in which the current and voltage of a subordinate electrode are controlled by the current and voltage signals of a reference electrode. FIG. 2 is a block diagram showing another embodiment of the invention. Figure 3 is a lamination diagram when Uranami welding is performed using the present invention with the electrodes of a two-electrode welding machine arranged in series in the welding progress direction in a V-shaped groove, and (a) shows a wide root spacing. case,
(b) shows the case where the route spacing is narrow. FIG. 4 is a graph showing the relationship between the current and voltage of the leading electrode and the trailing electrode to satisfy the conditions of FIGS. 3(a) and 3(b). FIG. 5 is a graph showing the relationship between the current and voltage of the leading electrode and the trailing electrode when the thickness of the welded portion changes during welding. Figure 6 is a lamination diagram of the first pass in horizontal double-sided welding when the electrodes on both sides are aligned in the welding direction.
(a) shows a good bead shape obtained using the present invention, and (b) shows a defective bead shape that may occur when the present invention is not used. 1... Reference electrode 2... Reference electrode welding control device 3
...Reference electrode welding power source 4...Reference electrode wire feeding device 5...Reference electrode current detection end 6...Reference electrode voltage detection end 7...Arithmetic unit 8...Subordinate electrode 9.
...Slave & electrode welding control side equipment 10...Slave night, @1
Welding power source 11-...Subordinate electrode wire feeding device 12-
... Delay device 13... Base material 14... Subordinate electrode current detection terminal 15... Subordinate electrode voltage detection terminal 16... Comparison calculation equipment Applicant Nippon Steel Corporation (and one other person) Agent Patent Attorney Minoru Aoyagi Figure 1 Figure 2 Figure 3 (a) (b) Figure 4 (d) (b) Light conduction type electric; ) 6 (a) Figure (1)) ↑ Figure (b)

Claims (1)

[Claims] In multi-electrode welding, a reference electrode is determined, and the welding current and voltage of the reference electrode is adjusted so that the welding current and voltage of the reference iV cedar and one or both of the welding current and voltage of the other electrodes maintain a constant relationship. A multi-electrode welding method characterized by detecting one or both of them, processing them in a computing unit, and using the processed signals to control one or both of the welding current and voltage of other electrodes.