SU450670A1 - The method of electroslag welding by melting the mouthpiece - Google Patents

Description

one

The invention relates to electroslag welding and can be used to improve the quality of a welded joint and to increase the productivity of a process.

At present, its time by electroslag welding with a melting cushion can be used to weld practically unlimited thicknesses (there is experience in welding billets with a cross section of 2000 x 3000 mm). In this case, 18-36 welding wires are fed into the welding gap. However, this is a complicated and time-consuming operation. Decreasing the number of wires leads to an increase in the distance between the electrodes and, accordingly, to an increase in the width of the plates of the melting mouthpiece. Usually the optimum distance between the electrodes is about 100 mm. This distance is due to the fact that the closer the electrodes, the more uniform the penetration of the welded edges is, which is very important for some steels that are prone to treshing with uneven penetration; In addition, with a larger number of electrodes to provide a given welding speed, the feed rate of the electrodes is significantly less than the critical one (the critical speed is the speed at which hot cracks appear in the seam).

With an increase in the distance between the electrodes (with an increase in the number of supplied welding wires for the same thickness

) will provide :, the required welding speed is possible by increasing the wire feed speed. This process can exceed the critical electrode feed rate, and the welding speed will be significantly lower than the required one. Then, under the PZ electrodes, excessive localization of the depth of the metal bath (a small weld shape factor) causes crystallization cracks. To eliminate this phenomenon, it is necessary to reduce the feed rate below the critical, which, in turn, dramatically reduces the productivity of the welding process.

Thus, with a large distance between the electrodes, the edge penetration will be uneven.

Pel - increase productivity and improve the quality of the weld.

For this, according to the proposed method, the feeding of the main and additional filler wires is carried out periodically.

After the electroslag process is established, the wires are fed only through the main channels, then, when the melting die loses contact with the slag bath, the feeding of the main filler wires is stopped and additional wires are fed until the die comes into contact with the slag bath.

After the melting die loses contact with the slag bath, without interrupting the feeding of the main filler wires, additional wires are fed.

FIG. 1 shows the moment when the main wires are fed when the mouthpiece plate is melted; in fig. 2 - the moment of supplying the auxiliary wires (during the period when the mouthpiece plate does not melt).

The metal is welded with a help of a melting die, in which the main I, 3, 5, 7 and 9 and auxiliary 2, 4, 6 and 8 channels for supplying the electrode wire are made. Auxiliary channels are located between the main. The distance between the main channels may in this case be 300-400 mm, the thickness of the mouthpiece plate is 15-20 mm.

After the electroslag process is established, the wire is fed through the main and auxiliary channels alternately as follows: first, the wire is fed through the main channels until the mouthpiece plate, which melts always faster than the speed of the slag bath, loses contact with the slag bath; then the supply of core wires is stopped and the auxiliary supply is switched on until the mouthpiece plate re-contacts with the slag.

Subsequently, the cycle for switching off the wire feed through the main and auxiliary channels is repeated.

Such a welding scheme makes it possible to increase the welding speed (increase the feed rate of the flute) by artificially displacing the heat centers in the volume of the slag bath.

In addition, alternating wire feed contributes to a more uniform penetration of the edges.

In order to obtain a good external formation of the seam, wire at the sliders (in the place of the largest heat sink) is continuously fed.

When one of the main welding parameters is uniform speed (this is important when welding steels sensitive to cold cracks in the heat affected zone), and the thickness of the melting die plate is 5-12 mm and the melting interruptions of the plate are relatively large melting includes additional wires without turning off the main ones, and when the plate is re-melting, the electrodes turn off the opposite (i.e., the main electrodes are turned off).

Practically implement the proposed welding scheme can be on existing equipment. The sensor for switching on the main and auxiliary wires can serve as a current relay, which reacts to a change in the magnitude of the welding current when the plate melts (maximum welding current) and only one electrode wires melt (minimum welding current).

The wires are pressed by electromagnets at the command of the welding current relay.

Subject invention

Claims (3)

1. The method of electroflame welding with a flute die, along which the main and additional filler wires located between the channels are fed through the channels, and the wires located along the edges of the mouthpiece of the devices forming the surface of the seam are made in order to increase productivity and improving the quality of the weld, nodachi basic and additional filler wires carry out periodically. 2. A method according to claim 1, characterized in that after the establishment of the electro-slag process, the wires are fed only through the main channels, then, when the melting nozzle loses contact with the slag bath, the supply of the main filler wires is stopped and additional wires are fed until the mouthpiece re-contacts with a shlakova bath. 3. A method according to claim 1, characterized in that after the melting die loses contact with the slag bath, without interrupting the supply of the main filler wires, additional wires are supplied.  2 3 4 5 6 7 8 5