Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,...
Patent
1992-08-18
1996-04-02
Ryan, Patrick J.
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
428359, 428397, 57253, 28240, 28243, 264167, 264171, 264232, 264280, 2642884, 2642888, 264291, 2642092, 2642095, 2642096, 26417211, D02G 102, D02G 322, D02G 324
Patent
active
055039286
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This invention relates to the manufacture of reinforced composites having reinforcing filaments within a matrix. The invention applies in particular to the manufacture of reinforced plastics composites in which the reinforcing filaments are incorporated in a resin matrix, and the invention is mainly described herein in relation to such composites. However, it is possible to use other materials as the matrix, such as metals, metal alloys, or ceramics, provided the reinforcing filaments can be incorporated into the material without destroying the integrity of their fibres.
The invention is especially, but not exclusively, applicable to the manufacture of reinforced composites by the method of filament winding. The technique of filament winding is well known and is used in the production of a wide variety of hollow articles. Typically a continuous filament, e.g., of carbon or glass fibre, is taken from a reel, led through a resin applicator and guided under generally uniform tension onto a rotating mandrel. Generally several filaments are wound onto the mandrel at the same time. Filament winding machines which are programmable for building up the required shape on the mandrel are known and available in the art. After the resin has cured, the composite is removed from the mandrel, to which release agent is applied as a preliminary step in the manufacturing process to facilitate this removal of the formed article. The filaments used in conventional filament winding methods consist of continuous fibres or previously spun staple yarn, which means they are of substantially uniform cross-section, and hence weight per unit length, along their length. In addition, while exhibiting good strength characteristics under longitudinal tension loads, it is also a feature of the filaments that they will not undergo any significant elongation, and as a consequence will break before being stretched to any significant extent under excessive loads.
The known filament winding methods are not without certain drawbacks. If, for example, a parallel cylinder is being wound, it is necessary to allow a certain dwell time at the end of the mandrel after winding each course of turns along the mandrel to avoid the turns at the end being drawn back away from the end due to the reversal of the filament guide movement. Because of this dwell time, there is formed an extra loop or bulge of material at each end which must be cut off and discarded as scrap. This is inconvenient and an obvious waste of material. If a non-cylindrical moulded article, e.g., a pressure vessel or a complicated shape, is to be produced, the known filament winding methods become less efficient. There is a tendency to wind more material onto a smaller diameter where it is not necessarily needed, and as a result the finished moulding may be heavier and more expensive than theoretically required. In addition, as a consequence of the uniform weight per unit length characteristic of the filaments, it is frequently not possible to ensure adequate strength in certain areas of the moulding without applying more filament than strictly necessary in other areas, due to the limitations of the winding process.
SUMMARY OF THE INVENTION
The present invention aims to at least alleviate the foregoing drawbacks and according to the invention there is provided a method of manufacturing a reinforced composite wherein a staple yarn reinforcing filament is incorporated in a matrix, characterised by the filament being a staple yarn spun from discontinuous fibres with sufficiently low twist to enable elongation of the yarn under tension forces, and the yarn being subjected to controlled stretching whereby the weight per unit length of the yarn is varied along the length thereof.
In the preparation of a conventional spun staple yarn filament for use in a filament winding process, the staple yarn is spun from discontinuous fibres typically 10 to 100 mm long. The fibres are initially spun into a coarse tow which is subsequently drawn and spun into a much longer, t
REFERENCES:
patent: 3719442 (1973-03-01), Schippers et al.
patent: 4242862 (1981-01-01), Neyishi et al.
New Millennium Composites Limited
Ryan Patrick J.
Weisberger Richard
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