Hard metal drill bit for use on a drill

  • US 6,629,805 B1
  • Filed: 06/05/2001
  • Issued: 10/07/2003
  • Est. Priority Date: 10/30/1998
  • Status: Expired due to Fees
First Claim
Patent Images

1. A hard-metal cutting tip for use on a drill (1), the cutting tip comprising a drill point (3) extending through an, axis (2) of rotation of the drill (1), and primary cutting edges (6) that slope downwardly on both sides, each cutting edge being composed of a primary land (4) and a primary flank (5), said primary flank (5) being inclined to a plane (12) perpendicular to the axis (2) of rotation to form a primary lip clearance angle (14), characterized in that the primary lip clearance-angle (14) decreases with increasing distance (15) from said drill point (3), wherein said primary flank (5) transitions to a conical transitional face (50) between said primary flank (5) and a small-side face (8), there being a change in an angle (21) of said primary cutting edge (6) at a distance (17) from said drill point (3), and wherein said small-side face (8) has an outer radius (7) adjoined by a flank (30) that is disposed thereafter in a direction of cutting motion (33) and that broadens with increasing distance from an outer edge (24).

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