| 摘要 |
A high frequency heat treatment method for a fine bottom-closed hole comprises preparing a coil so as to be completely inserted into the fine bottom-closed hole, preparing a core for controlling a magnetic flux within the coil such that the core protrudes from upper and lower sides of the coil, heat-treating a target part of the fine bottom-closed hole under conditions of a heating time of 2~3 seconds, an output power of 200~300 kW, a quenching time of 3~5 seconds, a positive electrode voltage of 4~8 kV, and a positive electrode current of 2.0~4.5 A, and quenching the heat-treated part of the fine bottom-closed hole with cooling nozzles fixed around the heat-treated part such that a sufficient amount of cooling water is injected uniformly over the whole heated part with a sufficient pressure via the cooling nozzles.
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