Method of making hollow articles

Claim 1

A method of making a hollow article from first and second preformed sections, each section having spaced apart bonding surfaces and a wall intermediate the bonding surfaces, comprising the steps of: (a) assembling the first and second sections in such a manner that the bonding surfaces of the sections are opposing and the intermediate walls of the sections define a cavity therebetween, (b) forming a substantially fluid impermeable precursor diffusion bond between the opposing bonding surfaces by subjecting the assembled sections to pressure-temperature-time conditions where (1) a first external pressure is so applied to the first section with the cavity evacuated as to reduce any gaps between the opposing bonding surfaces and (2) a second external pressure less than the first external pressure is so applied to the first section with the cavity evacuated as to form a substantially fluid impermeable precursor diffusion bond between the opposing bonding surfaces, (c) subjecting the sections to pressure-temperature-time conditions where a third external pressure greater than the second external pressure is so applied to the first section and an internal pressure of substantially the same magnitude as said third external pressure is so applied to the cavity as to diffusion bond the bonding surfaces, and (d) subjecting the sections to pressure-temperature-time conditions where an internal pressure is so applied to the cavity with the intermediate wall of the first section positioned relative to a rigid external shaping surface as to shape the intermediate wall to the shaping surface to remove any inward distortion of the intermediate wall resulting from step (b).

Claim 2

A method of making a hollow article from first and second preformed sections, each section having spaced apart bonding surfaces and a wall intermediate the bonding surfaces, comprising the steps of: (a) assembling the first and second sections in such a manner that the bonding surfaces of the sections are opposing and the intermediate walls of the sections define a cavity therebetween, (b) forming a substantially fluid impermeable precursor diffusion bond between the opposing bonding surfaces by subjecting the assembled sections to pressure-temperature-time conditions where (1) a first external pressure is so applied to the first section with the cavity evacuated as to reduce any gaps between the opposing bonding surfaces and (2) a second external pressure less than the first external pressure is so applied to the first section with the cavity evacuated as to form a substantially fluid impermeable precursor diffusion bond between the opposing bonding surfaces, (c) subjecting the sections to pressure-temperature-time conditions where a third external pressure greater than the second external pressure is so applied to the first section and an internal pressure of substantially the same magnitude as said third external pressure is so applied to the cavity as to diffusion bond the bonding surfaces, and (d) subjecting the sections to pressure-temperature-time conditions where an internal pressure is so applied to the cavity with the intermediate wall of the first section positioned relative to a rigid external shaping surface as to shape the intermediate wall to the shaping surface to remove any inward distortion of the intermediate wall resulting from step (b).

Claim 11

The method of claims 1 or 9 wherein the first and second sections include cooperating bonding surfaces inboard of said spaced apart bonding surfaces and said inboard bonding surfaces are precursor bonded in step (b) and diffusion bonded in step (c) to form a rib between said sections, said rib dividing the cavity.

Claim 13

A method of making a hollow article from first and second preformed sections, each section having spaced apart bonding surfaces and a wall intermediate the bonding surfaces, comprising the steps of: (a) assembling the first and second sections in such a manner that the bonding surfaces of the sections are opposing and the intermediate walls of the sections define a cavity therebetween, (b) forming a substantially fluid impermeable precursor diffusion bond between the opposing bonding surfaces by subjecting the assembled sections to pressure-temperature-time conditions where (1) a first external pressure is so applied to the first section with the cavity evacuated as to reduce any gaps between the opposing bonding surfaces and then (2) a second external pressure less than the first external pressure is so applied to the first section with the cavity evacuated as to form the precursor diffusion, and (c) subjecting the sections to pressure-temperature-time conditions where a third external pressure of greater magnitude than the second external pressure is applied to the second section and an internal pressure of substantially the same magnitude as the third external pressure is applied to the cavity while the intermediate wall of the first section is positioned relative to a rigid shaping surface such that the intermediate wall of said first section is conformed to said shaping surface to remove any distortion resulting from step (b) and such that the bonding surfaces are diffusion bonded.

Claim 14

A method of making a hollow article from first and second preformed sections, each section having spaced apart bonding surfaces and a wall intermediate the bonding surfaces, comprising the steps of: (a) assembling the first and second sections in such a manner that the bonding surfaces of the sections are opposing and the intermediate walls of the sections define a cavity therebetween, (b) forming a substantially fluid impermeable precursor diffusion bond between the opposing bonding surfaces by subjecting the assembled sections to pressure-temperature-time conditions where (1) a first external pressure is so applied to the first section with the cavity evacuated as to reduce any gaps between the opposing bonding surfaces and then (2) a second external pressure less than the first external pressure is so applied to the first section with the cavity evacuated as to form the precursor diffusion, and (c) subjecting the sections to pressure-temperature-time conditions where a third external pressure of greater magnitude than the second external pressure is applied to the second section and an internal pressure of substantially the same magnitude as the third external pressure is applied to the cavity while the intermediate wall of the first section is positioned relative to a rigid shaping surface such that the intermediate wall of said first section is conformed to said shaping surface to remove any distortion resulting from step (b) and such that the bonding surfaces are diffusion bonded.

Claim 22

The method of claims 12 or 19 wherein the first and second sections include cooperating bonding surfaces inboard of cooperating peripheral bonding surfaces and said inboard bonding surfaces are precursor bonded in step (b) and are diffusion bonded together in step (c) to form a rib between said sections, said rib dividing the cavity.