SU1234095A1 - Method of welding up crater - Google Patents

Description

JKP

U9.1

The invention relates to the durable production}, mainly for automatic arc welding under a layer of flux, in protective gas environments of extended external and internal welds of welded pipes, welded beams and similar products.

The purpose of the invention is increasing productivity due to the continuous welding process at a constant speed of movement of products.

With a continuous welding process. the additional arc is moved in the direction opposite to the welding direction, i.e. towards the movement of products, which ensures the crater brewing speed, which is lower than the welding speed of the main arcs without reducing the speed of moving the products. Moreover, the indicated direction of movement of the additional arc allows welding simultaneously from the main arcs and welding the crater with an additional arc even at In the case when the additional arc - continues welding of the crater of the welding seam of one product, and the main arcs began the subsequent welding.

An additional step of productivity is achieved due to the high constant speed of movement of products, equal to the speed of welding by the main arcs, and thus eliminating the interval between the successive supply of products for welding.

Moving an additional arc opposite to the direction of welding and the constancy of the speed of movement of the products, in addition, allow welding of other defects of the weld sections with an additional arc during welding of the same product with the main arcs, which also increases the productivity of the welding process and the quality of the weld.

Defects of the weld, in addition to the crater, which can be welded with an additional arc, can be local weakening of the weld, undercuts, lack of fusion with the edges of the product and others resulting from a short break of one of the main arcs, displacement of the arcs relative to the axis of the weld, disturbances in flux supply, and t .P. Usually such Defects are eliminated in the process of finishing a cooled product by semi-automatic welding, which does not ensure high quality of the weld and requires additional costs; Figure 1 shows the position of the main welding arcs 1, the additional arc 2 and successively moving products 3 and 4 during the welding of the product with the main arcs at the moment when the additional arc starts - welding of the crater of the product; figure 2 - the position when the main arc are welding the next - product 4, and an additional arc 2 continues the welding of the crater part of the first product 3.

It is known that the size of the crater (pJ decreases with decreasing welding speed, therefore, to reduce the size of the crater, the welding speed must be less than the welding speed. For

This additional arc is moved in 3 directions opposite to the welding direction, i.e. coinciding with the direction of movement of the product. Then the speed of the intake V is

the difference between the speed of the product V ,, and the speed of the additional arc v.

V ,, - V, a Vdj

Move an extra arc. with a speed of 1.25-3 times less

Vj, jj corresponds to the welding speed 1., 3-5.0 times less than the welding speed and V, fi. V „V i

When v; --- | (, -5) The additional arc of the flax is almost immobile, and the length of the crater of the seam decreases slightly.

When V, the additional arc moves almost over one weld (V), that

“Ii) T, 25

can cause the end-to-end burnout, and the distance the additional electrode moves, i.e. the optimal speed of movement of the additional arc should be considered a speed of 1.25-3 times lower than the speed of movement of products.

The method is carried out as follows.

The main arcs 1 are welding out of the factory. 3, moving at a constant speed. When welding the end section of product 3, a crater appears - a defect in the weld. For its welding, an additional arc 2 is used, which is included at a distance from the end of the product, determined by

loosening the weld, i.e. 0.8--1.5 1 p Lr the length of the brewed section greater than 1.5, the distance between the additional and main arcs increases so much that, when welding under a layer of flux, it can lead to deterioration of the welding process with an additional arc over the hardened pshak crust . The included additional arc 2 is moved in the direction of the SRI opposite to the welding direction, i.e. in the direction of moving the product at a speed of 1.25-3.0 times less than the speed of movement of products. Since the additional arc in the initial position is at a short distance from the main arcs, its excitation is stable and high-quality fusion of the welded seam from the additional arc to the seam of the main arcs is ensured.

After the end of the welding of the product 3, the main arcs 1 immediately begin welding of the next product 4, and the movement speed of all the products remains constant and equal to the welding speed of the main arcs. This allows products to be moved in series, welded practically without an interval. An additional arc at this time continues to weld the crater of the previous product. At the end of crater welding, the additional arc is cut off, and the additional electrode is moved to its original position.

In the event of a defect in an arbitrary place of the weld, the additional arc is turned on before the defect and also moves with a speed of 1.25-3 times less than the moving speed} of products in the direction opposite to the welding speed.

Main arc welding

Additional arc welding (welding)

j Q j Q

five

50

0

and provides welding of the defective frequency. The main arc at this time continue to weld the product. At the end of the welding of the defective area, the additional arc is turned off, and the additional electrode is retracted to its original position.

Example: Submerged-arc welding of large-diameter pipes from steel 17 PS with two main welding arcs and an additional arc moving against the welding speed. Brand flux AN-60, the brand of electrode wire Sv-08GA. Welding modes are presented in the table.

The technical and economic effect of the implementation of the invention can be obtained by a constant, equal to the welding speed, the movement speed of the products during welding with an additional arc of the crater and other defective parts of the weld, simultaneous welding with the main arcs of one product and welding with an additional arc of the crater part of the previous one, as well as elimination of the interval between successively moving products. The productivity of the welding process according to the proposed method increases by 5-10% (for pipes with a length of 11 m), the lifetime of the mechanical equipment increases, the cost of repairing it is reduced by using it at constant nominal modes. The length of the defective part, the weld, and, consequently, the cutting of the metal decreases, the strength and reliability of the weld increases, the likelihood of rupture decreases

(Pipelines in the process of their operation.

1.1-1.3

40-45

180

180

0.55-0.57 35-40

50

180

(

fP

ui. I

Editor M. Bandura

Compiled by, Kulik

Tehred O. Sopko Proofreader V. Sinitska

Order 2934 / t4 Circulation 1001 Subscription

VNIIPI USSR State Committee

for inventions and discoveries t13035, Moscow, Zh-35, Raushsk nab., 4/5

Production and printing enterprise. Uzhgorod, Projecto st., 4

Claims (1)

METHOD FOR WELDING THE CRATER of a weld in multi-arc welding of sequentially moving products, in which welding is carried out by an additional arc installed behind the main welding arcs ₍ at a speed lower than the welding speed, characterized in that, in order to increase productivity due to the continuous welding process at a constant the speed of movement of the products, the additional arc is moved in the opposite direction to the welding direction.