Method and apparatus for forming structural articles
AssigneeArmacel Pty Limited
InventorFrank Anthony Matich
Life of this patent
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Abstract
The present invention discloses structural articles such as helmets, cooler chests, pallets, building boards and a large number of diverse articles all formed from an inner, preferably air permeable, body to which a structural strength imparting skin or layer has been applied to either a single surface or opposite surfaces. The body can be expanded polystyrene, wood, particle board, cellulosic fiber cement, GECET or CARIL. The sheet or skin can be acrylonitrile butadiene styrene (ABS), polyester, styrene, or polycarbonate. Amorphous polyester (APET) is particularly preferred. A method of forming such structural articles and apparatus for use in carrying out the method are also disclosed.
Claims45
A method of forming an article having load bearing capabilities from a shape defining interior member, said shape defining interior member being not inherently load bearing and being at least partially fluid permeable, and at least one external skin, said method comprising the steps of:
- (1) heating a thermoplastic sheet intended to form said external skin;
- (2) bringing said heated sheet alongside said interior member to overlie;
- (3) applying a fluid pressure differential between opposite sides of said shape defining interior member and said thermoplastic sheet to conform said thermoplastic sheet to the shape of said shape defining interior member and mutually engage said shape defining interior member, air trapped between said thermoplastic sheet and said shape defining interior member passing through at least said shape defining interior member;
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- (4) maintaining the fluid pressure differential until said thermoplastic sheet has cooled whereupon tensional forces arise in said thermoplastic sheet in all directions.
An apparatus for forming an article having load bearing capabilities from at least one external skin and a shape defining interior member, said shape defining interior member being not inherently load bearing being and at least partially fluid permeable, said apparatus comprising:
- (1) a sheet holding device to hold a sheet of plastic material around a periphery of the sheet or adjacent a pair of opposite edges of the sheet;
- (2) a former to hold and support the shape defining interior member;
- (3) translation means to move said former relative to said sheet holding device, moving the sheet and shape defining interior member together;
- (4) heating means to heat a thermoplastic sheet held in said sheet holding device to at least partially soften said sheet;
- (5) pressure differential means to create a pressure differential between the sheet and shape defining interior member to conform the sheet to the member, so that air trapped between the sheet and the shape defining interior member passes through the shape defining interior member;
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- (6) a cooling system facing a surface of the sheet that is not engaged with the shape defining interior member, wherein said pressure differential means maintains the pressure differential until the sheet has cooled whereby tensional forces arise in the sheet in all directions.
The article as claimed in claim 26 having an internal void.
An article having load bearing capabilities, said article comprising a shape defining interior member and at least one external skin, said shape defining interior member not being inherently load bearing and being at least partially fluid permeable, said external skin being a thermoplastic sheet, wherein said thermoplastic sheet is softened by heating and conformed to the shape of said interior member by applying a fluid pressure differential that draws air trapped between the thermoplastic sheet and at least through said shape defining interior member, the fluid pressure differential being maintained until said thermoplastic sheet has cooled whereby tensional forces arise in said thermoplastic sheet in all directions.
Dependencies are inferred from the claim text.