Open-top shell molding apparatus

Claim 2

A moulding apparatus for use in the formation of an open-top bowl-like shell whereof at least some of the external surface is curved, comprising: a. a pliant, inelastic form layer which when tensioned both longitudinally and laterally assumes the shape required of the said external surface; b. a top rail member which conforms to the shape required of the shell rim bordering said curved surface and to which the upper edge of said form layer is attached; c. means to fixedly support said top rail member in conformity with said required rim shape; d. a pliant envelope spaced from and externally surrounding said form layer thereby to define with said form layer at least one enclosure; e. means to vary the fluid pressure within said enclosure so that the fluid pressure on the moulding face of said form layer is different from that on its opposite face thereby to bulge said form layer into a condition of tensed stiffness.

Claim 3

A moulding apparatus for use in the formation of an open-top bowl-like shell whereof at least some of the external surface is curved, comprising: a. a pliant, inelastic form layer which when tensioned both longitudinally and laterally assumes the shape required of the said external surface; b. a top rail member which conforms to the shape required of the shell rim bordEring said curved surface and to which the upper edge of said form layer is attached; c. a bottom rail member to which the lowermost portion of said form layer is attached; d. means to fixedly support said top rail member in conformity with said required rim shape; e. means to fixedly support said bottom rail member in relation to said top rail member; f. a pliant envelope spaced from and externally surrounding said form layer so as to define with said form layer at least one enclosure, said envelope having its top edges secured to said top rail member and a bottom portion secured to said bottom rail member; and g. means to vary the fluid pressure within said enclosure so that the fluid pressure on the moulding face of said form layer is different from that on its opposite face thereby to bulge said form layer into a condition of tensed stiffness.

Claim 4

A moulding apparatus for use in the formation of an open-top bowl-like shell whereof at least some of the external surface is curved, comprising: a. a pliant, inelastic form layer which when tensioned both longitudinally and laterally assumes the shape required of the said external surface; b. a top rail member which conforms to the shape required of the shell rim bordEring said curved surface and to which the upper edge of said form layer is attached; c. a bottom rail member to which the lowermost portion of said form layer is attached; d. means to fixedly support said top rail member in conformity with said required rim shape; e. means to fixedly support said bottom rail member in relation to said top rail member; f. a pliant envelope spaced from and externally surrounding said form layer so as to define with said form layer at least one enclosure, said envelope having its top edges secured to said top rail member and a bottom portion secured to said bottom rail member; and g. means to vary the fluid pressure within said enclosure so that the fluid pressure on the moulding face of said form layer is different from that on its opposite face thereby to bulge said form layer into a condition of tensed stiffness.

Claim 5

Moulding apparatus as claimed in claim 2, wherein separate sealed chambers are formed within said enclosure between the inner side of said mould surface and the opposed inner side of the remainder of said enclosure, such chambers extending over a defined region of said mould surface, and means for controlling the fluid pressure within said chambers, thereby to modify the contour of said mould surface.

Claim 6

Moulding apparatus as claimed in claim 2, wherein said means for controlling the fluid pressure within the enclosure comprises means for varying the volume of the enclosure.

Claim 7

Moulding apparatus as claimed in claim 4 wherein said means for varying the volume of the enclosure comprises adjustable means attaching the remaining surface of said enclosure to said frame.

Claim 8

Moulding apparatus as claimed in claim 2 wherein the said enclosure includes sections which may be removed or inserted thereby to alter the contour of ar least part of the mould surface.

Claim 9

Moulding apparatus as claimed in claim 6 wherein the mould surface is removably attached to the remainder of the enclosure.

Claim 10

Moulding apparatus as claimed in claim 2 wherein said mould surface includes rigid areas of fixed contour adjacent flexible regions thereof.

Claim 11

Moulding apparatus as claimed in claim 2 wherein means are provided for the application and control of tension in the material of said mould surface.

Claim 12

Moulding apparatus as claimed in claim 9 wherein said means is provided by the means for attachment of said enclosure to said frame.