| 摘要 |
PROBLEM TO BE SOLVED: To enhance entire surface hardness and abrasion resistance by providing a soft core body having the hardness lower than that of a hardened layer on the inner side of the hardened layer formed on an entire bit surface by executing a plasma carburization treatment, to prevent any local stress concentration by covering the bit with the hardened layer of a closed structure and forming the inner soft core body to be a cushion, and to form the hardened layer at an adequate depth so as to leave the soft core body therein through the plasma carburization treatment. SOLUTION: A rotary tool bit 1 subjected to the carburization treatment includes a hardened layer 2 formed by executing the plasma carburization treatment on the entire bit surface S, and a soft core body 3 located inside the hardened layer 2 and having the hardness lower than that of the hardened layer 2. COPYRIGHT: (C)2011,JPO&INPIT |
