US4049767A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Rotational molding process for forming a closed hollow toroidal article
Assignee: Individual
•
Filing: 1975-10-28
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Granted: 1977-09-20
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Expires: 1995-10-28
Abstract
Abstract Closed hollow toroidal articles such as hollow tires, which may be caused to be thickest at the tread, are molded on the inner surface of a closed toroidal mold slowly rotating on a horizontal axis by charging a fluid elastomer material in such quantity as to fill the bottom of the mold to a level above the wheel-supporting part of the tire and continuing rotation while causing the material to set to a solid elastomer progressively inwards from the liquid contacting surface of the mold. The relative thickness of different parts can be adjusted by changes in rotation, or by inducing different rates of setting in different parts of the mold.
Inventors
- 👤 Deepak V. Vaidya
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 08:51
CPC Classifications
B; B29; B29D; B29D30/00; B29D30/06; B29D30/0679; B29C; B29C41/00; B29C41/02; B29C41/04; B29C41/042; B29C41/047
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
138 words
A process for molding a closed hollow toroidal article thickest at its outer periphery, which comprises charging one part of a split hollow toroidal mold with a fluent material which can be caused to set to a solid, in a quantity substantially less than that required to fill the mold cavity but sufficient to fill completely the lower arc of the mold cavity such that the fluent material is in contact with all portions of the cross-sectional periphery of the lowermost radial section of the toroidal mold when its axis is horizontal, completely closing the mold, placing the mold with its axis horizontal, slowly rotating the mold on its axis, causing the material to set progressively from the inner surface of the mold until the entire charge of material is solidified, opening the mold, and removing the article.
Claim 2
Dependent Claim
138 words
A process for molding a closed hollow toroidal article thickest at its outer periphery, which comprises charging one part of a split hollow toroidal mold with a fluent material which can be caused to set to a solid, in a quantity substantially less than that required to fill the mold cavity but sufficient to fill completely the lower arc of the mold cavity such that the fluent material is in contact with all portions of the cross-sectional periphery of the lowermost radial section of the toroidal mold when its axis is horizontal, completely closing the mold, placing the mold with its axis horizontal, slowly rotating the mold on its axis, causing the material to set progressively from the inner surface of the mold until the entire charge of material is solidified, opening the mold, and removing the article.
Claim 3
Dependent Claim
17 words
A process as in claim 1, in which the material is caused to set by external heat.
Claim 4
Dependent Claim
20 words
A process as in claim 1, in which the material is one which becomes elastomeric upon setting to a solid.
Claim 5
Dependent Claim
15 words
A process as in claim 3, in which the material is a polyurethane elastomer mix.
Claim 6
Dependent Claim
37 words
A process as in claim 3, in which the inner periphery of the mold cavity has the contour of a wheel rim and the outer periphery of the mold cavity is shaped for producing a tire tread.
Claim 7
Dependent Claim
15 words
A process as in claim 5, in which the material is a polyurethane elastomer mix.
Claim 8
Dependent Claim
33 words
A process as in claim 1, in which the speed of rotation is increased to a centrifugal speed after a predetermined portion of the charge of material is set to a non-flowable condition.
Claim 9
Dependent Claim
40 words
A process as in claim 1, in which the material is set by heat and the supply of heat to the charge of material in the mold is greater at one zone than at the other zone of the mold.
Claim 10
Dependent Claim
33 words
A process as in claim 6, in which the speed of rotation is increased to a centrifugal speed after a predetermined portion of the charge of material is set to a non-flowable condition.
Claim 11
Dependent Claim
17 words
A process as in claim 9, in which the material is caused to set by external heat.
Claim 12
Dependent Claim
32 words
A process as in claim 10, in which the supply of heat to the charge of material in the mold is greater at one zone than at another zone of the mold.
Claim 13
Dependent Claim
27 words
A process as in claim 1, in which reinforcing strands are supported in the mold in positions in which they become embedded in the charge of material.
Claim 14
Dependent Claim
27 words
A process as in claim 11, in which reinforcing strands are supported in the mold in positions in which they become embedded in the charge of material.
References Cited (Backward Citations)
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US2944814A
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US3555141A
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US3645655A
Cited
US3751551A
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UST948001I4
Cited
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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) | 1980-09-19 | 1981-03-21 | 1981-09-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-09-19 | 1985-03-21 | 1985-09-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-09-19 | 1989-03-21 | 1989-09-20 | $7700.00 | Window Closed / Lapsed |