ELECTRO-RESISTANCE FURNACE
part III

    CONSTRUCTION
    The construction of the furnace is a welded unit in the shape of a cylinder built up of shaped and sheet steel. The heating chamber is built up with interlocked bricks which accommodate the heating coils. The furnace is heal-insulated with heat-resistant ceramic tiles and asbestos sheets. A crucible made of cast-iron is fitted into the furnace. A breakdown opening on the bottom of the furnace allows for the melted metal to flow out into a breakdown pit in case of damage to the crucible. A cover lilted to the upper part of the furnace seals the opening of the crucible. It is hand-operated by a special mechanism which lifts the cover and turns it round the vertical axis. A safety block terminal is welded to the jacket of the furnace. The heaters are connected to the block terminal. The temperature in the heating chamber is regulated by a thermocouple and a thermoregulator. The switching equipment is fined to the electric panel.

    INSTALLATION AND OPERATION
1. The user installs the furnace in a special concrete pit in compliance with the operating instructions.
2. The equipment should be grounded.
3. The furnace is dried up and put into operation in accordance with the operating instructions.
4. The following operating precautions should be taken:
- the furnace should not be heated to temperatures exceeding the indicated working temperature;
- the good working order of the automatic heat regulation equipment should be checked periodically; the connections between the heating elements as well as the power supply connections should be examined regularly for possible loosening up;
- the friction parts should be lubricated regularly with antifriction grease.
The normal, trouble-free operation of the equipment is guaranteed under the following operation conditions:
- ambient temperature +5^oC - +45^oC
- humidity up to 80%
- altitude up to 1000 mm.

    CONSTRUCTION
    The frame of the pit furnace is built up of shaped and sheet steel. The pit-like heating chamber is built tip with interlocked bricks. The electric heaters made from high-quality resistance conductor are installed over the whole area of the pit. The container fits closely inside the furnace. It is mounted on a stand specially prepared for the purpose and is built up of fire-proof steel. Special baskets of fire-proof steel are fitted into the container. Their size and number vary depending on the furnace capacity as well as the size of the parts to be heat-treated. A heat-insulated closely fitting cover seals the top of the container. The heating chamber, is sealed hermetically by tightening the boilts in the container cover. A ventilator on the inner side of the cover ensures the optimal blending of the gas mixture. The cover is raised or removed by means of an electro-mechanical device. Petrol, oil or other fuels can be used as carbonizes. The hardening gases are liberated inside the heating chamber. A thermocouple and a thermoregulator control the temperature. The furnace is fitted out with an electric panel where the switching equipment is installed.

    INSTALLATION AND OPERATION
1. The user installs the pit furnace in compliance with the operating instructions. The pit should allow for natural air ventilation so that the cooling off of the heat-treated parts could be effected.
2. The equipment should be grounded.
3. The furnace should be dried up in accordance with the operating instructions.
4. The following operating precautions should be taken:
- the furnace should not be heated to temperatures exceeding the indicated working temperature;
- the right dosage of the carbonize should be observed;
- the good working order of the automatic heat regulation equipment should be checked periodically; the connections between the heating elements should be examined regularly for possible loosening;
- the friction parts should be lubricated systematically with: antifriction grease.

Mono-Dimensional and Two-Dimensional Model
Measurement Devices
Three-Dimensional Model Of System Furnace-Heated Body
Energy Analysis Of ERF
Process Of Melting
Cooling Of The Bodies
Regulation Of The Process Of Heating
Regulation Of The Temperature
Model Of Regulation By Assigning Hysteresis
A Model Of PID Regulation
A Model Of PID Program Regulator
A Distribution Of The Installed Capacity In ERF

    CONSTRUCTION
    The pit furnace has a welded construction of shaped and sheet steel. The heating chamber is in the shape of a pit built up of interlocked bricks and insulated with heat-resistant ceramic tiles and asbestos sheet. The electric coil heaters made of electric resistance conductor are installed uniformly over the whole area of the pit. The temperature is regulated by thermocouples and thermoregulators. On raising the cover, the power supply to the electric heaters is cut off automatically.

    INSTALLATION AND OPERATION
1. The pit furnace is delivered in a finished state and complexly built up. In accordance with the operating instructions, the furnace should be fitted in a pit with natural air ventilation to effect the cooling off process.
2. The furnace is to be dried up before initial use in compliance with the operating instructions.
3. The following operating precautions are to be taken:
- The furnace should not be heated to temperatures exceeding the indicated working temperature;
- The good working order of the thermoregu-laior, the hoisting mechanism and the connections should be checked regularly;
- The friction parts should be lubricated with antifriction grease periodically.
- The normal, trouble-free operation of the equipment is guaranteed under the following conditions:
- ambient temperature: +5^oC +45^oC
- humidity: up to 80%
- altitude: up to 1000 mm

    CONSTRUCTION
    The furnace is fitted into a conveniently deep pit so that the upper end of the furnace should not exceed a measurement of 800 mm from the floor of the work place. The frame of the furnace is a cylinder built up of sheet and shaped steel. The heating chamber, shaped into a pit, is built up with interlocked bricks, and on these the heaters are installed. The furnace has a thermal insulation of heat-resistant ceramic tiles and asbestos sheets. A shield with the necessary facilities for arranging the parts to be heat-treated is fitted in the heating chamber. A ventilator fixed to the back end of the furnace secures the uniform diffusion of temperature in the heating chamber. A hand-operated heat-msulated cover closes the fufnace from the top. An automatic interlocking device switches off the heaters and the ventilator on removing the cover. The temperature is regulated automatically by means of a thermocouple and a heat regulator.

    INSTALLATION AND OPERATION
1. The user installs, connects and dries up the equipment in compliance with the operating instructions.
2. The equipment is to be grounded.
3. The following operation precautions are to be taken:
- The furnace should not be heated to temperatures exceeding the indicated working temperature;
- The good working order of the equipment as well as the connections of the healing elements and the power supply system should be examined regularly;
- The friction parts should be lubricated with antifriction grease periodically.
- The normal, trouble-free operation of the equipment is guaranteed at an ambient temperature within the range of +5^oC +45^oC, 80% relative humidity and an altitude of up 1000 mm.
- The control and regulation equipment should not be exposed to changeable atmospheric conditions or be subject to shock or mishandling.

    CONSTRUCTION
    The furnace is a welded construction of sheet and shaped steal. The heating chamber, shaped into a pit, is built up with interlocked bricks and is insulated with heat-resistance ceramic tiles and asbestos sheets. The electric heaters, fitted uniformly over the whole area of the pit, are coils of high quality resistance conductor. A block terminal is fixed to the furnace shield. The current carrying bars to the heating coil leads are fitted in the block terminal. Two thermal couples - current-carring (I, II) for the temperature regulation in each zone are fixed to the left of the terminal box. There are two heating zones in the pit furnace. A round cover seals off the top of the furnace. The cover and the container are lifted by means of special lift gear and a crane. The container is packed tightly to the heating chamber by means of a sand block, while an asbestos and rubber gasket seals off the cover of the container. The furnace is fitted out with a panel where the switching equipment is installed.

    INSTALLATION AND OPERATION
1. The pit furnace is delivered completely fitted out and built up. In accordance with the instructions the furnace should be fitted in a pit where the natural air flow for the cooling off process is ensured.
2. The furnace is dried in acompliance with the instructions. The drying up of the furnace in accordance with the given instructions guarantees its normal exploitation.
3. The normal, trouble-free operation of the furnace requires that:
- the furnace should not be operated at temperatures exceeding the indicated working temperature;
- the good working order of the equipment as well as the lift gear and the light-fitting connections should be checked regularly for possible loosening;
- the friction parts should be lubricated with antifriction grease periodically;
- the connections in the water-cooling equipment as well as the protection equipment should be checked regularly for possible loosening;
- the exploitation instructions as indicated in the operating guide should be observed strictly when protection gas is used.