Rotating rock drill bit for drilling wellshafts comprises fluted body carrying cutting elements on front face, with cross-sectional area or grooves in body reduced near rear face of body

摘要

A fluted body carries cutting elements on its front face. The cross sectional area of the grooves in the body is reduced near the rear face of the body. An Independent claim is included for a drill bit with a body and cutting elements which are placed on metal sheets fixed to the body so the rear part of the sheets is cut away. Silent blocks are placed between the sheet and the body and the front parts of the sheets are welded to the body. The cutting elements are on the front parts of the sheets and the rear part of the sheets is cut away. The metal sheets are fixed to the body by metal ties through the silent blocks. The metal sheets are spiraled. The sheet is fixed rigidly in several places to the body of the drill bit before use. Preferred Features: The drill bit has fixed edges. The grooves contain a median plot near the rear face of the body. The body includes an axial ring near the rear face which overlaps the grooves. The grooves have rounded longitudinal ridges with a radius of curvature greater than 1 mm, preferably 2-50 mm. The grooves are defined by ribs so the rear ridge is inclined to the axis of the body to form an acute angle with the longitudinal ridge of the ribs. The ribs include a cutting element on their rear ridge. The grooves are helical, with the angle of helix modified in the direction of rotation of the tool to diverge or converge in size or to change angle with constant size.