WO2003024662A1

WO2003024662A1 - Method for controlling composite preform elements during processing

Info

Publication number: WO2003024662A1
Application number: PCT/US2002/030121
Authority: WO
Inventors: William Hanusiak; Lisa Hanusiak; Jeffery Parnell; Charles Rowe; Steven Spear
Original assignee: Atlantic Research Corporation
Priority date: 2001-09-21
Filing date: 2002-09-23
Publication date: 2003-03-27
Also published as: CN1302893C; DE60232806D1; JP4452500B2; EP1438155A4; KR20040035856A; KR100972409B1; CN1556739A; US6568061B2; JP2005523379A; EP1438155B1; ES2331989T3; EP1438155A1; ATE435311T1; US20030056355A1

Abstract

A method of retaining composite preforms in the nature of fiber/metal matrix composites in position during processing, comprising the steps of positioning a predetermined assembly of fibers and metal matrix (30) on a mandrel (32). The metal matrix may be in the form of wires, powder or foil. A retaining wire (34) of a suitable heat resistant metal, such as titanium is spirally wound under tension over the fiber/metal matrix assembly to retain the assembly in a predetennined position on the mandrel during subsequent processing.

Description

METHOD FOR CONTROLLING COMPOSITE PREFORM ELEMENTS DURING PROCESSING

FIELD OF THE INVENTION

The present invention relates to composite preforms used in the formation

of continuous fiber/metal matrix composites, and more particularly, to a method

for retaining the composite preform elements in position during processing.

BACKGROUND OF THE INVENTION

Composite preforms such as those used in the formation of continuous

fiber/metal matrix composites are composed of an assembly of mono-filament

fibers and a matrix metal in the form of foil, powder or wire. These assemblies

may be used for the manufacture of a ring or a rod, for example. In each case,

an assembly of precursor fibers and metal is rolled onto a mandrel to build up

the reinforcement region. In a case of a ring, for example, this is accomplished

by rolling up a collection of metal wires and fibers on an annular, recessed,

substrate or mandrel to form the assembly. In the case of a rod, a pre-preg sheet

is first fabricated consisting of a layer of fibers and a layer of metal wires

bonded together with adhesive. This sheet is then rolled up onto a cylindrical

mandrel to form the assembly.

In the case of both ring and rod assemblies, the rolled assembly must be

held in place in such a way as to retain the relative positions of the fiber and metal elements throughout the fabrication process. In a case of the ring

assembly, this requires holding the roll up from unwinding, and in the case of

the rod assembly, this requires holding the roll-up from unwinding and

accommodating shrinkage in the roll-up due to debulking which occurs in the

rod roll-up during the off gas operation owing to the removal of the adhesive

used to fabricate the pre-preg sheets.

Currently, the rolled assembly in organic composite fabrication is held in

place through the use of an elastomeric bladder and an associated pressure

differential that holds the bladder against the assembly. In the case of metal

matrix composites, this processing hardware must be suitable for high

temperature operations which are much higher in temperature than is suitable

for the typical elastomer. Typically, therefore, the encapsulation hardware for

such processing is composed of either steel or titanium metal, neither of which

is elastomeric enough to be pushed against the rolled assembly by differential

pressure until the process temperature and pressure have reached very high

values. This results in a significant disadvantage for the reason that the

assembly is in an undamped state during most of the fabrication process which

allows for unwanted movement of the metal and fiber assembly elements during

processing. Accordingly, a need has arisen for a simple and effective method for

controlling the relative positions of the rolled assembly elements and clamping

them in place throughout the entire fabrication process. The method of the

present invention meets this need.

SUMMARY OF THE INVENTION

In accordance with the new and improved method of the present

invention, the assembly of fibers and metal on the mandrel or substrate is

clamped thereon and held in place during the entire fabrication process by

winding over the assembly in a spiral fashion a wire formed of a suitable heat

resistant metal such as a titanium. The ends of the clamping wire may be fixed

by inserting them in grooves or other apertures in the mandrel or substrate, or by

otherwise securing them to the mandrel or substrate. The pitch of the winding

and the tension applied by the clamping wire during the spiral winding thereof

is selected based on the specific roll-up assembly characteristics. In the case of

a metal powder/fiber assembly, for example, the clamping wire overwrap is

wound tight to itself, i.e., such that the overwrap wires are in engagement with

each other. This eliminates the migration of the power from the roll-up

assembly during processing. In the case of a metal wire/fiber assembly, or a

metal foil/fiber assembly, the spacing between the clamping wires can be

greater. In this manner, tension on the clamping wire during winding assures

intimate contact between the wire overwrap and the rolled assembly as well as

establishing a certain amount of elastic compliance to the overwrap. The

clamping wire overwrap may be tensioned during winding, for example, to

accommodate for a predetermined diameter contraction of the roll-up assembly

during processing.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a block diagram of a typical process flow for the formation of

continuous fiber/metal matrix composites made up of an assembly of fibers and

a matrix metal in the form of foil, powder or wire;

Figure 2 is a side elevational view, partly in section, of a metal wire/fiber

assembly for a ring component prior to fabrication processing;

Figure 3 is a side elevational view similar to Figure 2 wherein the

clamping wire is spirally wrapped over the metal wire/fiber assembly prior to

fabrication processing;

Figure 4 is a side elevational view, partly in section, of a metal fiber pre-

preg sheet assembly for a rod component; and

Figure 5 is a side elevational view similar to Figure 4 showing the

clamping wire spirally wrapped over the metal fiber pre-preg sheet assembly for

a rod component prior to processing. DESCRIPTION OF THE PREFERRED EMBODIMENTS

Fig. 1 illustrates in block form a typical process flow for the formation of

continuous fiber/metal matrix composites made up of an assembly of

monofilament fibers and a matrix metal in the form of foil, powder or wire. In

block 2, the mandrel is prepared for winding. Thereafter, the fiber and metal

elements are rolled up on the mandrel (block 4), and the mandrel and rolled

assembly thereon are then encapsulated in process hardware (block 6) in a

manner well-known to those skilled in the art. The encapsulated rolled

assembly on the mandrel is then off-gassed to remove adhesives and other

volatiles (block 8), and the assembly is consolidated to remove voids and bond

interfaces (block 10). Thereafter, the final reinforced component is produced

(block 12).

Fig. 2 illustrates the method step in block 4 in Fig. 1 for a ring component

wherein a metal wire/fiber assembly is rolled up within the annular recess 14 of

a mandrel or substrate 16. The rolled assembly comprises a selected or

predetermined number of alternate rows of rolled-up metal wire 18 and fiber 20

in any desired orientation. Instead of metal wire, the metal can be in the form of

a foil or powder and the rolled assembly can include layers of adhesive to hold

the components in place in a manner well-known to those skilled in the art. Fig. 3 illustrates the wire overwrap of the present invention applied to the

metal wire/fiber assembly of Fig. 2 in accordance with the process step of block

6 in Fig. 1. In accordance with the invention, instead of a metal bladder or the

like, a metal retaining wire 22 formed of a high temperature resistant metal is

spirally wound under a desired tension around the outer surface of the metal

wire/fiber assembly to hold the wires and fibers in their desired positions during

subsequent processing as indicated in blocks 8, 10 and 12 in Fig. 1. The metal

retaining wire 22 may be formed of titanium, molybdenum, tungsten, rhenium

or a titanium/niobium alloy. To hold the retaining wire in the desired tensioned

position, the ends 24 thereof are inserted into grooves 26 in the mandrel or

substrate 16 or are otherwise secured thereto in any suitable manner.

The size and shape of the retaining wire 22 and the spacing and tension

thereof on the metal wire/fiber assembly will be determined by the specific

construction and nature of the rolled assembly. For example, in the case of a

metal powder/fiber assembly, the wire overwrap would be wound tight to itself,

i.e., such that the clamping wires are in engagement with each other. This

would eliminate the migration of the metal powder from the assembly during

subsequent processing.

In the case of the metal wire/fiber assembly shown in Figs. 2 and 3, the

retaining wires 22 can be spaced apart typically 20 to 50 wires per inch for the metal foil/fiber assembly the spacing between the retaining wires 22 could be

even larger, e.g., five wires per inch.

Fig. 4 illustrates the method step in block 4 in Fig. 1 for a rod component

wherein a metal/fiber pre-preg sheet 30 is rolled up in a desired number of

layers on a mandrel 32. The pre-preg sheet 30 comprises a layer of fibers and a

metal matrix layer bonded together with a suitable adhesive (not shown). The

metal matrix layer may be in the form of wires, foil or powder.

Fig. 5 is a view similar to Fig. 4 which illustrates the metal retaining wire

34 of the present invention spirally wound under a desired tension around the

outer surface of the metal/fiber pre-preg sheet 30 on the mandrel 32. To hold

the retaining wire 34 in the desired tensioned position, its ends are secured to

the mandrel 32 in any suitable manner (not shown).

Through the use of the metal wire overwrap of the present invention, the

rolled-up metal and fiber components are maintained in the desired relative

positions during the subsequent fabrication steps, such as off-gassing, heating

and consolidating, and fabricating. The tension on the retaining wire 22, 34

assures intimate contact between the wire overwrap and the fiber/metal rolled

assembly as well as establishing a certain amount of elastic compliance to the

overwrap. In the case of a ring rollup with an outside diameter of 12 inches, for

example, the metal wire overwrap could be tensioned during winding to

accommodate for as much as 0.1 inches of diameter contraction during

C λ A OGA processing. The retaining wire 22, 34 becomes part of the metal structure

adjacent to the metal/fiber reinforcement after processing.

It will be readily seen that the use of the metal overwrap of the present

invention constitutes a significant improvement over the metal bladders

previously used for encapsulating the mandrel and rolled assembly prior to the

fabrication process. The metal overwrap of the present invention serves to

clamp and retain the rolled up metal and fiber components in place during the

entire fabrication process to ensure the formation of the desired reinforced

fiber/metal matrix composite component. Also, the metal overwrap of the

present invention is simple in construction, inexpensive and easy to apply over

the rolled assembly in a desired manner.

While the invention has been described in connection with what is

presently considered to be the most practical and preferred embodiment, it is to

be understood that the invention is not to be hmited to the disclosed

embodiment, but on the contrary, is intended to cover various modifications and

equivalent arrangements included within the spirit and scope of the appended

claims.

Claims

CLAIMSWhat is claimed is:

1. A method for retaining composite preforms in the nature of fiber/metal matrix composites in position during processing, comprising the steps of positioning a predetermined assembly of fibers and a matrix metal in the form of foil, powder or wire on a mandrel, spirally winding a retaining wire of a predetermined heat resistant metal over said assembly under tension to retain said assembly in position on said mandrel, and processing said assembly surrounded by said spirally wound wire to form the finished fiber/metal matrix composite.

2. The method of Claim 1 wherein said retaining wire is formed of titanium.

3. The method of Claim 1 wherein the ends of said retaining wire are connected to said mandrel.

4. The method of Claim 1 wherein said retaining wire is spirally wound under a tension such that adjacent coils of said retaining wire are in engagement with each other.

5. The method of Claim 1 wherein said retaining wire is spirally wound under a tension such that adjacent coils of said retaining wire are spaced from each other.

6. The method of Claim 1 wherein the retaining wire is spirally wound at a pitch, spacing and tension that are determined by the nature and construction of the rolled assembly of fibers and matrix metal.

7. The method Claim 1 wherein said assembly of fibers and matrix metal is rolled on said mandrel.

8. The method of Claim 1 wherein said retaining wire is formed of molybdenum.

9. The method of Claim 1 wherein said retaining wire is formed of tungsten.

10. The method of Claim 1 wherein said retaining wire is formed of rhenium.

11. The method of Claim 1 wherein said retaining wire is formed of a titanium niobium alloy.