The induction diathermy device is mainly used for the heating of metal thermoplastic processing (forging, extrusion, and rolling, etc.) and the overall heat treatment of various profiles. Their design and production are basically the same, but they have their own characteristics only because of different materials and physical parameters and different heating process requirements.
Due to the different process requirements, forging induction furnace (diathermy furnace) also has a variety of forms, and most are non-standard customized products. The heating proportion of solid cylindrical charge, especially steel, is the largest, so the examples are the focus of the discussion.
(1) In terms of heating mode, it can be divided into three types: periodic, sequential, and continuous:
Periodic formula. Place one charge at a time in the furnace. After heating, place another cold charge.
Sequential. There are multiple charges in the furnace at the same time. When a new charge is sent to the inlet end, a hot charge that meets the temperature requirement is given at the outlet end, and heating is carried out in a certain beat sequence.
Continuous. The charge passes through the furnace at a constant speed to meet the heating requirements.
(2) According to the charge material, it can be divided into non-magnetic material heating and magnetic material heating:
1) Heating of non-magnetic materials, such as heating before extrusion of aluminum, heating before forging of copper and induction heating of steel after heating by fuel furnace to above Curie point, etc.
2) magnetic material heating, mainly for iron, nickel, cobalt-based alloy material, the temperature of the steel in the Curie point below the heating is common, such as the blue brittle blanking of steel, surface anti-oxidation treatment, induction annealing (low temperature) and tempering of materials and machine parts.
The whole heating process from magnetic to non-magnetic mainly refers to the heating of steel from normal temperature to forging temperature or quenching temperature, the low-temperature section heated by high-power furnace section and the low-temperature section heated by steel in the dual-frequency heating (the relatively low-frequency section below Curie point), etc.
3) From the shape of the charge can be divided into cylindrical, rectangular sections, hollow, plate, strip, profile, and other structures and shapes.
4) From the furnace structure can be divided into a vertical furnace and a horizontal furnace, the vertical furnace is mostly used for the heating of large heavy burden, generally for the cycle type.
5) It can be divided into high frequency, intermediate frequency, and power frequency heating from the power source. At present, intermediate frequency heating is in the majority. Due to the development of power supply, the frequency band is increased, in order to improve the rationality of heating, now the use of dual-frequency and three-frequency power heating began to be popularized.
6) The heating mode can be divided into conventional heating (equal turn coil) and rapid heating (variable turn coil).