SU1103366A1 - Loop induction heater for local heating - Google Patents

Abstract

LOOP INDUCTOR FOR LOCAL HEATING, containing a multi-turn coil of turns with direct and return conductors, the direct conductors of which are covered by a U-shaped magnetic conductor, characterized in that, in order to reduce heating time and energy consumption during heat treatment of welds, the coils are different lengths, with the coils of greater length formed by the extreme coils, and the magnetic core is made of two parts, one part of which covers the conductors of all the coils, and the second, encompasses, and the conductors of the coils are large th length made of two L-shaped packages with an adjustable gap therebetween. Direct 8 / Genius Sights J / afff a B / ref ty ffjoffufe uft, / cpue.i

Description

The invention relates to electrical engineering and can be used for heat treatment of a weld immediately after welding.

In the production of thin-walled pipes, the main method of their manufacture is spiral-welded tape welding, and depending on the steel grade, heat treatment of the welded joint is necessary, for example, tempering, normalization.

For these purposes, local induction heating of the welded joint is used by loop inductors with U-shaped magnetic conductors operating at higher frequencies of alternating current, which is carried out by multipass release of circumferential welds by rotating the product near the stationary inductor 1.

Closest to the invention is a looped inductor for local heating, containing a multi-turn coil of turns with direct and return conductors, the straight conductors of which are covered by a U-shaped magnetic conductor 2.

However, having a constant specific target power over the entire length, a well-known inductor does not allow for an optimal thermal cycle of heat treatment, including the fastest possible reaching the set temperature and holding at this temperature, providing the minimum heat treatment time, energy costs, the length of the heat treatment zone.

The purpose of the invention is to reduce the heating time and energy costs during the heat treatment of welded welds,

The goal is achieved by the fact that in a looped inductor for local heating, containing a multi-turn coil of turns with direct and return conductors, the straight conductors of which are covered by a U-shaped magnetic conductor, the coils of the coil are made of different lengths, and the coils of greater length are formed by extreme turns, the magnetic circuit is made of two parts, one part of which covers the conductors of all turns, and the second, covering the conductors of turns of greater length, is made of two L-shaped packages with an adjustable gap ezhdu them.

This embodiment of the inductor allows, due to the greater number of turns of the coil of smaller length and with increased specific power supplied to the heated part, to accelerate heating of the weld to the tempering temperature, and due to the smaller number of turns of the coil of greater length having a lower specific power sufficient only for compensation of heat losses allows maintaining the tempering temperature at the same level until the heated part leaves the inductor.

FIG. 1 shows a looped inductor, a general view; in fig. 2 - section A-A along coils of shorter length; in fig. 3 - section BB on coils of greater length; FIG. 4 - coil winding circuit.

The proposed inductor consists of a loop loop 1 made of a copper tube and consisting of two coils of greater length 2 in series and coils of lesser length 3, aligned with one edge so that the elongated outer coils of the coil form a long window. The shorter coils cover the U-shaped magnetowire 4, and the longer coils are L-shaped packages 5. Sheet micanite is used for inter-turn insulation of the core from the magnetic core, followed by impregnation with epoxy compound and winding glass tape. To the protective housing 6 and to the textolite ends 7, the coil is attached with pins 8, and is protected from thermal radiation by thermal insulation 9, in which an opening 10 is made at the junction of the coils of the coil to sight the temperature sensor to the heating zone, to prevent the L-shaped magnetic circuit packets from closing when approaching between them, insulating strip II is selected in thickness. The temperature equalization under the coil with longer turns is achieved by changing the gap between the coil and the heated pipe 12. Screws 13 are provided for additional temperature equalization, allowing you to adjust the gap between the L-shaped magnetic cores, while slightly changing the width of the heating zone.

The operation of the device is as follows.

The metal pipe during welding with the help of a moving mechanism is pulled under the inductor. When passing under the turns 3, the product 12 is heated to a predetermined temperature, and under the turns 4 its temperature is maintained at the same level.

The uniformity of temperature under the coils 3 is ensured by preliminary regulation of the power released by the inductor due to a change in the width of the heating zone.

In comparison with the known ones, the proposed inductor allows to realize an optimal thermal heat treatment cycle, which provides the minimum heat treatment time, reduce power consumption by 10-ilS / o, and obtain an inductor length of less than half the pipe circumference. The latter is very significant for pipes of small diameter, since in the case of an inductor girth more than half the circumference of the pipe, the normal operation of the inductor is difficult.

Claims (1)

LOCAL HEATING INDUCTOR FOR LOCAL HEATING, containing a multi-turn coil of coils with direct and return conductors, the direct conductors of which are covered by a U-shaped magnetic circuit, characterized in that, in order to reduce heating time and energy costs during heat treatment of welds, the coil turns are made of various lengths moreover, the coils of greater length are formed by the extreme coils, and the magnetic circuit is made of two parts, one part of which covers the conductors of all coils, and the second, covering the conductors of coils of greater length , made of two L-shaped packages with an adjustable gap between them. o <e 9ί) δδΰΐΓ “’ ns line 1 0rs? And {e # ia mpyfib />