US5061418A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Thermal expansion resin transfer molding
Assignee: Tertm Inc
•
Filing: 1989-11-15
•
Granted: 1991-10-29
•
Expires: 2009-11-15
Abstract
Abstract A method of forming a composite sandwich core molded article, including forming a thermo-elastic rigid foam core into a desired shape, wrapping the preformed foam core with a fabric, placing said wrapped preformed foam core in a mold whose inner confining surfaces form the shape of the final article, injecting a liquid thermosetting resin into the mold such that the thermosetting resin surrounds and wets the fabric wrapped about the preformed foam core, heating the mold to a temperature sufficient to expand the rigid foam core to compress the fabric wrapped surface of the foam core against the inner confining surfaces of the mold; and cooling the mold and removing the article from the mold.
Inventors
- 👤 Maximilian Ware
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 08:56
CPC Classifications
B; B29; B29C; B29C70/00; B29C70/68; B29C70/86; B29C70/865; B29C43/00; B29C43/32; B29C44/00; B29C44/02; B29C44/12; B29C44/1209
Claims Analysis
Total Claims: 39
Claim 1
Independent Claim
155 words
A method of forming a composite sandwich core molded article, comprising: (a) preforming a thermo-expandable rigid foam core into (b) wrapping the preformed foam core with a fabric; (c) placing said wrapped preformed foam core in a mold whose inner confining surfaces form the shape of the final article and which provides the capability of heating selected areas of said preformed foam core; (d) injecting a liquid thermosetting resin into the mold such that the thermosetting resin surrounds and wets the fabric wrapped about the preformed foam core; (e) selectively heating desired areas of the mold to a temperature sufficient to expand the rigid foam core under the areas of the mold being heated to compress the fabric wrapped surface of the foam core against the inner confining surfaces of the mold and completing the heating of the rigid foam core to complete the molding process; and (f) cooling the mold and removing the article.
Claim 2
Independent Claim
155 words
A method of forming a composite sandwich core molded article, comprising: (a) preforming a thermo-expandable rigid foam core into (b) wrapping the preformed foam core with a fabric; (c) placing said wrapped preformed foam core in a mold whose inner confining surfaces form the shape of the final article and which provides the capability of heating selected areas of said preformed foam core; (d) injecting a liquid thermosetting resin into the mold such that the thermosetting resin surrounds and wets the fabric wrapped about the preformed foam core; (e) selectively heating desired areas of the mold to a temperature sufficient to expand the rigid foam core under the areas of the mold being heated to compress the fabric wrapped surface of the foam core against the inner confining surfaces of the mold and completing the heating of the rigid foam core to complete the molding process; and (f) cooling the mold and removing the article.
Claim 3
Dependent Claim
20 words
The method of claim 1, wherein said rigid foam core is shaped in step (a) by direct molding with heat.
Claim 4
Dependent Claim
20 words
The method of claim 1, wherein said rigid foam core is shaped in step (a) by compression molding with heat.
Claim 5
Dependent Claim
173 words
The method of claim 1, wherein said mold provides said selective heating capability by virtue of its construction which comprises at least two mold portions defining a mold cavity when brought together, at least one said mold portion comprised of spaced apart exterior and interior surfaces, said interior surface adjacent said mold cavity, said exterior and interior surfaces defining a hollow interior therebetween, in which a series of vertical baffles are placed in spaced apart relationship within the hollow interior between the exterior and interior metal surfaces of said mold portion with a hollow interior; and wherein said selective heating of said rigid foam core is achieved by passing a fluid heated to the desired temperature into said mold portion having a hollow interior so that the fluid flows into the hollow interior of said mold portion in a pattern which is defined by said baffles in order to provide a uniform distribution of heat to effect a controlled rate of expansion of the selected area of said rigid form core being heated.
Claim 6
Dependent Claim
43 words
The method of claim 4, wherein the molding process is completed by allowing said heated fluid to flow through all regions of the hollow interior of each mold portion to provide the heat necessary for the complete expansion of said rigid foam core.
Claim 7
Dependent Claim
73 words
The method of claim 4, wherein the composite molded article being formed is the blade of a paddle, and wherein the molding of the blade is effected by initially selectively heating the interior confining surfaces of each mold portion which define the broad surface area of the blade and then completing the molding of the blade by heating that portion of the foam core which is joined to the shaft of the paddle.
Claim 8
Dependent Claim
15 words
The method of claim 4, wherein the mold of step (c) is made of nickel.
Claim 9
Dependent Claim
18 words
The method of claim 1, wherein said fabric is compressed by the expanding foam core at 100 psi.
Claim 10
Dependent Claim
24 words
The method of claim 1, wherein the shape of the confining surfaces of the mold define the structure of the blade of a paddle.
Claim 11
Dependent Claim
23 words
The method of claim 1, wherein the heat expandable material of the rigid foam core is polyvinyl chloride, a polyurethane or a polyimide.
Claim 12
Dependent Claim
37 words
The method of claim 1, wherein said thermosetting resin is a low viscosity epoxy resin formulated with a gel time which is sufficiently long so as not to interfere with the expansion of the rigid foam core.
Claim 13
Dependent Claim
17 words
The method of claim 1, wherein the thermosetting resin has a viscosity of less than 8000 cp.
Claim 14
Dependent Claim
21 words
The method of claim 1, wherein the fabric wrapping of step (b) is a dry fabric, a prepreg or combination thereof.
Claim 15
Dependent Claim
18 words
The method of claim 1, wherein the dry fabric wrapping is made of aramid, fiberglass, graphite or polyester.
Claim 16
Dependent Claim
13 words
The method of claim 1, wherein the fabric wrapping is a prepreg material.
Claim 17
Dependent Claim
27 words
The method of claim 1, wherein during the expansion of the foam core in step (e), excess thermosetting resin is expelled from the interior of the mold.
Claim 18
Independent Claim
199 words
A method of forming a composite sandwich core molded article, comprising: a) preforming a thermo-expandable rigid foam core into desired shape by molding of a resin selected from the group consisting of polyimides, polyvinyl chlorides, and mixtures thereof; b) wrapping the pre-formed foam core with a fabric; c) placing said wrapped pre-formed foam core in a mold whose inner confining surfaces form the shape of the final article and which provides the capability of heating selected areas of said pre-formed foam core; d) injecting a liquid thermosetting resin into the mold such that the thermosetting resin surrounds and wets the fabric wrapped about the pre-formed foam core; e) selectively heating desired areas of the mold to a temperature sufficient to only apply heat in a given area of the rigid foam core, while other areas of the rigid foam core experience no substantial heating to expand the rigid foam core under the areas of the mold being heated to compress the fabric wrapped surface of the foam core against the inner confining surfaces of the mold and completing the heating of the rigid foam core to complete the molding process; and f) cooling the mold and removing the article.
Claim 19
Independent Claim
199 words
A method of forming a composite sandwich core molded article, comprising: a) preforming a thermo-expandable rigid foam core into desired shape by molding of a resin selected from the group consisting of polyimides, polyvinyl chlorides, and mixtures thereof; b) wrapping the pre-formed foam core with a fabric; c) placing said wrapped pre-formed foam core in a mold whose inner confining surfaces form the shape of the final article and which provides the capability of heating selected areas of said pre-formed foam core; d) injecting a liquid thermosetting resin into the mold such that the thermosetting resin surrounds and wets the fabric wrapped about the pre-formed foam core; e) selectively heating desired areas of the mold to a temperature sufficient to only apply heat in a given area of the rigid foam core, while other areas of the rigid foam core experience no substantial heating to expand the rigid foam core under the areas of the mold being heated to compress the fabric wrapped surface of the foam core against the inner confining surfaces of the mold and completing the heating of the rigid foam core to complete the molding process; and f) cooling the mold and removing the article.
Claim 20
Dependent Claim
169 words
The method of claim 17, wherein said mold provides said selective heating capability by virtue of its construction which comprises at least two mold portions defining a mold cavity when brought together, at least one said portion comprised of spaced apart exterior and interior surfaces, said interior surface adjacent said mold cavity, said exterior and interior surfaces defining a hollow interior therebetween, in which a series of vertical baffles are placed in spaced apart relationship within the hollow interior between the exterior and interior metal surfaces of said mold portion; and wherein said selective heating of said rigid foam core is achieved by passing a fluid heated to the desired temperature into said mold portion having a hollow interior so that the fluid flows into the hollow interior of said mold portion in a pattern which is defined by the said baffles in order to provide a uniform distribution of heat to effect a controlled rate of expansion of the selected area of said rigid foam core being heated.
Claim 21
Dependent Claim
43 words
The method of claim 18, wherein the molding process is completed by allowing said heated fluid to flow through all regions of the hollow interior of each mold portion to provide the heat necessary for the complete expansion of said rigid foam core.
Claim 22
Dependent Claim
73 words
The method of claim 18, wherein the composite molded article being formed is the blade of a paddle, and wherein the molding of the blade is effected by initially selectively heating the interior confining surfaces of each mold portion which define the broad surface area of the blade and then completing the molding of the blade by heating that portion of the foam core which is joined to the shaft of the paddle
Claim 23
Dependent Claim
15 words
The method of claim 18, wherein the mold of step (c) is made of nickel.
Claim 24
Dependent Claim
22 words
The method of claim 17, wherein the pressure of compression exerted by the expanding foam core is as high as 100 psi.
Claim 25
Dependent Claim
22 words
The method of claim 17, wherein the shape of the confining surfaces of the mold define the structure of a paddle blade.
Claim 26
Dependent Claim
37 words
The method of claim 17, wherein said thermosetting resin is a low viscosity epoxy resin formulated with a gel time which is sufficiently long so as not to interfere with the expansion of the rigid foam core.
Claim 27
Dependent Claim
17 words
The method of claim 17, wherein the thermosetting resin has a viscosity of less than 8000 cp.
Claim 28
Dependent Claim
21 words
The method of claim 17, wherein the fabric wrapping of step (b) is a dry fabric, a prepreg or combination thereof.
Claim 29
Dependent Claim
18 words
The method of claim 17, wherein the dry fabric wrapping is made of aramid, fiberglass, graphite or polyester.
Claim 30
Dependent Claim
13 words
The method of claim 17, wherein the fabric wrapping is a prepreg material.
Claim 31
Dependent Claim
25 words
The method of claim 17 further comprising expelling excess thermoset resin from the interior of the mold during the expansion of the foam core (e).
Claim 32
Independent Claim
166 words
A method of forming a composite sandwich core molded article, comprising: providing a thermo-expandable preformed foam core wrapped with reinforcing fiber; placing said fiber wrapped preformed foam core in a mold whose inner confining surfaces form the shape of the final articles and which provides the capability of selectively heating areas of said fiber wrapped preformed foam core; injecting a liquid thermosetting resin into the mold such that the thermosetting resin surrounds and wets the fiber wrapped about the preformed foam core; heating selected mold areas to a temperatures sufficient to expand the preformed foam core adjacent said selected areas to compress the wetted fiber against the inner confining surfaces of the mold in said selected areas, to expand the rigid foam core in said areas while other areas of the rigid foam core experience no substantial heating prior to heating to complete the molding step, heating remaining areas of said foam core to complete the molding process; and cooling the mold and removing the article.
Claim 33
Independent Claim
166 words
A method of forming a composite sandwich core molded article, comprising: providing a thermo-expandable preformed foam core wrapped with reinforcing fiber; placing said fiber wrapped preformed foam core in a mold whose inner confining surfaces form the shape of the final articles and which provides the capability of selectively heating areas of said fiber wrapped preformed foam core; injecting a liquid thermosetting resin into the mold such that the thermosetting resin surrounds and wets the fiber wrapped about the preformed foam core; heating selected mold areas to a temperatures sufficient to expand the preformed foam core adjacent said selected areas to compress the wetted fiber against the inner confining surfaces of the mold in said selected areas, to expand the rigid foam core in said areas while other areas of the rigid foam core experience no substantial heating prior to heating to complete the molding step, heating remaining areas of said foam core to complete the molding process; and cooling the mold and removing the article.
Claim 34
Dependent Claim
29 words
The method of forming a composite sandwich core molded article of claim 30 and wherein the fiber is chosen from the group consisting of: graphite, aramid, fiberglass and polyester.
Claim 35
Dependent Claim
39 words
The method of forming a composite sandwich core molded article of claim 30 and wherein the fiber is in the form of a unidirectional fabric, a woven fabric, a knitted material, a braided material, filaments, or hybrid braided fabric.
Claim 36
Dependent Claim
14 words
The method of claim 32 wherein the fiber is part of a prepreg fabric.
Claim 37
Dependent Claim
33 words
The method forming a composite sandwich core molded article of claim 30 and wherein the preformed foam core is provided by a method comprising: forming a thermo-expandable rigid foam core into desired shape.
Claim 38
Dependent Claim
23 words
The method of forming a composite sandwich core molded article of claim 34 and wherein the forming step includes direct molding with heat.
Claim 39
Dependent Claim
15 words
The method of claim 34 and wherein the forming step includes compression molding with heat.
References Cited (Backward Citations)
US4128963A
Cited
US4560523A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-10-28 | 1995-04-29 | 1995-10-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-10-28 | 1999-04-29 | 1999-10-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-10-28 | 2003-04-29 | 2003-10-29 | $7700.00 | Window Closed / Lapsed |