SU1100756A1 - Three-phase induction heater for through heating of lengthy articles - Google Patents

Abstract

THREE-PHASE INDUCTOR FOR THROUGH-HEATING OF LONG-DIMENSIONAL PRODUCTS, containing at least three cylindrical sections installed along the same axis on a common base, the turns of which are made of a conductor with the same tube size along the axis of the inductor, so that in order to increase the uniformity of the movement of the products in the axial direction, each section is made of three sections, the extreme length of which is 0.50, 75 of the internal diameter of the turns of the middle section, and the internal diameter of the turns of the short sections by 10-15% less than the inner diameter of the turns of the middle section, while the step of winding the turns of the outer sections is 13-16% less than the step of cutting (L turns of the middle section.

Description

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The invention relates to induction heating and can be used predominantly by heating laminated (more than 2000 mm) blanks for plastic deformation, for example, for cutting long products with a shearing press.

Inductors are known for periodically heating workpieces with a constant winding step and a constant diameter, consisting of a conductor made in the form of a water-cooled coil from a copper tube molded into heat-resistant concrete, while the electrical contact and pressure and drain connections of the water are placed outside the lining. The length of the known inductors does not exceed 1400 mm 1.

The disadvantage of such inductors when using them for heating long pieces is the complexity of the lining technology and its low mechanical strength. This is aggravated by the fact that inductors, for example, to heat the rolled metal before cutting on a shear press must have a length of 7000 mm.

In addition, such inductors are inconvenient to use, as the violation of the integrity of one of the turns leads to the failure of the entire inductor.

The closest to the present invention is a three-phase inductor for continuous heating of long products, containing at least three cylindrical, fixed along one axis on a common base, sections, coils of which are made of a conductor with the same tube size along the inductor axis. The known inductor consists of 12 unified sections with a uniform step of winding the coils and a constant diameter of coils along the entire length of the sections, molded into heat-resistant concrete and assembled on a common basis so that the end parts of the lining of the sections are joined. At the same time, the distance between the extreme turns of the sections joining the sections considerably exceeds the gap between the turns of the section. Electrical contact and cooling system outlets are outside the lining. The inductor is provided with a common rail that is attached to the frame of the heater. The step of winding the coils is constant and equal to 1.2-1.3 widths of coil 2,

The inductor works as follows. The power supply is turned on. In this case, in each section of the inductor and the part of the workpiece placed in it, a flow of electromagnetic induction arises, the value of which is constant in the middle section of the section and decreases by 30-40% in

end parts x. The reduction in the size of the ion begins at a distance of 0.15-0.20 of the section length from the joined ends of the section. As a result, the temperature of the part of the workpiece located in the joint zone (strip width 50-80 mm) is lower than the specified one at 150180 ° C.

When using an inductor for heating long products, when the number of sections is equal to h, the number of joints of sections is equal to n -1. So, for example, when heating rods before cutting on press shears, 11 joints are contained in the inductor.

The presence of cold strips in the workpiece reduces tool durability when cutting with a press scissors and rolling on machines by 40-50%, and when forging with hammers and radial forging machines does not generally allow to obtain a forging of a given shape.

Thus, the disadvantage of the known inductor is the uneven heating along the length of the workpiece.

The purpose of the invention is to increase the uniformity of heating of long-length caps in the axial direction.

This goal is achieved by the fact that in a three-phase inductor for end-to-end heating of long products containing at least three cylindrical sections installed along the same axis on a common base, the turns of which are made of a conductor with the same tube size along the axis of the inductor, each section is made of three sections , the length of the outermost of which is 0.5-0.75 of the inner diameter of the turns of the middle section, and the inner diameter of the turns of the extreme sections is 10-15% less than the inner diameter of the turns of the middle section, while arg winding turns of edge portions by 13-16% smaller than the pitch of the middle portion .namotki turns.

FIG. 1 shows an inductor, a general view; in fig. 2 is a section A-A in FIG. 1} in FIG. 3 is a diagram of temperature distribution along the length of the workpiece in the joining sections.

The inductor consists of several (at least three) sections 1 mounted on a common base 2. On the base 2, a guide 3 is fixed, passing through the cavities 4 of all sections 1. Each of sections 1 contains an all-welded conductor coil 5 made of copper tube with a different step of winding the coils and different internal diameter of the coils. The ends of the helix 6 and 7 are made with an inner diameter of coils 8 10-15% less than the inner diameter 9 coil

middle section 10, c step 11 ENPMOT turns of concept plots b and 7 less than step 12 winding turns of middle section 8 by 13 - 16%. The conductive coil 5 is molded into heat-resistant concrete 13 and provided with electrocontact pads 14 and fittings 15 for connection to a cooling water system (not shown).

The inductor works as follows.

In the cavity 4 of the sections 1 of the inductor, a heated workpiece 16 is placed on the direction of the 3. Electrical contact pads 14 are connected to a source of alternating current (not shown), and the fittings are connected to the cooling water system. The power and water supply is turned on. In this case, in each section 1 of the inductor and part of the workpiece 16 placed in it, a flux of magnetic induction arises that creates heating of the workpiece 16. As can be seen from the distribution diagram of temperature T ° C along the length of the workpiece 6-5 (Fig. 3) in the initial stage of heating 0.3 - 0.4 of the established total heating time, the temperature 17 of the part of the workpiece 16 located under the middle section 10 of section 1 increases evenly and equally throughout the length of section 10 and reaches, for example, 760 ° С, and the temperature 18 parts billet 16, located under the end. FLL ul J. ° J J °

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vyy plotsyksyu fi 1 7, pp ;.hp-lt its 90 -, i.e. by 10-1ch, thanks to the tension of the fiarHHTHOfo tension per unit length, and by reducing the step 11 of winding BITKOV and increasing the coefficient

beneficial effect, by reducing the diameter of 9 turns. At the same time, the temperature of 19 parts of the workpiece 16, located under the joint of two neighboring sections 1, i.e. outside the coil end sections 6 and 7, below the temperature of the part of the workpiece 16, which is located below the middle section 8 of section 1, is between 150 and 180 ° C.

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Upon expiration of the initial heating stage and until the end of the set heating time, the temperatures of the underheated and overheated parts of the workpiece 16, due to the action of the heat conduction mechanism, are equalized and

0 reach an average of a given value of 20, approximately.

The use of the proposed inductor will reduce energy consumption when heating blanks under

5 plastic deformation and cutting, reduce the consumption of metal from carbon monoxide in the scale and decarburized layer, increase by 40 - 50% the durability of the deforming tool, namely:

0 knives, press shears, rolls of rolling machines and die tooling radial forging machines, reduce the complexity of heating operations.

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Claims (1)

THREE-PHASE INDUCTOR FOR THROUGH HEATING OF LONG-DIMENSIONAL PRODUCTS - LII containing at least three cylindrical sections mounted on the same axis on a common base, the turns of which are made of a conductor with the same tube size along the inductor axis, characterized in that, in order to increase the uniformity of heating of the products in the axial direction, each section is made of three sections, the length of the outermost of which is 0.50.75 of the inner diameter of the turns of the middle section, and the inner diameter of the turns of short sections is 10-15% less than the inner diameter of the turns of the middle section, while of the end sections <g forks is 13-16% less than the step of winding the turns of the middle section. Fig l eleven