SU1171537A1 - Method of local heating of articles and device for effecting same - Google Patents

Abstract

1. The method of local heating of products, such as pipe weld ,. including continuous posler heating of the seam in the main and additional electromagnetic fields, characterized in that, in order to evenly heat the weld, an additional electromagnetic field is created by means of a looped inductor whose axis is oriented along the axis of the pipe seam, while the width of the flat inductor exceeds the width the heated zone is not more than 1.2-1.5 times. 2. A device for local heating of products, for example, a pipe weld, containing a flat inductor with inducing and reverse proo S pipes, distinguishing. its one That, in order to uniformly weld the welded weld rocket, it is equipped with a left inductor, the width of the loops of which is 0.5-1 of the width of the flat inductor. . 3. Device pop. 2, that is, so that, with the inductor efficiency increase circuit, a loop inductor is connected between the inductors and eaten by the reverse conductors of the inductor.

Description

11 The invention relates to induction heating and may be used in the local heating of the seam and heat affected zone of straight and spiral pipes, plates and similar products for heat treatment. The purpose of the invention is to ensure uniform heating of the weld pipe and increase the efficiency of the inductor. FIG. 1 shows an induction heater for local heating, a general view; in fig. 2 - the same, side view; in fig. 3 - inductor winding for local heating, general view; in fig. 4 - the same, side view; in fig. 5 - temperature curves. The heating of the section 1 of the seam 2 of the pipe 3 is carried out in series of inductors installed one after another. Inductor 4 (in this case, the inductor is of no fundamental importance, therefore, the inductor winding is shown) is installed opposite seam 2 and its axis is aligned with seam 2. The width in the inductor turns of the inductor is chosen in such a way as to produce a heating zone, the width of which It is specified from technological requirements, usually the width in the inductor is 1.2-1.5 times the width from the heating zone, depending on the gap between the inductor and the product. In the course of the movement of the pipe 3 and along the axis of the seam 2, there is an additional inductor 5, which has the form of a loop, the axis of which is aligned with the axis of the seam. The induction conductors 6 of the inductor 5 are located symmetrically with respect to the seam 2 on either side of it and are turned on opposite. The width d of the looped inductor 5 is chosen to be no more than the widths in the inductive conductors of the inductor 4, which produce the main heating, lies within (0.5-1) so that the heating band produced by the inductive conductors 6 of the looper inductor 5 falls on the border of section 1 local heating across its width. With the passage of the end 9 of the pipe 3 under the inductor 4, the induced current in the pipe body passes under the inductive conductors of the inductor 4, installed opposite the section 1 of the pipe 3 to be heated, intensively heats section 1 and closes with two branches on either side of the account 1, the end of the pipe 3 under the inductor 4 are symmetric 72 when heating the seams of spiral-seam pipes. When the conduit pipes heat up, the current induced by the inductive conductors of inductor 4 in section 1 of pipe 3, closed on either side of it by return-circuit currents on the axis of weld 2 does not reach the end, leaving this region underheated. With further movement of this region passes under the inductor 5. The current induced on the heating pipe section 1 by the inductor 5 repeats the shape of the inductor 5 and passes along the border of section 1 to the right on one side of the weld 2 and in the vicinity of the top of the inductor loop 5 seam 2 across the heating section 1 on the other side of section 1 and flows in the opposite direction of the SRI. With the passage of the end zone of the pipe under the inductor 5, the current in this zone flows across the seam 2 parallel to the end 9 and passes through the underheating area of section 1 by the inductor 4 and causes its preferential heating. Thus, with properly selected energy ratios between the inductors 4 and 5, the heating of the region 1 in the zone of the end 9 is equalized. The heating is equalized when the end face is located at any point along the length of the inductor 3, because in all these cases the current from one side of the heating section 1 passes to its other side. This transition always occurs through the underheating zone in the zone of the end face 9 of the pipe 3. When the spiral-seam pipes are heated, the heating at the end is sharply uneven. On the side of the obtuse angle formed by the seam with the end of the pipe, overheating is noted. From the side of the acute seam angle with the butt, underheating is noted. The branches of the reverse circuit at the end are asymmetrical. In this case, the heating leveling can also be achieved by passing a current across the seam using a loop inductor installed in the same row as the main heaters producing heat. At the same time as the heat grows, the local heating zone 1 at the end 9 uses a loop inductor to increase the heating efficiency. This is achieved by using a narrow inductor, i.e. inductor, the width of which does not exceed 1.2-1.5 width

from the zone of heating and heating the boundary in the zone with an additional current loop loop inductor 5.

When moving the pipe under the inductors 4 and 5, installed along the axis of the weld 2, each inductor produces heating, located below the zone. Inductor 4 heats the zone width c. (The characteristic temperature distribution at the end of heating by inductor 4 is given in Fig. 5, curve 7, where temperature values are plotted along the ordinate axis, and the distance across the width of the heated zone perpendicular to the seam 2 is plotted along the abscissa axis). In the center of the zone c along the axis of the weld 2, the temperature value is higher than at the boundaries of the zone — 10–15%, temperature T. The zone, heated with the specified temperature value, with further movement passes under the inductor 5, which produces heating of the areas located under the inductive conductors of the inductor 5. Due to the fact that the location of these sections is chosen in such a way that they are on the border of the area 1 local heating, the temperature rises at the boundary of section 1. As a result, the temperature is distributed over the width of section 1 more uniformly (curve 8 in Fig. 5). The temperature difference across the width of region 1 is 2-5%.

The proposed heating method can be carried out by inducers arranged one after the other, parts of which are flat inductors with inducting conductors located over the entire width of the heating section, others are loop type, mainly at the last stage of heating (such a variant of heating is shown in Fig. 1 and 2) . FIG. 3 and 4, an inductor is shown which, in order to simplify the construction, combines both of the described inductors. The inductor consists of two parts. Part 10 is a flat inductor for local heating, part 11 is a loop inductor. Loop inductor I 1 is connected in series to the gap between inductive 12 and reverse 13 conductors of flat inductor 10. Inductive conductors 14 and 15 of the loop inductor are oriented along inductive conductors 12 of flat inductor 10 and are located in the same area as inductive conductors of 12 inductor 10. If necessary loop inductor can be made on both sides of the flat inductor 1 €.

Pipe 3 o {) is ventilated so that its seam 2 is aligned with the axis of the inductors arranged one after the other and begins to move under them. A part of the inductors are flat inductors, the width of the inducing conductors of which is chosen in accordance with the width from the heating section 1 and greater than the width from the heating section (heat-affected zone) more than 1.2-1.5 times, some of the investors mainly in the last stages heating is loopback; a given section is heated by moving the pipe under flat inductors and additional heat is produced when moving the pipe under loop inductors. The heating leveling takes place both along the width of the section and along the ends of the product.

Example. The conductor of the conduit pipe with a diameter of 820 mm and a wall thickness of 12 mm is heated by two inductors installed coaxially one after the other. The first inductor is flat with a magnetic core with a diameter of 750 mm, the width of the groove of the magnetic circuit is 120 mm. The inductor is powered by an HRE-500 / 2.4 converter. The length of the inductor along the magnetic conductor is 800 mm, the number of turns is 5. The second inductor is loopback, its length is 800 mm, and the width is 80 mm. The inductor has two turns, one passes in one direction, the second in the opposite. Width of coils

on 20 mm. t

The loop inductor is powered through a step-down transformer with a transformation ratio of 5 from the HRO-50y / 2.4 converter. A 90 mm wide zone is heated at a pipe moving speed of 2 m / min up to 800-850 C. A temperature uniformity across the width of 90 mm zone is not worse than 5%, and when the end is heated, a small overheating (50 ° C) of the end face is observed within zones at a depth of 5-10 mm. Such overheating is permissible. Within the limits of a given zone in the region of the end, except for the described overheating, uniformity. temperatures not worse than 10%.

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Claims (3)

1. A method for local heating of products, for example, a pipe weld, including continuous but sequential heating of the weld in the main and additional electromagnetic fields, characterized in that, in order to uniformly heat the weld, an additional electromagnetic field is created by means of a loop inductor, the axis of which is oriented along the axis of the pipe seam, and the width of the flat inductor exceeds the width of the heated zone by no more than 1.2-1.5 times. 2. Device ⁴ for local heating of products, for example, a pipe weld containing a flat inductor with induction and return conductors, characterized in that, for the purpose of uniform heating of the weld, it is equipped with a loop inductor, the loop width of which is 0.5-1 the width of the flat inductor. 3. The device according to claim 2, with the fact that, in order to increase the efficiency of the inductor, a loop inductor is connected between the induction and return conductors of the flat inductor.