Widening drill bit for widening pilot hole in loose stone

摘要

The drill bit comprises a cylindrical axle body (1) which is divided in the axial direction corresponding to the number of cutting disks (2) which make up the single axle body. The single axle body has threaded parts connected to its opposite sides. The cutting disks, according to their arrangement and the various diameters of each disk, produce a corresponding spherical formed envelopment curve. The diameter of the last cutting disk corresponds to the maximum widened diameter of the pilot hole. Each cutting disk has rear cutting elements (4).