Screwdriver bit

摘要

The invention relates to a screwdriver bit with terminal driving-end region for insertion into a machine chuck, an intermediate portion (10) having a zone (T) capable of being subjected to torsion, and a driven region (screwdriver-tip portion) preferably for recessed head screws, and proposes, in order to obtain a load-optimised structural form of such a screwdriver bit, that the ratio of diameter to the length of the intermediate portion be less than 0.5 and greater than 0.2 and the modulus of torsion of the zone (T) subjected to torsion is such that, until the torque leading to plastic deformation/fracture is reached, the angle of reverse rotation resulting from the elastic restoring force of the intermediate portion (10) is 3.5 to 8 degrees. <IMAGE>