Black Decker Inc.

Rudolf Jungwirth

William R Stumpf

Thomas J Quinn

Florian Probst

Albert Leidl

Johann Riedl

Michael Mulroy

A cutting head for a drill bit has a body with an overall cruciform shape. One pair of opposing arms defines a main cutting edge. The other pair of opposing arms defines an auxiliary edge. The main cutting edge is defined by rake surfaces and relief surfaces. Each rake surface and relief surface is defined by a plurality of facets. The main cutting edge includes a chisel edge. A first pair of planar rake facets, one on each end of said chisel edge, and a first pair of planar relief facets, adjacent said chisel edge, defines a portion of the cutting edge. A remaining portion of the main cutting edge is defined at the apex of a plurality of curved rake facets and curved relief facets. The auxiliary edge is defined by a plurality of curved surfaces.

Drill bit including one piece cutting head

A roll-forged drill bit 1 comprising a shank 3 for insertion in a chuck of a drill, the shank 3 including an helically twisted web 7 defining a cutting tip 9, the cutting tip 9 including a central chisel edge 11 and a cutting edge 15 defining the maximum diameter of the cutting tip 9, wherein the cutting tip 9 is formed after the shank 3 has been roll-forged and includes a pair of faces 13 defining the chisel edge 11 and a pair of upturned flats 17 defining the cutting edge 15. A roll-forged drill bit 1 according to the present invention provides a significant improvement in cutting speed over known prior art roll-forged drill bits.

Roll-forged drill bit

Growing community of inventors

Hutthurm, Germany

Rudolf Jungwirth