SU1376277A1 - Travelling transverse field three-phase induction heater for heating sheet stock - Google Patents

Abstract

The invention relates to electrical engineering and is intended for use in the narrow-zone heating of sheet metal. The aim of the invention is to improve the uniformity of cozonal heating. The heater contains two groups of sections 1,2, between which a heated sheet 3 is placed. Each section is made in the form of a U-shaped magnetic circuit with a single-phase winding on its middle rod. When a voltage is applied to the windings, a transverse traveling field is created in the working gap, which heats the narrow zone in the sheet under the active windings of the windings. The current shift in the sections and their placement leads to the equalization of the total eddy current density and temperature distribution. 6 Il.

Description

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The invention relates to electro- and is intended for use in the narrow-zone heating of sheet metal, in particular when heating sheets before cutting.

The purpose of the invention is to improve the uniformity of narrow-zone heating.

FIG. 1 and 2 show the proposed induction heater; in fig. 3 is an electrical circuit for connecting sections of a heater to a three-phase power source; in fig. 4 - distribution of temperature in the heated zone; in fig. 5 and 6 are the vector diagram of currents in the windings of the sections and induction in the working gap.

The heater consists of two groups of sections 1 and 2, between which a gap is formed to accommodate the heated sheet 3. Each section contains a U-shaped magnetic circuit 4 and a single-phase winding 5 placed on its middle rod. The sections in the groups are installed in rows, with the ends of the magnetic circuits to each other so that the axial lines of the active parts of their windings are on the same straight line. The projections of the axial axial groups of sections onto the surface of the heated sheet coincide.,

 group of sections 2 contains tr sections with U-shaped rims installed on the opposite side of the working gap. The two sections 1 of the second group have a length shortened by cp neimib with sections 2 and are placed between these rmay in the zones of the joints of the sections of the first group. Their total active power is 10–15% of the total active power of the sections of the first group.

Winding. Sections of the first group under

are connected to a three-phase power source to a friend, with one group of sections

sh-w according to the star diagram (fig. 3) so that the currents are shifted in phase by 60, which reduces the resulting electrodynamic forces per sheet and reduces losses in the magnetic cores. The windings of the sections of the second group are connected to two phases of a three-phase source. In this case, the connection circuit provides currents in them compared to the currents of the sections of the first group by 30 °.

The induction heater works in the following way.

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The unit contains three sections designed to be connected to a power source by a voltage shift of 60 el. hail, and another group - two sections intended to be connected to the power supply by a shift of voltage by 30 al. with respect to the sections of the opposite group, which are shorter than their length, and installed in the areas of their joint, and between these sections are a frame for a three-section group.

When voltage is applied to the windings of sections, they create a transverse traveling magnetic field in the working gap that penetrates the heated sheet and induces eddy currents in it, heating a narrow zone 2g wide (Fig.2) under the active windings. Eddy density

The current in the places induced by the sections of the first group and in the zones of their junction is reduced, which in the absence of sections of the second group leads to dips in the temperature distribution along the heated zone (Fig. 4, curve 6). However, the presence of these sections and the current shift in them by 30 ° compared to the currents of the sections of the first group leads to equalization of the total eddy current densities in zones 2g and, accordingly, to equalize the temperature distribution (Fig. 4, curve 7). I

The presence of PM in the sections of the first group makes it possible to significantly reduce the scattering of the magnetic field and increase the e (|) heating efficiency.

Claims (1)

Invention Formula A three-phase, three-phase running transverse field heater for heating sheet material, containing two groups of groups arranged in a series of working widths in the form of windings equipped with magnetic conductors installed in a series of working gaps. in order to for uniformity of narrow-zone heating, the windings of the sections are made single-phase and placed on the middle rods of the U-shaped magnetic conductors installed by the ends of each 0 five The unit contains three sections designed to be connected to a power source with a cp voltage shift of 60 el. hail, and the other group - two sections, intended for connection to the power supply by the shift of the voltage by 30 degrees. with respect to the sections of the opposite group, which are shorter than their length, and installed in the zones of their joint, and between these sections are a frame for a three-section group. L n -T-Tl FIG. 2 If li II V) I-. II eleven  § 3-F S USA A Uc4 C about (fco Fi. H / L