Patent US4212461A successfully refreshed from Google Patents.
US4212461A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Composite high strength to weight structure having shell and weight controlled core
Assignee: Fansteel Inc
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Filing: 1978-07-10
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Granted: 1980-07-15
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Expires: 1998-07-10
Abstract
Abstract A novel structural member, such as a tennis racket frame, having an unusually high strength to weight ratio is provided comprising an expanded foamed plastic core integrally bonded to a shell comprising at least one layer of resin-coated unidirectionally oriented graphite fibers, the shell completely encasing the core at any transverse cross section of the structural member, said core comprising from about 25 to about 75 volume percent of a low density cellular filler material, such as chopped cork, and from zero to about 60 weight percent of a high density weight control material, such as barium sulfate. The structural member is prepared by preparing a foamable resin composition comprising a resin component, a blowing agent, from about 7 to about 50 weight percent of a low density cellular filler material and from zero to about 60 weight percent of a high density weight control material, forming said composition into an elongated core strip, wrapping said core strip with at least one sheet of resin-coated unidirectionally oriented graphite fibers, arranging said wrapped core within a mold cavity, sealing the mold cavity and activating the foamable resin composition to cause expansion and generate pressure within the mold cavity and thereby provide intimate bonding of the core to the shell.
Inventors
- 👤 Andrew M. Cecka
- 👤 Paul G. Pawling
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 15:10
CPC Classifications
A; A63; A63B; A63B49/00; A63B49/02; A63B49/10; A63B49/11; A63B60/00; A63B2209/00; A63B2209/02; A63B2209/023; A63B60/54
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
124 words
In a tennis racket frame having a handle and an ellipsoid head attached to one end of said handle and a grip element at the opposite end of said handle, an improved construction wherein said frame comprises a structural member of high strength to weight ratio comprising a core of an expanded porous resinous material integrally bonded to a shell comprising at least one layer of resin-coated unidirectionally oriented graphite fibers, said shell completely encasing said core at any cross section transverse to the length of said member and said core containing from about 25 to about 75 volume percent of chopped cork as a low density filler material and from zero to about 60 weight percent of a high density weight control material.
Claim 2
Dependent Claim
124 words
In a tennis racket frame having a handle and an ellipsoid head attached to one end of said handle and a grip element at the opposite end of said handle, an improved construction wherein said frame comprises a structural member of high strength to weight ratio comprising a core of an expanded porous resinous material integrally bonded to a shell comprising at least one layer of resin-coated unidirectionally oriented graphite fibers, said shell completely encasing said core at any cross section transverse to the length of said member and said core containing from about 25 to about 75 volume percent of chopped cork as a low density filler material and from zero to about 60 weight percent of a high density weight control material.
Claim 3
Dependent Claim
51 words
The tennis racket frame of claim 1 wherein said shell comprises a plurality of layers of resin-coated unidirectionally oriented graphite fibers, at least one of said layers having its fibers oriented in a direction different from the direction of orientation of the fibers in at least one other of said layers.
Claim 4
Dependent Claim
31 words
The tennis racket frame of claim 2 wherein said layers alternate in direction of orientation from about +45° to about -45° to the direction of the long dimension of the member.
Claim 5
Dependent Claim
24 words
The tennis racket frame of claim 2 wherein said plastic core has a density between about 20 and about 60 pounds per cubic foot.
Claim 6
Dependent Claim
74 words
The tennis racket frame of claim 2 wherein each end of said member is at the grip end of said handle, said member extending from one of its ends at the grip end of said handle up one side of said handle, around a major portion of the head of said frame and down the other side of said handle to the opposite end of said member at the grip end of said handle.
Claim 7
Dependent Claim
28 words
The tennis racket frame of claim 5 wherein said structural member is joined to a similar but shorter structural member which completes the ellipsoid shape of said head.
Claim 8
Dependent Claim
33 words
The tennis racket frame of claim 2 wherein said shell includes at least one layer of resin-coated unidirectionally oriented fibers at each of the opposite faces of said frame exterior to said shell.
Claim 9
Dependent Claim
17 words
The tennis racket frame of claim 2 wherein said high density weight control material is barium sulfate.
Claim 10
Dependent Claim
211 words
In a tennis racket frame having a handle and an ellipsoid head attached to one end of said handle and a grip element at the opposite end of said handle, an improved construction wherein said frame comprises a structural member of high strength to weight ratio comprising a core of an expanded porous resinous material occupying from about 20 to about 60 pounds per cubic foot and containing from about 25 to about 75 volume percent of chopped cork and from zero to about 60 weight percent of a high density weight control material, said core being integrally bonded to a shell comprising a plurality of layers of resin-coated unidirectionally oriented graphite fibers, at least one of said graphite fiber layers having its fibers oriented in a direction different from the direction of orientation of the fibers in at least one other of said layers, each end of said member being at the grip end of said handle, said member extending from one of its ends at the grip end of said handle up one side of said handle, around a major portion of the head of said frame and down the other side of said handle to the opposite end of said member at the grip end of said handle.
Claim 11
Dependent Claim
211 words
In a tennis racket frame having a handle and an ellipsoid head attached to one end of said handle and a grip element at the opposite end of said handle, an improved construction wherein said frame comprises a structural member of high strength to weight ratio comprising a core of an expanded porous resinous material occupying from about 20 to about 60 pounds per cubic foot and containing from about 25 to about 75 volume percent of chopped cork and from zero to about 60 weight percent of a high density weight control material, said core being integrally bonded to a shell comprising a plurality of layers of resin-coated unidirectionally oriented graphite fibers, at least one of said graphite fiber layers having its fibers oriented in a direction different from the direction of orientation of the fibers in at least one other of said layers, each end of said member being at the grip end of said handle, said member extending from one of its ends at the grip end of said handle up one side of said handle, around a major portion of the head of said frame and down the other side of said handle to the opposite end of said member at the grip end of said handle.
Claim 12
Dependent Claim
33 words
The tennis racket frame of claim 9 wherein said frame is a lightweight frame and said core composition contains from zero to about 10 weight percent of said high density weight control material.
Claim 13
Dependent Claim
35 words
The tennis racket frame of claim 9 wherein said frame is a medium weight frame and said core composition contains from about 10 to about 25 weight percent of said high density weight control material.
Claim 14
Dependent Claim
35 words
The tennis racket frame of claim 9 wherein said frame is a heavy weight frame and said core composition contains from about 25 to about 60 weight percent of said high density weight control material.
Claim 15
Dependent Claim
129 words
In a tennis racket frame having a handle and an ellipsoid head attached to one end of said handle and a grip element at the opposite end of said handle, an improved construction wherein said frame comprises a structural member of high strength to weight ratio comprising a core of an expanded porous resinous material integrally bonded to a shell comprising at least one layer of resin-coated unidirectionally oriented graphite fibers, said shell completely encasing said core at any cross section transverse to the length of said member and said core containing from about 25 to about 75 volume percent of a low density filler material and from 10 to about 60 weight percent of a high density weight control material having a density in excess of about 4.
Claim 16
Dependent Claim
129 words
In a tennis racket frame having a handle and an ellipsoid head attached to one end of said handle and a grip element at the opposite end of said handle, an improved construction wherein said frame comprises a structural member of high strength to weight ratio comprising a core of an expanded porous resinous material integrally bonded to a shell comprising at least one layer of resin-coated unidirectionally oriented graphite fibers, said shell completely encasing said core at any cross section transverse to the length of said member and said core containing from about 25 to about 75 volume percent of a low density filler material and from 10 to about 60 weight percent of a high density weight control material having a density in excess of about 4.
Claim 17
Dependent Claim
35 words
The tennis racket frame of claim 13 wherein said frame is a medium weight frame and said core composition contains from about 10 to about 25 weight percent of said high density weight control material.
Claim 18
Dependent Claim
35 words
The tennis racket frame of claim 13 wherein said frame is a heavy weight frame and said core composition contains from about 25 to about 60 weight percent of said high density weight control material.
Claim 19
Dependent Claim
17 words
The tennis racket frame of claim 13 wherein said high density weight control material is barium sulfate.
References Cited (Backward Citations)
US2583198A
Cited
US3206201A
Cited
US3644168A
Cited
US3856614A
Cited
DE2505454A1
Cited
US4061520A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-07-15 | 1984-01-14 | 1984-07-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-07-15 | 1988-01-14 | 1988-07-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-07-15 | 1992-01-14 | 1992-07-15 | $7700.00 | Window Closed / Lapsed |