Drill and drilling method for workpiece

• US 9,180,531 B2
• Filed: 12/23/2008
• Issued: 11/10/2015
• Est. Priority Date: 12/23/2008
• Status: Active Grant

• Current Assignee: Subaru Corp.
• Original Assignee: Fuji Jukogyo KK (Subaru Corp.)
• Inventors: Nakahata, Tatsuo, Saito, Manabu, Hosoi, Masanori, Takahashi, Hideharu
• Primary Examiner(s): Gates, Eric A
• Assistant Examiner(s): JANESKI, PAUL MARTENS
• Application Number:
  US12/318,249
• Publication Number:
  US 20100158626A1
• Time in Patent Office: 2,513 Days
• Field of Search: 408/230, 408/229, 408/227, 408/1.R
• US Class Current: 1/1
• CPC Class Codes: B23B 2222/56 Non-specified metals
• CPC Class Codes: B23B 2226/275 Carbon fibre reinforced carbon composites
• CPC Class Codes: B23B 2226/61 Plastics not otherwise provided for, e.g. nylon
• CPC Class Codes: B23B 2228/36 Multi-layered
• CPC Class Codes: B23B 2251/04 Angles, e.g. cutting angles
• CPC Class Codes: B23B 2251/082 Curved cutting edges
• CPC Class Codes: B23B 2251/14 Configuration of the cutting part, i.e. the main cutting edges
• CPC Class Codes: B23B 2251/18 Configuration of the drill point
• CPC Class Codes: B23B 35/00 Methods for boring or drilling, or for working essentially requiring the use of boring or drilling machines; Use of auxiliary equipment in connection with such methods
• CPC Class Codes: B23B 35/005 Measures for preventing splittering
• CPC Class Codes: B23B 51/02 Twist drills
• CPC Class Codes: Y10T 408/03 Processes
• CPC Class Codes: Y10T 408/9097 Spiral channel

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.

Claims

1. 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.

2. The drill according to claim 1, wherein a ridgeline of the cutting edge is a parabolic ridgeline formed of a part of a parabola.

3. The drill according to claim 1, wherein a ridgeline of the cutting edge is an arcuate ridgeline formed of a single arc.

4. The drill according to claim 1, wherein the cutting edge has a rake angle.

5. The drill according to claim 1, wherein the cutting edge has no rake angle.

6. The drill according to claim 1, further comprising:

two helical flutes;

lands formed between the helical flutes;

and margins at edges of the lands along the helical flutes.

7. The drill according to claim 1, wherein a length of the cutting edge along an axis of the drill is at least 1.6 times a maximum diameter of the drill.

8. 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.

9. The drilling method of claim 8, wherein the drilled a hole is formed in a multilayer component member comprising a reinforced composite material layer.

10. The drilling method of claim 9, wherein

the step of reaming includes removing delaminated portions of the multilayer component member.

11. The drilling method of claim 10, wherein the drilled hole is formed in the multilayer component member such that the hole is substantially free of burrs and substantially free of delamination between layers of the multilayer component member.

12. 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.

13. 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.

14. The drilling method of claim 13, further comprising:

wherein the drilled a hole is formed in a multilayer component member comprising a reinforced composite material layer.

15. The drilling method of claim 14, wherein the step of reaming includes removing delaminated portions of the multilayer component member.

16. The drilling method of claim 15, wherein the drilled hole is formed in the multilayer component member such that the hole is substantially free of burrs and substantially free of delamination between layers of the multilayer component member.