GB2104996A

GB2104996A - Hose

Info

Publication number: GB2104996A
Application number: GB08224106A
Authority: GB
Inventors: David Malcolm Marsh; Charles Fred Barber
Original assignee: TI FLEXIBLE TUBES Ltd
Current assignee: TI FLEXIBLE TUBES Ltd
Priority date: 1981-08-28
Filing date: 1982-08-23
Publication date: 1983-03-16
Also published as: GB2104996B

Abstract

A hose of multi-ply construction comprises a plurality of discrete layers which are wound onto a supporting wire helix. The discrete layers include a layer of polymeric film material which is impervious to the matter which is to be carried by the hose and a layer of reinforcing material. The layer of reinforcing material comprises a plurality of reinforcing filaments which are substantially linearly orientated and arranged in juxtaposed relationship over the whole or a substantial part of their length. The layers of material which form the hose are preferably substantially incompressible in the direction normal to their surfaces.

Description

SPECIFICATION Hoses This invention relates to hoses, and in particular to flexible hoses of multi-ply construction.

Flexible hoses may typically be formed as a multi-ply construction comprising a plurality of discrete layers which are wound onto a supporting wire helix. A further wire helix may then be wound around the outside of the layers, this outer helix being of the same pitch as the inner helix, and the turns being positioned intermediate of the turns of the inner helix. The layers that are wound upon the helical support include layers of polymeric film material, which are impervious to the fluid which is to be carried by the hose, and layers of reinforcing material. These layers of reinforcing material are conventionally woven fabrics.

The wire helices oppose the radial forces exerted by the pressure of fluid in the hose, or by loads applied externally of the hose. The wire helices are however free to expand and contract axially and the layers of reinforcing fabric are provided to take axial loads and also restrict the degree to which the hose will expand axially. In order to achieve this, the warp threads of the woven reinforcing material are laid as near as possible, parallel to the longitudinal axis of the hose, although in practice, in order that the fabric may be wound onto the helical support, the warp threads are normally wound at about 30 degrees to the axis of the hose. This inclination of the warp threads with respect to the axis of the hose and also the modulus of elasticity of the threads inevitably result in the hose being extensible to a certain degree.However, because of the nature of the woven fabric, the warp threads when not in tension will have a crimped configuration and when subject to an axial load will tend to straighten out to give a significant axial extension, which will add significantly to the degree to which the hose will extend under axial loads. Furthermore, the woven materials used hitherto are relatively compressible in the direction perpendicular to the plane of the material. As a result, when the hose is put under axial tension, the wire helices will compress the adjacent portions of the hose carcase, so that the convolutions of the hose are flattened. This again adds significantly to the axial extension of the hose.

According to one aspect of the present invention, a hose of multi-ply construction has a plurality of discrete layers which are wound onto a supporting wire helix, said layers including at least one layer of polymeric film material and at least one layer of reinforcing material, said layer of reinforcing material comprising a plurality of reinforcing filaments which are substantially linearly orientated and in juxtaposed relationship over the whole or a substantial part of their length.

The reinforcing layer formed in accordance with the present invention will have an overall thickness of the order of the thickness of a single layer of reinforcing filament from which it is made. The layer will consequently be substantially incompressible in the direction normal to its surface and as a result the overall compressibility of the hose carcase and the extensibility of the hose due to this characteristic will be reduced. The axial extensibility of the hose will be further reduced as a result of the linear orientation of the filaments, whereby extension of the reinforcing layers due to the filaments straightening out under load will be substantially avoided.

The term reinforcing filaments used above is intended to cover mono-filaments, for example individual fibres or wires, or multi4ila- ments in which for example, individual filaments are spun into threads or strands. These filaments may be made of any material with physical characteristics, for example tensile strength and modulus of expansion, suitable for reinforcing purposes, such as natural fibres, polymeric filaments or metals.

The reinforcing layer of the present invention may be formed from individual reinforcing filaments which are laid onto the hose carcase by suitable means, and are retained in place by the adjacent plies of the carcase and the inner and outer wire helices, in the completed carcase. In order to facilitate handling of the reinforcing filaments, it is however convenient to preform them into sheet material which may subsequently be wound onto the hose carcase using, for example, the techniques which have been used with the conventional woven reinforcing fabrics which have been employed hitherto.

One method of doing this is to form a nonwoven structure which is similar to that of a woven material, but instead of weaving the warp and weft threads together, the weft threads are laid across the warp threads and bonded thereto by a suitable means, for example an adhesive or by welding. With this form of material, the warp threads which are aligned as near as is practical to the longitudinal axis of the tube, provide the axial reinforcement of the tube. As the radial reinforcement of the tube is substantially provided by the wire helices, the weft threads do not take high load, and their main purpose is to hold the warp threads together. The reinforcing material may consequently be anisotropic, having a greater density of warp threads than weft threads.

In a further alternative, the reinforcing fila ments are loosely interlaced in the manner of a chain-link fence. While this construction does introduce a degree of overlap into the reinforcing layer construction and also bend into the reinforcing filaments, this will be only slight and insignificant in comparison with that occurring in conventionally woven materials.

An example of a reinforcing layer according to the present invention comprises an anisotropic non-woven fabric formed from polyester threads having a yarn count of 1100 d'tex.

These threads are laid so that the density of ahe warp threads is 4 threads per centimetre, and weft threads are laid over the warp threads at a density of 0.8 threads per cen cimetre. The warp threads are bonded to the weft threads by means of a polyvinyl acetate adhesive.

According to a further aspect of the present invention, reinforcing layers of the form described above, may be formed into a cover layer for the hose, by applying a layer of continuous material to one or both surfaces thereof. In order to maintain the full strength of the reinforcing layer in this composite cover material, there should be a mechanical difference between the reinforcing layer and the continuous layer, so as to avoid forming an effective monolithic structure. This mechanical difference may be achieved by selecting materials, which will give a relatively poor bond strength or which have physical properties, for example moduli or yield points, which differ significantly.

The continuous layer may be polymeric plastics or elastomeric material, which is applied to the reinforcing layer as a plastisol or elastomeric composition and is permitted to cure in contact with the filaments of the reinforcing layer. The curing conditions, for example temperature, of the plastisol or elastomeric composition, must of course be such that there will be no damage to the filaments of the reinforcing layer. Where the filaments of the reinforcing layer are fairly open, it may be necessary to provide a backing sheet of for example tissue, in order to keep the plastisol or elastomeric composition in a continuous layer while it cures.

In an example of a composite cover material formed in accordance with the present invention, a fibreglass tissue is bonded to one side of a polyester reinforcing fabric of the type described above. A layer of PVC plastisol is then applied to the glass tissue, on the same side as the polyester reinforcing layer, and is permitted to cure to form a reinforced cover material for a hose.

Claims

1. A hose of multi-ply construction having a plurality of discrete layers which are wound onto a supporting wire helix, said layers including at least one layer of polymeric film material and at least one layer of reinforcing material, said layer of reinforcing material comprising a plurality of reinforcing filaments which are substantially linearly orientated and in juxtaposed relationship over the whole or a substantial part of their length.

2. A hose construction according to Claim 1 in which the discrete layers are substantially incompressible in the direction normal to their surfaces.

3. A hose construction according to Claim 1 or 2 in which the reinforcing filaments are laid onto the hose carcase individually, to form a reinforcing layer, which is held in place by adjacent plies of the hose carcase.

4. A hose construction according to Claim 1 or 2 in which the reinforcing filaments are applied to the carcase in the form of a nonwoven sheet.

5. A hose construction according to Claim 4 4 in which the non-woven sheet is formed by laying reinforcing filaments parallel to one another in juxtaposed position and laying weft threads across the reinforcing filaments and bonding them thereto.

6. A hose construction according to Claim 5 in which the density of the reinforcing filaments is greater than the density of the weft threads.

7. A hose construction according to Claim 1 1 or 2 in which the reinforcing filaments are loosely interlaced in the manner of a chainlink fence.

8. A hose construction according to any one of the preceding claims including a cover formed from a reinforcing layer as claimed in any one of Claims 1 to 7, bonded to a layer of continuous material.

9. A hose construction according to Claim 8 in which there is a mechanical difference between the reinforcing layer and the continuous layer that form the cover.

10. A hose construction according to Claim 9 in which the materials which form the reinforcing layer and continuous layer of the cover, are selected to give a relatively poor bond strength.

11. A hose construction according to Claim 9 in which the materials which form the reinforcing layer and continuous layer of the cover have significantly differing physical properties.

12. A hose construction according to any one of Claims 8 to 11 in which the reinforcing layer of the cover is provided with a backing sheet and the continuous layer is applied to the reinforcing layer as a plastisol or elastomeric composition which is subsequently cured.

13. A hose of multi-ply construction substantially as described herein, with reference to the examples.