SU811507A1 - Method of making flat electric heater - Google Patents

Description

The invention relates to electrothermia, in particular, to the technology of manufacturing wire electric heaters, mainly intended for operation at temperatures up to 700-750 ° C and pressures up to 5-10 MPa.

Methods are known for manufacturing a flat heater, including by applying a conductive film 1 to the plate of an electrically insulating material.

These methods are difficult to implement and do not ensure the operability of heaters at high temperatures (700-800 °) and high, periodically varying, pressures (5-10 MPa).

There is a known method of manufacturing a flat electric heater by laying a resistive element on an insulating base mounted on the bottom plate of a pressing device with fixing the resistive element with pins, laying a second insulating base on the plate, covered with adhesive, and removing the calipers at the same time as laying the second base and securing a resistive element at the base, for example, by curing the adhesive composition in a furnace or in air 2.

The disadvantages of the latter method are:

a) long-term drying of the heater in the furnace, under the press or in another device

for the purpose of curing the adhesive composition deposited on the insulating base, associated with the release of volatile substances, which complicates the technology of production, requires ventilation devices, contributes to the pollution of the environment;

b) punching the insulating base to fix the resistive element with pins complicates the process;

c) the use of the adhesive composition limits the use of heaters to an area of relatively low temperatures (130-150 ° C), since at higher

temperatures, the electrical and mechanical properties of the adhesive compositions deteriorate dramatically;

d) heaters manufactured according to the described method cannot operate with

the effects of high and periodically varying pressures, since in this case the insulating bases can be cut through by a resistive element, i.e. the specific pressure on it is much higher than the pressure per area of the heater;

e) this method is applicable only for one-sided laying of a resistive element on an insulating base.

The aim of the invention is to simplify the method of manufacturing flat heaters and increase the use of heaters with fiberglass base at elevated temperatures and pressures, as well as the possibility of both one-sided and two-sided laying of its resistive element.

This goal is achieved by fixing the resistive element by pressing it into the base body flush with its surface.

FIG. Figure 1 shows a section of an electric heater with one-sided laying of a resistive element in the manufacturing process prior to its pressing in; in fig. 2 - the same, after pressing; in fig. 3 - section of the heater with double-sided winding reznstivnogo element before pressing it; in fig. 4- the same, after pressing.

When one-sided laying of the resistive element 1 is placed on the pins 2, placed in the upper part of the lower plate 3 of the detachable pressing device. The pins 2 are spring-loaded springs 4, placed in the sockets 5.

On the pins 2, an insulating base 6 of micaceous layer is laid, and the wire is pressed flush with the surface of the base. By overlaying the plate 7 of the pressing device, the pins 2 are then inserted into the sockets 5 and do not prevent the pressing of the wire. After pressing in, the plates 3, 7 are opened, and the finished heater is removed, and the pins 2 exit through the openings of the upper part of the plate 3 under the action of the springs 4.

In case of double-sided laying, the resist element is wound around the insulating base and the wire 1 wound on it is placed between press plates without locking pins. The press plates are closed in order to press the resistive element into the base 6 flush with its surfaces. Next, the plate is opened, and the heater is removed from the press.

Heaters made in this way can be used to heat non-conductive (glass, ceramic, etc.) and electrically conductive objects. In the first case, the heater is pressed directly to the surfaces of the object. If the heating object is electrically conductive (metal plates, etc.), the heater is additionally isolated on the outer surface.

In the manufacture in the laboratory of a prototype heater by the proposed method, a flat spiral of 0.4 mm nichrome wire under pressure was flush pressed into a plate of mica layer 2 mm thick.

150 MPa. The heater included in the industrial grid operated for a long time under a cyclically varying pressure MPA at temperatures up to 200 ° C. 5 A heater was used to heat steel plates of size 600 X 600 mm. Other test heaters were used to heat steel plates to 700 ° C.

The pressed resistive element is protected from damage and, to a large extent, from oxidation. When heating, for example, non-conductive parts, no intermediate parts are required to reduce the heat transfer effect.

A device for carrying out the method is easy to manufacture, it is convenient to handle, the pins are sunk during pressing and are released onto the surface of the plate without any additional operations, which leads to high productivity.

Heaters manufactured according to the proposed method can be widely used in industry, for example, in the manufacture of various household appliances, heated plates, presses, and other heating devices.

The economic effect from the introduction of the proposal may be more than 0 5 million rubles. in year.

Claims (2)

Invention Formula A method of manufacturing a flat electric heater, in which the insulating base and the resistive element of the electric heater are placed on the bottom plate of the pressing device, fix the resistive element relative to the base 0 and secured it in deposition by overlaying an upper insulating plate of the pressing device, characterized in that, in order to simplify the manufacturing process and increase the performance of the work under increased, varying pressure and elevated temperatures of the micaceous base, the resistive element is fixed by pressing it flush with the surface 0 insulation base. Sources of information taken during the examination 1. Patent of Great Britain No. 1416591, cl. H 05B 3/10, 1975. 2. USSR author's certificate number 417923, cl. H 05B 3/28, 1973 (prototype). FIG. I Phage. 2 3 / s 7.X7v Fy