| 摘要 |
Tools for cutting threads in certain extremely hard materials like the aluminum bronzes, such tool being characterized by four lineal arrays of teeth equally spaced around a longitudinal axis and substantially equidistant therefrom. One pair of said arrays has a series of long teeth interspersed with a series of short teeth, and the other such pair has teeth of uniform length which are slightly shorter than the long teeth in the first mentioned arrays. An inwardly inclined chip clearance surface on each tooth extends rearwardly to a point below the root of the tooth. A flat cutting face on the teeth in each pair of lineal arrays extends below the root thereof, and is disposed at substantially right angles to a transverse medial plane through the other pair of lineal arrays.
|
