SU963757A1 - Method of automatic electric arc welding of butt joints - Google Patents

Description

U4) METHOD FOR AUTOMATIC ELECTRIC ARC WELDING OF JOINT CONNECTIONS

The invention relates to methods of automatic electric arc welding of metals of greater thickness and is intended primarily for use in automatic electric arc welding of joints with a slotted groove. A known method of automatic electric arc welding with transverse displacement of the electrode and a change in the magnitude of the welding current along sinusoid 1. This method performs automatic electric arc welding of horizontal and large joints with a large thickness, at which the electrode performs continuous transverse reciprocating bars of the bath between the edges to be welded. During the oscillation of the electrode wire, the welding current varies from maximum value to minimum. The maximum value of the welding current is reached at the moment when; The electrode approaches the lower edge of the joint to be welded, the minimum value - to the upper edge. The disadvantage of this method is the possibility of poor penetration and non-fusion at the upper edge of the joints due to a decrease in the magnitude of the welding current. A known method of automatic electric arc welding of thick butt joints with a V-shaped groove, in which the electrode wire is given a transverse reciprocating motion, the transverse motion speed of the electrode wire must be increased when it moves along the downward-sloped V-groove edge, and when transversely moving along the opposite edge (from bottom to top), the speed is reduced by C2. When arc welding butt joints in a narrow or slotted groove The electrode wire performs a transverse reciprocating motion between the parallel edges of the groove; therefore, failure to weld against the groove walls can occur when the velocity of the transverse displacement of the electrode wire changes. A known method of automatic electric arc welding, by which it is proposed to control the feed rate of the electrode wire and the welding current, depending on the parameters of the groove, the change of which is monitored by tracking t3.

The disadvantages of this method are the complexity of the design and adjustment of the tracking system during the welding process, as well as the need to adjust the tracking system for each pass. .

A method of automatic arc welding of butt joints, based on the principle of automatic control of the welding speed and (or) the wire feed speed, is known. The parameter for regulating the welding process is the width of the penetration zone, i.e. the width of the weld pool, the control of which is carried out by photocontrast or photocells. As the bath width increases, the welding speed and feed rate of the electrode wire increase, and vice versa. In addition, the positioning of the electrode wire relative to the groove 4 is automatically performed.

However, this method cannot be used for butt joints with narrow or slotted grooves, since during welding the width of the weld pool may be greater than the width of the grooves and the determination of its true dimensions is difficult. In addition, when welding butt joints using granulated filler material (GPM), the weld pool is in some cases located under the top layer of the GMP and constant control over the change in its width is difficult. As a result, a discrepancy arises between the true dimensions of the weld pool and the welding conditions, which leads to the appearance of such defects — a weld seam, such as non-fusion, lack of welding, i.e. lower quality of welded joints.

The aim of the invention is to improve the quality of the welded joint. This goal is achieved by the method of automatic arc welding with a melting electrode, including moving the electrode wire along the joint, adjusting the feed rate of the wire depending on the change in the width of the groove and shifting the electrode wire across the edge with increasing welding current at the edges, adjusting the feed rate the electrode wire is produced by changing the width of the cut-up to 25% of the nominal

dependencies

BtflB

p..p.nom..in

- feed rate of the electrode where Vn.n of the wire .m / h,

Vn number electrode wire feed rate at nominal cutting width m / h;

B - nominal width of cutting, mm i

DV - change the width of the groove: {+ I - increase, / - / decrease, and transverse displacements of the electrode wire are produced by increasing the width of the groove over 25%, maintaining the maximum electrode wire feed speed achieved, the oscillation amplitude being set at 5 dependent types

A (0.5 t 0.6; LV,

where A is the amplitude of the transverse displacement of the electrode wire, mm, and an increase in the welding current at the edges is made by 10-15%.

Changing the electrode wire feed rate when the cutting width changes to 25% of the nominal, maintaining the maximum electrode wire feed speed reached earlier when this limit is exceeded, while simultaneously changing the linear motion of the electrode wire to sinusoidal, the amplitude of which also depends on the cutting width, this welding current by 10-15% of its nominal value at the moment when the electrode wire is at a minimum distance from the groove walls allows dissolved establish satisfactory conditions to give rise to metallurgical weld processor forming and eliminate 0 defects such as incomplete and poor fusions, i.e. significantly improve the quality of the welded joint.

Increasing the feed rate of the electrode wire with an increase in the width of the groove up to 25% of the nominal one allows high-quality welding without changing the straight-line displacement and electrical parameters. welding arc.

0 When the proportionality factor is less than 0.5, to determine the amplitude of the sinusoidal displacement, the electrode wire does not reach the groove walls and therefore 5 inconsistencies are possible and uncoupling, and if the coefficient is greater than 0.6, there is a risk that the electrode wire with the slotted groove wall, t. e. danger of stopping the normal welding process.

When the electrode wire is at the minimum distance from. the walls of the slotted groove during its sinusoidal movement, an increase in the heat of the welded parts occurs and an increase in the welding current value of not less than 10%, which fully compensates for these heat losses. However, as the results of studies have shown, an increase in the welding current by more than 15% negatively affects the uniform penetration of the edges of the main metal and an increase in the proportion of the base metal in the weld metal, which affects the mechanical and strength characteristics of the welding joint.

FIG. Figure 1 shows a section of a welding joint when passing through a layer of pre-filled GMP; in fig. 2 shows a section of a welded joint when making the first passage after turning over a layer of PMG; in fig. 3 is a welded joint with the trajectory of movement of the electric wires of the wire, top view.

An example. Steel plates were welded with a length of 1 m, sl 60.mm in slotted groove of variable width from 10 to 18 mm. The welding was carried out with the A-1417 serial automat in CO2 atmosphere, at a constant current, reverse polarity, with an electrode wire of 4 mm in diameter. Chopped welding wire 2x2 mm in size was used as a GPM (grit). Nominal, the cutting width of the welded joint to regulate the feed rate of the electrode wire and the amplitude of its sinusoidal displacement was set to 12 mm. For this width of cut, the following welding parameters were set:

1. Welding speed

 30 m / h

ev

2. The nominal electrode wire feed speed is 160 m / h. 3. Nominal welding toklr- „750-780 A.

4. Conduction of the arc Hd 38-42 V.

5. The frequency of oscillation of the sinusoidal movement to 60 cycles / min.

Before making the first roller 1, the granular filler material 6 is pre-filled to a height of 25-30 mm in a slit groove formed by edges 2 and 3 of plates 4 and 5. In order to hold the PMG in the back of the joint, a support bar 7 is installed. During the first welding pass, the weld metal (i.e., feather 1) is formed by the welding of electrode wire 8, GPM 6 and edges 2 and 3 of the base metal, t . plates 4 and 5. After the crystallization of the first roller, a part of the previously filled grains is sintered on its reverse side. Thickness

The crumbled layer 9 is 3-5 mm. When performing the subsequent rollers 10 and 11, the grains 12 are pre-filled with a layer of 57 mm before each pass. After filling the slotted cutting on one side, the welding is performed on the layer of sintered crumbs 9. The slotted cutting, formed by colors 1 and 2 and 3 of parts 4 and 5, is conventionally divided into sections; 13 - 25 cm long with a width of cutting from B 10 mm to a nominal B 12 mm, 14 - length 37.5 cm with a width of cutting from B 12 mm to B, 1, 25 mm and 15- long

5 37.5 cm with a cutting width from Вg 15 mm to B 3 18 mm.

In the process of welding each pass section 13 with an increase in the width of the groove from 10 mm to B 12 mm

0 increase the feed rate of the electrode wire 8 from V V „.

-L | A, .e. from U „.„

 133 m / h doU „„ „, 160 m / h.

Movement of the electrode wire 8

5 is carried out in a straight line :: path 16 along the center of the groove.

In the process of welding each pass section 14 with an increase in the width of the cut from 12 mm to BQ 15 mm

0 / t. 25% / increase the feed rate of the electrode wire 8 from

m / h to its maximum

p.N.01L B-kAR

values of UE ,, „.„. „„ „in-.dv

eight

those. DOW.p.u 160

five

200 m / h The movement of the electrode wire about is carried out similarly to section 13 along the path 16.

By increasing the width of the groove

0 section 15 from 15 mm to 18 mm, the feed rate of the electrode wire 8 remains constant and equal to pnmax 200 m / h, and the movement of the electrode wire is given a sinusoidal character (along the trajectory 17) with an oscillation frequency of 60 cycles per minute and an amplitude varying according to the dependence of A (0.5 - 0.6) - dB, 9 .A About to

 (0.5 - 0.6) X 6 3.0 gp;

- 3.6 mm. At the same time, at the moment when the electrode wire 8 is located at a minimum distance from the walls of the groove 2 and 3, i.e. in position 8 and 8, increase the welding current from its rated value

5 750 750-780 A to D ce 840-870 A, i.e. by 10-15%.

The use of this method of automatic electric arc welding of butt joints with cutting of crook will allow during the welding process to adjust the feed rate of the electrode wire depending on the change in the width of the groove, keeping it straight linear movement, and the value

Claims (4)

five . the amplitudes of the sinusoidal movement, also depending on the change in the width of the groove and, in addition, increase the welding current by 10-15% when the electrode wire is at a minimum distance from the groove wall, which significantly improves the quality of the welded joints. Compared with the existing technology using the proposed method, the productivity of automatic electric arc welding is increased and 1.5–2 times, 25% of expensive equipment and busy workers are released. An approximate calculation showed that the use of the method in one enterprise as compared with the existing, automatic arc technology, welding of butt joints with groove, will give an economic effect in the order of 35 thousand rubles. in year. The invention of the method of automatic arc welding of butt joints with a fused electrode, including moving the electrode wire along the joint, regulating its feed rate depending on the change in the width of the groove and moving the electrode wire across the joint with an increase in the amount of welding current at the edges, characterized in that improving the quality of the welded joint; the adjustment of the wire feed rate is carried out with at Figure 1 cutting widths up to 25% of the nominal, depending on the Vn Vn .. “,, l |, where Vn.n is the feed rate of the electrode wire m / h 1 ppt. P. feed rate of the electrode wire at the nominal width of cutting, m / h; B — nominal width of cutting, mm; U B - change the width of the groove; (+ y - increase, (- decrease, mm, and transverse displacements of the electrode wire are made by increasing the width of the cut more than 25%, maintaining the maximum value of the electrode wire feed rate, and the oscillation amplitude is set according to A (.0.5 4 0.6) LV where A is the amplitude of the transverse displacement of the electrode wire, mm; and an increase in the welding current at the edges is made by 10-15%. Sources of information taken into account during the examination 1. Japan Patent No. 53-10936, class 12 B 112.4, 1979. 2. Japanese Patent No. 53-16767, 12 В 112.4, 1979. 3. The UK patent number 1506621, cl. 23 K 9/00, 1962. 4. The patent of Germany 1817042, cl. 49 5/00, 1968 (prototype). VV t1  / Z 15 n J