| 摘要 |
PROBLEM TO BE SOLVED: To make it practical of a tip used for machining shafts of small articles to be given super-precision machining in a wide cutting range to easily obtain center height and to perform high dimensional precision machining. SOLUTION: A positive type tip having a nose radius R1 not more than 0.5 mm, a cutting edge 3 gradually being in a low position as it separates from the nose 2, and equipped with a breaker groove 4 along the cutting edge 3 without providing with a land has the region, which is to the nose tip 2a side among the faces 6 and composing a circular arc cutting edge 7, as a flat surface 11 parallel to the bottom of the tip. When the nose tip 2a is to be brought to the center height of a work, it is easy to get the center height because they are brought together on the flat surface 11. The circular arc cutting edge 7 being located on the outer fringe of the flat surface 11 makes an accurate circular arc on a single plane, therefore machining precision does not go wrong.
|
