Twist drill with unequal flute spacing and unequal relief angles
First Claim
1. A twist drill having a shaft with a longitudinal axis, the twist drill comprising:
- a first flute extending about the longitudinal shaft along a helix angle and a first land adjacent to the first flute and extending about the longitudinal axis of the shaft along the helix angle, wherein the first land has a first margin, and a first cutting edge adjacent the first flute;
a second flute extending about the longitudinal shaft along the helix angle and a second land adjacent to the second flute and extending about the longitudinal axis of the shaft along the helix angle, wherein the second land has a second margin, and a second cutting edge adjacent the second flute;
a third flute extending about the longitudinal shaft along the helix angle and a third land adjacent to the third flute and extending about the longitudinal axis of the shaft along the helix angle, wherein the third land has a third margin, and a third cutting edge adjacent the third flute;
a cutting point located at a forward end of the shaft;
a first forward cutting surface adjacent the first cutting edge and extending from proximate the cutting point axially rearward a predetermined length in a direction of the longitudinal axis of the shaft;
a second forward cutting surface adjacent the second cutting edge and extending from proximate the cutting point axially rearward the predetermined length in the direction of the longitudinal axis of the shaft; and
a third forward cutting surface adjacent the third cutting edge and extending from proximate the cutting point axially rearward the predetermined length in the direction of the longitudinal axis of the shaft,wherein the first forward cutting surface and the second forward cutting surface have unequal primary radial relief angles.
1 Assignment
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Accused Products
Abstract
A twist drill having a shaft with a longitudinal axis, wherein the cutting tool includes a plurality of flutes extending about the longitudinal shaft along a helix angle and a plurality of lands adjacent the flutes. Each land has a cutting edge adjacent a corresponding flute and a margin (i.e. relief surface). A cutting point is adjacent a forward end of the shaft. A first, second and third forward cutting surfaces are adjacent the first, second and third cutting edges, respectively, and extend proximate the cutting point axially rearward for a predetermined length about the longitudinal axis of the shaft. The cutting edges are unequally angularly spaced from each other, and each forward cutting surface has a primary relief angle that are unequal to each other.
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Citations
19 Claims
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1. A twist drill having a shaft with a longitudinal axis, the twist drill comprising:
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a first flute extending about the longitudinal shaft along a helix angle and a first land adjacent to the first flute and extending about the longitudinal axis of the shaft along the helix angle, wherein the first land has a first margin, and a first cutting edge adjacent the first flute; a second flute extending about the longitudinal shaft along the helix angle and a second land adjacent to the second flute and extending about the longitudinal axis of the shaft along the helix angle, wherein the second land has a second margin, and a second cutting edge adjacent the second flute; a third flute extending about the longitudinal shaft along the helix angle and a third land adjacent to the third flute and extending about the longitudinal axis of the shaft along the helix angle, wherein the third land has a third margin, and a third cutting edge adjacent the third flute; a cutting point located at a forward end of the shaft; a first forward cutting surface adjacent the first cutting edge and extending from proximate the cutting point axially rearward a predetermined length in a direction of the longitudinal axis of the shaft; a second forward cutting surface adjacent the second cutting edge and extending from proximate the cutting point axially rearward the predetermined length in the direction of the longitudinal axis of the shaft; and a third forward cutting surface adjacent the third cutting edge and extending from proximate the cutting point axially rearward the predetermined length in the direction of the longitudinal axis of the shaft, wherein the first forward cutting surface and the second forward cutting surface have unequal primary radial relief angles. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A twist drill having a shaft with a longitudinal axis, the twist drill comprising:
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a first flute extending about the longitudinal shaft along a helix angle and a first land adjacent to the first flute and extending about the longitudinal axis of the shaft along the helix angle, wherein the first land has a first margin, and a first cutting edge adjacent the first flute; a second flute extending about the longitudinal shaft along a helix angle and a second land adjacent to the second flute and extending about the longitudinal axis of the shaft along the helix angle, wherein the second land has a second margin, and a second cutting edge adjacent the second flute; a third flute extending about the longitudinal shaft along a helix angle and a third land adjacent to the third flute and extending about the longitudinal axis of the shaft along the helix angle, wherein the third land has a third margin, and a third cutting edge adjacent the third flute;
a cutting point located a forward end of the shaft;a first forward cutting surface adjacent the first cutting edge and extending from proximate the cutting point axially rearward a predetermined length about the longitudinal axis of the shaft; a second forward cutting surface adjacent the second cutting edge and extending proximate the cutting point axially rearward the predetermined length about the longitudinal axis of the shaft; and a third forward cutting surface adjacent the third cutting edge and extending proximate the cutting point axially rearward the predetermined length about the longitudinal axis of the shaft, wherein the first cutting edge, the second cutting edge and the third cutting edge are unequally angularly spaced from each other, and wherein the first forward cutting surface and the second forward cutting surface have unequal primary radial relief angles. - View Dependent Claims (16, 17, 18, 19)
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Specification