SU1281355A1 - Method of arc welding with non-consumable electrode - Google Patents

Abstract

The invention relates to the field of argon arc welding and can be used in the manufacture of straight conduit pipes. The method allows to increase the productivity and quality of welding. The pipes are welded by a cathode consisting of three tungsten rods, two of which are arranged symmetrically with respect to the symmetry axis of the support-welding rollers, and the end of the third rod is recessed relative to the total dullness of the other two rods by 1-1.5 mm. Argon is fed through an axial channel formed by tungsten rods, with an argon flow rate of 0.9-1 L / min with a rod diameter of 2.9 mm and an arc length of 1 mm. When using this method, it increases the spatial stability of the heating arc to a higher rate than the welding speed .. 3 Il. 9 (L

Description

The invention relates to arc-arc welding with a non-consumable electrode, preferably straight conduit pipes.

The aim of the invention is to increase the productivity and quality of welding.

FIG. 1 shows the scheme of implementation of the proposed method; in fig. 2 composite cathode; FIG. 3 is a section A-A in FIG. 2

The method consists in the following. . The heat required for preheating is obtained from two arcs symmetrical about the pipe axis. The arcs have self-contained active spots 1 located on the respective edges 2 of the tube blank 3 and are formed by axial separation by a stream of argon with a flow rate proportional to the length of the arc gap and the diameter of the rod. Cathode 4 consists of three sharpened tungsten rods, two of which (3) are arranged symmetrically with respect to the axis of symmetry of the support-welding rollers 6, and the end of the third rod 7 is recessed relative to the total dullness of the other two rods by 1-1.5 mm.

Before starting the welding, the electric arc 4 of the heating arc is placed in front of the convergence point 8 of the edges 2 at a distance L, characterized by a gap between the edges equal to 5 bar diameters. The non-melting electrode of the propellant arc 9 is located beyond the convergence point at a distance L 5-10 mm from her. Then, the billet 3 is set in motion with the welding speed, argon is fed through the axial channel of the cathode 4; excite the preheating and penetrating arcs and perform welding. The argon flow rate in the axial channel is determined from the ratio

k I, cd ;,

where Q; - argon flow rate, l / min;

. - the length of the arc intermediate,

 mm; .

 - bar diameter, mm; k is the empirical coefficient

equal to 0.3 l / min-mm; c is the empirical coefficient

equal to 83 10 l / min mm. The equation establishes the relationship of argon flow rate through an axial channel with an arc length and cross-sectional size of an axial channel, constructively

O

ABOUT

five

five

0

five

dependent on the diameter of the tungsten rod constituting the electrode assembly.

Experiments to study the effect of welding mode parameters (arc length 1 ", discharge current 1, gas flow through the axial channel of the electrode node Q, section of the channel) on the separation of the arc discharge were carried out at a facility equipped with a power source, a welding torch knot and massive copper water-cooled anode. The length of the arc gap is established and controlled with probes with an accuracy of 0.01 mm. The flow rate of argon (l / min) supplied to the axial channel of the cathode is established and monitored using a flow meter — a rotometer of the type RM and a calibration graph to it. The parameters of sharpening the working part of the electrode assembly: blunting diameter, 0.65; d p (- bar diameter) and the sharpening angle s 30 are kept constant in the measurement process; . The diameters of the tungsten rods constituting the electrode assembly are chosen to be 1.9; 2.9; 3.9 mm. The range of investigated technological lengths of the arc gap is 1-6 mm. The magnitude of the discharge current varies within 120-300 A. Each experiment is repeated at least three times. The criterion for estimating the separation of the arc discharge into arc components at given values of 1: fj ,, is the axial flow of argon to the anode surface, which is visually fixed at a 25-fold increase in the discharge zone.

The formula for calculating the gas flow rate: (argon) through the axial channel of the electrode assembly in the form of a regression equation is obtained by statistical processing on the computer of an array of experimental data.

The method allows precise dosing of the amount of argon through the axial channel, which ensures the separation of the heating arc into two components having independent active spots. At a flow rate less than (+ djip), an incomplete separation of the discharge occurs with the formation of a common anodic spot, leading to an unstable burning mode and defects in the welded joint. Gas consumption greater than (k-f + c d p) violates

the spatial stability of the arcs that form, impairs their protection, draws air into the atmosphere of arcs and leads to a defective melting edge.

The Z value for the above, range of arc lengths, currents and bar diameters is I-1.5 mm. It is determined experimentally, on the basis of excluding the formation of a third arc (1 mm) and the discontinuity of the flow of protective gas flowing from the axial channel (1.5 mm).

2.9 mm, the length of the heating arc is 1 mm., the minute flow rate of argon through the axial channel, defined by the formula, is 0.9-1 l / min.

The application of the proposed method for welding steel pipes in an electric arc welding machine can improve the performance and quality of welding, as well as eliminate the defective formation of a welded joint and increase the spatial stability of the heating arc at elevated welding speeds.

The invention will allow to increase

The gap between the edges of the pipe shutter-f5, the performance of the pipe-wrap, equal to 5 diameters of the rod machine at 40% with a good canal of distance L from the point of convergence of the edges, on which the preheating arc is placed, ensures the non-impact of the welded joint.

Claims (1)

Invention Formula The passage of the protective gas flow through the axial channel is chosen to be equal to the largest channel size. Distance l 5-10 mm from the point 20 The method of arc welding with a non-consumable electrode, predominantly right-hand tube pipes with preheating, an arc burning from the cathode, a coincidence of edges, on which 25 of the three rods forming the melting arc is formed, is a feed channel. axial flow, which is optimal from the point of view of ensuring that, in view of the quality of the weld formation (without comb-shaped pressing of the molten metal) and finding the welded section 30, the joint with reduced technological strength in the area of compressive Silius musculoskeletal welding rollers. EXAMPLE Industrial testing of 35 of the ratio is carried out when welding pipes of size 38 2,0 of steel. Welding mode: welding current of the heating arc 160-180 A, welding current of the main penetrating arc 450 A, speed To increase the productivity and quality of welding by dividing the arc into two components, symmetrical about the pipe axis, the working end of one of the rods is embedded with respect to the other two, and the flow rate of argon through the channel is determined, the outcome Q, k Е - s, - argon flow rate, l / min; welding speed 3.2 m / min, the size of the gap between the edges at the location of the heating arc 1.0 mm, the diameter of the rod in the electrode assembly where q. . . Ig is the arc length, mm; - bar diameter, mm; k is the empirical coefficient equal to 0.3 l / min mm; c is an empirical coefficient of 83 10 l / min-mm 40% pipe and machine tool productivity with ho welded joint. productivity of pipe welding machines by 40% with good quality Invention Formula 20 The method of arc welding with a non-consumable electrode is mainly pre-tube suture pipes with preheating, an arc burning from a cathode consisting of three rods forming a channel with feed of axial flow, due to the fact that - To increase the productivity and quality of welding by dividing the arc into two components, symmetrical about the pipe axis, the working end of one of the rods is embedded with respect to the other two, and the flow rate of argon through the channel is determined, the outcome ratios Q, k Е - s, - argon flow rate, l / min; Q. . . Ig is the arc length, mm; - bar diameter, mm; k is the empirical coefficient equal to 0.3 l / min mm; c is an empirical coefficient of 83 10 l / min-mm L "N 5f MJ , - (pu2.2 Redastor V. Ivanova Compiled by G. Tyutchenkova Tehred N.Glushchenko Proofreader. Cherni fPuz.f A-A four , fpu2.3