| 摘要 |
PURPOSE: To attain operations of roughing and finishing, finishing and polishing, or roughing, finishing and polishing simultaneously with turning conducted in the lengthwise direction by disposing an additional cutting edge behind a main cutting edge when viewed from the feed direction of an insert. CONSTITUTION: This insert involves at least one cutting corner having a main cutting edge 13 and a secondary cutting edge 14, and is provided with the linear portion of the main cutting edge 13 formed at a set angle (α), such as 90 degrees, a relief angle (δ) variable over a wide range, and a nose radius R ranging from 0.2 to 3.2 mm. The cutting depth h2 of the secondary cutting edge 14 is less than 0.5 mm, and its setting angle (β) is a specific angle, such as 3 degrees. The relief angle (ε) is set at less than 2 degrees, and a distance between both points 16 and 17 on a straight line 15 coming into contact with the cutting corner at a point 16 and passing through an endpoint 17 on the secondary cutting edge 14 placed at a distance from the main cutting edge 13 is set at 0.5 to 2 mm. The production of a chip 18 is attained with the main cutting edge 13 by means of lengthwise turning, a very thin chip 19 is produced with the secondary cutting edge 14, thus it is possible to improve surface finishing positively. |
