Patent US4884571A successfully refreshed from Google Patents.
US4884571A
Expired / Lapsed
US
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Cranial perforator with reentrant cutting segment
Assignee: BWXT Intech Inc
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Filing: 1985-09-30
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Granted: 1989-12-05
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Expires: 2005-09-30
Abstract
Abstract A new drill-type cranial perforator is disclosed of the type which comprises a front drill head assembly made up of a leading inner drill and a trailing outer drill, and a rear support and drive assembly adapted to enable both drills so long as the leading inner drill is encountering a resistive surface and to disable both drills when the leading inner drill stops encountering the resistive surface. The leading inner drill has at least one drilling flute with a forward cutting edge including a reentrant cutting segment axially rearward from the outer end of the forward cutting edge and extending inwardly towards the longitudinal axis of the perforator.
Inventors
- 👤 John W. Baker
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 20:23
CPC Classifications
A; A61; A61B; A61B17/00; A61B17/16; A61B17/1695; B; B23; B23B; B23B51/00; B23B51/0081; B23B51/009; A61B90/00; A61B90/08; A61B2090/0814; B23B2251/00; B23B2251/14; Y; Y10; Y10T; Y10T408/00; Y10T408/89; Y10T408/895; Y10T408/8957; Y10T408/905; Y10T408/906; Y10T408/9065
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
87 words
A drilling implement for drilling holes in bone structures comprising, a drill head assembly including inner and outer coaxial drill members with the inner member having at least one drilling flute with a forward cutting edge, and with each cutting edge including a reentrant cutting segment spaced axially rearward from the outer end of said forward cutting edge and extending inwardly toward the axis of said drill members whereby a disk-like configuration from the bone structure is formed as the inner drill penetrates through the bone structure.
Claim 2
Dependent Claim
87 words
A drilling implement for drilling holes in bone structures comprising, a drill head assembly including inner and outer coaxial drill members with the inner member having at least one drilling flute with a forward cutting edge, and with each cutting edge including a reentrant cutting segment spaced axially rearward from the outer end of said forward cutting edge and extending inwardly toward the axis of said drill members whereby a disk-like configuration from the bone structure is formed as the inner drill penetrates through the bone structure.
Claim 3
Dependent Claim
44 words
A drilling implement for drilling holes as set forth in claim 1 having a plurality of said flutes and with each said reentrant cutting segment edges extending outwardly from a common center point, said common center point projecting forwardly of said forward cutting edges.
Claim 4
Dependent Claim
47 words
A drilling implement as set forth in claim 2 wherein the outer ends of said forward cutting edges form shoulders having a radial length shorter than the length of said reentrant segment which project forwardly to a point short of the forwardmost portion of said center point.
Claim 5
Dependent Claim
47 words
A drilling implement as set forth in claim 1 wherein said outer end of each said forward cutting edge projects forwardly of said reentrant cutting segment of substantially 0.005" and each said reentrant cutting segment extends inwardly a major fraction of the diameter of said inner drill.
Claim 6
Dependent Claim
29 words
A drilling implement as set forth in claim 4 including three of said flutes and a common center point from which said reentrant cutting segments of said flutes radiate.
Claim 7
Dependent Claim
68 words
A drilling implement for drilling holes in bone structures comprising a drill head assembly, including inner and outer coaxial drill members with the inner member having at least one drilling flute with a forward cutting edge, each said cutting edge including means for cutting a wafer having a disc-like configuration from the bone structure as the inner drill member penetrates through the bone structure by an annular cut.
Claim 8
Dependent Claim
68 words
A drilling implement for drilling holes in bone structures comprising a drill head assembly, including inner and outer coaxial drill members with the inner member having at least one drilling flute with a forward cutting edge, each said cutting edge including means for cutting a wafer having a disc-like configuration from the bone structure as the inner drill member penetrates through the bone structure by an annular cut.
Claim 9
Dependent Claim
47 words
A drilling implement as set forth in claim 6 wherein said means for cutting a wafer includes; means for forming thin bridge-like segments of bone in said annular cut between said wafer and the remaining bone structure, as the inner drill member penetrates through the bone structure.
Claim 10
Dependent Claim
32 words
A drilling implement as set forth in claim 7 wherein said means for cutting a wafer includes means for cutting a wafer having a center thinner than the periphery of said wafer.
Claim 11
Dependent Claim
30 words
A drilling implement as set forth in claim 7 wherein said means for cutting a wafer includes means for cutting a wafer with a hole axially located in said wafer.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-12-04 | 1993-06-05 | 1993-12-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-12-04 | 1997-06-05 | 1997-12-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-12-04 | 2001-06-05 | 2001-12-05 | $7700.00 | Window Closed / Lapsed |