RU1776520C - Method of electroslag welding by strip electrode - Google Patents

Abstract

The proposed method relates to welding production, namely electroslag welding using tape electrodes. In the process of electroslag welding, a strip electrode is melted in a slag bath, which is profiled when it is supplied. The current is distributed over the electrode cross section by raising the welded product at an angle a of 8-60 ° amp; to the horizontal plane and conducting the welding process in electroslag mode. A split tape electrode is fed into the slag bath, in which the parts profiled during the feeding process are arranged with an adjustable distance between them and parallel to each other and to the welded edges in their middle zone. The tape parts of the electrode during the feeding process are profiled in the front part according to the radius R, determined from the following, 21 actLt R: S × 4, where later is the size of the active spot of the arc across the width at the end of the tape electrode, mm. Lz - the gap (cutting width) between the edges to be welded, mm. In addition, during the welding process, the trailing edges of the electrode in the tail portion of the slag bath are opened. The tape parts of the electrode profiled during the feeding process are placed in the front part of the slag bath either with rounded edges against each other, or with rounded overlap edges. 2 s.p. f-ly, 14 ill with -s | XI SK SL U O

Description

The invention relates to the field of welding production

A known method of multi-pass electric arc welding with a tape electrode (see ed. St. N ° 707710. class. 23 K 9/00, 1975), in which the tape electrode is given a V-shape, and as the filling section of the passage from one passage to another change the length of the sides of the V-shaped tape electrode. The disadvantage of this method is the low productivity of the process and the possibility of formation

defects in the weld during multi-pass welding.

A method of arc welding with a split tape electrode is also known, in which the tape electrodes are fed into the welding zone symmetrically to the longitudinal axis of the seam, to which the tape electrograms are facing with their wide side (see autom. No. 397288, CL 23 K 9/16, 1972) Two tape the electrode supplied to the welding zone have a different distance between the trailing and leading edges, and the distance between the trailing edges is larger than between the leading edges, and it can be adjusted by changing the shape of the weld directly in the welding process of method it is also low process productivity and the possibility of forming defects in the weld seam in multipass welding.

There is also a known method of arc welding with two electrodes (see ed. St. No. 502721, class B 23 K 9/00, 1973), in which the wire electrode is placed in front of the tape, and the tape electrode is profiled along the wire to obtain mutual contact in arc burning zone. Moreover, the tape electrode is given a U-shape with straight sections parallel to the axis of the weld in the welding direction. The disadvantage of this method is the unstable supply of two electrodes, which leads to the formation of weld defects such as undercuts, etc.

The closest in technical essence and the achieved result is the ESW method adopted by the prototype for tape electrodes with regulation of the heat content of the slag bath along its length, for which the tape electrode is given the corresponding shape (profile) in the front part and the item to be welded is placed at an angle a 8-60 ° to the horizontal plane (see ed. St. No. 1441637, class B 23 K 25/00, 1986)

Figures 1, 2 and 3 show the shape and geometrical dimensions of a variable cross-section tape electrode for an ESW method selected as a prototype. However, obtaining the specified shape (profile) of a tape electrode requires significant pulling (pushing) forces. In addition, the ESW method adopted as a prototype does not allow one to control the depth and nature of the penetration of the welded edges in height, to ensure guaranteed penetration of the root of the seam, and because of this, the seams have low technological and operational strength.

The aim of the present invention is to increase the productivity of the process and improve the quality of the welded joint by adjusting the penetration depth along the height of the welded edges and improving the penetration of the root joint

This goal is achieved by the fact that in the ESW method, in which a ribbon electrode is molded in a slag bath, which is profiled during its filing with a rounded shape in its head zone, and the current distribution over the cross section is changed

electrode by tilting the welded products at an angle a 8, .. 60 ° to the horizontal plane and conducting the process in an electric arc-slag mode, characterized in that, in order to increase the productivity of the process and improve the quality of the welded joint by adjusting the penetration depth along the height of the welded edges and to improve weld root penetration, welding is carried out by a split electrode, in which two profiled parts are arranged with an adjustable distance between them and parallel to each other and to the welded edges in their middle zone, the radius R, which profiled parts of the electrode in the head zone, is determined by the following relationship

ur - R - braz - L,

where 1 act is the size of the active spot of the arc across the width at the end of the electrode, mm;

Lye width of the gap (cutting), and the tail sections of the electrode during profiling open.

In addition, in addition, during the welding process, the profiled parts of the electrode are arranged in the head zone with rounded edges against each other, or rounded overlapped edges.

Figures 4 and 5 show the shape and geometrical dimensions of a split tape electrode according to the inventive ESW method. (The schematic diagram in Fig. 4 corresponds to one of the variants of the proposed ESW method when the radii of the profiled tape electrodes are located butt to each other. Fig. 5 corresponds to another variant of the claimed ESW method when the radii of the profiled tape electrodes are overlapped (overlapping each other friend).

For the proposed ESW method, when two profiled strip electrodes are located in front of the slag bath, it is possible to obtain two separate arc processes, i.e. on each of the electrodes will burn its arc. The effectiveness of this combination is quite high. If the electrodes are located with radii end-to-end to each other, then each of the arcs burning along the radius of the tape electrode will melt its welded edge, i.e. the one that is closer to her.

Fig. B shows a diagram of the arc processes in the front part of the slag United for the proposed ESW method. The numbers in Fig. B designate 1 1 - tape

electrodes, 2 - welded plates, 3 - lining, 4 - bath of molten metal. 5 - liquid slag, 6 - the place of burning of the arc on the electrode. For this case, it is possible to obtain a common bath of molten metal, which was formed as a result of melting of the electrode metal and welded edges from separately burning arcs.

If one tape electrode is located in front of the other, then this corresponds to the arc burning scheme shown in Fig. 7.

Figures 9-14 show the relative position of the tape electrodes and the welded edges for three options for changing the ratio of the middle and tail of the electrode: 1 MN NK. 2 MN 0.5NK. 3 MN 0 with the same profiling radius Rnp (the width and thickness of the tape electrode are the same for all three options). Having drawn the secant planes 1-1, 2-2, and 3-3 for all the variants, it can be verified that moving the point N to the head of the electrode also causes the N-N line to shift to the root of the weld in the cross section of the welded joint. The melting of the tail of the electrode (outside T.M.) occurs in electroslag mode. Then, when placing the NISI line (when MN 0) in the lower part of the seam, each subsequent section drawn after section 1-1 shows that the distance between the electrode and the vertical groove wall is reduced. Consequently, the process of edge melting is intensified depending on the opening angle of the tail of the electrode. T.O. adjusting the length of the electrode portion MN causes a change in the penetration rate of the vertical walls.

Fig. 8 is a diagram illustrating the implementation of this method. The welded product 2, which is installed at an angle a to the horizontal, is a plate (sheets) of medium thickness (c5 sheet 12-16 mm), laid on a steel substrate 3. The split tape electrode 1 is installed with the narrow side symmetrically relative to the welded edges in the direction Vcb. wide side - vertically, i.e. perpendicular to the slag bath mirror b. To prevent the flow of molten meth ;. , la (metal bath) 7 and slag bath 6 from the back side of the split ribbon electrode, a spring-loaded copper water-cooled crystallizer 4 is installed. According to the proposed method, it is recommended that the beginning of the process be brought to input strips. When turning on the feed

The tape electrode closes down the hot chain and is excited by an arc process under the flux between the tape electrode and the lining. After some time, as the flux melts in the gap between the welded edges, a mixed melting process is established. Thus, the arc melting process occurs mainly in the head part and partly in the middle portion of the tape electrode. As the electrode metal melts, the metal bath 7 fills the space between the welded edges and crystallizes, forming the weld metal 5. Upon reaching the upper level of the slag bath, or the reference level of the crystallizer, the relative movement of the split tape electrode and the article being welded starts at a welding speed of VCB.

The inventive ESW method was tested on prototypes simulating the central joint of a beam of mechanized shaft supports.

When testing the ESW technology according to the claimed method, the VSJ-1600 power supply with a rigid current-voltage characteristic and the open circuit voltage Ux x were used. 52 V, two tape electrodes with a cross section of 50.0 x 0.5 mm, the angle of rise of the samples was about 14-18 °, welding current 1sv 840-880 A, the electrode feed speed VnoA 46-48 m / h. Slag bath voltage 32-34 V, welding speed VCB 16.8-19.2 m / h, flux AN-60, length of the weld pool LB - 80-88 mm.

The proposed ESW method allows to improve the quality of the welded joint by adjusting the depth of penetration of the welded edges in height. In addition, the shape of the split strip electrode ensures the concentration of the arc process in the front of the weld pool, which ensures high-quality penetration in the root of the weld.

The use of a split ribbon electrode intensifies the electroslag process, which leads to an increase in the melting performance of the electrode metal.

Claims (3)

1. A method of electroslag tape welding, in which the tape electrode is molten in a slag bath. profiled in the process of its bedding, giving its head zone a rounded shape, and changing the current distribution over the electrode cross section by tilting the article to be welded by an angle of 8-50 ° to the horizontal plane and conducting the process in an electroslag-arc mode, characterized in that, in order to increase process productivity and improving the quality of the welded joint by adjusting the depth of penetration along the height of the welded edges and improving weld root penetration, welding is carried out by a split electrode, in which two profiles ated part of a controlled distance therebetween and in parallel to each other and welded edges in their middle region, wherein the radius R, on which profiled portion of the electrode in the head area is determined by the following relationship J & 2 1 act L  R Lray - L, where 1 act is the size of the active spot of the arc across the width at the end of the electrode, mm; Lraz is the width of the gap (cutting), and the tail sections of the electrode during profiling open. 2. A method according to claim 1, characterized in that the profiled parts of the electrode are arranged in the head zone with rounded edges against each other. 3. The method according to claim 1, characterized in that the profiled parts of the electrode are arranged in the head zone with rounded overlapping edges. . & At J & Ј L 1K / ki 4 -44 about um 1L ID G- - ABOUT LZQJI L US $ LrM FIG. 9 figlo MA 11 Type A FIG. 12 Fig.13