DRILL ELEMENT FOR PERCUSSION DRILLING

摘要

This invention relates to a drill element (10;11;12) for percussion drilling, said element having a cylindrical screw thread (13;14;15) having one single entry. The screw thread, that is intended for thread diameters of less than 30 mm, has a pitch (s) of less than 12 mm, a shoulder angle (.beta.) of less than 69.degree. and a pitch angle (.alpha.) of less than 11.degree. but more than 5.6.degree..