Medium frequency quenching: deeper hardened layer (3~5mm), suitable for parts subjected to torsion and pressure loads, such as crankshafts, large gears, grinding machine spindles, etc. (The materials used are 45 steel, 40Cr, 9Mn2V and ductile High frequency quenching, can be a short period of time of the surface layer of the quenching! Crystal organization is very fine! Structural deformation is small Medium frequency surface stress is smaller than high frequency 50HZ called industrial frequency, heating depth 5-10 1000-10000HZ called medium frequency. "High-frequency quenching" and "medium frequency quenching" in principle is the same, so there are certain guidelines in the selection of medium frequency quenching equipment.
High-frequency quenching: quenching layer shallow (1.5 ~ 2mm), high hardness, the workpiece is not easy to oxidize, deformation is small, good quenching quality, high productivity, suitable for friction conditions of the work of the parts, such as general smaller gears, shafts (the material used in the No. 45 steel, 40Cr). 10,000HZ or more is called high-frequency quenching.
Most of the high-frequency quenching is used for industrial metal parts surface quenching, is to make the surface of the workpiece to produce a certain amount of induction current, rapid heating of the surface of the parts, and then rapidly quenching a metal heat treatment method. Induction heating equipment, that is, induction heating of the workpiece for surface quenching equipment.
The principle of induction heating: the workpiece is placed in the inductor, which is generally a hollow copper tube fed with medium or high frequency alternating current (1,000-300,000 Hz or higher).
Generate an alternating magnetic field in the workpiece to produce the same frequency of the induced current, the distribution of this induced current in the workpiece is not uniform, strong in the surface, and in the interior is very weak, to the heart of the close to 0, the use of this skin effect, the surface of the workpiece can be rapidly heated in a few seconds the surface temperature rises to 800-1000 ° C, while the heart of the temperature rise is very small.
Medium frequency quenching, on the other hand, is to place the metal parts in an induction coil, which is energized by alternating current, generating an alternating electromagnetic field, which induces an alternating current in the metal parts.
Due to the skin effect, the current is mainly concentrated on the surface of the metal parts, so the temperature of the surface is the highest, in the induction coil immediately below the water spray cooling or other cooling, due to the heating and cooling is mainly concentrated on the surface, so the surface modification is very obvious, while the internal modification is basically not, you can have a very special heat treatment effect.