About Heating of Induction Furnace: Analysis of Main Flux and Leakage Flux

The melting furnace body of the circuit is mainly composed of induction coil, refractory material and magnetic yoke. The induction coil is wound from a hollow copper tube, and then the tube is cooled by water. The section of the copper pipe can be round or square, and the square is more efficient.

Inside the induction coil, a crucible made of refractory material is knotted. The metals to be smelted, such as various steels, are placed in the crucible, and then the electromagnetic induction heating principle is used. When the induction coil passes an intermediate frequency current, an intermediate frequency magnetic field is generated , in which most of the magnetic field passes through the steel and is called the main flux. However, there is still a part of the magnetic field that does not pass through the steel, which is called leakage flux.

Only the main magnetic flux can generate an induced potential in the steel, form an eddy current, and make the steel in the furnace heat up. The leakage magnetic flux forms a leakage current, which only reduces the voltage on the circuit, but cannot complete the heating.

The relative magnitude of the main flux and leakage flux will be affected by many factors, such as:

The thicker the crucible and the smaller the furnace, the more leakage flux and less the main flux. Therefore, the newly knotted crucible has more leakage flux. After several furnaces are smelted, the crucible becomes thinner and the leakage flux is reduced.

When the amount of steel in the furnace is relatively small, the main magnetic flux decreases and the leakage flux increases.

When the steel is melted into a liquid state, the molten steel fills the furnace, so that the magnetic flux entering the furnace all passes through the molten steel, so the main magnetic flux increases and the leakage flux decreases.

Different metal materials smelted will also affect the distribution of the magnetic field. When smelting copper and aluminum and other metals, due to the low resistivity, the penetration rate is larger than that of steel, and the eddy current loop induced in copper and aluminum has a small resistance, so the intermediate frequency main magnetic flux will be offset by the induced eddy current as soon as it enters the copper and aluminum. , resulting in a decrease in the main magnetic flux.

This is what we share today about the knowledge of the main magnetic flux and leakage magnetic flux in the smelting process of the induction furnace, I hope it can be helpful to you.

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Video of the use process of the furnace