Patent ID: 7225890

Claim:
An auxiliary cutting plate for a multi-cutting plate drill bit, the auxiliary cutting plate comprising: an overall rectangular shaped body for fixing into a slot in the drill bit and a profiled tip, said body having a pair of lateral faces and an inner and outer side face, said inner side face being substantially flat for abutting a portion of the drill bit, said outer face having a surface different from said inner face for transitioning with an outer surface of the drill bit; said body has a central longitudinal axis and the profiled tip protrudes from one end of the body, said profiled tip comprises a cutting edge defined by a transition between a rake face and a relief face extended from their respective lateral faces, said rake face and the relief face each slope axially rearward from opposite sides of the cutting edge to said lateral faces, an angle of inclination θ of at least a portion of the rake face measured from a plane perpendicular to the longitudinal axis decreases with increasing distance from the cutting edge.