Metal working – Method of mechanical manufacture – Shaping fiber or fibered material
Reexamination Certificate
2000-10-30
2003-12-09
Bryant, David P. (Department: 3726)
Metal working
Method of mechanical manufacture
Shaping fiber or fibered material
C029S889710, C228S190000, C428S615000
Reexamination Certificate
active
06658715
ABSTRACT:
The present invention relates to a method of producing elements of composite material, in particular, circular-geometry elements such as countershafts, turbine and compressor disks for turbomachines, etc.
BACKGROUND OF THE INVENTION
As is known from Italian Patent Application n. TO96A000979 filed on Dec. 3, 1996 by FIATAVIO S.p.A, composite-material elements of the above type are produced by forming a number of disks, each formed by winding a continuous reinforcing fiber about an axis to form a flat spiral; stacking the disks with the interposition of respective spacer sheets of metal material; and axially compacting the stack to form a metal matrix in which the various spirals of reinforcing fibers are embedded.
The physical characteristics of such composite-material elements depend mainly on the distribution of the reinforcing fibers inside the metal matrix; and the extent to which the fibers are distributed evenly depends on the extent to which the turns in each disk are equally spaced a predetermined distance apart, and the extent to which the freedom of movement of the various turns is restricted, especially at the compacting stage.
For which reason, the turns of reinforcing fiber are locked in place with respect to one another by fastening wires wound about each turn and extending spokefashion with respect to the axis of the spiral.
More specifically, the turns are equally spaced a given distance apart by forming, alongside formation of the spiral, a further two flat spirals of spacer wire, which are removed from the spiral of reinforcing fiber once the fastening wires are wound about the turns.
The method described briefly above involves several drawbacks.
In particular, producing composite-material elements using disks of reinforcing material and metal spacer sheets of given thicknesses means it is impossible to obtain any given desired distribution of the reinforcing fibers inside the metal matrix.
Moreover, the above method comprises various fairly complex, and therefore fairly high-cost, operations (weaving the spirals of reinforcing wire separately and fastening the relative turns; stacking the disks of ceramic material and spacer sheets; and placing the stacks inside a final container to form the composite-material elements).
In the case of a titanium metal matrix, the spacer sheets are not easy to procure in the form required by the methods described, i.e. of constant 0.1 mm thickness, and call for various dedicated machining operations (cutting, grinding, welding, etc.) which further increase the already high cost involved.
Finally, the fastening wires must be made of inert material, with respect to both the metal matrix and the reinforcing fibers.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a method of producing an element of composite material, designed to eliminate in a straightforward, low-cost manner the aforementioned drawbacks typically associated with known methods.
According to the present invention, there is provided a method of producing an element of composite material comprising a metal matrix and a reinforcing structure, said method comprising the steps of:
forming a first distribution of first elements defining said matrix;
forming a second distribution of second elements defining said reinforcing structure; and
compacting said first and second elements to obtain a distribution of said reinforcing structure inside said matrix;
characterized in that said first elements are metal wires; and in that said step of forming said first distribution comprises the step of assigning each said second element an orderly distribution of said metal wires.
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patent: 5460774 (1995-10-01), Bachelet
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Ponzi C: “Metal Matrix Composite . . . Structures”; Composites Manufacturing; GB; Butterworth Scientific; Guildford; Surrey; vol. 3, No. 1 Jan. 1992, pp. 32-42.
Bryant David P.
FiatAvio S.p.A.
Ladas & Parry
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