# US 2014/0193220 A1 · Bit exchangeable drill

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- Number: US 2014/0193220 A1
- Document ID: US20140193220A1
- Status: Published application
- Kind: A1
- Application number: 14/239,778
- Filed: 2013-04-05
- Published: 2014-07-10
- Earliest claimed: 2012-04-11
- Assignees: Sumitomo Electric Hardmetal Corp.; Fuji Jukogyo Kabushiki Kaisha; Sumitomo Electric Industries, Ltd.
- Applicants: Sumitomo Electric Hardmetal Corp.; Fuji Jukogyo Kabushiki Kaisha; Sumitomo Electric Industries, Ltd.
- Inventors: Takumi Tamura; Masahiro Yoshida; Yoshiharu Kaimori; Yuzuru Ono
- Web page: https://patentgrep.com/patent/US20140193220A1

## CPC

- B23B 51/02: Twist drills
- B23B 2215/04: Aircraft components
- B23B 2226/275: Carbon fibre reinforced carbon composites
- B23B 2251/02: Connections between shanks and removable cutting heads
- B23B 2251/18: Configuration of the drill point
- B23B 2251/443: Double margin drills
- Y10T 408/9097: Spiral channel
- Y10T 408/9098: with means to retain Tool to support
- B23B: TURNING; BORING (arrangements for copying or controlling B23Q)
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

A bit exchangeable drill includes a detachable cutting head at the tip of a drill body, and the cutting head includes a cutting edge extending linearly from a rotation center to a radial outer end in axial end view, and a helical flute. At a rake face continuous with the cutting edge, a thinning face inclined relative to the rotation axis and rendering an axial rake angle of the cutting edge negative is formed entirely from a radial inner end to a radial outer end of the cutting edge.

## Claims

### Claim 1

A bit exchangeable drill including a detachable cutting head at a tip of a drill body, said cutting head including a cutting edge extending linearly from a rotation center to a radial outer end in axial end view, and a helical flute, wherein
a thinning face inclined relative to a rotation axis, and rendering an axial rake angle of the cutting edge negative is formed at a rake face continuous to said cutting edge, and said thinning face is arranged entirely from a radial inner end to a radial outer end of said cutting edge.

### Claim 2 (depends on 1)

The bit exchangeable drill according to claim 1, wherein a tilt angle θ of said thinning face relative to the rotation axis satisfies a condition of 0°<θ<25°.

### Claim 3 (depends on 1)

The bit exchangeable drill according to claim 1, wherein a width dimension of said thinning face in a direction of the rotation axis at a radial outer end of the cutting edge is set at 0.2 mm to 1.0 mm.

### Claim 4 (depends on 1)

The bit exchangeable drill according to any of claim 1, wherein a main margin adjacent to said helical flute and a submargin arranged backward of said main margin in a drill rotation direction are formed at an outer circumferential land of said cutting head, and a size of clearance formed between the two margins is set at 0.3 mm to 1.0 mm.

### Claim 5

A bit exchangeable drill including a detachable cutting head at a tip of a drill body, said cutting head including a cutting edge extending linearly from a neighborhood of a rotation center to a radial outer end in axial end view, and a helical flute, wherein said cutting edge has a chisel edge less than or equal to 0.5 mm,
a thinning face inclined relative to a rotation axis, and rendering an axial rake angle of the cutting edge negative is formed at a rake face continuous to said cutting edge, and said thinning face is arranged entirely from a radial inner end to a radial outer end of said cutting edge.