US3709628A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Twist drills
Assignee: Osborn Mushet Tools Ltd
•
Filing: 1970-10-19
•
Granted: 1973-01-09
•
Expires: 1990-10-19
Abstract
Abstract A twist drill having a point angle within the range of 55* to 73*, a helix angle within the range of 10* to 20*, and a web thickness within the range of 18.5 to 25 percent of the drill diameter.
Inventors
- 👤 C Hibbert
- 👤 F Kirk
- 👤 K Siddall
- 👤 M Howard
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 09:20
CPC Classifications
B; B23; B23B; B23B51/00; B23B51/02; C; C22; C22C; C22C38/00; C22C38/12; C22C38/18; C22C38/22; C22C38/30; C22C38/32; B23B2251/00; B23B2251/04; B23B2251/043; B23B2251/40; B23B2251/406; Y; Y10; Y10T; Y10T408/00; Y10T408/89; Y10T408/909; Y10T408/9095
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
47 words
A twist drill particularly adapted for drilling grey cast iron having a point angle within the range of 55* to 73*, a helix angle within the range of 10* to 20*, and a web thickness within the range of 18.5 to 25 percent of the drill diameter.
Claim 2
Dependent Claim
47 words
A twist drill particularly adapted for drilling grey cast iron having a point angle within the range of 55* to 73*, a helix angle within the range of 10* to 20*, and a web thickness within the range of 18.5 to 25 percent of the drill diameter.
Claim 3
Dependent Claim
20 words
A twist drill according to claim 1, in which the point angle is within the range of 58* to 62*.
Claim 4
Dependent Claim
21 words
A twist drill according to claim 1, in which the helix angle is within the range of 13* to 18* .
Claim 5
Dependent Claim
20 words
A twist drill according to claim 1 in which the helix angle is within the range of 14* to 16*.
Claim 6
Dependent Claim
25 words
A twist drill according to claim 1, in which the web thickness is within the range of 20 to 22 percent of the drill diameter.
Claim 7
Dependent Claim
20 words
A twist drill according to claim 2 in which the helix angle is within the range of 13* to 18*.
Claim 8
Dependent Claim
25 words
A twist drill according to claim 2 in which the web thickness is within the range of 20 to 22 percent of the drill diameter.
Claim 9
Dependent Claim
15 words
A twist drill according to claim 1 in which the helix angle is approximately 15*.
Claim 10
Dependent Claim
15 words
A twist drill according to claim 2 in which the helix angle is approximately 15*.
Claim 11
Dependent Claim
15 words
A twist drill according to claim 1 in which the point angle is approximately 60*.
Claim 12
Dependent Claim
15 words
A twist drill according to claim 10 in which the helix angle is approximately 15*.
Claim 13
Dependent Claim
16 words
A twist drill according to claim 11 in which the drill comprises a high speed steel.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-01-09 | 1976-07-10 | 1977-01-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-01-09 | 1980-07-10 | 1981-01-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-01-09 | 1984-07-10 | 1985-01-09 | $7700.00 | Window Closed / Lapsed |