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US 4,126,659 AGranted
Method of making a hollow article
AssigneeLockheed Aircraft Corporation
InventorLeiv H. Blad
Life of this patent
Estimating the term…
Abstract
The invention relates to a method and apparatus for making hollow, resin-impregnated fibrous fabric articles. Specifically, it relates to a method wherein a reusable mandrel is made sufficiently rigid to receive a lay-up of the article to be manufactured. The rigidized assembly is placed within a female mold, derigidized and expanded to apply pressure from within, thereby forcing the lay-up against the interior of the mold. Heat is applied to cure the resin, producing an article having a very high degree of dimensional accuracy.
Claims22
A method for making a hollow, resin-impregnated fibrous article comprising the steps of:
- fabricating from a flexible, porous material a pressurizable inflatable and re-usable mandrel incorporating pressurization means for introducing into and extracting from said mandrel a liquid rigidizing medium, said mandrel having an external configuration substantially corresponding to the intended interior of the article;
- flowing a liquid rigidizing medium into the mandrel at a temperature above ambient;
- reducing to ambient temperature the liquid medium, thereby causing the medium to solidify and the mandrel to rigidize;
- assembling at least one layer of resin-impregnated fibrous material upon the rigidized mandrel;
- covering the assembled fibrous material and rigidized mandrel with an envelope having an internal configuration corresponding to the desired external configuration of the article;
- derigidizing the mandrel;
- pressurizing the interior of the mandrel to a pressure above ambient;
- heating the assembly within the envelope to a temperature above ambient for a time sufficient to cure the resin;
- reducing the temperature of the cured article to ambient temperature;
- reducing the pressure within the mandrel to ambient pressure;
- removing the envelope from the exterior of the cured article;
- and
- removing the mandrel from within the cured article.
10 more elements
A method for making a hollow, resin-impregnated fibrous article comprising the steps of:
- fabricating from a flexible, porous material a pressurizable inflatable and re-usable mandrel incorporating pressurization means for introducing into and extracting from said mandrel a liquid rigidizing medium, said mandrel having an external configuration substantially corresponding to the intended interior of the article;
- installing the mandrel in a mold having an internal configuration substantially conforming to the intended internal configuration of the article;
- heating a rigidizing medium which is normally rigid at ambient temperature until it is liquified;
- flowing the liquidized medium into the mandrel until the mandrel is filled;
- sealing off the filled mandrel;
- cooling the liquid rigidizing medium until it is solidified and the mandrel is thereby rigidized;
- removing the mold from around the rigidized mandrel;
- assembling at least one layer of resin-impregnated fibrous material upon the rigidized mandrel;
- covering the assembled fibrous material and rigidized mandrel with an envelope having an internal configuration corresponding to the desired external configuration of the article;
- derigidizing the mandrel;
- pressurizing the interior of the mandrel to a pressure above ambient;
- heating the assembly within the envelope to a temperature above ambient for a time sufficient to cure the resin;
- reducing the temperature of the cured article to ambient temperature;
- reducing the pressure within the mandrel to ambient pressure;
- removing the envelope from the exterior of the cured article;
- and
- removing the mandrel from within the cured article.
14 more elements
A method for making a hollow, resin-impregnated fibrous article comprising the steps of:
- fabricating an inflatable and re-usable mandrel of predetermined external configuration, the mandrel incorporating pressurization means for introducing and extracting a rigidizing medium liquid above ambient temperature, but rigid at substantially ambient temperatures;
- rigidizing the mandrel by introducing said liquid rigidizing medium into said mandrel at a temperature above ambient and then cooling the same to substantially ambient temperature;
- assembling at least one layer of resin-impregnated fibrous material upon the rigidized mandrel;
- inserting the assembled fabric and rigidized mandrel in a rigid envelope having an internal configuration substantially corresponding to the desired exterior of the article;
- placing an impervious flexible cover over the envelope and sealing it therearound;
- evacuating the region internally of the cover;
- derigidizing the mandrel by elevating the temperature and extracting said liquid rigidizing medium;
- heating the assembly above ambient temperature for a time sufficient to cure the resin;
- returning the cured article to ambient temperature;
- removing the cover and envelope from the exterior of the cured article;
- and
- removing the mandrel from within the cured article.
9 more elements
A method for making a hollow, resin-impregnated fibrous article comprising the steps of:
- fabricating a flexible hollow sleeve having an external configuration substantially corresponding to the intended interior configuration of the article;
- fabricating an uncollapsed, non-inflated mandrel incorporating pressurization means for introducing and extracting a liquid rigidizing medium, the mandrel having an external configuration substantially corresponding to the sleeve interior;
- placing the sleeve on the mandrel;
- flowing a liquid rigidizing medium into the mandrel;
- solidifying the medium causing the mandrel to rigidize, so as to support and rigidize the sleeve;
- assembling at least one ply of resin-impregnated fibrous material upon the rigidized sleeve;
- locating the assembled material and rigidized sleeve within an envelope having an internal configuration substantially corresponding to the intended exterior of the article in a mating relationship;
- derigidizing the mandrel;
- increasing to above ambient the pressure interiorly of the mandrel;
- heating the assembled material, sleeve and envelope above ambient temperature for a time sufficient to cure the article;
- returning the cured article to ambient temperature;
- returning the pressure within the interior of the mandrel to ambient;
- removing the mandrel from within the sleeve;
- and
- removing the sleeve from within the cured article.
12 more elements
A method for making a hollow, resin-impregnated fibrous article comprising the steps of:
- fabricating a flexible hollow sleeve having an external configuration substantially corresponding to the intended interior configuration of the article;
- fabricating an uncollapsed, non-inflated mandrel incorporating pressurization means for introducing and extracting a liquid rigidizing medium, the mandrel having an external configurating substantially corresponding to the sleeve interior;
- placing the sleeve on the mandrel;
- installing the mandrel in a mold having substantially the intended internal configuration of the article;
- heating to a liquid state a rigidizing medium;
- filling the mandrel with the liquid medium;
- sealing off the filled mandrel;
- cooling and solidifying the liquid medium and the mandrel;
- removing the mold from around the rigidized mandrel, so as to support and rigidize the sleeve;
- assembling at least one ply of resin-impregnated fibrous material upon the rigidized sleeve;
- locating the assembled material and rigidized sleeve within an envelope having an internal configuration substantially corresponding to the intended exterior of the article in a mating relationship;
- derigidizing the mandrel;
- increasing to above ambient the pressure interiorly of the mandrel;
- heating the assembled material, sleeve and envelope above ambient temperature for a time sufficient to cure the article;
- returning the cured article to ambient temperature;
- returning the pressure within the interior of the mandrel to ambient;
- removing the mandrel from within the sleeve;
- and
- removing the sleeve from within the cured article.
16 more elements
A process for making a hollow, resin-impregnated fibrous article comprising the steps of:
- fabricating a flexible, hollow sleeve having an external configuration substantially corresponding to the intended interior of the article;
- fabricating a collapsible, inflatable mandrel with pressurization means therein for introducing and extracting a liquid rigidizing medium, the mandrel normally having an external configuration substantially corresponding to the interior of the sleeve;
- placing the sleeve around the mandrel;
- flowing a liquid rigidizing medium into the mandrel;
- solidifying the medium causing the mandrel to rigidize, so as to support and rigidize the sleeve;
- assembling at least one ply of resin-impregnated fibrous material upon the rigidized sleeve;
- assembling the material and rigidized mandrel and sleeve into an envelope having an internal configuration substantially corresponding to the intended exterior of the article;
- placing an impervious flexible cover over the envelope and sealing it to the sleeve, thereby defining a container around the envelope and assembled material;
- evacuating the container;
- derigidizing the mandrel;
- heating the assembled material above ambient temperature for a time sufficient to cure the resin-impregnated material and define the article;
- returning the cured article to ambient temperature;
- removing the flexible cover and envelope from around the cured article;
- removing the mandrel from within the sleeve;
- and
- removing the sleeve from within the cured article.
13 more elements
Dependencies are inferred from the claim text.