| 摘要 |
<p>PROBLEM TO BE SOLVED: To prevent occurrence of melting deformation or distortion around openings or open holes caused by abnormal heating due to electric current concentrated around the openings or open holes, in case induction hardening is applied to a formed steel plate member with openings or open holes. SOLUTION: A steel plate or a formed steel plate, which is plastically processed to a half-way punched state for the openings or open holes, is induction hardened and then pressurized by rolls or a press to remove the half-way punched portions.</p> |
