Medium frequency induction heating furnace is a kind of medium frequency induction heating furnace, which can convert the power frequency of 50 Hz to medium frequency (300 Hz to 20 K) Hz) power supply device, three-phase power frequency AC, after rectification into DC, and then DC into adjustable intermediate frequency current, to supply the medium frequency alternating current flowing through the capacitor and induction coil, in the induction coil to produce high-density magnetic line of force, and cut the metal material contained in the induction coil, which will produce great eddy current in the metal material. This kind of eddy current also has some properties of intermediate frequency current, that is, the free electrons of metal itself flow in the metal body with resistance to generate heat. For example, if a metal cylinder is placed in an induction loop with alternating medium frequency current, the metal cylinder does not directly contact with the induction coil, and the temperature of the electrified coil itself is very low, but the surface of the cylinder is heated to be red or even melted. Moreover, the speed of reddening and melting can be realized by adjusting the frequency and the strength of the current. If the cylinder is placed in the center of the coil, the temperature around the cylinder is the same, and the heating and melting of the cylinder will not produce harmful gas and strong light pollution to the environment. Medium frequency electric furnace is widely used in the smelting of non-ferrous metals, mainly used in smelting ferrous materials such as steel, alloy steel, special steel, cast iron, stainless steel, zinc and other non-ferrous materials. It can also be used for smelting, heating and heat preservation of copper, aluminum and other non-ferrous metals, and can be operated in double connection with blast furnace. Forging heating is used for diathermy and temperature compensation of bar, round steel, square steel and steel plate, on-line heating and local heating of blue quenching blanking, on-line forging of metal materials (such as precision forging of gears, axle shaft connecting rods, bearings, etc.), heating before extrusion, hot rolling, shearing, spraying heating, hot assembly, as well as quenching and tempering, annealing and tempering of metal materials as a whole. Heat treatment is mainly used for surface heat treatment of shaft (straight shaft, reducer shaft, camshaft, crankshaft, gear shaft, etc.); gear class; sleeve, ring, disc type; machine tool lead screw; guide rail; plane; ball head; hardware tools and other mechanical (automobile, motorcycle) parts surface heat treatment and metal material whole body quenching and tempering, annealing, tempering, etc.