Method Of Manufacturing A Shaped Element Of Fiber-reinforced Material

Abstract

A shaped element of fibre reinforced material comprises a bundle of wires, each enclosed in a jacket of matrix substance, which has been subjected to a mechanical working, such as drawing, to reduce to cross-sectional area of the wires and jackets and to bond the jackets together. The bundle of jacketed wires may be enclosed in an outer casing of the matrix substance prior to mechanical working and each jacket may consist of a tube into which a wire is threaded.

Parent Case Text

This is a continuation of application Ser. No. 203,381, filed Nov. 30, 1971, now abandoned.

Description

BACKGROUND OF THE INVENTION

The invention relates to a shaped element of fibre-reinforced material in which a large number of aligned fibres are embedded in a matrix substance, and to methods of manufacturing such shaped elements.

Combinations of glass, ceramic, polymer or metallic fibres embedded in metallic or non-metallic matrix are known in industry as fibre reinforced materials. Such fibre-reinforced materials based on metallic and non-metallic substances are used on a large scale and possess many advantageous physical and chemical properties as compared with other known materials. These properties depend upon a number of factors and in particular upon the characteristics of the matrix and/or fibre material, that proportion of the total cross-sectional area constituted by the fibres, and the arrangement, distribution and bonding of the fibres. Optimum properties can generally be obtained in such fibre-reinforced substances only if the fibres are oriented and distributed in the matrix substance in a particular manner.

The known methods of producing fibre-reinforced materials are based on surrounding the prepared fibres with matrix metal by fusion processes, by powder-metallurgy methods or by sintering under compression between compact materials. In other known methods, prepared fibres are surrounded by the matrix substance by treatment in a melting bath, a slurry or an electrolytic bath, or by spraying, vacuum deposition or other deposition processes. Finally, the composite material is produced with uniformly distributed fibres by stacking and compressing the fibres pretreated in this manner. Also known are methods of manufacture in which randomly arranged pretreated fibres are first put into the matrix substance and then aligned by plastic-shaping processes.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a shaped element of fibre-reinforced material which can be produced in a simple manner without the use of pretreated fibres, advantageous physical properties being obtained by means of the subsequently produced and oriented fibres.

According to the present invention the improved shaped element comprises a bundle of wires, each enclosed in a jacket of matrix substance, which bundle has been subjected to mechanical working whereby to reduce the cross sectional area of the wire and jackets and to bond the jackets together. Mechanical working processes that may be advantageously used are drawing, rolling and swaging. A shaped element of this kind is expediently additionally provided with an outer casing of matrix substance which is also shaped during the mechanical working process.

An advantageous method of producing the shaped elements of this invention comprises the steps of providing a wire with a jacket of matrix substance, arranging a plurality of jacketed wires in a bundle, and subjecting the bundle to mechanical working whereby to reduce the cross sectional areas of the wires and jackets and to bond the jackets together.

Expediently, the bundle of jacketed wires may be enclosed in an outer casing constituted by a thin layer of matrix substance in the solid phase, e.g. in the form of a tube. This enclosed bundle is then compressed by a mechanical-shaping operation and particularly by drawing. During this shaping operation metallic bonding of the jacket materials with each other and with the additional outer casing takes place on the one hand, and at the same time there occurs a cross-sectional reduction of the entire shaped element and thus also of the embedded wires. This shaping operation is expediently carried out several times and continued until the required fibre cross-section is obtained. In some cases, it may be advantageous to carry out intermediate annealing for softening the core material and/or for bonding the matrix substance by diffusion. The required proportion by volume of the fibres can be established beforehand by the correct choice of jacketed wires and can be varied within wide limits.

In a preferred form both the wire and the jacket are made of metallic materials.

An example of a particularly advantageous fibre-reinforced material will now be given for the purpose of describing how the invention may be carried out. In this example, the matrix substance consists of pure silver in which a fibre material consisting of an austenitic chromium-nickel steel wire is to be embedded. The starting material for each of the jacketed wires is constituted by a silver tube of an outer diameter of 10 mm and a thickness of the wall of 3.4 mm the interior surface of which has been cleaned by any suitable known method and into which a core of a round shape of 3 mm diameter of copper-coated alloy steel has been introduced. In the method of production used, the volume of alloy steel is about 10 percent of the silver matrix substance. The starting material will be worked to an outer diameter of about 1 mm; i.e., by 10 drawings. The jacketed wires of round cross-section having a diameter of about 1 mm., are bundled and inserted into a thin-walled silver tube, 5 mm., outside diameter and 0.2 mm., thick, which is to form an additional outer casing. This semi-finished product was then shaped by undergoing 25 drawing passes and in such manner that finally, whilst the fibres were thus formed, a shaped element in the form of a wire was obtained in which steel fibres having a diameter in the order of magnitude of a few .mu. were embedded in the matrix substance. On account of the bundling, an almost ideal distribution of the fibres in the matrix substance was achieved. Furthermore, these shaped elements may be advantageously arranged in the above-described manner and shaped again, and possibly several times, in order to obtain a still smaller diameter of fibre.

The method of manufacture described may be modified in various ways; for example, apart from being disposed parallel with each other, the jacketed wires can also be arrayed in a special manner, e.g. in groups extending in a preferred direction, or helically, so that it is always possible to obtain given directionalities of the fibres even when a pure matrix core and the like are used.

The method is not limited to the production of cylindrical elements; elements of rectangular or other cross-sectional shapes can also be obtained by the method described.

BRIEF DESCRIPTION OF THE DRAWINGS

Some cross-sections of shaped elements of fibre-reinforced material are illustrated in the drawings in which:

FIGS. 1, 3, 5, 7 and 9 show cross-sections through semi-finished products composed of jacketed wires, prior to mechanical working, and

FIGS. 2, 4, 6, 8 and 10 show cross-sections through the finally shaped elements in accordance with the invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows on an enlarged scale a tube 1 of matrix substance which forms an additional outer casing and in the interior of which is placed a plurality of jacketed wires 2. The core 3 of each of these jacketed wires 2 consists of the desired fibre material, whereas the jacket 4 contains the matrix substance.

After all the components of the element have been jointly shaped by drawing, a homogeneous shaped element consisting of matrix substance in which the fibres are embedded parallel with each other is obtained (FIG. 2).

The remaining FIGS., 3 to 10, show other geometrical arrangements, a core 5 of matrix substance or any other appropriately advantageous material (e.g. one of high electrical conductivity) being present in the arrangements shown in FIGS. 5 and 6 and FIGS. 9 and 10.

As shown in FIGS. 9 and 10 the element can have such a distribution of the fibres to provide for a metallic homogeneous core. Such a metallic homogeneous core may be of advantage if the element should combine high electrical conductance and good spring qualities. In the example of FIG. 9 jacketed wires 4 of high-grade steel of 1 mm-square, as well as a solid fine-silver sheet 5 of 2 mm., thickness are arranged in a rectangular tube 1 having an inside dimension of 6 .times. 30 mm and about 1 mm thickness of the wall, and also being made of solid fine-silver. All parts are arranged in the way shown in FIG. 9.

By the forming of this element, for instance by a five-times drawing through correspondingly stepwise reduced dies, a body of 0.8 .times. 5 mm is obtained, the section of which is as shown in FIG. 10 (not to scale).

An element built in this way will offer spring-bending limits or up to 100 kp/mm.sup.2 and an electrical conductivity of up to 45 SE.

Claims

What we claim is:

1. A method for producing a shaped element formed of a homogeneous matrix substance and having intimately embedded therein a plurality of substantially circular reinforcing fibers of a diameter in the magnitude of microns, the ductility properties of said matrix substance and said fibers being substantially different, said method consisting essentially of the steps of:

rigidly and metallurgically connecting to each of a plurality of substantially circular wires of reinforcing material a jacket of said matrix substance, each of said wires having a diameter in the magnitude of millimeters;

arranging said plurality of thus jacketed wires in a loose bundle in contact with each other; and

subjecting said bundle to a non-cutting mechanical working operation;

thereby reducing the cross-sectional area of said wires and said jackets, the cross-sectional area of said wires being reduced from a magnitude of mm.sup.2 to a magnitude of 10.sup.-.sup.6 mm.sup.2, mechanically bonding said jackets together into a uniform homogeneous matrix, subjecting said jacketed wires to a diffusion treatment to facilitate the mechanical bonding of said matrix, and generating said substantially circular micron sized fibers embedded in said uniform homogeneous matrix, thereby reinforcing said matrix.

2. A method as claimed in claim 1, further consisting essentially of enclosing said bundle of jacketed wires in an outer casing of matrix substance prior to said step of mechanical working.

3. A method as claimed in claim 2, wherein said outer casing has a shape designed to suit the geometrical form which the element has after the mechanical working.

4. A method as claimed in claim 1, wherein said plurality of jacketed wires are arranged about a core of matrix substance prior to said step of mechanical working.

5. A method as claimed in claim 1, wherein each said jacket of matrix substancee is a tube into which one of said wires is threaded.

6. A method as claimed in claim 1, wherein said matrix substance is silver and said wire is a copper-coated austenitic chromium-nickel steel.

7. A method as claimed in claim 1, wherein said mechanical working is effected by drawing.