SU1558597A1 - Method of welding with arc revolving in magnetic field - Google Patents

Abstract

The invention relates to arc welding, in particular to arc-welding methods, burning between the ends of the parts to be welded and rotating in a magnetic field with subsequent downfall, and can be used mainly in pipe welding. The purpose of the invention is to improve the quality of welded joints by reducing the effect of inaccuracies in the machining of the ends and simplifying the process of preparing them for welding. Prior to the beginning of the process of the welded ends of the rotating arc, the parallelism of the gap between the parts to be welded 1 and 2 is mechanically set. Then they are heated by the rotating arc. At the end of heating, parts 1 and 2 are installed coaxially with a simultaneous increase in current before the subsequent slump. The method allows to eliminate the time-consuming operation of mechanical cleaning of the ends of the welded parts. 1 il.

Description

The invention relates to arc welding, in particular, to methods of welding with heating by an arc burning between the ends of the parts to be welded and rotating in a magnetic field, followed by upsetting, and can be used primarily for welding pipes.

The aim of the invention is to improve the quality of welded joints 10 by reducing the impact of inaccuracies in the processing of the ends and simplifying the process of preparing them for welding.

The drawing shows a diagram of a device for implementing the proposed method.

The essence of the method is as follows.

Prior to the start of the process of heating the welded ends by a rotating arc, mechanically set the parallelism of the gap between the parts to be welded. Then carry out their heating by a rotating arc. At the end of heating, the axes are aligned _; 25 parts with simultaneous increase * of current and compression (draft) of heated ends. Welded parts 1 and 2, pre-. they are pieces of steel pipes with a diameter of 60 mm and a wall thickness of 5 mm, with the help of clamps 3-5, developing a force of P = 20 · 10 ⁴ Η, set coaxially. Between the pipes leave a gap of 2 mm, determined by the minimum distance between the ends. Kosina 35 of each end is 1 mm. Clips 3 and 4 are connected to the terminals of the VDU-1201 source, which can be switched from one current value to another using relay contacts. In close proximity to the welded joint are placed electromagnets 6 connected to a VDU-504 source.

To establish pipes having oblique ends in such a way that there is a parallel gap between them, an articulated clamp 5 serves.

'The device operates as follows.

With a force of P ₂ approach 50 and the compression of the welded ends of the pipes. Then the clamp 4 is withdrawn from the pipe 2, and the force of the clamp 5 on the pipe is reduced to those values at which the pipe 2 in the hinge of the clamp 5 is rotated. This 55 occurs due to the action of a moment equal to P _g <-5-, ^{where d} “is the diameter of the parts to be welded. In this case, the perimeters of both pipes are combined and fit snugly against one another.

In the case of the use of ends, without kosin pipe does not change its position. If the pipes have oblique ends, then the axis of the pipe 2 changes its position and becomes at a certain angle (equal to the total kosin of the pipes) with respect to pipe 1. Next, the welding source 7 is turned on and the pipes are bred to a gap of 2 mm. In this case, an arc is excited, which has the following parameters: current 200 A, voltage 28 V. In this mode, the pipes are heated for 9 s. At the end of heating, the pipe 2 is secured with a clamp 4 with a force of 20'10 N. The force P is partially removed from the pipe 2. With this, the pipe axes are aligned. At the same time, the welding current is increased to 1100 A within 0.2 s and the pipes being welded are reduced with a force of 11 · 10 ⁴ > N. The upsetting speed is .200 mm / s and the shortening value is 6 mm. · Then the welding current and the current of the electromagnets are switched off .

Mechanical tests of a batch of welded pipe joints show their equal strength with the base metal of the pipes. For a comparative assessment of the proposed method with a known one, welding is carried out on the same pipe size, but with a butt cut equal to 1 mm. Arc excitation and heating of pipes with a cut of more than 1 mm without special devices are difficult. The arc breaks off in places of maximum clearance.

Welded a batch of pipes with a kosin end faces 1 mm and mechanical tests of the joints .. They show the instability of the quality of the pipe joints. In the fractures of the joints, oxides are observed. Welding a batch of pipes with a cut of 0.2-0.3 mm ends shows the stability of welded joints. The produced pipes of usual accuracy have a kosin much larger (up to 1 mm) and their use in machines for welding with a rotating arc is unacceptable. Additional processing of their ends is required.

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The application of the proposed method will eliminate the time-consuming machining operation. Particularly time-consuming is the processing of the ends in the field with a large length of parts. This dramatically reduces the productivity of welding plants.

Analysis of the surface condition of the ends of the heated pipes (before the upset) shows that during a sharp increase in current, the ends of the pipes heated to melting are aligned and their non-parallelism is not more than 0.20.3 mm. The initial braid of each pipe is 1.0 mm.

Claims (1)

Claim A method of welding by an arc rotating in a magnetic field, in which the edges of the parts to be joined are preheated, and then the edges to be welded are heated by increasing the current, followed by draft 5 characterized in that, in order to improve the quality of welded joints by reducing the influence of inaccuracies in the machining of the ends and simplifying the process of preparing them for welding, the ends of the parts are installed parallel to each other before heating, and coaxially before the draft.