US3598500A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Twist drill
Assignee: National Twist Drill and Tool Co
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Filing: 1969-04-07
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Granted: 1971-08-10
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Expires: 1989-04-07
Abstract
Abstract Numerical control drill system employing stubbing collet, and a double-margin drill for improving support and rotational accuracy by the collet, that portion of the drill extending beyond the collet having the trailing margin removed.
Inventors
- 👤 Carl J Oxford Jr
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 16:56
CPC Classifications
B; B23; B23B; B23B51/00; B23B51/02; B23B31/00; B23B31/02; B23B31/10; B23B31/12; B23B31/20; B23B31/201; B23B31/2012; B23B31/20125; B23B2251/00; B23B2251/40; B23B2251/406; B23B2251/44; B23B2251/443; B23B2251/56; B23B2251/62; Y; Y10; Y10T; Y10T408/00; Y10T408/86; Y10T408/89; Y10T408/898; Y10T408/909; Y10T408/9095; Y10T408/9097
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
128 words
The method of using a double-margin drill in a machine tool adapted to numerical control, the machine tool having a contractable collet adapted to grip an intermediate portion of the drill which comprises providing a double-margin drill each land of which has circumferentially spaced leading and trailing margins, removing the portion of the trailing margins from the active portion of the drill which will extend forwardly of the collet in use while leaving the trailing margins on the remainder of the drill, inserting the shank end of the drill through the collet into engagement with a positioning stop and contracting the collet to grip an intermediate portion of the drill directly adjacent its active portion at a plurality of zones including both the leading and trailing margins thereof.
Claim 2
Independent Claim
128 words
The method of using a double-margin drill in a machine tool adapted to numerical control, the machine tool having a contractable collet adapted to grip an intermediate portion of the drill which comprises providing a double-margin drill each land of which has circumferentially spaced leading and trailing margins, removing the portion of the trailing margins from the active portion of the drill which will extend forwardly of the collet in use while leaving the trailing margins on the remainder of the drill, inserting the shank end of the drill through the collet into engagement with a positioning stop and contracting the collet to grip an intermediate portion of the drill directly adjacent its active portion at a plurality of zones including both the leading and trailing margins thereof.
Claim 3
Dependent Claim
45 words
The method as defined in claim 1 which comprises periodically making a forward adjustment of the stop, resharpening the drill and thereby reducing its length, and removing the trailing margins from that portion of the drill which is to be extended into the active zone.
Claim 4
Dependent Claim
293 words
A drill having a forward cutting portion and an intermediate support portion at which the drill is adapted to be gripped circumferentially, the drill being designed for resharpening by removal of stock at its forward end and for use thereafter by shifting the support portion at which it is gripped rearwardly by the amount of stock removed, said drill having continuous flutes extending longitudinally thereof throughout both its cutting and support portions and rearwardly of its support portion, lands extending longitudinally of said drill between each adjacent pair of flutes, the radially outer surface of each of said lands having a continuous substantially cylindrical leading margin which extends for the full length of said land and intersects the surface of the adjacent flute to define a cutting edge which determines a continuous uniform hole size formed by said drill throughout its useful life, the radially outer surface of each of said lands having a substantially cylindrical trailing margin spaced circumferentially from the aforesaid leading margin and of the same radius as the leading margin, which trailing margin is continuous throughout the intermediate support portion of said drill and rearwardly thereFrom for the remaining fluted length of said drill, the radially outer land surfaces between said leading and trailing margins being relieved, the leading and trailing margins at the intermediate support portion of said drill providing a multiplicity of circumferentially spaced, substantially cylindrical, concentric support areas double in number to the number of flutes, the trailing margin of each land being omitted forwardly of the intermediate support portion throughout the cutting portion and the entire land area throughout the cutting portion of said drill at the radially outer surface thereof except for the leading margin thereon being relieved to improve the cutting action thereof.
Claim 5
Dependent Claim
293 words
A drill having a forward cutting portion and an intermediate support portion at which the drill is adapted to be gripped circumferentially, the drill being designed for resharpening by removal of stock at its forward end and for use thereafter by shifting the support portion at which it is gripped rearwardly by the amount of stock removed, said drill having continuous flutes extending longitudinally thereof throughout both its cutting and support portions and rearwardly of its support portion, lands extending longitudinally of said drill between each adjacent pair of flutes, the radially outer surface of each of said lands having a continuous substantially cylindrical leading margin which extends for the full length of said land and intersects the surface of the adjacent flute to define a cutting edge which determines a continuous uniform hole size formed by said drill throughout its useful life, the radially outer surface of each of said lands having a substantially cylindrical trailing margin spaced circumferentially from the aforesaid leading margin and of the same radius as the leading margin, which trailing margin is continuous throughout the intermediate support portion of said drill and rearwardly thereFrom for the remaining fluted length of said drill, the radially outer land surfaces between said leading and trailing margins being relieved, the leading and trailing margins at the intermediate support portion of said drill providing a multiplicity of circumferentially spaced, substantially cylindrical, concentric support areas double in number to the number of flutes, the trailing margin of each land being omitted forwardly of the intermediate support portion throughout the cutting portion and the entire land area throughout the cutting portion of said drill at the radially outer surface thereof except for the leading margin thereon being relieved to improve the cutting action thereof.
Claim 6
Dependent Claim
19 words
A drill as defined in claim 3, said drill being a two-fluted drill in which said flutes extend helically.
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) | 1974-08-09 | 1975-02-08 | 1975-08-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-08-09 | 1979-02-08 | 1979-08-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-08-09 | 1983-02-08 | 1983-08-10 | $7700.00 | Window Closed / Lapsed |