Induction Furnace Principle - Induction Melting Furnace

The induction furnace is to convert the three-phase power frequency alternating current into direct current after rectification, and then convert the direct current into an adjustable current to supply the alternating current flowing through the capacitor and the induction coil. Thus, high-density magnetic force lines are generated in the induction coil, and the metal material contained in the induction coil is cut, and a large eddy current is generated in the metal material.

There are three types of AC power used: 

Power frequency (50 Hz or 60 Hz), 

Intermediate frequency (60-10000 Hz)

High frequency (higher than 10000 Hz). 

The specific induction furnace principle is as follows

Power Frequency Induction Furnace

Industrial frequency furnaces are induction furnaces powered by industrial frequency current (50 or 60 Hz). The power frequency induction furnace has developed into a kind of smelting equipment with a wide range of uses.

It is mainly used as a melting furnace to smelt gray cast iron, malleable cast iron, ductile iron and alloy cast iron. In addition, it is also used as a holding furnace.

Power frequency induction furnace principle

The working principle of the power frequency induction furnace is the specific application of the law of electromagnetic induction, that is, when an alternating power supply is applied to the induction coil, an alternating magnetic flux is generated, and this magnetic flux links the metal charge in the crucible, thus causing induction in the charge. electromotive force.

Since the charge system conductor is in a closed loop, a strong induced current is generated under the action of the electromotive force; and due to the current surface effect, the strong current flows only along the surface of the charge, generating a large amount of Joule heat, which heats the charge to the point of melt.

Medium Frequency Induction Furnace

Intermediate frequency induction furnace is metal induction heating equipment, which is widely used in metal thermal processing in various industries, such as pre-forging heating, casting heating, metal quenching and tempering heating, hot stamping heating, hot extrusion heating, etc.

Medium frequency induction furnace principle

The intermediate frequency induction furnace puts the metal workpiece into the inductor coil of the intermediate frequency induction furnace, and generates a variable frequency current through the intermediate frequency induction power supply cabinet and sends it to the induction coil. 

This variable frequency current with a certain frequency is in the spiral copper tube of the induction coil According to the right-hand rule of middle school physics, an induced current (eddy current) with the same frequency and opposite direction will be generated inside the metal workpiece. Due to the eddy current flow, according to Joule Lenz's law, the metal workpiece will generate a certain amount of heat. 

The heat value and the current are in a square relationship, and the -time is a linear relationship. This heat causes the metal workpiece to heat itself. This is the basic principle of medium frequency induction furnace heating.

High Frequency Induction Furnace

High-frequency induction is an advanced heating method, because the high-frequency power output is only available when the sample is burning, and the high-frequency induction will stop immediately after the combustion is completed. After the high-frequency furnace is started, there is no need for warm-up time, and the sample can be analyzed at any time. 

The high-frequency furnace has very excellent combustion performance, and the conversion rate of carbon and sulfur is higher than that of the tube furnace. The carbon can be considered as almost 100%, and the sulfur can reach more than 99% according to the relevant information.

High frequency induction furnace principle

Put the workpiece into the inductor, which is generally a hollow copper tube that inputs medium-frequency or high-frequency alternating current (1000-300000Hz or higher). An alternating magnetic field is generated to generate an induced current of the same frequency in the workpiece. 

The distribution of this induced current in the workpiece is uneven, strong on the surface, but weak inside, and close to 0 in the center, using this skin effect , can rapidly heat the surface of the workpiece, and the surface temperature rises to 800-1000°C in a few seconds, while the core temperature rises very little.

No matter what kind of induction melting furnace, EAF, SAF, LF, etc., Xi'an Hani Tech will provide suitable, professional, efficient and low energy consumption induction furnaces to every customer according to specific raw materials and melting requirements. If you have any questions or needs, please feel free to contact me for discussion.

E-mail: saleswn@hanrm.com / inquiry66@hanmetallurgy.com (Daisy Zhai)

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Xi'an Hani Tech Co., Ltd.