SU1173564A1 - Method of induction-resistance heating of edges of conductive plate - Google Patents

Abstract

METHOD OF ELECTRICAL CONTACT AND INDUCTION HEATING OF ELECTRIC POWER SHEET SHEET, at which conduction currents are passed through a multipoint contact block, simultaneously induced by current leads to the contacts of currents, spatially coincide with common conductive currents in the direction of perpendicular to the current, in the direction of the perpendicular to the current, in the direction of the contact heating, set the current leads with equal pitch parallel to each other and the sheet planes at a distance from it, determined by the formula, T (f (), h is the distance from the current lead to the sheet plane, m; d is the sheet thickness, m; Cf is the angle between the edges of the sheet edges, degrees, the axes of the extreme current leads with con (Set by the lateral boundaries of the heated zone of the sheet. currents in current leads and maintain the same current value IgB to current leads installed from side zone boundaries at distances greater than the thickness of the sheet, and the current value determined by the formula where 11 is the current in each current lead. BUT; k is the number of the current lead, counted (L from the center to the side boundary; b is the size of the heated zone along the sheet edge, m; a is the distance between the contacts and current leads along the edge of the sheet, in the current leads set from the side borders at a distance of less than the thickness of the sheet, and the current frequency is chosen according to the formula ki ft dsin where k is a coefficient equal to from 25 - to 30.

Description

The invention applies to the electrotermine and can be used to heat the surface areas of products from an electrically conductive sheet material, for example, to heat up the tempering surfaces of the flame-retardant edges.

The aim of the invention is to increase the heating uniformity,

.On. FIG. 1 shows a device that implements the proposed method; general form; in fig. 2 shows section A-A in FIG. one; in fig. 3 - product edge, cross section; in fig. 4 heated edge area; in fig. 5 - scan of the heat exchanger section.

A device for carrying out the proposed method contains paired point contacts 1, mounted on spring-loaded contact-holding materials. -, x 1 2, located in a line with equal pitch. The current to the contact holders 3 is supplied with the help of the current leads 3 and cables. In this case, the current leads 3 can be connected to a common source of electricity (not shown) or each to an independent one.

The distance 4 between the current leads 3 and the surface 5 of the edge 6 is equal to h, the boundaries 12 of the heated zone 13 are defined by width 14. The heating zone 13 is divided into the following areas: medium-; SRI 14 and border 15, with a width of 16, equal to the thickness of sheet 11, which is indicated by d.

The distance 4 between the current leads 3 and the surface 5 of the edge 6 is chosen in accordance with the equality

If cf

h (He). (one)

where q) is the angle between the edges of edge 7

and 8; d - sheet thickness, m

Such a choice of the distance 4 makes it possible to adjust the ratio of the densities of the conduction currents to the induced currents 10 depending on the thickness 11 of the sheet product and the angle between the edges 7 and 8 of the edge 6 and to provide the required equal dimension of heating.

The number of unipolar point contacts 1, in order to avoid strip heating, is chosen in accordance with the ratio

p- | ...

In this case, the step size between the one polar contacts 1 is chosen in the range of 0.02-0.03 m, where b is the width of the zone, m; a - step between contacts, M.

The proposed method can be considered at the device,

The boundaries 12 of the zone 13 to be heated, parallel to the edges 6 of the sheet material, supply conduction currents 9 and simultaneously induce edges 6 in the zone 13 currents 10 spatially coinciding and in phase with conduction currents 9. The total density of currents across the width 14 of section 13, beyond With the exception of the border areas 15 of 16 width equal to the thickness of 11 sheet material, they are supported by the same way to supply point contacts 1 of one large current value of 1o. In order to compensate for heat losses in the border areas 15 (additional heat losses are through the lateral boundaries, 17 of the heated zone 13 of the edge 6) and heating of the border areas to a uniform heating temperature of the entire zone 13, the total density of conduction currents 9 and induced currents 10 within the border areas 15, change yut in the direction from the middle section to the lateral boundaries 17 of the heated-zone 13 by supplying a current to each opposite pair of contacts 1 in accordance with the formula

I, IO (H).

(2)

.. The value of the coefficient k is chosen equal to, 1,2,3, ..., which corresponds to the numbering of the point contacts 1 of the border sections 15 in the direction to the lateral boundaries 17 of the heated zone 13. In this case, the zero contact is the closest contact I to the border between middle and border area 15.

Such a distribution of conduction currents provides for an increase in the uniformity of heating of the entire zone 13 due to an increase in both section 15 and 16 of both the density of conduction currents 9 and the density of induced currents 10, which are more easily controlled and more sharply damped. The optimum frequency of the currents. The conductivities of the currents 9 and the induced currents 10 are chosen in accordance with the ratio f .. In this case, the value of the coefficient k is set to 25 - 30, More than the value of the coefficient k corresponds to a sheet material with a higher thermal diffusivity. When using higher frequency currents, they flow along the surface 5 of the edge 6 and, due to a difficult tap from the area 18 bounded by faces 7 and 8, edge 19 of the edge 6 overheats. When using currents of lower purity, the area 18 limited by faces 7 and 8 appears transparent to them and is not exposed to heat. In this case, the edge 19 of the edge 6 is underheated, i.e. When using currents with a frequency other than optimal, uniform heating of the edge 6 in height is not possible. . The location of the boundaries 12 of the heated zone 13 parallel to the edge of the product reduces the volume of the heated metal to a minimum and thereby increase the energy characteristics of the heating process. Example. Whether heating is used for tempering the edge of a product made by the method of flame cutting from. (steel sheet, 80 mm thick. Number of a pair of contacts O 1

700

H

Current

Zero number had a pair of contacts, located on the border of the middle and border areas.

The optimum frequency of the current was 3.9 kHz, however, due to the absence of the source of the indicated frequency, a source with a frequency of 2.4 kHz was used.

The temperature distribution along the edge during the heating process was determined with the help of chased thermocouples in the amount of 5 pieces, installed across the width of the section. As a result of heating

716.5 732.9 749.35 765.8

the edge zone during 615 s its temperature reached 580 s, while the heating irregularity was.

The use of the proposed heating method for tempering the fire-cut edges of products made from: sheet materials allows an increase. to reduce labor productivity in the implementation of heat treatment, to realize (energy saving, energy saving, due to exclusion in product samples, the so-called witnesses. The edge to be released was a dihedral angle of 90. Due to the lack of power required for simultaneous tempering the entire edge, tempering was carried out in areas 850 mm wide and 200 mm long. The device for contact and current induction had 43 pairs of opposite contacts located with a step of 20 mm. The drives to the contact holders of all contacts were made parallel to each other and located at a distance of 20–24 mm from the heated surface of the product edge.The system of point contacts of the device was located on the surface of the edge of the heated product so that there were 33 unipolar contacts in the middle zone, zones - 5 contacts each, while all contacts were located at a distance of 100 mm from the edge of the edge.The total value of the currents was determined with the help of Rogowski, dressed in TOKODES to the contacts. Regulating the voltage on each of the pairs of opposite contacts installed on opposite boundaries of the heated zone, the current through each pair of contacts in the middle section was maintained at A, and the current in each of the pairs of contacts in the border area was set in accordance with the formula (2.

15

IS

FIG L

t / 2

t

Yu

P

Claims (1)

METHOD OF ELECTRIC CONTACT INDUCTION HEATING ELECTRO- EDGE. WIRING SHEET, in which conduction currents are passed through a multi-point contact block, while simultaneously inducing currents spatially coinciding and in-phase with conduction currents in the direction perpendicular to the edges of the sheet using current leads to the contacts, characterized in that, in order to increase the uniformity of heating, they are installed current leads with equal steps parallel to each other and to the planes of the sheet at a distance from it, determined by the formula, za h = £ (1 + l ^'80 ), where h is the distance from the current supply to the sheet plane, m; d is the thickness of the sheet, m; Cf is the angle between the faces of the edges of the sheet, deg., And the axis of the extreme current leads with contacts set along the lateral boundaries of the heated zone of the sheet. Control currents in the current-supplying support and the same current value 1 ₀ to the current lead set from the lateral limits at distances zone larger sheet thickness, and the current value determined by the formula I _fc - current in each current lead, A; β to - current supply number, counting from the center to the lateral boundary; b - the size of the heated zone along the edge of the sheet, m; a - the distance between the contacts and current leads along the edge of the sheet, in current leads installed from the lateral borders at a distance less than the sheet thickness, and the current frequency is selected by the formula d’sinf ’; where k ^ is a coefficient equal to 25 to 30. SU.n, 11735G4 1173564.