| 摘要 |
PURPOSE: A method and an apparatus for expanding a hole are provided to improve productivity by rapidly and partially heating a part where the hole is processed by induction heating. CONSTITUTION: A method for expanding a hole expands the hole in a state where a part of a target processing material containing a martensite structure is rapidly and partially heated at a tempering temperature. The tempering temperature is within 500-600 deg. C.. The rapid heating is implemented within 2-10 seconds. The target processing material is a DP(Dual Phase) steel containing a ferrite structure and the martensite structure. |
