Patent ID: 8753056

Claim:
A thread-tapping screw comprising: a screw head; a screw shank having a front section at an end opposite the screw head and a longitudinal axis; and a thread formed on at least part of the screw shank, the screw shank having four longitudinal grooves formed on the front section, starting at the end, each longitudinal groove delimited on the screw shank by two lengthwise sides running essentially radially relative to the longitudinal axis, each longitudinal groove having at least one lengthwise side of the two lengthwise sides oriented at an angle α between 1° and 20° relative to a straight line running parallel to the longitudinal axis, the other lengthwise side of the two lengthwise sides being formed as an arc with a radius R; wherein the four longitudinal grooves include first and second longitudinal grooves having first and second flat sides, respectively, the first and second flat sides being parallel, and include third and fourth longitudinal grooves having a third and fourth flat sides respectively, the third and fourth flat sides being parallel.