DRILL FOR PRODUCING CYLINDRICAL HOLES

摘要

Drills with a straight shank are used for making cylindrical holes in concrete or the like. In the case of conventional drills, jamming or canting often occurs when they penetrate the masonry. …A drill for making cylindrical holes is proposed, the shank (5) of which is provided with two or more crowned widened portions (6, 7) which are arranged one behind the other and the maximum diameter of which approximately corresponds to the diameter of the drill head. Wide webs (12) which provide a good bearing surface in the area of the apex points of the widened portions of the shank remain between the flutes. ……