GB449974A - An improved boring and drilling tool - Google Patents

Abstract

449,974. Well &c. drills. ASSAM OIL CO., Ltd., Britannic House, Finsbury Circus, London.-(Corstorphine, J. ; Digboi P.O., Assam, India) April 29, 1935, No. 12717. [Class 85] In a tool for drilling wells &c. comprising a plurality of substantially radial blades each with a lower transverse cutting edge and a substantially vertical reaming edge, the forward face of each blade has incorporated therewith one or more cutting teeth each presenting one or more vertical cutting edges towards the direction of rotation of the tool. The teeth may 'be made integral with the blade. In Fig. 1, each blade 1, 2, has three cutters 3, welded thereto and relatively staggered. Each cutter may have a protruding point 11 and may be made of a triangular bar, Figs. 6 and 7, with a recess 6 in which a bar 12 of hard metal carbide is fixed ; the recess is then filled with a low carbon steel, the faces of the latter being coated with hard metal carbide. Metal carbide 15 may also be applied to each blade and to the face 16 of the reaming edge, in which inserts of metal carbide may be provided. In another form, the metal carbide is omitted and the cutters of the blades are not relatively staggered, while in a further form, the cutters do not protrude below the transverse edges of the drill and may be built up integral with the metal carbide coating 15 of the blades. In Fig. 12, each blade has slots cut therein in which cutters 19 are welded ; the cutters may be similar to the cutters 3 of Fig. 1 or may have a narrow flat cutting face the lower part of which is coated with hard metal carbide 20. End cutters 22 are wider and their coating extended to form a reaming face 23.