| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a polygonal turning insert which has a cutting edge that includes a nose cutting edge situated in a corner and two main cutting edges connected to the nose cutting edge, and in which a primary flank surface that guides chips is arranged behind the nose cutting edge along a bisector between the two main cutting edges, and a pair of secondary flank surfaces is arranged on the inside of the main cutting edges. <P>SOLUTION: A primary flank surface (21) is curved in a projecting form and delimited by a lower boundary line (22). The lower boundary line (22) has an apex point (AP) which is opposed to the nose cutting edge (12) and arranged along the bisector (B), and includes two symmetrical curved lines (22a). The curved lines (22a) extend from the apex point (AP) to a pair of end points (EP) located to be opposed to each other. The end points (EP) are arranged along a straight reference line (RL). The reference line (RL) and the bisector (B) cross each other at a right angle at a middle point (MP) between the pair of end points (EP). <P>COPYRIGHT: (C)2013,JPO&INPIT |
