SU1743757A1 - Method of submerged arc welding - Google Patents

Abstract

Use: mechanical engineering, assembly and welding of metal structures. Essence: welding is carried out with a fusion electrode and an additional heated filler wire. The wire is fed in front of the electrode during welding at an angle of 45-55 ° & to the welded surface. The distance between the points of intersection of the axes of the electrode and the wire with the surface of the parts at the same time. A negative lead wire is connected to the product being welded behind the main electrode. An additional filler wire is fed at a rate of from 0.6 to 0.7 times the magnitude of the voltage of the filler wire. 1 ill., 1 tab.

Description

The invention relates to the field of fusion welding, relates to methods of mechanized arc welding under a layer of flux using additional heated filler wire and can be used in welding metal structures of various configurations.

The known method of two-arc mechanized submerged arc welding includes the supply of a main electrode and an additional filler wire to the weld pool, which is fed in front of the main electrode during welding and melted under the action of its own welding arc.

There is a known method of submerged arc welding, which includes the connection of the negative welding wire and the surface to be welded, and the melting of the main electrode and the additional heated filler wire, which is fed in front of it during the welding at an angle

Yo

55 to the welded surface with constant contact with it at a distance between the points of intersection of the axes of the electrode and the filler wire with the welded product, determined by the dependence

Vj

four

SA) VJ

Sya

where S is the distance between the points of intersection of the axes of the electrode and the additional heated filler wire with the welded surface, mm;

I - welding current, A;

U is the arc voltage. AT;

D is the diameter of the main electrode, mm;

V - welding speed, m / h;

d - diameter of additional heated filler wire, mm.

Possessing high productivity, this welding method does not ensure the quality of the welds due to the instability of the geometric dimensions of the weld beads, which leads to inconsistencies, slagging and undercuts. ,

The aim of the invention is to improve the quality of the welded joint while maintaining the productivity of the process.

To achieve this goal in the method of submerged arc welding, in which welding is carried out with a melting electrode with an additional heated filler wire, which is fed in front of the electrode during welding at an angle of 45-55 ° to the surface to be welded with constant contact with it between the points of intersection of the axes of the electrode and the filler wire with the surface of the product to be welded, which is determined by the dependence

d S Oh, V4d.

1 X

where S is the distance between the intersection points of the axes, mm;

I - welding current, A;

U is the arc voltage, V;

V - welding speed, m / h;

D is the diameter of the electrode, mm;

d is the diameter of the filler wire, mm,

and the negative welding wire is connected to the product to be welded, according to the proposal, the negative welding wire is connected to the product to be welded behind the main electrode, and the additional filler wire is fed with a speed of 0.6-0.7 heating voltage.

The connection point of the negative welding wire and the supply of additional filler wire with speed, according to the proposal, ensures the elimination of its destabilizing effect on the welding arc and molten metal bath by optimizing the melting of the additional filler wire.

It is known that under the influence of a magnetic field, the welding arc can move and change its shape.

If the negative welding wire is located behind the axis of intersection of the axis of the electrode with the surface to be welded, then the transverse magnetic field (see drawing) deflects the arc away from the additional wire, which eliminates the possibility of direct interaction of the arc with additional welding wire, if these conditions are met. case DL 5%. For the maximum permissible value of the relative change in the width of the roller per unit length, the adopted value is Db 5%, characteristic of single-arc mechanized submerged arc welding and determined by the formula

JM3KC

to

min

Esr

xyo%

where Lmax is the maximum width of the roller, mm;

Bmin-minimum width of the roller, mm; Lsr - average size of the roller, mm.

In this case, the distance from the connection point of the negative wire along the axis of the electrode can be arbitrary.

If the negative welding wire is located on the side of the additional

filler wire and closer (to the left) of the axis of intersection of the axis of the electrode with the surface to be welded, the transverse magnetic field deflects the arc in the direction of the additional wire. In this case, subject to

of the specified conditions, the arc directly interacts with the additional filler wire, and the relative change in the width of the roller is 5%.

To obtain a high-quality weld bead, it is necessary that the additional wire be heated to the pasty state in the head section of the molten bath without contact

while directly with the arc. With an additional heated wire feed rate of V 0.71) n cm / s (where UH is the heating voltage of the filler wire, B) the wire does not have time to reach the required temperature and melts not in the head of the weld pool, but in the arc zone. Electromagnetic interaction and convection currents in the weld pool increase and, consequently, D L 5%. As a result

with high productivity, weld defects such as slagging, non-fusion, and undercuts occur. At the feed rate, the welding performance due to V 0,6UH, cm / s, the welding performance drops due to the lower feed speed of the additional wire. Due to the increase in the contact time of the additional wire with the solid substrate, it does not melt until the weld pool.

The process becomes unstable and the relative change in the width of the roller increases, i.e. L 5%.

The proposed method is illustrated in the drawing, where 1 is the main electrode, 2 is an additional heated filler wire, 3 is the surface to be welded, 4 is the welding arc, 5 is the negative welding wire, 6 is the direction of welding.

The method is carried out as follows. The welding arc 4 is excited between the main electrode 1 and the surface to be welded 3. Additional heated filler wire 2 is fed at an angle of 45-55 ° to the product to be welded. Depending on the welding mode, the distance between the main and filler wires is set. Negative welding wire 5 is connected behind (to the right) the axis of intersection of the axis of the electrode with the surface to be welded. The welding is carried out in direction 6. The feed rate of the additional heated filler wire is set depending on the heating voltage. The additional wire, due to constant contact with the product being welded, is heated by the passing current and fed to the head of the molten bath.

The proposed method produced arc welding under flux of the FC-16 type with single pass rollers on low alloyed Cr-Ni-Mo-V steel. Low-alloyed Cr-NI-Mo wire with a diameter of 5 mm (main electrode) and a diameter of 2 mm (additional heated filler wire) were used as filler materials. The welding mode parameters were as follows: welding current I 600 A, arc voltage U 32 V, welding speed V 28 m / h, heating voltage UH 16 V, distance between the filler wires S 10.5 mm, additional feed angle filler wire.

The feed rate of the additional wire is determined as follows. When the heating voltage UH 16B, substituting in the formula we get: the minimum allowable feed rate

Umin 0,6kh 16 9,6 cm / s

maximum allowed feed rate

Umax 0.7 x 16 11.2 CM / S

Thus, the optimum feed rate of the additional heated filler wire with a heating voltage of UH 16B should be within 9, 2cM / c.

The table presents data characterizing the quality of welds and the performance of the process of the heated filler wire and the connection points of the negative welding wire. As a criterion for assessing the quality of welding, the value of the relative change in the width of the rollers D b was accepted, not exceeding 5%. As a criterion for the productivity of the process, the deposition coefficient was taken as It kg / h.

Thus, the use of the proposed method of submerged arc welding with additional heated

5, the filler wire, in comparison with the prototype, provides an increase in the quality of the welded joint by producing weld beads and consistently small deviations from geometrical sizes and eliminating defects such as non-fusion, undercuts, slag, while maintaining the productivity of the method.

Claims (1)

5 claims The method of submerged arc welding, in which welding is conducted with a melting electrode with an additional heated filler wire, which is supplied 0 in front of the electrode during welding at an angle of 45-55 ° to the surface to be welded with constant contact with it at a predetermined distance between the points of intersection of the axes of the electrode and the filler wire with the surface of the welded product, which is determined by the dependence oh 1 / i-u (i6 + P) WiFiTssiso.ix 2V X  G-irb + rT v2 v 4d where S is the distance between the intersection points of the axes, mm; I - welding current, A; U is the welding voltage, V; V - welding speed, m / h; d is the diameter of the filler wire; D is the diameter of the electrode, and the negative lead wire is connected to the product to be welded, which is characterized in that, in order to improve the quality of the welded joint, the lead wire is connected behind the main electrode, and the additional filler wire is fed at a speed equal to 0.6 to 0.7 current voltage of the filler wire. The characteristic of the built-up rollers