SU1760660A1 - Arc heating method - Google Patents

Abstract

Use: for heating metals with electric arc. Creatures of the proposal: change the pulse frequency of a longitudinal pulsed magnetic field induced in the gap between the electrodes 2 by means of an electromagnet 1. This increases the intensity of the radiation flux from the area of the electric arc. 1 il.

Description

The invention relates to mechanical engineering technology and can be used for processes in which materials are heated by an electric arc controlled by a magnetic field.

The purpose of the invention is to increase the heating efficiency by reducing electrode erosion and loss.

A change in the intensity of radiation from an electric arc fed by an alternating current, when it is compressed by a longitudinal pulsed magnetic field with a variable pulse frequency, is produced by changing the wave impedance of the arc. A change in the wave resistance of an arc is achieved due to a change in the number of its contractions — discontinuities under the action of a pulsed longitudinal magnetic field. The synchronization of the arc supply voltage and the electromagnet supply voltage by matching the frequency of the current feeding the arc and the pulse frequency of the longitudinal magnetic field allows the tones of the natural frequencies of oscillations occurring in the arc to be synchronized. At the same time, the process of increasing the intensity of radiation from the arc region with increasing frequency of the longitudinal magnetic field acquires optimal characteristics in the case when the ratio of the frequency of the magnetic field to the frequency of the arc arc is a multiple of an integer.

The implementation of the method is possible with the installation, the scheme of which is shown in the drawing.

The device contains electromagnets 1, electrodes 2 are introduced into the central channels of the cores. The electric arc between electrodes 2 is excited by alternating current from source 3. The electrodes of coils 1 are powered by pulsed current from direct current source 4 through interrupter 5. Pulse frequency is set by sound generator frequency 6.

The temperature in the region adjacent to the interelectrode gap is measured using a thermocouple 7 connected to

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galvanometer 8. The power supply of the electric arc was carried out by an alternating current of 50 Hz frequency, voltage of 220 V, current strength was equal to 60 A and did not change during the experiment. The windings of electromagnets 1 are connected in series and fed with a constant pulse current of 30 A at a voltage of 40 V, the pulse frequency was set in the range of 30 ... 500 Hz by gradually changing the frequency in the direction of increase. As electrodes 2, carbon electrodes with a diameter of 9 mm were used. During the experiment, thermocouple 7 was located at distances of 7, 10, and 15 mm from the axis of the electrodes. After initiating the arc between the electrodes 2 by closing them and subsequent dilution, the arc is impacted by a pulsed magnetic field created by electromagnets 1. Due to the fact that electromagnets 1 are fed with a direct current in a pulsed mode, the magnetic field excited by them is pulsed . its direction along the axis of the electrodes 2 remains unchanged. Since in this case the arc is supplied with alternating current of industrial frequency, i.e. the magnetic field of the arc changes its direction to l: through the half-frequency of the current frequency, then when the electrodes of the electromagnets 2 and the arc coincide, the latter is compressed, and when the directions mismatch, the gap breaks, which leads to a change in the intensity of radiation fluxes from the electric arc region. In this case, the alternation of the intensity maxima is a multiple of half the frequency of the alternating current feeding the arc, i.e. 25 Hz. Since the number of compressions — arc discontinuities per unit time — increases with an increase in the pulse frequency of the magnetic field of electromagnets 1, the number of quanta in the radiation flux increases, which leads to an increase in the intensity of the radiative heat flux from the electric arc region. In this case, the alternation of maxima and minima of intensity turns out to be a multiple of half the frequency of the alternating current feeding the arc,

those. 25 Hz. Since the number of compressions — arc discontinuities per unit time — increases with an increase in the pulse frequency of the magnetic field of electromagnets 1, the number of quanta in the radiation flux increases, which leads to an increase in the intensity of the radiative heat flux from the electric arc region.

Thus, the application of this method allows in fairly wide

limits to vary the amount of energy in the radiation flux without changing the parameters of the arc, i.e. without changing the distance between the electrodes and the current in the arc. This leads in the first place to

significantly more rational use of energy costs, and in addition, simplifies the management of changes in the intensity of radiation flows,

Claims (1)

Invention Formula Electric arc heating method, in which an arc of alternating current is ignited between two electrodes and placed in an alternating longitudinal magnetic field, characterized in that, in order to increase heating efficiency by reducing electrode erosion and loss in them. A longitudinal magnetic field is pulsed with a pulse frequency multiple of the arc current frequency.