| 摘要 |
<p>1. Tap comprising at least two chases (1) peripherally separated by a flute in which, when it is seen in transverse section over the whole of its cutting length : - the base of the flute (2) is convex, notably starting from the end of the tap ; - the two flanks (4a, 4b) of each chase are straight and - each chase extends according to a convex shape (10) between its two flanks, characterised in that the radial cutting angle gamma of each chase is negative and in that the base of the flute (6) has a shape of a projecting V.</p> |
