According to the frequency of the alternating current output by the equipment, the induction heating technology can be divided into five categories according to the working frequency: low frequency induction heating, medium frequency induction heating, ultra audio induction heating, high frequency induction heating and ultra-high frequency induction heating. Therefore, electromagnetic induction heating technology is mainly used to heat metal materials and graphite. Therefore, the workpiece will rapidly heat up in a very short time (mostly in seconds). If necessary, any metal material can reach the melting point and graphite can sublimate.
Comparison of electromagnetic induction heating characteristics:
1. The frequency of low-frequency induction heating mode is the lowest, and the frequency range is about power frequency (50Hz) to 1kHz. Most of the commonly used frequencies are power frequency. The relative heating depth is the deepest and the heating thickness is the largest, about 10-20mm;. It is mainly used for overall heating, annealing, tempering and surface quenching of large workpieces.
2. Frequency range of medium frequency induction heating mode: generally about 1kHz to 20kHz, and the typical value is about 8kHz. The heating depth and thickness are about 3-10mm. It is mainly used for heating, annealing, tempering, quenching, tempering and surface quenching of large workpieces, large diameter shafts, large diameter thick wall pipes, large modulus gears and other workpieces, as well as red stamping and forging of small diameter bars.
3. Frequency range of super audio induction heating mode: generally about 20kHz to 40KHz (because the audio frequency is 20Hz to 20kHz, it is called super audio). Heating depth and thickness, about 2-3mm. It is mainly used for deep heating, annealing, tempering and tempering of workpieces with medium diameter, heating, welding and hot assembly of thin-walled pipes with large diameter, quenching of medium gears, etc.
4. High frequency induction heating mode frequency range: generally about 40KHz to 200kHz, commonly 40KHz to 80kHz. Heating depth and thickness, about 1-2mm. It is mainly used for deep heating, red stamping, forging, annealing, tempering, quenching and tempering, surface quenching of small workpieces, heating, welding and hot assembly of medium diameter pipes, pinion quenching, etc.
5. The frequency of UHF induction heating mode is relatively the highest, and the frequency range is generally more than 200kHz, up to tens of MHz. The minimum heating depth and thickness is about 0.1-1mm. It is mainly used for quenching and welding of local very small parts or very fine bars, surface quenching of small workpieces, etc.
What are the common heat treatment methods? What are the characteristics of each?
Because of the skin effect when alternating current flows in the conductor, that is, with the increase of current frequency, the current will tend to flow on the surface of the conductor. Therefore, these five induction heating methods have different characteristics.