Design and construction of induction Hardening Machine (Controlled Rectifier Module)

When surface hardening is done by means of induction heating, the method is known as induction hardening. This method involves heating the component by an induced current to very high temperature and then quenching it to get required level of hardness. The advantage of the induction over the conventional methods is mainly the rapid heating of the surface of the component without an appreciable rise in the temperature of the core. This condition makes it possible to case harden components in a few seconds with very little distortion. In induction hardening process, a single phase ac power source is converted to a pulsating de supply and filtered. Then, the adjustable dc output of the filter is fed to a single phase bridge inverter circuit. At the last process, the medium frequency output current from the inverter is applied to the induction coil which also acts as heating coil In this paper, design calculation and test results for converter section of prototype model 5kW, 4kHz induction hardening machine is described. The bridge type rectifier circuit for induction hardening machine is designed and constructed by using SCRs as controlled elements. Thyristor gate triggering control circuit is also constructed to get the controlled range between 0° and 180°