US 6,713,008 B1Granted

Method for making composite structures

OwnerDarrin Blake Teeterinventor

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Abstract

The present invention is a method for making a composite structure that includes three resin impregnated structural cloth layers including a bottom sheet, a top sheet and a core sheet. The core sheet is a continuously curved shape with flat valleys that are bonded to the bottom sheet and flat peaks that are bonded to the top sheet. In the invention process, a dry core sheet is sandwiched between two wax core molds that form the core sheet. The core molds and the core sheet are sandwiched between dry top and bottom sheets by rigid molds as the flat peaks and valleys of the core sheet make contact with the top and bottom sheets through openings in the core molds. Liquid resin is transferred into the dry sheets and then cured. The lay up is disassembled and the wax core molds are melted and drained from the finished, rigid structure.

Claims21

Dependent claims

A method for making a structure that includes at least two resin impregnated structural fibrous cloth layers including at least one face sheet and a core sheet having a continuously curved, three-dimensional shape with peak areas that are bonded to the at least one face sheet, the method comprising the following steps;

(a) sandwiching a dry core sheet of structural fibrous cloth between two core molds that fit together in an opposing manner so as to form the core sheet into a three-dimensional shape having alternating elevations and depressions that include peak areas and valley areas, the core molds having peak areas and open valley areas for exposing the valley areas and the peak areas of the core sheet, the core molds fashioned from a material that melts at a core mold melting temperature,
(b) sandwiching the core molds and the core sheet with at least one face sheet of structural fibrous cloth so that the peak areas of the core sheet contact the at least one face sheet,
(c) forming the resulting lay-up with at least one mold so as to press the layers of the lay-up together and shape the resulting lay-up to conform to a desired shape,
(d) transferring liquid resin into the core sheet and the at least one face sheet, the liquid resin having a curing temperature that is below the core mold melting temperature and a cured degradation temperature that is higher than the core mold melting temperature,
(e) curing the liquid resin that is in the layers of the structure resulting from step (d) at a temperature that is below the core mold melting temperature,
(f) melting and draining the core mold material out from between the cured layers of the structure resulting from step (e) at a temperature that is between the core mold melting temperature and the cured resin degradation temperature.

3 more elements

A method for making a composite panel from sheet of structural fiber cloth impregnated with hardened resin, the panel including a top sheet that conforms to a top surface, a bottom sheet that conforms to a bottom surface and a core sheet inter-connecting the top sheet and the bottom sheet, the core sheet having alternating elevations and depressions that vary in a continuously curving, three dimensional manner about a neutral geometric surface that is located between the top surface and the bottom surface, the elevations of the core sheet including substantially flat peak areas that match the top surface and that are bonded to the top sheet, the depressions of the core sheet including substantially flat valley areas that match the bottom surface and that are bonded to the bottom sheet, the method for making the composite panel comprising the following steps;

(a) obtaining a lower mold having a mold surface that conforms in shape to the shape to the bottom surface of the panel,
(b) placing a bottom sheet of dry structural fiber cloth on top of the lower mold,
(c) placing a first core mold on top of the bottom sheet, the first core mold fashioned from a material that melts at a melting temperature, the first core mold having a lower surface that matches the mold surface of the lower mold, the upper surface of the first core mold having alternating elevations and depressions that vary in a continuously curving, three dimensional manner corresponding to the desired shape of the core sheet, the first core mold also having openings located to correspond with the substantially flat valley areas of the core sheet,
(d) placing a second sheet of dry structural fiber cloth on top of the first core mold,
(e) placing a second core mold on top of the second sheet, the second core mold fashioned from a material that melts at a melting temperature, the second core mold having an upper surface that matches the upper mold, the lower surface of the second core mold having alternating elevations and depressions that vary in a continuously curving, three dimensional manner corresponding to the desired shape of the core sheet in an opposite fitting relationship with the shape of the upper surface of the first core mold, the second core mold having openings located to correspond with the substantially flat peak areas of the core sheet,
(f) placing a top sheet of dry structural fiber cloth on top of the second core mold,
(g) placing an upper mold on top of the top sheet having a lower surface that conforms in shape to the shape of the surface of the top sheet,
(h) pressing the bottom sheet, the first core mold, the core sheet, the second core mold, the top sheet and the upper mold together so that the bottom sheet is in contact with the core sheet at the locations of the valley areas of the core sheet and the top sheet is in contact with the core sheet at the locations of the peak areas of the core sheet,
(i) introducing a liquid thermosetting resin that cures at a temperature below the core melting temperature into the bottom sheet, the core sheet and the top sheet so that the thermosetting resin transfers into the bottom sheet, the core sheet and the top sheet, the thermosetting resin, when cured, having a resin degradation temperature that is above the melting temperatures of the first and second core molds,
(j) heating the panel to cure the thermosetting resin at a temperature below the melting temperatures of the first and second core molds so that the resin of the resin impregnated bottom sheet, core sheet and top sheet hardens and causes the top sheet, core sheet and bottom sheet to become cured and bonded to each other,
(k) removing the lower and upper molds to expose a cured panel that includes the cured top, bottom and core sheets with the lower core mold sandwiched between the bottom sheet and the core sheet and the upper core mold sandwiched between the core sheet and the top sheet,
(l) heating the cured panel to a temperature that is higher than the melting temperatures of the first and second core molds but lower than the resin degradation temperature to cause the core molds to melt and drain out of the panel to leave a cured panel having a cured bottom sheet, a cured top sheet and a cured central reinforcing core sheet with peak areas that are bonded to the top sheet and valley areas that are bonded to the bottom sheet.

9 more elements

Dependencies are inferred from the claim text.

Facts

Application: 10/092,192Filed 6 Mar 2002 · continuation in part
Priority: 23 Jun 2000
Granted: 30 Mar 2004
Term ends: Not estimatedThe source records don’t support an estimate.

Classification6 codes

B29C 70/48
Using matched moulds, e.g. for deforming sheet moulding compounds [SMC] or prepregs: and impregnating the reinforcements in the closed mould, e.g.…
B29C 70/025
Combinations of fibrous reinforcement and non-fibrous material: with particular filler
B29C 33/52
With means for, or specially constructed to facilitate, the removal of articles, e.g. of undercut articles: soluble or fusible
B29L 2024/003
Articles with hollow walls: comprising corrugated cores