US 5,323,536 AGranted

Method of manufacturing an article by superplastic forming and diffusion bonding

AssigneeROLLS-ROYCE plc

InventorsJohn O. Fowler, Brian Richardson

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Abstract

A plurality of workpieces are assembled into a stack. Two of the workpieces are machined on one surface at predetermined positions from the edges of the workpieces. The workpieces are stacked so that the machined surfaces of the workpieces face away from each other. Two workpieces are provided with a stop off material on one of their surfaces to prevent diffusion bonding at predetermined positions. The edges of the workpieces are welded together and a pipe is welded to the stack to interconnect with the stop off material to form a sealed assembly. The workpieces are diffusion bonded together. The integral structure formed is heated and opposite ends of the integral structure are twisted relatively to contour the integral structure to a predetermined shape. The integral structure is heated and the machined portions on the workpieces are isothermally forged and then the twisted integral structure is internally pressurised to superplastically form one workpiece to produce an article, eg a fan blade.

Claims36

Dependent claims

A method of manufacturing an article by superplastic forming and diffusion bonding at least two workpieces comprising the steps of:

(a) forming a first workpiece which has a flat surface,
(b) forming a second workpiece which has a flat surface, the first and second workpieces defining the outer profile of the finished article,
(c) machining a portion of a surface of at least the first workpiece at a predetermined distance from at least a portion of the periphery of the first workpiece, the said surface being opposite to the flat surface of the first workpiece,
(d) applying a stop off material to prevent diffusion bonding to preselected areas of at least one of the flat surfaces of at least one of the at least two workpieces,
(e) assembling the at least two workpieces into a stack relative to each other so that the flat surfaces are in mating abutment,
(f) applying heat and pressure across the thickness of the at least two workpieces to diffusion bond the at least two workpieces together in areas other than the preselected areas to form an integral structure,
(g) applying heat and pressure to the integral structure to isothermally forge the machined portion on the first workpiece which forms part of the integral structure to substantially produce the required finished peripheral shape and dimensions of the finished article,
(h) heating the integral structure and internally pressurising it to cause the preselected areas of at least one of the workpieces to be superplastically formed to produce an article of predetermined shape,
(i) finish machining the article to remove excess material from the isothermally forged peripheral shape to produce the finished article.

6 more elements

A method of manufacturing an article by superplastic forming and diffusion bonding at least two workpieces comprising the steps of:

(a) forming a first workpiece which has a flat surface,
(b) forming a second workpiece which has a flat surface, the first and second workpieces defining the outer profile of the finished article,
(c) machining a portion of a surface of at least the first workpiece at a predetermined distance from at least a portion of the periphery of the first workpiece, the said surface being opposite to the flat surface of the first workpiece,
(d) applying a stop off material to prevent diffusion bonding to preselected areas of at least one of the flat surfaces of at least one of the at least two workpieces,
(e) assembling the at least two workpieces into a stack relative to each other so that the flat surfaces are in mating abutment,
(f) sealing the edges of the at least two workpieces together, except where a pipe is to be inserted, and joining a pipe to the stack to provide a sealed assembly,
(g) sequentially evacuating the interior of the sealed assembly and supplying inert gas to the interior of the sealed assembly through the pipe to remove oxygen from the interior of the sealed assembly,
(h) placing the sealed assembly in an oven while continuously evacuating the sealed assembly,
(i) heating the sealed assembly while it is within the oven to evaporate volatile binder from the stop off material while continuously evacuating the sealed assembly to remove the volatile binder from between the at least two workpieces of the sealed assembly,
(j) sealing the pipe,
(k) applying heat and pressure across the thickness of the at least two workpieces to diffusion bond the at least two workpieces together in areas other than the preselected areas to form an integral structure,
(l) applying heat and pressure to the integral structure to isothermally forge the machined portion on the first workpiece which forms part of the integral structure to substantially produce the required finished peripheral shape and dimensions of the finished article,
(m) heating the integral structure and internally pressurising it to cause the preselected areas of at least one of the workpieces to be superplastically formed to produce an article of predetermined shape,
(n) finish machining the article to remove excess material from the isothermally forged peripheral shape to produce the finished article.

11 more elements

Dependencies are inferred from the claim text.