| 摘要 |
<p>PURPOSE:To reduce quenching strains and to form hardened layers which are thin, strong and tough by subjecting casting parts to high frequency heating under specific conditions then to force air cooling at specific temp. and recuperating the same up to specific temp. by allowing the parts to cool then cooling the parts further. CONSTITUTION:Casting parts 2 are held at the center of a coil 1 for heating and high frequency current of about 10kHz frequency is flowed to the coil 1 to heat the hardening parts 2a of the parts 2 up to 1,050-1,100 deg.C at 100-300 deg.C/sec heating rate. Air is then injected through ejection holes 3 for cooling water and air provided to the coil 1 to cool the parts 2 forcibly up to 800-850 deg.C. The parts 2 are allowed to cool to recuperate the surfaces thereof down to 850-900 deg.C, whereafter cooling water is injected through the holes 3 to cool the parts 2. The induction hardening is thus made possible.</p> |
