Patent ID: 6640914
Filing Date: 2003-11-04
Classification: B23B,B28D,E21B,E21D

Abstract:
A percussion borer for forming bores in stone material (11), comprising a chisel stem (2) having a prismatic cross-section, an axial cylindrical through-bore (3), a chiseling head (7), and at least one radial opening (4); a twist drill (6) extending through the cylindrical through-bore (3), projecting beyond the chiseling head (7), and having at an end thereof projecting beyond the chiseling head (7), a drilling head (10) with cutting elements (9) and, at an end thereof opposite the drilling head (10), a shank (12); and a stop (13) provided between the shank (12) and the chisel stem (2), with a drill stem being offset radially inwardly with respect to an outer diameter of the shank (12), whereby an impact shoulder impacting the stop (13) is formed.