Larry N Nielsen

US Patent:

47398442, Apr 26, 1988

Filed:

Dec 12, 1986

Appl. No.:

6/940932

Inventors:

Oscar E. Farris - Longmont CO
Larry C. Nielsen - Aurora CO

Assignee:

Becker Drills, Inc. - Commerce City CO

International Classification:

E21B 1002

US Classification:

175215

Abstract:

A cylindrical hammer drill bit with a central fluid passage and having a first group of circumferentially spaced lowermost cutting surfaces located on lowermost arcuate segments spaced by elongated upwardly extending circumferentially spaced slots and a second group of circumferentially spaced uppermost cutting surfaces located in intermediate arcuate segments at the upper end of the slots. Each of the cutting surfaces has an arcuate segment portion on the outer periphery of the drill bit formed at the intersection of upwardly inwardly sloping surfaces with the periphery of the drill bit; and radially inwardly upwardly inclined radial segment portions located on radially rib portions on the upwardly inwardly sloping surfaces. Each radial rib portion is connected to an elongated inwardly facing fluid slot.