Induction furnace is the use of material induction electric heating effect and make the material heating or melting of the electric furnace. The basic part of the induction furnace is the induction loop wound with copper tube. Induction loop on both ends of the AC voltage, generating alternating electromagnetic field, conductive materials placed in the induction loop, due to electromagnetic induction in the material to produce eddy currents, by the role of resistance and electrical energy into heat to heat the material; therefore, can also be considered as induction heating is a direct heating type of resistance heating.
Induction heating is characterized by the transformation of the heated material in the electric power (current distribution) is very uneven, the surface of the largest, the center of the smallest, known as the skin effect. In order to improve the thermal efficiency of induction heating, the power supply frequency should be appropriate, small melting furnace or surface heating of materials using high-frequency electricity, large melting furnace or deep penetration of the material heating using intermediate-frequency or industrial-frequency electricity. Induction loop is a fairly large inductance load, its power factor is generally very low. In order to improve the power factor, the induction loop is generally connected in parallel with medium-frequency or high-frequency capacitors, known as resonant capacitance. The gap between the induction loop and the material should be small, the induction loop should be made of square copper tube, the tube is cooled by water, the gap between the turns of the induction loop should be as small as possible, and the insulation should be good. Induction heating device, mainly used for heating and melting casting of steel, copper, aluminum and zinc, etc., fast heating, less burnout, high degree of mechanization and automation, suitable for configuration in the automatic operating line.
Induction furnace series heating furnace features:
(1) Fast heating speed, high production efficiency, less oxidization and decarburization, saving material and forging mold cost.
As the principle of medium frequency induction heating for electromagnetic induction, the heat generated in the workpiece itself, ordinary workers with medium frequency electric furnace can be forged after ten minutes of continuous work tasks, do not need to burn furnace professional workers in advance to burn and seal the furnace work. There is no need to worry about the waste phenomenon caused by power failure or equipment failure of the coal furnace has been heated billet. Because of the heating method of heating speed, so the oxidation is very little, each ton of forgings and burning coal furnace compared to save at least 20-50 kg of steel raw materials, the material utilization rate of up to 95%. Because of the heating mode heating uniformity, core surface temperature difference is very small, so in the forging also greatly increase the life of the forging die, the roughness of the surface of the forgings is less than 50um.
(2) Superior working environment, improve the labor environment of workers and the company's image, no pollution, low energy consumption.
Induction heating furnace and coal furnace, compared with the workers will not be subjected to the hot sun under the coal furnace baking and smoke, but also to meet the requirements of the environmental protection department of the indicators, and at the same time to establish the company's external image and the future development trend of the forging industry. Induction heating is the most energy-saving heating in the electric heating furnace from room temperature to 1100 ℃ tons of forgings consume less than 360 degrees.
(3) Heating uniformity, core surface temperature difference is very small, high precision temperature control.
Induction heating furnace has a small size, light weight, high efficiency, excellent thermal processing quality and favorable environment and other advantages are rapidly eliminating coal-fired furnaces, gas-fired furnaces, oil-fired furnaces and ordinary resistance furnace, is a new generation of metal heating equipment.
Industrial applications of induction melting furnace crucible furnace (coreless induction furnace) and melting ditch furnace (core induction furnace). The crucible is made of refractory material or steel, with a capacity from several kilograms to tens of tons. The melting is characterized by the crucible melt by the electric force, forcing the melting pool liquid surface raised, the melt from the center of the liquid surface flow to the surrounding area and cause the circulation flow. This phenomenon is called electric effect, can make the melt composition uniform, the disadvantage is that the slag is biased toward the periphery, poor coverage. Compared with the melting ditch furnace, crucible furnace operation flexibility, high melting temperature, but the power factor is low, high power consumption. Melting groove furnace inductor by the iron core, induction ring and melting groove furnace lining composition, the melting groove for one or two band ring ditch, which is full of melts and melting pool connected to the melt. In principle, the groove furnace can be regarded as the secondary only one turn coil and short-circuit core transformer. The induced current flows in the melt in the trench, which realizes the electro-thermal transformation.
In production, after each furnace metal melting is completed, the melt pool can not be emptied, otherwise it will be easy to dry out, and must retain a part of the melt as the next furnace starting melt. Melting ditch temperature is higher than the melt pool, but also to withstand the melt flow scouring, so the melting ditch furnace lining is easily damaged, in order to facilitate maintenance, the modern furnace inductor made of easy-to-replace fittings. Melting ditch furnace capacity from a few hundred kilograms to more than a hundred tons. Melting ditch furnace for industrial frequency electricity, due to the iron core made of silicon steel sheet for the magnetic flux path, electrical efficiency and power factor are very high. Melting furnace is mainly used for cast iron, copper, zinc, brass and other melting, but also as a mixing Shanghai, used to store and heat the melt.
