RU2278008C2 - Large-size thick-wall parts welding method - Google Patents

Abstract

FIELD: processes for automatic welding of constructions having large-size thick-wall parts.

SUBSTANCE: method comprises steps of dressing edges for welding by means of metal cutting tool simultaneously on both parts after tack welding of parts at side opposite relative to tack welding zone; using milling cutter whose profile corresponds to dressing contour as metal cutting tool.

EFFECT: automatic welding process of parts made of forged or formed blanks without preliminary working of butt surfaces of welded parts.

2 cl, 1 dwg, 1 ex

Description

Technical field

The invention relates to the automatic welding of structures from thick-walled large-sized parts with cutting edges and can be used in various fields of technology, in particular in the field of power engineering.

State of the art

In automatic welding of thick-walled large-sized parts, the main problem is to ensure a constant geometric shape of the gap between the parts to be welded, since the unevenness of the gap leads to fluctuations in the welding conditions, and as a result, defects in the weld, such as lack of penetration, pores, cracks, cuts, etc. (see V. Vinokurov. Welding deformations and stresses, Moscow: Mashinostroenie, 1968, p.200).

GOST 5264-80 defines the sequence of cutting edges of parts in bilateral automatic welding of thick-walled parts. At the same time, the edges of the parts are first cut on the one hand with their subsequent joining in the fixture and welding, then on the other hand, the root of the previously applied seam is removed to clean metal with a metal cutting tool of a certain profile, as a result of which the edges of both parts are simultaneously processed to the required size, then welding is performed split joint.

The disadvantage of this solution is that for the production of automatic welding, it is necessary that both the welded workpieces have pre-prepared surfaces for cutting, without distortions in length and width.

In the method described in ed. testimonial. USSR No. 806310, 1978, it is proposed to produce welded structures from thick-walled large-sized parts using the following operations. On a metal cutting machine, the edges of the parts are cut from one side. Next, on the assembly fixture, the assembly and fixation of the position of the parts to be welded are carried out. Mark the joints with the maximum clearance. Then, the joints are welded, while at the junction with a maximum gap, the grooves are filled only with side rollers, and for the rest of the joint, central rollers are used over the entire width of the groove.

The disadvantage of this welding method is that it is possible to use only manual welding, since it uses various techniques when applying rollers. The use of automatic welding is excluded due to the occurrence of fluctuations in welding conditions due to the presence of significant differences in the gap values along the entire joint, which entails a deterioration in the quality of the weld and the appearance of various kinds of defects in it.

The present invention is the creation of such a method of welding thick-walled large-sized parts, in which it is possible to use automatic argon-arc welding.

The technical result from the use of the invention is to automate the welding process of thick-walled large-sized parts of any configuration, including workpieces obtained by forging or stamping, and not having undergone preliminary machining of joined surfaces.

This problem is solved due to the fact that in the method of welding thick-walled large-sized parts, including cutting their edges with a metal cutting tool, assembling the parts, their subsequent tacking and welding, while cutting the edges for welding is performed simultaneously on both parts after tacking and from the side opposite tack.

Another difference of the welding method is that a cutter having a profile corresponding to the shape of the groove is used as a metal cutting tool.

Brief Description of the Drawings

The drawing shows a graphical depiction of the implementation of the method.

An example implementation of the invention

To perform welding take two thick-walled large-sized billets of irregular shape 1 and 2, obtained, for example, by stamping or forging.

In the assembly fixture, these parts are assembled and their position is fixed.

Then the assembled parts are welded by manual argon arc welding with tacks 3 from the side opposite to the main weld.

At the next stage, the joint is cut at the same time for both parts to be welded, which is carried out by a mill, the cutting part of which corresponds to the configuration and dimensions of the cross-section of the edges for welding.

Edging of the cutting edges is carried out until the formation of the metal surface of the joint obtained by the tack, which avoids the formation of various kinds of defects at the tack point during welding of the joint.

Then, automatic multi-pass welding of the cut joint of two parts in an inert gas atmosphere, for example argon, is performed.

In the process of welding the specified joint, the welding modes remain unchanged, since the geometrical dimensions of the groove are unchanged, therefore, the deformation of the weld is minimal.

The use of the claimed welding method when creating structures from large-sized thick-walled, previously untreated parts obtained, for example, by stamping or forging, can dramatically increase the productivity of the process in serial production.

Example.

A batch of welded structures was made of high alloy steel with a wall thickness of 25 mm. A milling cutter with a working cut angle of 60 ° and a radius of 2.5-3 mm was preliminarily made. After the assembly of its elements in the form of plates of the indicated thickness and tack by manual welding of a joint with a height of 2-3 mm, both edges were machined with a prepared mill to form a groove of a given configuration, and processing was carried out until the metal surface of the stuck joint was formed. Next, automatic welding was performed in three passes. In the first pass, the welding speed was 30 m / h with a current strength of 410 ± 10A and a voltage of 30 ± 2V. In the second pass, the welding speed is 25 m / h with a current strength of 400 ± 20A and a voltage of 30 ± 2V. On the third pass, the welding speed is 20 m / h at a current strength of 380 ± 10A and a voltage of 32 ± 2V. Welding modes throughout the batch were the same.

The analysis of X-ray inspection showed that the quality of the welded joint is fully consistent with the requirements of technical conditions, namely: the absence of various kinds of defects - pores, cracks, slag inclusions, non-fusion.

Industrial applicability

The use of this welding method is possible in many areas of technology where there is a need to weld structures from thick-walled large-sized workpieces that have not undergone preliminary machining for welding.

Claims (2)

1. A method of welding thick-walled large-sized parts, including cutting their edges with a metal cutting tool, assembling parts, their subsequent tacking and welding, characterized in that the cutting of the edges for welding is performed simultaneously on both parts after tacking and from the side opposite the tacking. 2. The welding method according to claim 1, characterized in that as a metal cutting tool, a mill having a profile corresponding to the shape of cutting is used.