Patent US2536723A successfully refreshed from Google Patents.
Patent US4529341A successfully refreshed from Google Patents.
US4529341A
Expired / Lapsed
US
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Drill bit for Kevlar laminates
Assignee: Boeing Co
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Filing: 1982-09-29
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Granted: 1985-07-16
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Expires: 2002-09-29
Abstract
Abstract An improved drill bit for drilling Kevlar laminates or the like, has a pair of helical edges each terminating in an outer cutting point; a center point; and concavely curved cutting edges extending between the center point and each of the outer cutting point. The cutting edges curve back sharply from the cutting points in a plane transverse to the longitudinal drill bit axis and in a direction opposite to normal rotation of said drill bit so as to draw material served by the cutting points radially inwardly from the edge of a bore. A method is disclosed for modifying a conventional drill point to the novel configuration by grinding on a grinding wheel.
Inventors
- 👤 Eddie A. Greene
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 12:57
CPC Classifications
B; B23; B23B; B23B51/00; B23B51/02; B23B2251/00; B23B2251/18; B23B2251/185; Y; Y10; Y10T; Y10T408/00; Y10T408/89; Y10T408/899; Y10T408/90; Y10T408/909; Y10T408/9095; Y10T408/9097
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
150 words
An improved drill bit for drilling Kevlar laminates or the like, said drill bit having a pair of helical leading edges each terminating in an outer cutting point; a center point; and concavely curved cutting edges extending between said center point and each said outer cutting point, said cutting edges curving back sharply from said cutting points as viewed along the longitudinal drill bit axis and in a direction opposite to normal rotation of said drill bit so as to draw material severed by said cutting points radially inwardly from the edge of a bore, said helical leading edges having a reduced rake angle along a leading edge segment adjacent to said cutting points relative to the rake angle of said leading edges along portions removed from said outer cutting points to thereby increase the shearing effect of said edges and minimize lifting of workpiece material by said leading edges.
Claim 2
Dependent Claim
150 words
An improved drill bit for drilling Kevlar laminates or the like, said drill bit having a pair of helical leading edges each terminating in an outer cutting point; a center point; and concavely curved cutting edges extending between said center point and each said outer cutting point, said cutting edges curving back sharply from said cutting points as viewed along the longitudinal drill bit axis and in a direction opposite to normal rotation of said drill bit so as to draw material severed by said cutting points radially inwardly from the edge of a bore, said helical leading edges having a reduced rake angle along a leading edge segment adjacent to said cutting points relative to the rake angle of said leading edges along portions removed from said outer cutting points to thereby increase the shearing effect of said edges and minimize lifting of workpiece material by said leading edges.
Claim 3
Dependent Claim
43 words
The drill bit of claim 1 wherein each of said cutting edge in the immediate vicinity of said outer cutting point forms an angle of less than 65 degrees with a line tangent to the drill bit circumference at said outer cutting point.
Claim 4
Dependent Claim
25 words
The drill bit of claim 1, wherein said reduced rake angle is less than 25 degrees relative to the longitudinal axis of the drill bit.
Claim 5
Dependent Claim
27 words
The drill bit of claim 1, wherein said reduced rake angle is between 4 degrees and 15 degrees relative to the longitudinal axis of the drill bit.
Claim 6
Dependent Claim
36 words
The drill bit of claim 1, wherein said outer cutting points extend in the direction of rotation of said drill bit and lead said cutting edges in a plane transverse to the drill bit longitudinal axis.
Claim 7
Dependent Claim
21 words
The drill bit of claim 5, wherein said segments of reduced rake angle are leading edges of said outer cutting points.
Claim 8
Dependent Claim
15 words
The drill bit of claim 1, further comprising parabolic flutes defined between said helical edges.
Claim 9
Dependent Claim
22 words
The drill bit of claim 1, wherein said center point is slightly higher than said outer cutting points in an axial direction.
Claim 10
Dependent Claim
21 words
The drill bit of claim 1, wherein said cutting edges also recede from said outer cutting points in an axial direction.
References Cited (Backward Citations)
US228421A
Cited
FR944587A
Cited
US2600286A
Cited
US2613710A
Cited
US4209275A
Cited
US4285620A
Cited
US4330229A
Cited
JPS57132908A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-07-15 | 1989-01-14 | 1989-07-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-07-15 | 1993-01-14 | 1993-07-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-07-15 | 1997-01-14 | 1997-07-16 | $7700.00 | Window Closed / Lapsed |