Patent DE2376C successfully refreshed from Google Patents.
US3674101A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Drill construction
Assignee: Hilti AG
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Filing: 1970-04-08
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Granted: 1972-07-04
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Expires: 1990-04-08
Abstract
Abstract A spiral or twist drill having a hard metal cutting edge and particularly useful for drilling concrete or artificial stone includes a cutting edge having a centering projection of a diameter which is smaller than the outside diameter of the drill. The cutting edge is formed by a hard metal plate which is secured such as by soldering within a cross groove of the drilling head. The centering tip is formed either by a separate hardened metal element which projects outwardly from the center of the cutting plate or is defined by notches which are formed on each side of a central centering tip portion of the hard plate.
Inventors
- 👤 Franz Chromy
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 11:27
CPC Classifications
E; E21; E21B; E21B10/00; E21B10/44; E21B10/445; E21B10/46; E21B10/58
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
215 words
A spiral or twist drill comprising an axially elongated drill having a shank portion with a spiral groove defined in the exterior surface thereof and terminating in a head, the head of said drill having a groove therein extending diametrically across and inwardly from its end, a flat planar hard metal plate positioned within said groove and securely attached to said drill, said plate having a pointed edge extending axially from said head of said drill with the point thereof located on the axis of said drill, said pointed edge comprising two surfaces each sloping from the point in a diametrically opposite direction toward the circumferential periphery of said drill, each said surface of said edge extending rectilinearly from the point to the circumferential periphery of said drill and each said surface having a notch formed therein through said plate from one side to the other, each notch spaced between and from the point and the circumferential periphery of said drill, said notches being symmetrically arranged relative to the axis of said drill, and the portion of said surfaces of said edge extending from said notches to the point of said edge forming a centering projection having a dimension in the diametrical direction of said drill which is less than the diameter of said drill.
Claim 2
Dependent Claim
215 words
A spiral or twist drill comprising an axially elongated drill having a shank portion with a spiral groove defined in the exterior surface thereof and terminating in a head, the head of said drill having a groove therein extending diametrically across and inwardly from its end, a flat planar hard metal plate positioned within said groove and securely attached to said drill, said plate having a pointed edge extending axially from said head of said drill with the point thereof located on the axis of said drill, said pointed edge comprising two surfaces each sloping from the point in a diametrically opposite direction toward the circumferential periphery of said drill, each said surface of said edge extending rectilinearly from the point to the circumferential periphery of said drill and each said surface having a notch formed therein through said plate from one side to the other, each notch spaced between and from the point and the circumferential periphery of said drill, said notches being symmetrically arranged relative to the axis of said drill, and the portion of said surfaces of said edge extending from said notches to the point of said edge forming a centering projection having a dimension in the diametrical direction of said drill which is less than the diameter of said drill.
Claim 3
Dependent Claim
13 words
A drill, according to claim 1, wherein the notches are of curved configuration.
Claim 4
Dependent Claim
11 words
A drill, according to claim 1, wherein the notches are rectangular.
Claim 5
Dependent Claim
43 words
A drill, as set forth in claim 1, wherein said plate has a dimension in the diametrical direction of said drill which is slightly larger than the diameter of said drill so that said plate extends laterally from the head of said drill.
Claim 6
Dependent Claim
30 words
A drill as set forth in claim 1, wherein said surfaces of said edge of said plate being disposed at a bevel angle in the range of 45* to 60*.
Claim 7
Dependent Claim
31 words
A drill, as set forth in claim 1, wherein said head of said drill being notched to form a continuation of said notch in said edge of said hard metal plate.
References Cited (Backward Citations)
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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) | 1975-07-04 | 1976-01-03 | 1976-07-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-07-04 | 1980-01-03 | 1980-07-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-07-04 | 1984-01-03 | 1984-07-04 | $7700.00 | Window Closed / Lapsed |