Patent ID: 6431295
Filing Date: 2002-08-13
Classification: E21B

Abstract:
A drill, comprising a stem (2) having a shank at one end thereof and at last two discharge grooves (3,4) for discharging drilling dust and helically circumscribing the stem (2); a drill head (5) provided at an end of the stem (2) opposite the end provided with the shank, the drill head (5) being provided with bits (7-9), which are formed of hard metal and project radially beyond the drill head (50), and with a plurality of drilling dust grooves (10-12) which are located between the bits and the number of which exceeds a number of the discharge grooves (3,4) with at least one pair of the drilling dust grooves (10, 12) passing into a common discharge groove (4); and a helical groove section (13) forming a common transitional region between the at least one pair of the drilling dust grooves (10,12) and the common discharge groove (4) and having a passing cross-section smaller than a passing cross-section of the common discharge groove (4), wherein with an uneven number of the drilling dust grooves (10-12), the discharge grooves (3,4) have different passing cross-sections, with the common discharge groove having a larger passing cross-section.