RU1779504C - Method of multielectrode arc welding - Google Patents

Abstract

SUMMARY OF THE INVENTION: The welding voltage is applied simultaneously to all the electrodes and, before starting the welding, the transverse magnetic field is switched on to the arc gaps. Welding is carried out according to a predetermined program. To do this, the arc is sequentially ignited on the next electrode by switching off the transverse magnetic field on it. 2 silt

Description

The invention relates to a welding technique, particularly to methods for arc welding predominantly thin sheet structures with several electrodes.

A welding method is also known, in which the joint is divided into equal sections, welding is performed by several electrodes by applying welding current pulses to each electrode according to a predetermined program, whereby the previous points are blocked by subsequent ones. This increases labor productivity and improves the quality of welded joints, reducing welding stresses and deformations.

However, when welding by this method, it is necessary to switch the power welding circuit according to a given program in order to switch the power source from one electrode to another. It is necessary to use a special high-power switch. In addition, the electrodes must be isolated from each other. All this also complicates the design of the welding installation and increases its cost.

. It is an object of the invention to save energy by switching low current circuits.

In the method, low-current circuits of the windings of the solenoids generating magnetic fields at each of the electrodes are switched. This allows the use of a simple in design and relatively cheap switch. In addition, since there is no need to switch the power welding circuit, it is not necessary to isolate welding electrodes from each other, which, when welding according to the proposed method, are electrically connected to each other and connected to the arc power source.

Figure 1 shows the connection diagram of the elements of the welding and control circuits for implementing the method; in Fig.2 is a sequence diagram of the welding process.

Against the arc gaps formed by the electrodes 1 and the welded article 2, electromagnets 3 are installed, generating magnetic fields transverse to the axes of the electrodes 1. The electrodes 1 are interconnected and connected to an arc power source, the second pole of which is connected to the welded product 2. Switch 5 provides the ability to connect electromagnets 3 to their power source 6 according to a predetermined program.

(L

WITH

xi

VI

YU

word about

Figure 2 shows the sequence diagram of the welding process, where Ice is the strength of the welding current; 1M - current strength in an electromagnet; tgi - tg4 are time axes on which changes in the welding current passing through 1 to 4 electrodes are reflected; tMi - tn4 are time axes on which changes in the current passing through 1 to 4 electromagnets are reflected; tn is the pulse duration of the welding current; tn is the duration of the pause between pulses of the welding current at this electrode; tM is the duration of the activation of the electromagnet on this electrode.

Example. We carry out argon-arc welding of a flange with a diameter of 100 mm with a thin-walled shell 2 mm thick of stainless steel. Through switch 5, the sequence of arcing was set; first on the 1st electrode, then on the 3rd, on the 2nd and on the 4th. To carry out such a cycle, a power supply was connected to the power supply. All electromagnets, except those located at the electrode 1, turned on the arc power source and ignited the arc on the electrode 1 by any known method (for example, using an oscillator). At other times, the arc cannot be ignited at this time, because the transverse magnetic field generated by the switched-on electromagnets will prevent this; ignition of the arcs is blocked by a magnetic field. At the end of the specified pulse duration using the switch 5 include a magnetic field on the electrode 1, the arc goes out. At the same time, the magnetic field on the electrode 3 was turned on and an arc was ignited on it. Then, these operations were repeated with respect to electrodes 2 and 4 and again transferred to electrode 1. After each cycle, all electrodes were displaced by the step size, which provided overlapping of the weld points. The cycles were repeated until a weld was completed. If necessary, the method may be carried out

connected with any number of electrodes. The duration of the pause between pulses of the welding current during welding by the proposed method will be equal to the sum of the pulse durations for all other electrodes for this electrode

n- 1

tn - 2

where n is the number of electrodes.

The duration of the activation of the electromagnet at each electrode will be equal to the pause duration tM tn.

The method allows to simplify the design of welding equipment due to the fact that low-current electromagnet circuits are switched, the currents of which are measured in units of amperes, while in the known methods it is necessary to commute a secondary welding circuit, the currents of which will be hundreds of amperes, which complicates the design of the switch and increases its value. In addition, all electrodes are interconnected electrically. In the design of the welding head, there is no need to use parts that insulate the electrodes from each other and from the head housing, as well as separate current leads to each electrode. This makes the design of the welding multi-electrode cheaper and cheaper.

5

0

5

0

5

Claims (1)

heads and saves energy. SUMMARY OF THE INVENTION A method of multi-electrode arc welding, in which an arc is ignited on each of the electrodes sequentially according to a predetermined program, characterized in that, in order to save energy by switching low-current circuits, before starting welding, a transverse magnetic field is switched on to the arc gaps, the welding voltage is applied simultaneously to all electrodes, and welding according to a given program is carried out by sequentially switching off the transverse magnetic field on the working electrode. Fig: i