GB2199629A

GB2199629A - Kink resistant hose

Info

Publication number: GB2199629A
Application number: GB08630982A
Authority: GB
Inventors: John Kerr Mcgregor
Original assignee: Dunlop Ltd
Current assignee: Dunlop Ltd
Priority date: 1986-12-30
Filing date: 1986-12-30
Publication date: 1988-07-13
Also published as: ZA879724B; GB8630982D0

Abstract

A kink resistant hose comprises at least one helically wound reinforcement strip 14, 15 of a kind comprising a polymer coated high stretch reinforcement fabric 17, preferably a knitted fabric of polyester yarn, in which the high stretch fabric 17 is supported by a layer of the polymer coating material e.g natural or synthetic rubbers, plastics or a thermoplastic elastomer. The hose may be constructed by helically winding about a mandrel at least one reinforcement strip of polymer coated high stretch reinforcement fabric. Preferably the reinforcement fabric comprises elements having component sections some of which extend parallel with the length of the hose and some perpendicular thereto. <IMAGE>

Description

HOSE This invention relates to hose and in particular, though not exclusively, to hose of a kind which has good resistance to kinking when caused to bend and/or twist.

Hoses having a good kink resistance are known but suffer disadvantages such as being thick and heavy, expensive in use of materials and/or expensive and inconvenient to manufacture.

The present invention seeks to provide an improved hose and method of manufacture of a hose which has good resistance to kinking, is not unduly heavy or thick and which is convenient to manufacture.

In accordance with one of its aspects the present invention provides a hose comprising at least one helically wound reinforcement strip of a kind comprising a polymer coated high stretch fabric as herein defined in which the high stretch fabric is supported by a layer of said polymer coating material.

The expression "high stretch fabric" is used herein to refer to a fabric of a type which, prior to being polymer coated, has a significantly greater ability to extend under a given applied tensile stress in either of two mutually perpendicualr directions in the plane of the fabric than the ability of any of the individual elements comprising the fabric to extend under that applied tensile stress.

Under initial application of load in either of two mutually perpendicular directions the fabric will undergo a geometric deformation; in general the individual filaments will extend significantly in response to increasing applied load only after substantial geometric deformation of the fabric.

Although the term "stretch fabric" sometimes is used to relate to fabrics of a kind having a capacity for stretch and recovery from stretch it is to be understood that the "high stretch fabric" as herein defined is not necessarily to be of a kind having a capacity to recover from stretch by itself.

The high stretch fabric preferably is a knitted fabric, which may for example be a plain, lockstitch or wrap knit fabric or other type of fabric in which a plurality of elements such as filaments, strands or yarns are interconnected to one another by intermeshing of loops of the elements thereby to form a fabric, but other types of fabric may be employed. The fabric may, for example, be comprised by a layer of polymeric material stamped or otherwise formed to comprise a contiguous arrangement of warp and weft components, the flexibility of the polymeric material being sufficient to ensure that adjacent sections of warp and weft components are substantially free to move angularly one relative to the other in the plane of the fabric.

By providing a fabric in which intersecting or neighbouring component sections of the fabric elements are substantially free to move angularly one relative to the other in the plane of the fabric there is attained an ability for the fabric to stretch by relative movement of the component parts of the fabric to an extent substantially greater than the ability of each component section to extend by itself when subject to the same tensile stress. In contrast, conventional woven type fabrics do not possess a sufficient degree of extensibility in each of two mutually perpendicualr directions for them to be suitable for use on their own in the hose of the present invention.

Suitable materials for forming the high stretch fabric include polyester, nylon and Kevlar and also mixtures of materials. The fabric may be formed from elements of various kinds such as monofilaments, strands or yarns.

In order that intersecting or neighbouring component sections are substantially free to move angularly one relative to the other the fabric is to be of an open type structure, the elements of the fabric on average comprising in the plane of the fabric no more than 80% and preferably no more than 70% of the total area of a section of fabric.

When built into the hose the spaces between the elements of the fabric should be occupied by the polymer coating which optionally may be bonded to the fabric.

In accordance with another of its aspects the present invention provides a method of manufacture of a kink resistant hose comprising helically winding about a mandrel at least one reinforcement strip of said polymer coated high stretch fabric.

Preferably the fabric is at least partially embedded in the layer of polymer coating material prior to helical winding so that polymer coating material is able to restrain the fabric from undue extension due to the tension experienced by the strip during winding.

Additionally or alternatively the fabric may be adhered to the layer of polymer coating material prior to winding of the strip.

The polymeric material which supports the high stretch fabric may be a natural rubber, synthetic rubber, a material having properties similar to the properties of natural or synthetic rubber, a plastics material or a thermoplastic elastomer. The polymeric material, when vulcanised in the finished hose in the case of vulcanisable material, should be a material that is capable of recovering from large deformations quickly and forcibly.

Other suitable polymeric coating materials include styrene butadiene rubber, polychloroprene, butyl rubber and ethylene propylene diene monomer.

The component sections of the fabric elements, being respective sections of the length of an element between successive points of crossover or intersection with one or more other elements of the fabric, may be angled obliquely relative to the length of the reinforcement strip. That angle and the angle of the reinforcement strip relative to the length of the hose preferably are such that component sections of the fabric elements extend some substantially parallel and some substantially perpendicular to the length of the hose. This requires generally the use of fabric in which the elements of the fabric extend in substantially mutually perpendicular directions and one particularly suitable material is a diamond mesh type of knitted fabric.

The hose may comprise a reinforcement formed wholly of one or more of said helically wound strips of polymer coated high stretch fabric or alternatively a reinforcement of one or more of said helically wound polymer coated high stretch fabric strips may be supplemented by a conventional type of hose reinforcement. For manufacturing convenience it is preferred that the additional reinforcement be comprised one or more helically wound reinforcement strips such as rubberised strips of close square woven fabric.

If additional reinforcement is provided, preferably it is disposed radially inwards of the polymer coated high stretch fabric reinforcement and preferably spaced therefrom by a layer of polymeric material which may be the polymer coating material of the high stretch fabric.

One embodiment of the present invention will now be described, by way of example, with reference to the accompanying diagrammatic drawings in which: Figure 1 is a perspective view of a hose in accordance with the invention cut away to show the component layers, and Figure 2 shows part of a strip of diamond mesh type knitted fabric.

The hose 10 comprises an inner tube layer 11 of polychloroprene selected in accordance with the intended use of the hose and- formed by extrusion or, especially for larder diameter hose, by winding of strip material about a mandrel.

The inner tube 11 is surrounded by an inner reinforcement assembly comprising two helically wound strips 12,13 of rubberised close square woven cotton fabric, the strip 12 being wound helically at an angle Less than the neutral angle of 540 44 minutes, typically at an angle in the order of 45 relative to the length of the hose, to form one inner reinforcing layer. The surrounding strip 13 is wound at a similar angle but optionally in an opposite sense so as to form a second inner reinforcement layer sunxunlrg the layer formed by strip 12.

The strips 12 and 13 are surrounded by a pair of rubberised knitted fabric layers 14,15, described in more detail below, the strip 14 being applied also at an angle in the order of 450 relative to the length of the hose and optionally in an opposite sense to the sense of the strip 13. The strip 15 is applied optionally in an opposite sense to that of the strip 14 and also at an angle in the order of 450 The reinforcement comprised by the helically wound strips 12 to 15 is surrounded by a cover layer 16 formeS by a helically wound strip of a material such as ethylene propylene diene monomer or other material selected having regard to the intended use of the hose.

The strips 12,13 of close square woven rubberised cotton fabric each comprise hose. duck fabric in accordance with British Standard 1103 and rubberised with natural rubber.

The strips 14,15 of polymer coated knitted fabric each comprise a strip of diamond mesh type knitted fabric 17 (see Figure 2) of polyester yarns such as the type R 6262 ex Fryma Fabrics Limited.

The component sections 18,19 of the fabric elements each extend in one of two directions relative to the length of the strip, said two directions being disposed at angles of equal magnitude relative to the length of strip and substantially mutually perpendicular.

The fabric 17 is of a high stretch kind before being coated with polymer and built into the hose. It can readily be stretched by at least 10% in either of two mutually perpendicular directions by application of a light tensile load and under maximum burst its extensibility is in the range 35 to 45%. In contrast, the maximum extensibility of the individual polyester yarns at break is in the order of half of that of the fabric.

To form the strips 14,15 the. strips of fabric 17 are rubberised, for example with natural rubber, styrene butadiene rubber or polychloroprene. The rubberising may be performed in such a manner as to provide polymeric coatings on one or both sides of the fabric.

If both sides of the fabric 17 are coated, the two layers of coating preferably should interconnect through the openings 20 of the fabric which openings comprise approximately 35% of the surface area of the fabric. If only one side is coated, the layer of coating preferably should extend into the openings 20 thereby to form a mechanical interlock between the coating and fabric so that the coating is able to support the fabric.

The aforedescribed hose is manufazhred by extruding the inner tube around a rigid mandrel (not shown) and then spirally wrapping around the mandrel the successive reinforcing strips 12,13,14 and 15.

Subsequent to application of the cover 16 the resulting hose assembly is wrapped in a nylon restraining fabric in known manner so as to ensure consolidation of the hose between the mandrel and nylon wrapping tape during a subsequent vulcanisation operation.

The use of a rigid mandrel is not essential. If the inner tube 11 is sufficiently self-supporting subsequent to having been formed for example by extrusion, the helically applied strips 12 to 15 may be wound directly onto the inner tube, with the inner tube thereby acting as a mandrel.

In order that the resultant hose possesses good kink resistance it is required by the present invention that the high stretch fabric should be interlocked and/or adhered to the polymer coating whereby the coating material assists the fabric in restoring itself to or maintaining substantially its initial configuration.

Claims

CLAIMS:

1. A hose comprising at least one helically wound reinforcement strip of a kind comprising a polymer coated knitted type fabric in which the knitted fabric is supported by a layer of said polymeric coating material.

2. A A hose comprising at least one helically wound reinforcement strip of a kind comprising a polymer coated high stretch fabric as hereinbefore defined in which the high stretch fabric is supported by a layer of said polymeric coating material.

3. A hose according to claim 1 or claim 2 wherein the fabric is of a substantially open construction in which as viewed in plan the area occupied by elements forming the fabric occupies less than 80% of the area of a section of the fabric.

4. A hose according to claim 3 wherein the elements of the fabric occupy less than 70% of the area of a section of the fabric.

5. A hose according to any one of the preceding claims wherein component sections of elements of the fabric lying between successive points of interconnection or intersection of elements extend some substantially parallel and some substantially perpendicular to the length of the hose.

6. A hose according to claim 5 wherein the fabric is a knitted fabric arranged in the strip such that component sections of the fabric elements all extend at substantially equal angles of magnitude relative to the length of the strip.

7. A hose according to any one of the preceding claims wherein the fabric is embedded between two layers of polymer coating material which interconnect throngh openings in the fabric.

8. A hose according to any one of the preceding claims wherein the fabric is adhered to a layer of said polymer coating material.

9. A hose according to any one of the preceding claims and comprising radially inwards of the helically wcund strip of fabric an additional reinforcement of relatively inextensible fabric.

10. A hose according to claim 9 wherein the layers of said polymer coated and relatively inextensible fabric are separated by a layer of polymeric material.

11. A hose constructed and arranged substantially as hereinbefore described with reference to the accompanying drawings.

12. A method of manufacture of a kink resistant hose comprising helical winding about a mandrel at least one reinforcement strip of polymer coated high stretch fabric as hereinbefore defined.

13. A method according to claim 12 wherein the fabric is at least partially embedded in the layer of polymer coating material prior to helical winding of the strip.

14. A method according to claim 12 or claim 13 wherein the fabric is oriented in the strip and the strip is wound helically at an angle such that in the resulting hose assembly component sections of elements forming the fabric extend some substantialy parallel and some substantially perpendicular to the length of the hose.

15. A method according to any one of claims 12 to 14 wherein the polymer coating material is caused to extend into openings in the fabric and thereby interlock with the fabric, 16. A method of manufacture of hose substantially as hereinbefore described with reference to the accompanying drawings.

AMENDMENTS TO THE CLAIMS HAVE BEEN FILED AS FOLLOWS CLAI#'S : - 1. A hose comprising at least one helically wound reinforcement strip of a kind comprising a polymer coated knitted type reinforcement fabric in which the knitted fabric is supported by a layer of said polymeric coating material.

2. A hose comprising at least one helically wound reinforcement strip of a kind comprising a polymer coated high stretch reinforcement fabric as hereinbefore defined in which the high stretch fabric is supported by a layer of said polymeric coating material.

3. A hose according to claim 1 or claim 2 wherein the reinforcement fabric is of a substantially open construction in which as viewed in plan the area occupied by elements forming the fabric occupies less than 80% of the area of a section of the fabric.

7. A hose according to any one of the preceding claims wherein the fabric is embedded between two layers of polymer coating material which interconnect through openings in the fabric.

9. A hose according to any one of the preceding claims and comprising radially inwards of the helically wound strip of fabric an additional reinforcement of relatively inextensible fabric.

11. A hose according to any one of the preceding claims wherein the spaces between the elements of the fabric are occupied by said polymer coating material.

12. A hose constructed and arranged substantially as hereinbefore described with reference to the accompanying drawings.

13. A method of manufacture of a kink resistant hose comprising helically winding about a mandrel at least one reinreinforcement strip of polymer coated high stretch fabric as hereinbefore defined.

14. A method according to claim 13 wherein the fabric is at least-partially embedded in the layer of polymer coating material prior to helical winding of the strip.

15. A method according to claim 13 or claim 14 wherein the fabric is oriented in the strip and the strip is wound helically at an angle such that in the resulting hose assembly component sections of elements forming the fabric extend some substa.l- tially parallel and some substantially perpendicular to the length of the hose.

16. A method according to any one of claims 13 to 15 wherein the polymer coating material is caused to extend into openings in the fabric and thereby interlock with the fabric.

17. A method of manufacture of hose substantially as hereinbefore described with reference to the accompanying drawings.