Drill
AssigneeFuji Jukogyo Kabushiki Kaisha
InventorsManabu Saito, Tatsuo Nakahata, Hideharu Takahashi
Life of this patent
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Abstract
A drill includes a cutting edge having a ridgeline. The ridgeline has a part of an ellipse and a straight line. It is assumed that the coordinates of a separation point of an ellipse portion from a straight line portion are (x0, y0). The straight line is a tangent to the ellipse at the separation point. It is assumed that a1 is an area from a tip end of the drill to x0, a2 is an area from x0 to the origin of the ellipse, and a3 is a negative area, along the x-axis. The ridgeline of the cutting edge is formed straight along the tangent in the area a1, and is formed along the ellipse in the area a2. A margin is formed in the area a3 continuously from a relief face of the cutting edge.
Claims17
A drill comprising:
- a cutter edge section comprising a cutting edge having a ridgeline, a maximum diameter position, and a predetermined point located closer to a tip end of the drill than the maximum diameter position,
- wherein at least a part of the ridgeline is formed along a part of a reference ellipse, with a portion of the ridgeline continuously extending from the predetermined point toward the tip end of the drill formed straight along a tangent to the reference ellipse at the predetermined point,
- wherein the cutting edge has a relief angle δ1 at a position closest to the tip end of the drill and a relief angle δ2 at the maximum diameter position, the relief angles δ1 and δ2 having a relationship δ1>δ2,
- wherein, in at least a part of an area from the position closest to the tip end of the drill to the maximum diameter position, the relief angle gradually decreases from the relief angle δ1 to the relief angle δ2,
- wherein the cutter edge section comprises a length L from the maximum diameter position to the tip end of the drill and a maximum diameter ΦD at the maximum diameter position, with the length L and the maximum diameter ΦD satisfying a ratio L/ΦD from 1.4 to 1.6, and
- wherein a point angle of the drill is in a range from 100° to 140°.
A drill comprising:
- a cutter edge section comprising a cutting edge having a ridgeline, a maximum diameter position, and a predetermined point located closer to a tip end of the drill than the maximum diameter position,
- wherein at least a part of the ridgeline is formed along a reference curve that is defined by connecting end points of a plurality of arcs, each of the arcs having end points on a reference ellipse, with a portion of the ridgeline continuously extending from the predetermined point toward the tip end of the drill formed straight along a tangent to the reference curve at the predetermined point,
- wherein the cutting edge has a relief angle δ1 at a position closest to the tip end of the drill and a relief angle δ2 at the maximum diameter position, the relief angles δ1 and δ2 having a relationship δ1>δ2,
- wherein, in at least a part of an area from the position closest to the tip end of the drill to the maximum diameter position, the relief angle gradually decreases from the relief angle δ1 to the relief angle δ2,
- wherein the cutter edge section comprises a length L from the maximum diameter position to the tip end of the drill and a maximum diameter ΦD at the maximum diameter position, with the length L and the maximum diameter ΦD satisfying a ratio L/ΦD from 1.4 to 1.6, and
- wherein a point angle of the drill is in a range from 100° to 140°.
Dependencies are inferred from the claim text.