| 摘要 |
According to the invention a combined drilling and threading tool is provided which includes an elongated shank and a conical front portion (11) provided at its front end, said portion being provided with symmetrically shaped cutting edges (22,23) and symmetrically twisted ribs (13,14) arranged axially rearwardly thereof. Cutting teeth (18) for threading operations are provided on these ribs with a certain mutual spacing (d) and radial clearance and axial clearances. The symmetrically shaped cutting edges shall be configured such that the inner parts have contour differing from the contour of the outer parts thereof. Further according to the invention a method for drilling and threading is provided which, inter alia, includes rotation of the tool simultaneously as it is circularly interpolated one turn around and one pitch axially forwardly or rearwardly. |
