Patent ID: 9033624
Filing Date: 2015-05-19
Classification: B23G,Y10T

Abstract:
1. A set of screw taps, each of which is rotatable about a rotational axis, comprising: two or more screw taps, each comprising: a plurality of thread-cutting teeth, which respectively have a radially outer tip cutter and are disposed mutually offset, with a predefined thread pitch, in an arrangement running spirally or helically around the rotational axis; wherein, in a lead region adjoining one end of the screw tap axially to the rotational axis, the maximum radial distance of the tip cutters of the thread-cutting teeth from the rotational axis increases with increasing axial distance of the tip cutters from one end of the screw tap according to a predefined radial distance function; wherein radially is defined as perpendicular to the rotational axis and axially is defined as along or parallel to the rotational axis; wherein at least some of the thread-cutting teeth in the lead region respectively have a defined cutter rounding between tool face and tool flank comprising an outer surface that is separated from an ideal wedge shape by a reduction depth, wherein the ideal wedge shape is an unrounded cutting edge defined by an end point of lines extending from tool face and tool flank, and wherein the reduction depths are respectively chosen based on: 1) the number of thread-cutting teeth in the lead region; and 2) the thread pitch; wherein the reduction depths of the cutter roundings of at least some of the thread-cutting teeth in the lead region are directly proportional to the thread pitch and inversely proportional to the number of thread-cutting teeth in the lead region.