The method of electric arc welding

 

(57) Abstract:

The invention relates to a consumable electrode welding in shielding gases. In the interval of short circuit welding current does not increase, and leave minimal. After the formation of a reliable contact between the welding bath and a drop of molten metal on the end face of the electrode, when the process of transition to a drop in the weld pool becomes irreversible, miss metered pulse of current through the arc gap. This electrodynamic force accelerates the transition metal droplet to the weld pool, and the end of the current pulse is obviously before the end of the short circuit. The method can improve the weld quality. 1 Il.

The invention relates to welding, and the welding constant current short circuit arc gap.

The known method (see A. with. USSR N 1371821, B 23 K 9/09, 1987), which is a decrease of welding current before short circuit and break the bridge. After a short decrease of the welding current, the time gap jumper, it increases the delay is inversely proportional to the ratio of the magnitude of the energy released in the arc mycanae, moreover, the duration of the subsequent predetermined period of melting of the electrode will change in proportion to the duration of the delay of the beginning of the current increase after the break-up jumpers. This inclusion of welding current allows you to control the formation of seam welding in various positions, regardless of current in the welding process typical disturbances in the melting rate of the electrode.

However, a significant drawback of this method is the loss of control of the process on the interval of a short circuit, as during a short circuit transition drops is a natural way with an increase of the short circuit current exponentially. When the duration interval of a short circuit depends on the diameter of the droplets from the welding current before the short circuit, the length of the arc gap before the short circuit and from the alignment drop with the electrode, and is the amount is not constant. Therefore, the amplitude of the short circuit current and the energy stored in the inductor is equal to LI2/2, will not be constant, which leads to instability of the gas-dynamic effects on the weld pool at the time of rupture of the jumpers to the volatility of fluctuations in swell increases the variability of the frequency of short circuits, all this affects the quality of the welded connection.

Known invention (see and.with. USSR N 1310140, B 23 K 9/00, 1987), where arc welding with consumable electrode lead with a power source containing a smoothing choke. Before the short circuit produces a momentary decrease in the current. At the beginning of a short circuit of the smoothing choke off of the welding circuit through the bypass smoothing inductor resistance partitioned resistor. By the time gap jumper liquid metal again reduce the welding current. At the same time include a smoothing choke and a slice resistor respectively off.

The disadvantages of this method are the same as in the previous.

A prototype of the proposed patent is a method (see A. C. the USSR N 1168367, B 23 K 9/00, 1985) arc welding short circuit arc gap, which reduce the amount of welding current before short circuiting of the arc gap and the gap of the bridge, and the magnitude of the peak value of the short circuit current is chosen inversely proportional to the duration of the pause before short circuiting of the arc gap. However, the limitation is on the amplitude of the short circuit current, but only tighten the duration of the short circuit current that occurs in a natural way, so the prototype has all the drawbacks.

The aim of the invention is the stability of the process by reducing the duration of the short circuit, the guaranteed transition drops during short circuits, reducing splashing and increase productivity by reducing the duration of the short circuit.

This objective is achieved in that in the method of electric arc welding with forced short circuit provided by the reduction of the welding current before the short circuit, the current reduction in the interval of the gap jumpers and regulation of the amplitude of a current of short circuit, the welding current in the range of short circuit leave minimal to the end of the short circuit, but with a delay relative to the beginning of a short circuit predetermined current pulse. With the end of the pulse occurs before the moment of rupture of the bridge, and the dosage of energy to melt drops is carried out in function of time after disconnection of the arc gap.

The inventive method is characterized by the presence of the following smolnym before the end of the short circuit protection;

b) a time-delay relative to the beginning of a short circuit predetermined current pulse;

at the end of the pulse occurs before the moment of breaking jumper;

d) the dosage of energy to melt drops is carried out in function of time after disconnection of the arc gap.

Research on the patent and scientific literature revealed a number of technical solutions for a similar purpose, however, the signs of "a, b, C, d" are missing. Therefore, the claimed method meets the criteria of protection of the invention of "novelty" and "inventive step".

The graph shows the timeline of welding current and voltage.

On the interval I under normal welding current corresponding to the feed speed of the welding wire, arc, and the amount of energy to melt droplets of a given size is dosed in time. After dosing energy welding current is sharply reduced to a value which ensures the stability of the arc, but in fact does not affect the melting of the electrode. This value of welding current, under the influence of the sum of three components: the movement of the electrode to the weld puddle, making a drop coaxially with elec the Vale paused, which is directly proportional to the pause before the short circuit, and serves a powerful, 5 - 10 times higher than the welding current, short current pulse 1 - 1.5 MS, which obviously ends before the end of the short circuit. Compared with the prototype and similar to the proposed method provides more stable process that improves the quality of welded joints and provides good weld formation in different spatial positions. Moreover, the amplitude of the pulse applied to the interval of a short circuit, is determined by the spatial position of the welding bath. At the moment of rupture jumpers include the welding current and the process repeats.

The method of electric arc welding with forced short circuit provided by the reduction of the welding current before the short circuit, the current is reduced to the interval of the gap jumpers and regulation of the amplitude of the current short circuits, characterized in that the welding current in the range of short circuit leave minimal to the end of the short circuit, but with a delay relative to the beginning of a short circuit predetermined current pulse and end pulse occurs before the moment is akania the arc gap.

 

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