| 摘要 |
PURPOSE:To improve finishing accuracy of a round hole and prolong the service life of a tool by using edge lines of a plate-shaped polygon tip having a bottom edge or both a bottom edge and a peripheral edge as the edges for cutting a rotating center part. CONSTITUTION:A tip 2 is a square plate and composed of a plane 21 becoming a rake face in a state of being locked on the tip seat 12 of a shank body 1 and a side face (not illustrated). The edge lines formed by intersection of the plane 21 and the side face are reqarded as a bottom cutting edge and a peripheral cutting edge respectively and cavities 23, 231 are provided from the plane 21 to the side face adjacent to a nose 27. The edge line parts formed by cavities, planes, and side face are regarded as cutting edges 24, 241 cutting the part adjacent to the rotating center of the tool thus maching efficiency being improved. |
