| 摘要 |
<p>PURPOSE:To prevent the formation of an oxide film on the surface of a work by carrying out forced cooling with an inert gas injected at a proper temp. in a stage for cooling the work after high frequency heating. CONSTITUTION:A high frequency coil 2 for heating is placed near the ring- shaped top 11 of a work 1 and a jacket 3 for cooling having plural injection nozzles 31 is put in the coil 2. Electric current is supplied to the coil 2 for a prescribed time to heat the upper part of the work 1 to a prescribed temp. An inert gas is then injected at a proper temp. on the heated part from the nozzles 31 of the jacket 3 to force the part to be cooled. Thus, hardening is carried out.</p> |
