| 摘要 |
PURPOSE:To obtain an accurate, finished hole by making a prepared hole having a diameter equal to or smaller than a hole diameter finished by laser beam machining or electron beam machining and then making an additional work to this prepared hole. CONSTITUTION:The prepared hole 2 is made by laser beam machining or electron beam machining at the root of a needle stock 1. This prepared hole 2 is composed of a sharpened or dulled depth part 2a which has a slightly trumpet-like inlet part and a wavy and flat central part 2c. The root of this needle stock 1 is heated by a burner 3 as far as the neighborhood of the melting point and a drill which is rotated by a motor 4 and has a specified diameter or a boring tool 5 such as tungsten wire is pushed into the prepared hole 2 of the needle stock 1 to form a finished hole. In this way, the prepared hole and the finished hole are formed easily and surely on the root of the needle stock to obtain an accurate, finished hole. |
