RU1782197C - Method for welding by pulsating arc - Google Patents

Abstract

Usage: in the technology of arc welding. SUMMARY OF THE INVENTION: the method consists in supplying an arc with current pulses with a total duration of 4-20 µs and a frequency of 15-20 kHz. In this case, an arc is formed by synchronous ignition of two or more arcs from parallel electrodes located at the corners of an equilateral polygon. Due to the compression of the arc by its own magnetic field, the concentration of input of arc energy into the product increases, which leads to an increase in welding productivity and quality. 3 ill.

Description

The invention relates to the field of welding production, namely, arc welding technology, including the formation of a highly concentrated arc, like an electron or laser beam.

There is a known method of magnetically controlled arc welding, in which two DC arcs are ignited at the ends of two melting hand electrodes located parallel to each other with a minimum distance between themselves. Due to the action of the intrinsic magnetic field of two parallel DC arcs, an increased stability of the droplet transfer process and a decrease in the wandering spot of heating on the product are achieved (1).

The disadvantage of the prototype method (1) is the low degree of compression (mutual attraction) of two DC arcs.

The aim of the present invention is to increase the productivity of the arc welding process by increasing the relative penetration depth with increasing arc power density at the heating spot and weld quality by introducing ultrasonic vibrations into the weld pool.

The goal is achieved in that when welding with a pulsed arc, the arc is fed with current pulses with a total duration of 4-20 μs and a frequency of 15-20 kHz, while the arc is formed by synchronous ignition of two or more arcs from parallel electrodes located at the corners of an equilateral polygon.

The productivity of the arc welding process can be increased by a number of factors. For example, as the arc current increases, the penetration depth and the mass of the melt increase. An increase in the current density in the heating spot causes an increase in pressure and, as a consequence, an increase in the penetration depth. An increase in the voltage of the near-electrode regions due to a change in the composition of the shielding gas leads to an increase in arc power and, consequently, productivity. Short arc welding reduces wandering of active spots and

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with

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increases the depth of penetration. The introduction of ultrasound into the weld pool increases the fluidity of the melt, and thereby productivity. The current density in the heating spot can be increased by introducing dynamic modes of operation, i.e. arc supply by current pulses. As shown in the results of the study of spark discharge (2), the channel diameter, current density and voltage gradient are related to the time elapsed after the breakdown as follows:

Time after

gas sample (μs) 0.50 2.00 8.00 Channel diameter (cm) 0.11 0.19 0.29. Current density

(kA / cm) 29.00 7.80 2.40

Voltage gradient (V / cm) 125.00 60.00 30.00 Arc current 250 A changed by 1/2 in 10 μs

(2)

When igniting, for example, two high-frequency pulsed arcs located adjacent to each other and parallel to each other, they interact.

This interaction has an electromagnetic basis, i.e., due to two induced magnetic fields from the currents of both arcs.

The pressure that tends to bring these arcs closer to each other is determined by the formula:

Mjj

P.

8p 4p 4p

where P is the pressure, H is the magnetic field strength, I is the arc pulse current, J is the arc current density, x is the distance between the arcs From formula (1) it follows that the compression (pressure) is proportional to the square of the magnetic field strength, squared current, current density and inversely proportional to the square of the distance between the electrodes When the number of arcs is more than two, the effect of increasing the compression force is determined by the geometric addition of the acting forces. In general, the compression force with the number of electrodes is more than two is proportional to the number of electrodes.

The following distinctive features can be distinguished from a comparison of the proposed method with rtpfrro ™ nOM: the formation of a column4 of an arc from several (more than one) high-frequency pulsed parallel arcs, the arrangement of arcs in the corners of the equilateral of its polygon, the use of its own magnetic field of arcs to compress the common arc column, synchronized arc pulses of matching forward and reverse polarity total duration

4-20 μs, frequency 15-25 kHz, which meet the criterion of significant differences. Analogues with one of these signs are absent, therefore,

the above features satisfy the novelty criterion.

Some process flow diagrams of the method are shown in FIG. 1, 2, 3, where indicated. 1 - non-floating

electrodes, 2 - the total spot of heating on the product during the burning of several high-frequency pulse arcs, 3 - the spot of heating from the action of an electric arc of a constant current of equal power, 4 - melting

Electrode or laser beam

Technological circuits consist of electrodes 1, from which high-frequency synchronized pulsed arcs are ignited. When the intrinsic magnetic fields of each burning arc interact, the latter are attracted to each other and a spot of heating 1- forms on the product.

Depending on the number of arcs, the spot of heating varies in area and in shape.

the comparison in all the figures is shown in the form of a circle 3 spot of heating from a DC arc with equal power. When welding with a consumable electrode, there can be a flow chart of FIG. 1, when both

the melting electrode or with one melting electrode 4 located in the center between the electrodes. Similarly, technological schemes of combined laser-arc welding are implemented when

the laser is fed in the center and between the same as the melting electrode 4

An experimental verification of the method was carried out on a pilot installation consisting of 4 DC sources of the VDU-504 type and a block of 4 high-frequency transistor switches. The keys are each implemented on 30 transistors KT825. The keys gave pulses with a duration of 2 to 30 μs and a frequency of 5 to 30 kHz forward and reverse polarity. The output voltage was set at VDU-504 sources. As a burner, two, three, four tungsten were used

an electrode with a diameter of 3 mm installed around a ceramic tube with a diameter of b mm and fixed with ceramic gaskets. Argon was introduced into the tube. Studies have shown that the pressure created by a single pulsed arc at the hole at the anode with a diameter of 0.5 mm with a pulse duration of 5 μs, a frequency of 20 kHz, and an average current of 80 A is 600 Pascal m, which is six times more than from a constant arc current of 80 A, equal to 100 Pascals,

The experimentally obtained power densities in the heating spot reached 10 e W / cm, the pressure at the hole at the anode with a diameter of 0.5 mm with a pulse duration of direct polarity of 4 μs and 10 μs of reverse polarity with a frequency of 20 kHz and currents from each of the four electrodes 20 A was 4600 Pascals. The relative penetration depth based on AMG-b was 4-6. welding speed reached up to 120-200 m / h.

The effectiveness of the method is most pronounced when applying two-electrode technological schemes in manual process control, three-electrode in mechanized processes, and four- and

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more electrode circuits in robotic production.

Claims (1)

SUMMARY OF THE INVENTION A method for welding with a pulsed arc, in which the arc is supplied with current pulses with a total duration of 4-20 μs and a frequency of 15-20 kHz, characterized in that, in order to increase the productivity and quality of welding by increasing the concentration of input of arc energy into the product beyond due to compression of the arc by its own magnetic field, the arc is formed by synchronous ignition of two or more arcs from parallel electrodes located at the corners of an equilateral polygon. .5