| 摘要 |
PURPOSE: A micro drill which is used in manufacturing nozzles for spinning synthetic fiber molten solution is provided, and a method for heat treating the micro-drill are provided. CONSTITUTION: The method for heat treating a micro drill comprises the processes of instantaneously heating a micro drill having a diameter of 0.05 to 0.5 mm at a temperature of 150 to 250 deg.C for 5 to 15 seconds in the state that vibration of fire does not exist, that is, in the non-speed state, wherein heating indirectly heats the blade tip by heating a part of the blade tip, thereby heat conducting the whole blade tip; rapidly cooling the micro drill by dipping the heated micro drill into a quenching solution; indirectly heating the micro drill with heat of 80 to 90 deg.C for 30 to 40 seconds by heating thus heat conducting the iron plate after putting the micro drill on a thin iron plate; and heat treating the micro drill by dipping the heated micro drill again into the quenching solution for cooling used in the heat treatment process. The micro drill comprises a blade (chisel edge) part which has a diameter of 0.05 to 0.5 mm and formed at the blade end of the drill, and a surface (rake surface) part of the blade end which is formed all over the length of the drill and effective in cutting as the blade (chisel edge) part is provided as the wall surface of the surface (rake surface) part.
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