GB2060472A

GB2060472A - Improvements in or Relating to Hose Manufacture

Info

Publication number: GB2060472A
Application number: GB8029564A
Authority: GB
Original assignee: Dunlop Ltd
Current assignee: Dunlop Ltd
Priority date: 1979-09-14
Filing date: 1980-09-12
Publication date: 1981-05-07
Also published as: GB2060472B

Abstract

The continuous manufacture of reinforced hose is performed by forming an assembly of a tubular reinforcement structure 23 and a tubular lining layer 24 surrounded by but not united with the reinforcement structure. The assembly is fed to separation means, such as a tubular mandrel 10, and cover material for the hose is applied, e.g. by extrusion, to the reinforcement structure whilst the lining is maintained spaced from the reinforcement by said separation means. The separation means may serve also to provide support for the reinforcement structure during application of the cover material. Subsequent to formation of the cover the lining is united with the reinforcement structure. <IMAGE>

Description

SPECIFICATION Improvements In Or Relating To Hose Manufacture This invention relates to a method of and apparatus for the continuous manufacture of hose and in particular, though not exclusively, hose of the kind having a woven reinforcement jacket.

One method commonly employed for the manufacture of hose, e.g. fire hose, having a woven reinforcement jacket is described in the specification of U.K. Patent 856,955. In use of general methods of this kind a pre-woven textile reinforcement jacket is fed to an extruder which forms a coating of, for example, thermoplastics material on the outer surface of the jacket and also urges the thermoplastics material through the interstices of the woven jacket so as simultaneously to form a lining. This method facilitates the reliable manufacture of high quality hose but has the disadvantage that high haul-off tensions are required in order to pull the jacket through the extruder.In consequence there is a danger of the jacket becoming damaged and in some cases to ensure that the required haul-off tension can be withstood by the jacket it is necessary to incorporate more reinforcement material than is required for subsequent satisfactory service of the hose. Thus the weight and cost of the hose is greater than required to meet operational conditions.

In accordance with one aspect of the present invention a method of continuous manufacture of hose comprises forming an assembly comprising a tubular reinforcement structure which surrounds a tubular lining causing the lining and the reinforcement structure to be maintained spaced relative to one another whilst applying cover material to the reinforcement structure and then uniting the lining with the covered reinforcement structure.

In accordance with another aspect of the present invention apparatus for the continuous manufacture of hose comprises feed means for feeding through cover applying means an assembly comprising a tubular reinforcement structure which surrounds a tubular lining, and separation means for maintaining the lining spaced from the tubular reinforcement structure during application of cover material to the tubular reinforcement structure.

The separation means for maintaining the lining spaced from the tubular reinforcement structure may be a tubular mandrel. The separation means may act as a support for the tubular reinforcement structure during application thereto of the cover material.

Further aspects of the invention will be apparent from the following description of embodiments of the invention, given by way of example, with reference to the accompanying drawings in which~ Figure 1 shows schematically apparatus in accordance with the present invention; Figure 2 is a cross-sectional view of the separation mandrel and cover applying means of Figure 1; Figure 3 is an alternative separation mandrel and cover applying means; Figure 4 shows a further alternative means for mandrel location, and Figure 5 shows means for mandrel location for use in the manufacture of spirally reinforced hose.

Apparatus for the manufacture of a textile reinforced fire hose comprises a supply drum 1 from which a part-formed hose assembly, comprising a synthetic rubber lining 24 surrounded by a woven polyester jacket 23, may be drawn by a feed drum 4 which is rotatable at a constant pre-selected speed.

The hose assembly may pass through three closely spaced rollers 3 which grip the hose assembly and impart a controlled tension to that length of the assembly passing to the drum 4, or said rollers 3 may be omitted and tension may be applied by braking of the supply drum 1 or other means.

The part-formed hose assembly may alternatively be drawn from a bin 2 and in this case said rollers 3 or other suitable means may be used to apply an initial tension.

The feed drum 4 supplies the part-formed hose assembly to cover applying means comprising an extruder 6 having a T-head 5 which applies a cover layer to the jacket. The T-head and extruder are described in more detail below.

Downstream of the extruder a cooling chamber 7 is provided to cool the hose issuing from the extruder. A haul-off roller 8 draws the covered hose assembly from the extruder through the cooling chamber and feeds it to a coiler 9.

The cover applying means is described in more detail with reference to Figure 2. Said means comprises a hollow mandrel 10 which extends into the T-head 5 and is dimensioned such that an annular passage is formed between the T-head and the outer surface of the mandrel. The mandrel 10 serves as separation means to separate the lining 24 from the jacket 23 of the part-formed hose assembly and maintain them spaced during application of cover material to the reinforcement jacket.

The upstream end of the mandrel 10 is provided with an entry zone 14 which aids separation of the lining from the reinforcement jacket and also co-operates with a retention member in the form of a frusto-conical form ring 12 to prevent axial movement of the mandrel through the extruder. The jacket passes around the outside of the mandrel through an annular gap between the radiused surface 11 at the downstream end of the entry cone 14 and the frusto-conical form ring 12. The ring 12 may be cooled by admitting air or water through passage 13. At least the surface of the entry cone 14 is formed from PTEE or like material having low friction properties, i.e. coefficient of friction less than 0.1, and the form ring 12 is manufactured from steel or a like material having suitable strength and wear resisting properties.

The form ring 12 is located in a predetermined relationship relative to the T-head extruder and thereby supports the hollow mandrel substantially concentric with the bore of the T-head.

The downstream end of the mandrel 10 is formed with a radially outwardly extending shoulder 1 Oa that locates a male die 15 which is in the form of a metal sleeve free to rotate relative to the mandrel 10. The male die 15 co-operates with a female die 17 to control the thickness of the cover material applied to the reinforcement jacket. Upstream of the female die 1 7 the extruder is provided with a metal sleeve 16 which acts as a seal to restrain flow of the extruder cover material in an upstream direction. The bore of the sleeve 1 6 is greater than the outer diameter of the male die 15 by a dimension slightly less than twice the thickness of the reinforcement jacket. Therefore the reinforcement jacket is compressed whilst passing between the sleeve 16 and the male die 15 and accordingly restrains upstream flow of the cover material.The rotatable mounting of male die 15 is intended to prevent the helical form of weft yarns within the jacket inducing a twisting movement in the hose.

Subsequent to cover material being applied to the jacket, the covered jacket passes over the downstream end of the mandrel and the lining and covered jacket are then able to become united. The assembled hose then passes through the afore-described cooling chamber 7, haul-off unit 8 and coiler 9.

Suitable materials for the cover include rubbers such as natural or synthetic rubbers, e.g.

neoprene or nitrile rubber, and thermoplastic materials such as polyurethane, poly vinylchloride, Hytrel (registered Trade Mark) or blends thereof. The lining may also be formed from similar materials and may be of the same or a different material to that of the cover. Suitable lining materials include thermoplastics such as Hytrel and P.V.C.

Suitable reinforcement materials include also nylon, polyester, steel and Kevlar (Registered Trade Mark), and in a woven reinforcement the warp and weft may be dissimilar.

Preferably the lining and cover are formed of materials which can be united together e.g. by bonding or adhesives, so as to form a coherent hose structure in which the reinforcement jacket is firmly embedded. Especially where the lining and cover are of materials which can unite to one another without adhesives it is preferred that during application of the cover material said material is caused to penetrate the jacket and more preferably form a thin coating on the inner surface of the jacket. If, however, the lining and cover are not of compatible materials which unite to one another under the application of heat and/or pressure, adhesives may be employed.

That is, the lining may be coated with a suitable adhesive, preferably before being surrounded by the reinforcement jacket, and caused to effect a bond with the cover material and/or reinforcement jacket subsequent to passage through the hollow mandrel 10.

In the case of a hose formed with a thermoplastic lining and cover, the lining and cover may be bonded by passing steam or other fluid at a suitable temperature and pressure through the lining. In the case of a hose having a rubber lining or cover curing of the lining or cover and bonding of the liner and cover to one another and/or to the reinforcement may also be achieved by passing steam or other high pressure fluid through the lining. Other known curing and bonding techniques may be employed such as a heated fluidised bed, or a micro-wave heater.

The above curing vulcanisation and like processes to unite the lining cover and reinforcement may be performed in line with the hose construction steps or, especially where pressurised/heated fluid is to be passed through the hose bore, they may be performed as a separate operation.

A particular feature of the afore-described hose manufacturing method is that the haul-off tension required of the haul-off unit 8 is less than in other hitherto commonly employed processes such as those based on that of U.K. Patent 856,955, and the reinforcement jacket does not require to have a strength in the direction of the length of the hose greater than that necessary for in-service conditions. The haul-off tension required to draw the reinforcement jacket through the annular gap between the entry cone 14 and frusto-conical ring 12 is found to be determined at least in part by the angle beta (see Figure 2) which is the half apex angle of the inner surface of the form ring 12.Low angles of beta result in a high tension in the jacket; it has been found that satisfactory operation is achieved with angles of beta in the range 60O to 750.

In the afore-described apparatus the feed drum 4, in combination with the haul-off unit 8, feeds the jacket and lining to the cover applying means at a constant rate and the cover material is therefore applied uniformly. Variations in the haul-off tension due to changing conditions in the extruder head of the cover applying means therefore do not cause a varying jacket feed rate.

In consequence undesirable surging of the jacket in the extruder is avoided.

The feed drum 4 also serves to impose a tension on the jacket as it is fed to the extruder and this prevents bunching of warp yarns as they pass between the form ring 12 and the radiused surface 1 1 of entry cone 14.

It has been explained above that the method of the present invention permits the continuous manufacture of a hose in which the lining and cover may if desired be formed of different materials depending on the required surface applications. Similarly the method may be employed with reinforcement jackets which are either of a textile material, such as polyester, rayon, nylon, or Kevlar, or a metallic reinforcement such as brass plated wires. It is preferred that the reinforcement is woven so as readily to retain the required relative disposition of the reinforcing filaments when passing over the separation mandrel, but other reinforcement structure such as non-woven constructions may be employed.A non-woven reinforcement may, for example, be in the form of a number of filaments substantially randomly arranged and, optionally, interconnected such as by melting at their cross-over points. Alternatively a non-woven reinforcement may, for example, comprise one or more layers each formed of a plurality of helically wound filaments, wires etc.

In general it is preferred that the reinforcement structure is permeable so that the cover material may be urged into interstices of the reinforcement and subsequently united with the lining layer material to fully encapsulate the reinforcement jacket. However, it is not essential that the reinforcement structure per se be permeable and nonwoven impermeable reinforcements such as a thin high strength nylon tube may be used. In the case of an impermeable reinforcement, a hose may be manufactured by a co-extrusion process in which a single T head is fed by two or more extruders which provide the required tubular lining and reinforcement layers.

The part-formed assembly of the lining and reinforcement jacket may be formed by techniques already well known. Preferably the lining is maintained under light tension whilst the reinforcement jacket is woven therearound. For a rubber lining an extension in the range 0 to 20%, typically 6 to 7%, is suitable and for a thermoplastic lining an extension in the range 0 to 10%, typically 1 to 2%, is suitable.

Alternative methods for locating the mandrel 10 against axial movement through the extruder are shown in Figures 3-5.

In Figure 3 there is illustrated a construction in which the upstream end of the mandrel is formed with an extension 18 having a central portion 1 8a lying between end portions 1 8b and of reduced diameter relative thereto. A series of circumferentially spaced rollers 19 surround the central portion 1 8a and bear against the upstream end portion 1 8b to restrain movement of the mandrel through the extruder.

Radial location of the mandrel 10 in the extruder is obtained by means of a mandrel shoulder 1 Oa provided upstream of the male die 15. The shoulder 1 Oa co-operates with sleeve 16 in the same manner as the male die 1 5 cooperates with the sleeve as described above, and also provided in respect of Figure 3 construction, to effect location of the mandrel.

The rollers 19 may be driven to assist movement of the reinforcement jacket over the mandrel extension.

In Figure 4 there is illustrated a mandrel 10 also formed with a mandrel extension having a central portion of reduced diameter compared with end portions of the mandrel extension as in the Figure 3 construction. In this construction, however, the centre portion of the mandrel extension is formed with a series of circumferentially spaced non-driven rollers 20 over which the reinforcement jacket may pass.

Driven rollers 21 corresponding substantially to rollers 19 shown in Figure 3 assist movement of the reinforcement jacket over the mandrel extension and also resist axial movement of the mandrel through the extruder.

Figure 5 shows a construction suitable for manufacture of hose having a non-woven reinforcement. In this case the mandrel 30 extends further upstream of the extruder 31 than the mandrel described above. The mandrel is firmly supported at the upstream end and the reinforcement is formed around the exposed part of the mandrel upstream of the extruder 31 by means of spaced guides 32 around which warp threads 33 are drawn onto the mandrel.

A pair of contra-rotatable winding heads 34 are provided to wind two layers of weft threads 35 around the mandrel and the warp threads.

In the afore-described method the weft threads typically are formed with a helix angle in the order of 50. However, the warp threads may be omitted and in that case the weft threads preferably are wound at a helix angle in the order of 550.

Claims

1. Apparatus for the continuous manufacture of hose comprising feed means for feeding through cover applying means an assembly comprising a tubular reinforcement structure which surrounds a tubular lining, and separation means for maintaining the lining spaced from the tubular reinforcement structure during application of cover material to the tubular reinforcement structure.

2. Apparatus according to Claim 1 wherein the separation means serves also to support the tubular reinforcement structure during application thereto of cover material.

3. Apparatus according to Claim 1 or Claim 2 wherein the separation means comprises a tubular mandrel.

4. Apparatus according to Claim 2 or Claim 3 wherein an extruder is provided and the separation means extends within the extruder to support the tubular reinforcement structure during extrusion of cover material thereon.

5. Apparatus according to Claim 4 wherein an upstream end of the separation means is provided with an entry zone portion shaped to co-operate with fixed retention means to prevent axial movement of the separation means through the extruder.

6. Apparatus according to Claim 5 wherein at least the surface of the entry zone portion of the separation means is formed of a material having a co-efficient of friction less than 0.1.

7. Apparatus according to Claim 5 or Claim 6 wherein the retention means has a substantially frusto-conical shaped surface to prevent axial movement of the separation means into the extruder whilst also facilitating movement of a textile reinforcement structure between the retention means and the entry zone portion of the separation means.

8. Apparatus according to Claim 7 wherein the half-apex angle of said frusto-conical surface is in the range 600 to 750.

9. Apparatus according to any one of Claims 4 to 8 wherein at least a portion of the separation means is free to rotate relative to the extruder.

10. Apparatus according to any one of the preceding claims substantially as hereinbefore described with reference to the accompanying drawings.

11. Method of continuous manufacture of hose comprising forming an assembly comprising a tubular reinforcement structure which surrounds a tubular lining, causing the lining and the reinforcement structure to be maintained spaced relative to one another whilst applying cover material to the reinforcement structure and then uniting the lining with the covered reinforcement structure.

12. Method according to Claim 11 wherein the cover material is applied by extrusion.

13. Method according to Claim 1 1 or Claim 12 wherein the reinforcement structure is permeable.

14. Method according to Claim 13 wherein interstices of the reinforcement structure are filled during extrusion of the cover material and a thin coating of the extruded material is formed on the inner surface of the reinforcement structure.

15. Method according to any one of Claims 12 to 14 wherein a tubular mandrel is used to support the reinforcement structure during extrusion thereon of cover material.

16. Method according to Claim 15 wherein the tubular mandrel is selected in relation to the diameter of a tubular entry portion of the extruder such that the bore of said entry is greater than the outer diameter of the tubular mandrel by dimension slightly less than twice the thickness of the reinforcement jacket.

1 7. Method for the continuous manufacture of hose according to any one of Claims 1 1 to 16 substantially as hereinbefore described with reference to the accompanying drawings.

18. Hose manufacture by a method according to any one of Claims 11 to 17.