Drill and drilling method for workpiece
AssigneeFuji Jukogyo Kabushiki Kaisha
InventorsTatsuo Nakahata, Manabu Saito, Masanori Hosoi, Hideharu Takahashi
Life of this patent
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Abstract
A drill includes a cutting edge. The cutting edge has a point angle which is continuously decreased from a center-position point angle A (herein, 0°<A<180°) at a center position to a maximum-diameter-position point angle of 0° at a maximum diameter position. The cutting edge has a relief angle which is continuously decreased from the center position to the maximum diameter position. The cutting edge of the drill has a relief angle at the maximum diameter position. Hence, the cutting edge also serves as a cutting edge for reaming. The ridgeline and relief face of the cutting edge have no corner, thereby providing good wear resistance.
Claims16
A drill comprising:
- a cutting edge,
- wherein the cutting edge has a point angle which is continuously decreased from a center-position point angle A at a center position to a maximum-diameter-position point angle of 0° at a maximum diameter position,
- wherein the cutting edge has a radial relief angle which is continuously decreased from the center position to the maximum diameter position,
- wherein the point angle A at the center position satisfies the condition 0°<A<180°, and
- wherein an axial relief angle at the center position is δ, and the center-position point angle A and the center-position axial relief angle δ satisfy a relationship of δ>(180°−A)/2.
A drilling method for a workpiece, comprising:
- a first step of drilling a hole in the workpiece by using a drill including a cutting edge, the cutting edge having a point angle which is continuously decreased from a center-position point angle A at a center position to a maximum-diameter-position point angle of 0° at a maximum diameter position, the cutting edge having a radial relief angle which is continuously decreased from the center position to the maximum diameter position, and by cutting the workpiece by the cutting edge at the center-position;
- and
- a second step of reaming by cutting the drilled hole formed in the first step, by the cutting edge at the maximum-diameter-position while gradually shifting from the first step,
- wherein the point angle A at the center position satisfies the condition 0°<A<180°, and
- wherein an axial relief angle at the center position is δ, the center-position point angle A and the center-position axial relief angle δ satisfy a relationship of δ>(180°−A)/2.
A drill comprising:
- a cutting edge,
- wherein the cutting edge has a point angle which is continuously decreased from a center-position point angle A at a center position to a maximum-diameter-position point angle of 0° at a maximum diameter position,
- wherein the cutting edge has a radial relief angle which is continuously decreased from the center position to the maximum diameter position,
- wherein the cutting edge has the radial relief angle at the maximum diameter position,
- wherein the point angle A at the center position satisfies a condition 0°<A<180°, and
- wherein an axial relief angle at the center position is δ, and the center-position point angle A and the center-position relief angle δ satisfy a relationship of δ>(180°−A)/2.
A drilling method for a workpiece, comprising:
- a first step of drilling a hole in the workpiece by using a drill including a cutting edge, the cutting edge having a point angle which is continuously decreased from a center-position point angle A at a center position to a maximum-diameter-position point angle of 0° at a maximum diameter position, the cutting edge having a radial relief angle which is continuously decreased from the center position to the maximum diameter position, and by cutting the workpiece by the cutting edge at the center-position;
- and
- a second step of reaming by cutting the drilled hole formed in the first step, by the cutting edge at the maximum-diameter-position while gradually shifting from the first step,
- wherein the cutting edge has the radial relief angle at the maximum diameter position,
- wherein the point angle A at the center position satisfies the condition 0°<A<180°, and
- wherein an axial relief angle at the center position is δ, and the center-position point angle A and the center-position relief angle δ satisfy the relationship of δ>(180°−A)/2.
Dependencies are inferred from the claim text.