SU1808560A1 - Process of automatic electric arc welding - Google Patents

Description

The invention relates to automatic electric arc welding of metals and alloys with a consumable and non-consumable electrode by direct and alternating current. It can be used for surfacing with a consumable electrode in a protective gas environment or under a flux and non-consumable electrode in an inert gas environment.

The aim of the invention is to increase the stability and quality of welding with a consumable electrode.

This goal is achieved by the fact that in the automatic electric arc welding method, in which an additional filler electrode is used, it is preheated and fed to the tail of the weld pool, the filler electrode is heated from the power source of the welding arc, and the electric circuit is closed through the welding electrode, arc, liquid metal of the weld pool, filler electrode, power source, the distance from the place of entry of the filler electrode to the welding is set within 2 / 3L _B .x _B. >L> 10 mm, g de 1_ _c . _hv . the length of the tail of the weld pool.

Setting the distance from the insertion point of the filler wire to the axis of the welding wire is more than 2 / 3L _BXB . will lead to freezing of the filler electrode to the bottom of the weld pool, since the temperature of the bath from its head and tail

1808560 A1 parts is reduced, which violates the stability of the welding process.

Setting the distance from the point of entry of the filler wire to the axis of the welding wire less than 10 mm can lead to the formation of a welding arc between the filler and electrode wires, which violates the stability of the welding process,

The invention is illustrated in the drawing.

Electrode wire 1 (welding electrode) using a feed mechanism (a standard automatic machine or a semiautomatic device for arc welding with a consumable electrode) with a given feed rate (UE), providing a given (calculated) value of the welding current (1 _C in), welding arc 4 is lit between the electrode 1 and the product 5 from the power source 6 (direct or alternating current). Using the contactor 11, the pole of the power source 6 is connected to terminal 12 and the welding process begins as a normal welding process, that is, the arc 4 is excited between the product 5 and the electrode ^. When a weld pool 9 is formed of sufficient size (usually after 5-10 s) by the contactor 11, the pole of the source 6 is connected to terminal 13, that is, to the sliding current supply 10 and simultaneously supply filler wire 7 using a feed mechanism 8 (welding machine, or semiautomatic device for welding with a consumable electrode). The filler wire feed rate (Pack) ensure such that it corresponds to its melting rate with the excess heat of the liquid weld pool and the joule heat at the reach (h) when the welding current flows through it (1 sv-). The diameter of the filler wire is limited only by the possibility (technical characteristic) of the used machine, or semiautomatic device. In this case, it is necessary to use the feeding mechanisms of automatic machines (semi-automatic), which allow smoothly adjusting the wire feed speed.

The distance from the insertion point of the filler wire to the axis of the welding electrode 1 (L) is a parameter that allows you to adjust the performance of the process of melting the filler wire (Vn.n.), ceteris paribus (Ice.h, V _C b). The smaller the distance L, the faster the filler wire 7 melts (the higher the temperature of the molten metal of the weld pool). However, the distance Lne should be too small so that a welding arc between the electrodes 1 and 7 does not form. It has been experimentally established that the minimum distance L should be LminiS 10 mm (for methods of welding with a floating electrode at a welding current of 1 _CB > 300 A). The maximum distance L should not exceed 2/3 of the length of the tail of the bath (Lb.xb), that is, Lmax - 2 / 3Lb.xb. (established experimentally). If Lmax> 2 / 3Lb.xb-, then the electrode 7 may freeze to the bottom of the weld pool 9.

When carrying out the welding process, a non-consumable electrode is not used. wire feed mechanism 2. and electrode 1 is a non-consumable (tungsten) electrode.

Example. The welding process was performed by the method adopted as a prototype and the method according to the claimed technical solution. For comparison, the usual welding process was performed in the same modes, that is, without filler wire. During the welding process, for each option (mode), the productivity (g / s) of the melting of the electrode (welding) wire (Ga.n.) and filler wire (Gn.n.) was measured.

Welding was carried out with wire Sv08A (GOST 2246-70) with a diameter of 4 mm, filler wire of the same composition also had a diameter of 4 mm. We used an automatic gun type ADS-1002, equipped with an additional DC motor (and gear), which allowed filler wire to be fed into the weld pool area. Welding was performed on reverse polarity from a rectifier type VDU-1201. Welded (butt without cutting edges) plates of steel VMStZsp (GOST 380-75) with a thickness of 20 mm under the flux AN-348A (GOST 908-75).

In all experiments, the welding speed Vcb = 30 m / h and the arc voltage and _d = 32-34 V were kept unchanged.

The extension of the electrode wire in all experiments was kept unchanged N = 45 mm,

In one series of experiments, the value of the welding current was changed, keeping the value of the output of the filler wire constant h = 45 mm, in another series, the value of the departure of the filler wire was changed, keeping the value of the welding current constant.

In all experiments the input space filler wire was constant L ^{= =} 25 mm.

When implementing the method of welding along the protop, the VDU-1201 rectifier (optional) served as a power source.

The relative filler wire consumption was calculated

The increase in productivity of the welding process when using a filler wire compared to the welding process without a filler wire was calculated by the expression β = 1 + a

The experimental results shown in the table show that the coefficient β practically does not depend on the welding current.

The values of the coefficient β significantly depend on the extension of the filler wire h (see table). Therefore, by varying the offset h, the productivity of the welding process can be effectively controlled.

As one would expect, with the welding method according to the prototype, if the heating current is equal to the welding current with the welding method according to the claimed technical solution (with equal cores of the filler wire), the effect of increasing productivity (β) is almost the same (see table).

The maximum increase in productivity was β = 1.98 (with a reach of 120 mm), that is, 2 times. A further increase in productivity is limited by the fact that with an increase in h (over 120 mm) due to heating of the filler wire (its stiffness), the welding process may occur (the occurrence of an arc between the bathtub and filler wire).

Therefore, this method allows to increase the productivity of the welding process (as in the method adopted as a prototype), but significantly simplify the installation for welding (abandon the use of an additional power source for heating the filler wire), reduce the cost of production (welded structures).

This method is advisable to apply when welding butt joints of metal of large thickness, when the weld is being cut, and in other cases, when the weld is formed due to the molten electrode metal.

When welding according to the proposed method, it was noted that due to the presence of a conductor with current (filler wire) near the arc, the arc deviates to the side of the filler wire, which leads to a significant increase in the width of the seam.

Given this, as well as the above-mentioned increased productivity of melting of the electrode metal, the proposed method is also advisable to apply for electric arc surfacing.

Claims (2)

Claim A method of automatic arc welding, in which an additional filler electrode is used, it is preheated with a passing current and fed to the tail of the weld pool, and the electric circuit is closed through the weld electrode, arc, liquid metal of the weld pool, filler electrode, and a common power source, which is different the fact that, in order to increase the stability of the process and the quality of welding when welding with a consumable electrode, the distance from the point of entry of the filler electrode to the welding is set in ah 2/31 - L - 10 mm, where Lb.hv. “The length of the tail of the weld pool. Ί Example Welding method Welding mode Distance L, mm Coefficient β Notes niya 1 St. A n mm h mm 1 According to the prototype 500 45 45 25 1.42 Process is stable 2 750 45 45 25 1.51 and 3 and 1000 45 45 25 1.52 ♦ "·. 4 Proposed 500 45 45 25 1.59 n 5 750 455 45 25 1,60 If 6 1000 45 45 25 1,62 . 7 According to the prototype 500 45 25 25 1.38 _e lt_ 8 m 500 45 90 25 1.60 h 9 500 45 120 25 1.90 and 10 Proposed 500 45 25 25 1.49 eleven 500 45 90 25 1.71 12 *1 500 45 120 25 1.98 thirteen - - 500 45 ⁴⁵ 8 >  * Process violation 14 M 500 45 45 10 1.55 Process is stable fifteen 500 45 45 fifty 1.40 16 N 500 45 45 75 0-> Lb.xb) Process violation L S.xS.