SU1750885A1 - Multiarc welding method for curvilinear closed seams - Google Patents

Abstract

Use: mechanical engineering, welding of melting and non-melting electrodes of flange connections. Essence: multi-arc welding of closed curved seams, performed by two or more torches. The burners are located around the seam perimeter. The product rotates. The counting of the welding cycle of each burner starts from the moment of initiation of the arc of the previous burner. 2 Il.

Description

The invention relates to the welding industry, in particular to the fusion and non-consumable electrode welding of curvilinear seams of shaft-gear type parts, welded flange connections, etc. in various fields of engineering.

Known specialized semi-automatic A-948. when using which, the method of double-arc welding with semiautomatic devices located diametrically relative to the pipe is applied. The use of a double-arc welding of a circumferential weld makes it possible to almost double the productivity of the process.

The disadvantages of this method are the instability of the filing of the welding wire, the inertia, large gaps in the feeder of the welding welded wire, slippage of the wire in the feed rollers. In addition, the failure of the mechanisms and systems of one of the semi-automatic devices is possible. Due to these drawbacks, non-simultaneous ignition of welding arcs is possible.

Non-simultaneous ignition of welding arcs leads to the formation of such defects as the absence of overlapping the beginning and end of the annular welds. Welding of the weld is incomplete due to the lack of the total amount of weld metal.

A well-known multi-arc welding method with torches located diametrically along the weld seam, carried out by the device for automatic welding of chokes. The fittings are welded with two torches with dbum welding wire feeders. Compared to single-arc, this allows an almost twofold increase in welding productivity. The absence of a long wire feed path can somewhat increase the stability of its feed and the reliability of ignition of welding arcs.

However, this welding method cannot provide simultaneous excitation of two welding arcs.

Simultaneous excitation of two welding arcs is practically impossible for a number of reasons related to the instability of this process, which depends on the unequal free reach of the electronic wire of different distances (L

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neither from the end of it to the product, the temperature and geometry of the end, as well as the cleanliness of the wire surface and the base metal, the intensity of the electric field between the base metal and the electrode, the static and dynamic characteristics of the arc and power sources, the wear of conductive tips, etc.

Similar negative consequences are observed when one-arc automatic welding of circular seams with rigid cyclic program control.

The aim of the invention is to obtain an optimal overlap of the beginning of the weld of the previous burner with the end of the weld followed by multi-arc welding, regardless of the moment of initiation of welding arcs.

The goal is achieved by the fact that, according to the method of welding of closed seams with a cyclic program control, the welding cycle of each of the burners starts counting from the moment of initiation of the arc of the previous burner.

Known technical solutions for welding of closed welds and welds performed by multi-arc heads do not take into account the time of instability of ignition of welding arcs, at which gaps between the beginning and end of the weld of the previous and subsequent burners are possible.

The welding of annular welds according to the proposed method with two or more burners located along the weld perimeter is carried out taking into account the time required for the excitation stability of the arc burners.

Fig. 1 shows a flow chart of welding a circumferential weld with two arcs; Fig. 2 shows a technological scheme for the welding of an annular weld with three arcs.

The multi-arc welding method of curved closed loop seams with programmed control is carried out as follows.

The welding cycle includes turning on the product rotation, simultaneous voltage supply to the product to be welded and welding torch wire, simultaneous turning on the electrode wire (welding) wire feed mechanisms, arcing, counting the specified welding time, turning off the electrode wire feed, relieving voltage from the electrode wire and products and stopping the rotation of the product.

At the time of the start of the welding process, the arc of the torch 1 is excited, and the arc of the torch 2 is excited with a delay of time At. As you can see, in order to overlap the seam,

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50

five

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five

five

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T2

performed by burner 2, the total time of the arc of burner 1 must be increased by At. In this case, the total burning time of the arc of the burner 1 is

Ti K + At rf + At, VCBVCB

and the arc time of the burner 2 is:

-At-rf-At,

VCBVCB

where Us is the length of the weld:

R is the seam radius;

VCB - welding speed:

K - coefficient taking into account the overlap of the seams.

Consider welding with three torches 1-3 (FIG. 2). All three arcs 4-6 are excited at different times with a delay of Ati, At2, At3. Arc 6 of burner 1 is excited at point MI, arc 5 of burner 2 at point Ma, arc b of burner 3 at point M3. Then the starting time of the arc 4 burner 1 should be made from the point MF, which corresponds to the point M2, for the burner 2 - from point 02, which corresponds to the point Mo, for the burner 3 from the point Oz. which corresponds to the point Mi Then the burning time of arc 6 of burner 1 will be:

ri K | -Ati + At2,

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arc 5 burner 2

r2 K | --At2 + At3,

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arc 6 burner 3, 2lN

- At3 + Ati,

 3VCB

At the same time, the welding time of the product corresponds to the longest burning time of one of the arcs.

Example. The product is installed with a sleeve in the installation rotation mechanism, the welding torches are adjusted relative to the fillet weld diametrically opposite, since two torches are involved, and the welding equipment of the one and the other is prepared.

The welding cycle includes turning on the product rotation, simultaneously applying voltage to the product to be welded and to the welding wire of both torches, simultaneously turning on the electrode wire feeding mechanisms, and initiating the welding arcs. The excitation of one of the two arcs, as a rule, is late. But the control system starts counting the arc time of the subsequent burner 2 from the moment of the ignition of the arc of the burner 1, and at the time of initiation of the arc of the burner 2, the arc burning time of the arc of the burner 1 begins.

Programming the burning time of the arcs of different burners, one after the other, ensures optimum overlap of the welds.

Modes for each of the burners: + 40 A; B: m / h; dnp-1.2 mm; , 1 is chosen empirically.

Material sprocket 18HGT;

Sleeve material - p.20;

Wire material - sv08G2S.

Weld radius

The overlap of the seams is mm.

The proposed method of multi-welding welding of curved closed loop seams with programmed control allows to obtain overlapping of seams of specified sizes and to increase welding productivity by 2 times.

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Claims (1)

Invention Formula The multi-arc welding method of curved closed welds, in which welding is performed1 by two or more torches located around the seam perimeter, and rotates the product, feeds the electrode wire, turns on power sources, initiates arcs, performs welding and turns off arcs, so that, in order to improve the quality of welds, by overlapping the beginning of the weld of the previous burner with the end of the weld of the next weld, the countdown of the welding cycle of the welds performed by each of the burners begins from the moment of initiation of the arc of the previous mount ki. 1  0 l M- "TO 02