Patent US4260331A successfully refreshed from Google Patents.
US4260331A
Expired / Lapsed
US
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Root attachment for a gas turbine engine blade
Assignee: Rolls Royce PLC
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Filing: 1979-09-17
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Granted: 1981-04-07
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Expires: 1999-09-17
Abstract
Abstract A root attachment of the firtree type for a blade of a gas turbine engine. The shape of the root falls within certain closely defined parameters which have been found to give optimum properties to the root. Thus the arrays of teeth forming the root diverge at 35°±1°, the pair of angled faces making up each tooth are at an angle of 60°±1° to each other, and each outer tooth face is at 45°±2° to a normal to the central plane of the root. Also the ratio of the tooth height to the radius of the radiused portions lies in the range 1.5:1 to 2:1.
Inventors
- 👤 John R. Goodwin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 16:18
CPC Classifications
F; F01; F01D; F01D5/00; F01D5/30; F01D5/3007
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
163 words
A root attachment for a blade of a gas turbine engine comprises a firtree root on the blade, and a rotor having a correspondingly shaped groove formed therein and with which the root engages, the root having a plurality of teeth each comprising a pair of angled faces joined by a convex radiused portion and concave radiused portions which join each tooth to the next adjacent teeth, the teeth being disposed in two plane arrays symmetrical about a plane through the longitudinal axis of the root and diverging from the innermost part of the root at an angle of 35°±1°, each said pair of angled faces being disposed at an angle of 60°±1° to each other and the outermost of each pair of faces lying at an angle of 45°±2° to a normal to said plane, the ratio of the tooth height measured at right angles to said plane, to the radius of said radiused portions lying in the range 1.5:1 to 2:1.
Claim 2
Dependent Claim
163 words
A root attachment for a blade of a gas turbine engine comprises a firtree root on the blade, and a rotor having a correspondingly shaped groove formed therein and with which the root engages, the root having a plurality of teeth each comprising a pair of angled faces joined by a convex radiused portion and concave radiused portions which join each tooth to the next adjacent teeth, the teeth being disposed in two plane arrays symmetrical about a plane through the longitudinal axis of the root and diverging from the innermost part of the root at an angle of 35°±1°, each said pair of angled faces being disposed at an angle of 60°±1° to each other and the outermost of each pair of faces lying at an angle of 45°±2° to a normal to said plane, the ratio of the tooth height measured at right angles to said plane, to the radius of said radiused portions lying in the range 1.5:1 to 2:1.
Claim 3
Dependent Claim
22 words
A root attachment as claimed in claim 1 and in which there are five of said teeth in each said plane array.
Claim 4
Dependent Claim
26 words
A root attachment as claimed in claim 1 and in which said ratio of the tooth height to the radius of the radiused portions is 1.58:1.
Claim 5
Dependent Claim
17 words
A root attachment as claimed in claim 1 and in which the blade comprises a cast superalloy.
Claim 6
Dependent Claim
17 words
A root attachment as claimed in claim 4 and in which the rotor comprises a wrought superalloy.
Claim 7
Dependent Claim
18 words
A root attachment as claimed in claim 4 and in which the rotor comprises a powder formed superalloy.
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) | 1984-04-06 | 1984-10-06 | 1985-04-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-04-06 | 1988-10-06 | 1989-04-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-04-06 | 1992-10-06 | 1993-04-07 | $7700.00 | Window Closed / Lapsed |