The induction furnace whose power frequency is in the range of 150-10000 Hz is called intermediate frequency induction furnace, and its main frequency is in the range of 150-2500 Hz. The power frequencies of domestic small frequency induction furnace are 150, 1000 and 2500 Hz.
Medium frequency induction furnace is a special smelting equipment suitable for smelting high-quality steel and alloy. Compared with power frequency induction furnace, it has the following advantages:
1) Fast melting speed and high production efficiency. The power density of medium frequency induction furnace is high, and the power configuration per ton of molten steel is about 20-30% higher than that of power frequency induction furnace. Therefore, under the same conditions, the melting speed of medium frequency induction furnace is fast and the production efficiency is high.
2) Strong adaptability and flexible use. The liquid steel of each furnace of medium frequency induction furnace can be completely discharged, and it is convenient to change the steel grade; The liquid steel of each furnace of the power frequency induction furnace is not allowed to be discharged, and a part of the liquid steel must be reserved for the start-up of the next furnace. Therefore, it is inconvenient to change the steel grade, which is only applicable to the treatment and smelting of a single variety of steel.
3) The effect of electromagnetic stirring is good. Because the electromagnetic force borne by liquid steel is inversely proportional to the square root of power frequency, the stirring force of medium frequency power supply is smaller than that of power frequency power supply. For removing impurities in steel, uniform chemical composition and uniform temperature, the stirring effect of medium frequency power supply is better. The excessive stirring force of power frequency power supply increases the scouring force of molten steel on the furnace lining, which will not only reduce the refining effect, but also reduce the collapse life.
4) Easy to start and operate. Because the skin effect of medium frequency current is much greater than that of power frequency current, there is no special requirement for furnace charge when starting the medium frequency induction furnace, and it can be heated quickly after charging; The power frequency induction furnace requires specially made furnace opening blocks (cast steel or cast iron blocks similar to the collapse increasing size and about half of the collapse increasing height) to start heating, and the heating speed is very slow. Read this, medium frequency induction furnace is mostly used under the condition of periodic operation. Another advantage of convenient starting is that power can be saved during periodic operation.
Due to the above advantages, medium frequency induction furnace has been widely used not only in the production of steel and alloy, but also in the production of cast iron, especially in the periodic casting workshop.