Drag blade bit with diamond cutting elements

A cutting element for a drag blade bit having a hollow metal bit body open at one end for connection to a drill string and closed at the other end,

• said cutting element comprising a metal blade member adapted to be welded to said bit body in a position having forwardly and radially extending cutting edges and longitudinally extending gage edges comprising wear surfaces,
• said blade member having a plurality of recesses spaced along said cutting edge,
• a plurality of cutters positioned one in each of said recesses,
• said cutters each comprising a cylindrical supporting stud of sintered carbide having an angularly oriented supporting surface with a disc-shaped element bonded thereon comprising a sintered carbide disc having a cutting surface comprising polycrystalline diamond,
• said blade member comprises a plate-shaped member having an inner edge contoured to fit the surface of said bit body for welding thereto with said cutting edge positioned radially of said bit body closed end and said gage edge extending longitudinally of the outer peripheral surface of said bit body,
• said cutting edge having a notch extending substantially the entire length thereof,
• said edge recesses being positioned in said edge notch, and
• said cutters having said cylindrical inserts positioned in said recesses with said cutting discs extending above the bottom of said notches with the back wall of each notch supporting each cutter against flexure,
• said blade member cutting edge includes a beveled surface at the same angle of bevel as the angled surface of said cylindrical supporting stud, and
• said cutters are positioned in said recesses at a depth such that the flat surfaces of said cutting discs lie in substantially the same inclined plane as said beveled surface.

A cutting element for a drag blade bit having a hollow metal bit body open at one end for connection to a drill string and closed at the other end,

• said cutting element comprising a metal blade member adapted to be welded to said bit body in a position having forwardly and radially extending cutting edges and longitudinally extending gage edges comprising wear surfaces,
• said blade member having a plurality of recesses spaced along said cutting edge,
• a plurality of cutters positioned one in each of said recesses,
• said cutters each comprising a cylindrical supporting stud of sintered carbide having an angularly oriented supporting surface with a disc-shaped element bonded thereon comprising a sintered carbide disc having a cutting surface comprising polycrystalline diamond,
• said blade member comprises a plate-shaped member having an inner edge contoured to fit the surface of said bit body for welding thereto with said cutting edge positioned radially of said bit body closed end and said gage edge extending longitudinally of the outer peripheral surface of said bit body,
• said cutting edge having a notch extending substantially the entire length thereof,
• said edge recesses being positioned in said edge notch, and
• said cutters having said cylindrical inserts positioned in said recesses with said cutting discs extending above the bottom of said notches with the back wall of each notch supporting each cutter against flexure,
• each of said cutting edges has an outer end portion beveled in relation to the longitudinal axis of said bit body,
• said notch extends along said beveled end portion, and
• at least one of said cutters is positioned in said notch on said beveled end portion.

A cutting element in combination with a drag blade bit having a hollow metal bit body open at one end for connection to a drill string and closed at the other end,

• said cutting element comprising a metal blade member adapted to be welded to said bit body in a position having forwardly and radially extending cutting edges and longitudinally extending gage edges comprising wear surfaces,
• said blade member having a plurality of recesses spaced along said cutting edge,
• a plurality of cutters positioned one in each of said recesses,
• said cutters each comprising a cylindrical supporting stud of sintered carbide having an angularly oriented supporting surface with a disc-shaped element bonded thereon comprising a sintered carbide disc having a cutting surface comprising polycrystalline diamond;
• said blade member cutting edge includes a beveled surface at substantially the same angle of bevel as the angled surface of said cylindrical supporting stud, and
• said cutters are positioned in said recesses at a depth such that the flat surfaces of said cutting discs lie in substantially the same inclined plane as said beveled surface.

A cutting element in combination with a drag blade bit having a hollow metal bit body open at one end for connection to a drill string and closed at the other end,

• said cutting element comprising a metal blade member adapted to be welded to said bit body in a position having forwardly and radially extending cutting edges and longitudinally extending gage edges comprising wear surfaces,
• said blade member having a plurality of recesses spaced along said cutting edge,
• a plurality of cutters positioned one in each of said recesses,
• said cutters each comprising a cylindrical supporting stud of sintered carbide having an angularly oriented supporting surface with a disc-shaped element bonded thereon comprising a sintered carbide disc having a cutting surface comprising polycrystalline diamond,
• said blade member comprises a plate-shaped member having an inner edge contoured to fit the surface of said bit body for welding thereto with said cutting edge positioned radially of
• said bit body closed end and said gage edge extending longitudinally of the outer peripheral surface of said bit body,
• said cutting edge having a notch extending substantially the entire length thereof,
• said edge recesses being positioned in said edge notch, and
• said cutters having said cylindrical inserts positioned in said recesses with said cutting discs extending above the bottom of said notches with the back wall of each notch supporting each cutter against flexure,
• each of said cutting edges has an outer end portion beveled in relation to the longitudinal axis of said bit body,
• said notch extends along said beveled end portion, and
• at least one of said cutters is positioned in said notch on said beveled edge portion.