British Aerospace Public Limited Company

British Aerospace Plc

David J Irwin

Martin H Mansbridge

John Norton

David Stephen

Paul W Beazley-Long

A method of forming a diffusion bonded joint during superplastic forming of a hollow metal structure (43) from sheet material (15, 16, 17, 18) using a two-piece die (1) having opposed clenching faces (9, 10) disposed along a split line (2) thereof, the structure 43 being formed with a joint at the split line, the method including placing the sheets (15, 16, 17, 18) between the faces (9, 10) clenching the sheets with a pressure sufficient to locate same during superplastic forming while being insufficient to deform the metal and prevent superplastic flow in the sheets between the clenching faces (9, 10), heating the sheets to a superplastic forming temperature and applying a gas pressure between the sheets to commence superplastic forming, when superplastic metal flow between the clenching faces substantially ceases upset forging metal from between the faces towards the interior of the die to increase wall thickness at the joint upon trimming off a flange formed by that part of the sheets trapped between the clenching faces. A die to carry out the above method, a die and sheet assembly and a structure manufactured according to the method are also provided.

Forming of diffusion bonded joints in superplastically formed metal

A method of superplastically forming a metal article and an article formed by such a method are provided. The method includes the steps of placing sheet material including at least one sheet of superplastically formable material (2, 3) and a sheet of reinforcing material (10) adjacent a said sheet (2) of superplastically formable material within a mold tool having a male former (18) protruding from the tool surface positioned to contact the sheet of reinforcing material during forming and causing the at least one superplastically formable sheet (2, 3) adjacent the reinforcing sheet (10) to be superplastically formed into conformation with the surface (28) of the mold tool and simultaneously to urge the sheet of reinforcing material (10) against the male former (18). The method is characterised by thinning at least one selected area (14, 15, 16, 17) of the sheet of reinforcing material (10), the at least one area being adapted to form around at least one region of high curvature (19, 20, 21, 22) of the male former (18) whereby to promote controlled folding of the reinforcing sheet (10) about the former.

Forming of metal articles

A structural box beam of the type formed by a method using superplastic forming and diffusion bonding techniques (SPF/DB). The basis is a SPF/DB four sheet cellular structure box beam, for particular application to a flap track beam for aircraft, said box beam including integrally formed flap track flanges and corrugated shear webs. The corrugations serve the dual purpose of reacting local track bending moments. Internal shear webs are integrally formed as part of the cellular structure. The box beam is designed to be manufactured from a flat blank assembly consisting of four chemically-etched sheets with local reinforcements placed between the core and skin sheets providing a low cost means of tailoring the beam to minimum thickness requirements.

Structural box beams

A method of forming a stiffened panel from first and second metal sheets, at least the first sheet being capable of both superplastic deformation and diffusion bonding, and also provided with at least one control region of different thickness compared with other regions of the sheet, includes the steps of:

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Bristol, United Kingdom

David J Irwin