APPARATUS FOR MANUFACTURING SAME

The present invention relates to reinforced elongate products, such as tubes, pipes, hoses and other tubular products, made from plastics and/or natural or synthetic rubber material and reinforced with filament, tape or other flexible reinforcing elements. The elongate product may comprise a preformed tubular body of finite length which is subsequently reinforced. Alternatively, it may be continuously formed as an endless tubular body which is simultaneously reinforced during its formation. For example, it may be an extruded plastics tube or may be formed by helically winding a strip of plastics material or rubber about a rotating mandrel device along which the helically formed layers are advanced with adjacent turns abutting and bonded together either during the winding process or subsequently.

The traditional process of braiding involves passing an object such as a tube through a hole in the centre of a round steel plate surrounded by bobbin carriers travelling circumferentially on continuous figure of eight tracks, thus producing an "over and under" tubular weave, which is deposited on the wall of the tube as it passes through the centre of the steel plate. The tube can be advanced vertically or horizontally. A braided shoe lace is a typical example. The operation is extremely slow and machines for this purpose are so noisy that it is necessary to enclose them with insulated boxes or place them in sound proof rooms.

An alternative to braiding is so-called lap-winding. This involves two counter rotating plates each typically loaded with up to sixteen 1 kg thread bobbins for lap-winding a tube of approximately 75 mm diameter. Such prior art methods tend to result in a very high downtime which may be in the region of 30-40% of total machine operation time. This is caused by the necessity regularly to repiace the bobbins which

have to be small because of space considerations. The bobbins used for such prior art winding techniques never run out simultaneously and frequently include concealed breaks which add to the number of times the process has to be halted. The high down time makes the process particularly unsuitable for reinforcing products manufactured on a continuous basis such as by extrusion or helical winding, since the extruded or wound product is wasted while the reinforcing process is interrupted.

Furthermore, in such prior art systems it is difficult accurately to regulate the tension of each reinforcing element being wound onto the tube and often it is only 60% of the filaments of the braid which are contributing to the tensile strength, the remaining filaments being so called "passengers".

The downtime and consequential high scrap produced and the unreliable tension of the filaments is the main reason for the present absence of large, 75mm (3 inches) diameter and upwards braiding machines in the flexible hose industry.

To manufacture large diameter pipes and hoses by the traditional processes of braiding requires rotating steel plates of at least 180cm (6 ft) diameter and the breakage of filaments, and consequential down time, would be enormous and uneconomical. Hence, larger diameter hoses are not currently textile reinforced. This is a fact and regrettably it is the very large industrial hoses that require this reinforcement due to their large cross sectional area. Therefore, to compensate for the lack of reinforcement the wall thickness is maαe excessive, for example up to 2cm ( ³ / inch), to enable the containment of even low pressures. Consequently, large bore hoses only work at low pressures in relation to small bore hoses of 25 to 50mm (1 to 2 inches) diameter, and even these plastic hoses are borαerline from a profitability point of view due to this weakness.

An object of the present invention is to provide an improved method and apparatus for reinforcing an elongate body with braiding which provide for fast, quiet and economic manufacture and which are suitable for use in a continuous production process. Another object of the invention is to provide a method and apparatus for reinforcing an elongate body which can be readily controlled by computer utilising NC or CNC techniques.

Yet another object of the invention is to provide a method and apparatus for reinforcing an elongate body with braiding which can easily accommodate body diameter, weave spacing and weave pitch variations over the length of the body. This cannot be achieved with presently available machines and methods.

From one aspect, the present invention consists in a method of manufacturing a reinforced elongate product having an elongate body made from plastics and/or rubber material, comprising the steps of guiding one or more flexible reinforcing elements on to an external surface of the elongate body via guiding means, advancing the body relative to the guiding means whilst simultaneously imparting to the body and guiding means both a relative rotational movement about a longitudinal axis of the boαy and a relative reciprocating movement in the direction of said axis, and bonding the flexible reinforcing element to the body.

With the invention, during each stroke of the relative reciprocating or oscillating movement, a reinforcing element is applied to the elongate body in the form of a helical or other spiral winding with the section of the winding applied during a return stroke crossing over the section of the winding applied during the preceding forward stroke on the outside of such section, and vice versa, and with the sections applied during successive forward strokes and during successive return stroκes being disposed in juxtaposed relation, respectively, wnereby a reinforcing

braiding is produced about the body. The reinforcing element or elements applied to the tubular body by the method of this invention produce a braiding having a diamond-like pattern or other pattern of generally parallelogram configuration. The elongate body may be non-rotating and be simply advanced relatively to the guiding means which is rotated about the body whilst simultaneously being reciprocated in the direction of the longitudinal axis of the body. However, preferably, the body is rotated as it is advanced relatively to the guide means which is simply reciprocated or oscillated in the direction of the longitudinal axis of the body. In either event, the invention enables the same degree of reinforcement per unit area to be produced, using solely a single bobbin of the flexible reinforcing element, as can be produced by hitherto known braiding machines. Considerably larger bobbins (e.g. containing 10kg of reinforcing element) may be used and containing longer lengths of the reinforcing element. As a result, machine down time can be reduced. Rotating the elongate body and simply reciprocating the guide means has the added advantage that the or each bobbin of reinforcement may be mounted on a stationary spindle and when one bobbin runs out the flexible reinforcing element can be joined to the next bobbin without stopping production.

The reinforcing element may be in the form of a filament, woven mesh or laminar tape or any combination thereof and may be made of synthetic or natural textile material, wire, fibreglass, carbon fibre, PTFE, KEVLAR, silicon, polyester fibre, or aluminium or other metal. The elongate body being reinforced may be a hose (ie. a flexible tube) a pipe (ie. a rigid tube) or of any other section.

During feeding of the reinforcing element onto the body it is preferably stretch orientated m order to maximise the potential strength of the reinforcing element and the utilisation of that strength. Preferably the guide means, such as an eye. is reciprocateα on a

path positioned substantially parallel to a central longitudinal axis of the elongate body. The stroke of the reciprocation may, for example, be between approximately 10-30 cm, although large strokes of up to 90 cm (36 inches) can also be utilised. The braiding produced with the reinforcing element may be internal or external or a combination of both or in any desired position with respect to a wall of the product and may be in the form of an open weave allowing material subsequently deposited on the body to bond effectively with a layer of material underlying the braiding thus increasing the bursting strength of the product, if hollow. Preferably the pitch angle of the spiral winding formed by a reinforcing element is between 127cm and 191cm (50 and 75 inches), and more preferably, between 153cm and 172cm (60 and 67.5 inches), with respect to the longitudinal axis of the body. In order to increase the hoop strength of a hollow elongate product reinforced by the invention, the reciprocating motion of the guide means relatively to the hollow body may be temporarily interrupted or slowed at the end of each stroke in order to apply at least one and, preferably, several, generally peripheral turns of a reinforcing element about the body. This may be achieved by interrupting the reciprocating motion of the guide means for a predetermined period at the end of each stroke or by merely controlling the reciprocating motion with respect to the continuously advancing body so that the guide means advances together with the body for a predetermined period at the end or beginning of each stroke. In order for the disposed turns to add significantly to hoop strength, they are preferably positioned at between 204cm and 229cm (80 and 90 inches) to the longitudinal axis of the body. For hign pressure applications, the hoop sections may consist of as many turns of reinforcing element as desired, and prererably equally spaced. The length of reinforcing element used to form the hoop section at each end

of the stroke can be wetted by a suitable mechanism to cover the element with a curing resin, such as an epoxy resin coating, to further strengthen the hoop and give anti-crush characteristics to the hollow body as well as anti-bursting characteristics. Upon completion of the hoop section, the mechanism for applying the epoxy resin coating is disengaged and an appropriate flexible coated element is applied. Additional reinforcing material may be applied by an automatic chopped roving gun affixed to the reciprocating guide means support.

One of the advantages of the above descnbed braiding system is the ability to produce wound hoops or loops in conjunction with the braiding. The hoops or loops superimposed at equal distances gives a dramatic improvement to burst strength of a hose or pipe. The stroke of the oscillation of the guide means may be from 12-36mm or as required. Additional tapes or filaments may be superimposed onto the surface of the hose or pipe. Also, for extra high pressure applications, such as hydraulic hoses, the spiral windings of the reinforcing element may criss-cross leaving substantially no openings therebetween and plural layers of reinforcing element and other matenals may be employed. A product so formed can be flexible or rigid and exhibit high crush, burst and/or hoop strength.

In a modification which provides for increased hoop strength, a filament or tape for forming hoops is guided on to the external surface of the elongate body via second guiding means, such as an eye, which is independent of the first or main oscillating guiding means. This second guiding means is adapted to reciprocate over a shorter stroke than the first guiding means ana moves in synchronism with the aavance of the elongate body during each forward stroke, to produce a hoop section about the body formed of overwound filament or tape, and flies back on each return stroke to a position in which it winds a successive hooo section. The filament or tape for this second guiding means may be

epoxy resin coated by depressing it into a container of resin, under mechanical, pneumatic or electrical control, so that the filament or tape can be hoop wound to provide a required degree of hoop strength. Moreover, the filament or tape may be coloured or locally coloured and printed so that the hoops may be electronically recorded to assure formation of the hoops and quality control.

Hitherto, in the production of rigid fibreglass pipes, the pipes were filament wound onto long steel mandrels in lengths up to 9-15m (30-50ft) or more as dictated by the length of the mandrel. The filament, usually glass fibre, was wound onto the mandrel end to end. Another aspect of the invention is to produce a fibreglass pipe on a short mandrel or mandrels with a forward revolving motion on a continuous basis. The thickness of the wall depends on the amount of reinforcing filament and resins deposited on the short mandrel or mandrels, covered with a release tape or PTFE.

A further embodiment of the invention is to produce a pipe or hose, thin wall or otherwise, without utilizing extruders. For example, a plastics material in tape or web form is layered and bonded to itself on a forward moving mandrel or mandrels thus forming a flexible or rigid tube onto which various filaments and resins, as described, can be superimposed onto the mandrel or mandrels to produce a continuous flexible or rigid pipe.

So as to increase the longitudinal tensile strength of the product, reinforcing filaments or other reinforcing means may be applied substantially parallel to the longitudinal axis of the body.

Particularly, when the body being reinforced is flexible, for example a hose, and/or is still in an uncured or heated state, means are preferably provided to support the body as it is being reinforced. Such support means may take the form of internal pressunsation, a supporting mandrel or former or a tensioning device.

The method is conveniently computer CNC controlled. If the tubular body is spirally produced and made from a soft plastic and a rigid plastic (co-extruded sections), the revolutions per minute (RPM) of each extruder screw and a mandrel on which the body is wound (see for example that described in EP-A-0 046 080), the speed and oscillation stroke length of the guiding means, the speed of advancement of the body, are ail controlled by computer. This in turn controls the size of the diamond shaped openings in the reinforcing braiding. According to the program on the computer, the method can be used simultaneously to weave-braid one or more hoses which may differ in diameter.

More particularly, the pitch of the spiral winding is computer controlled with reference to output from body rotation and feed rate. So that the oppositely directed spirals of the reinforcing element are deposited on the body with equal pitch angles, even when the body is travelling in the longitudinal direction, preferably, the body advances through a first oscillation work station including the guide means and the guide means is controlled to travel at different speeds during travel in opposite directions. The difference in speed being determined by the longitudinal feed rate of the body. The body may advance through subsequent oscillation work stations in which one or more coatings and/or one or more layers of the same and/or different reinforcing element materials are applied to the body. Layers of materials, such as plastic or rubber, may conveniently be applied by means of extrusion. Different layers can be chosen to provide the product with different qualities eg. non-toxic, oil resistant, anti-abrasive, electrically conαucting etc... A metal skin would provide appropriate protection for a pipe which is to be located underground or exposed to ultra-violet radiation or smoke. An application of metallic filament may be useα to accelerate the bonding process by passing the hose or pipe through an electrical inαuction coil. Wire or other

conductive filament may also serve as a screening or location device for a hose or pipe buried in the ground. A flat or round plastic spiral may be applied externally to prevent surface wear.

So as to speed up the rate at which the body is reinforced, two or more reinforcing elements of the same or different materials may be simultaneously deposited on or applied to the body. All reinforcing elements may be guided by an eye from closely adjacent locations onto the body or guided thereonto from circumferentially spaced locations, for example diametrically opposed locations. Increased production efficiency can also be achieved by providing a reciprocating guide means which guides two or more flexible reinforcing elements simultaneously onto two or more tubular bodies driven by the computer.

Rotation of the body typically occurs when the body is a spiral reinforced hose, such as a lap wound hose formed from hot extruded profile (see for example the hose described in EP-A-0046080 and marketed under the trade name Springvin). Such a crush resistant hose includes a high carbon steel wire and/or plastic spiral and is rotated about its longitudinal axis as it is produced.

The invention enables pipes or hoses of up to 90cm (3 ft) diameter or more to be satisfactorily filament reinforced, thus resulting in a considerable and economical reduction in wall thickness compared with conventional large diameter products. That is, a hose or pipe having particular dimensions and produced using the invention can be designed to have a higher bursting strength than a hose or pipe manufactured using prior art methods. For example, a 100mm to 150mm diameter pipe conventionally having a wall thickness of 6mm to 9mm can be produced with a wall of roughly half that thickness while exhibiting a similar bursting pressure. Furthermore, a considerable capital saving can be achieved by reinforcing and making two hoses or more at the same time. With the invention, it is possible to produce, on a continuous basis,

adjacent rigid and soft sections. This can be achieved, irrespective of the reinforcement element used, by the use of rigid and/or flexible (e.g. polyurethane) resins in conjunction with the use of rigid plastics and soft plastics for producing the body being extruded for reinforcement. From another aspect, the invention consists in apparatus for manufacturing a reinforced elongate product having an elongate body of plastics and/or rubber material, comprising guide means arranged to guide one or more flexible reinforcing elements on to an external surface of the body, and means for advancing the body relatively to the guide means and for imparting to the body and guide means a relative rotational movement about a longitudinal axis of the product and a relative reciprocating movement in the direction of said axis. The apparatus may also include means for achieving any of the steps discussed above in connection with the method of the invention. The means for producing reciprocating movement is preferably adapted to have a stroke length of between about 10cm and about 100cm.

From yet another aspect, the invention consists in a reinforced elongate product wherein one or more flexible reinforcing elements are wound about an elongate body of plastics and/or rubber material in a regular array of spiral or part-spiral windings having spiral paths alternately extending in opposite axial directions of the body. The product and/or reinforcing element may include any of the features discussed above in connection with the methoα of the invention. All aspects of the invention are particularly applicable to tubular products.

The invention will now be described, by way of examde only, with reference to the accompanying drawings, in which:

Figure 1 A is a schematic perspective view of a first amccciment of the invention.

Figure 1 B is a schematic perspective of a detail of the machine illustrated in Figure 1A,

Figure 1 C is an elevational view of an extrusion system incorporating the embodiment illustrated in Figure 1A, Figure 1 D is a horizontal cross-sectional view illustrating in more detail a machine according to the first embodiment,

Figure 2 is a side elevation from the direction of arrow C of the machine shown in Figure 1 D,

Figure 3 is a vertical cross-section on the line AA of the machine shown in Figure 1 D,

Figure 4 is a vertical cross-section on the iine BB of the machine shown in Figure 1 D,

Figure 5 is a partial horizontal cross-sectional view illustrating a modification, Figures 6-8 are schematic illustrations of a tubular member according to the third aspect of the invention reinforced using the method according to the first aspect of the invention,

Figures 9 and 10 are computer generated views of a cylindncal body reinforced according to the invention, Figure 11 is a schematic view of part of a machine according to the invention for reinforcing a continuously advancing tubular body, and Figure 12 is a schematic view illustrating the simultaneous reinforcement of two continually advancing tubes produced by apparatus similar to that of Figure 11. While the invention is described below with reference to the production of a reinforced tubular product, such as a hose or pipe, it is to be understood that a wide variety of elongate articles or bodies may be reinforced using the method and apparatus described.

Referring to the accompanying drawings, Figures A. B and C schematically illustrate a system for the reinforcement of a non-rotating

tubular plastics extrusion 36 for use as standard hose or pipe. The machine 1 for applying the reinforcement is floor-mounted on legs 4,6 and includes a horizontal drum 8 rotatably mounted on the legs for rotation about its axis and about the tubular extrusion 36 which is fed coaxially through the drum. A caterpillar haul off 3 (see Figure 1 C) is used to pull the hot tubular extrudate from an extruder 5 through a water cooled calibrator (not shown) and a second caterpillar haul off 7 or the like placed approximately 2-3m downstream and operating at a slightly faster speed than the first haul off 3 has means to permit the tubular product to slip, thus maintaining a slight tension. The tubular extrusion 36 can be further stiffened by incorporating a metal shaft to give support at the point of braiding. The reinforcing machine 1 is disposed between the two haul offs 3,7 so that the extrusion is advanced coaxially through the drum 8 from end to end of the drum. Mounted in the drum 8 for rotation with the drum is a bobbin 52 of reinforcing filament which is fed from the bobbin to the external surface of the extrusion 36 via a guide eyelet 70 which is also mounted within the drum for rotation therewith and which is reciprocated in the direction of the axes of the drum and extrusion as the drum revolves about the extrusion. The reciprocation or oscillation of the eyelet 70 may be produced by a servo motor 9 (see Figure 1 B) which is computer controlled through electrtc slip rings. The entire drum unit revolving about the tubular extrusion 36 is driven by a computer controlled servo motor responding to extruder output. The bobbin 52 containing the reinforcing filament, tape, etc, may be a large bobbin, for example, of the order of 10-12 kg and the drum 8 may be suitably counterbalanced and include a hinged cover 11 providing access to the interior of the drum and the bobbin. An adhesive coating may be applied to the extrusion 36 upstream or the reinforcing machine to key the reinforcing windings to the tubular piastic extrusion. As the tubular extrusion is advanced through the arum 3. the

reciprocating or oscillating movement of the eyelet 70 rotating about the extrusion winds the reinforcing filament about the extrusion in a regular array of helical windings having helical paths alternately extending in opposite axial directions of the extrusion. The resulting product P pulled from the reinforcing machine 1 by the downstream haul off 7 is reinforced with a braiding having a diamond-like pattern. This reinforced tubular product may, if desired, be fed to a second plastics extruder for depositing a tubular layer of plastics material over the braid reinforcement. Figures 1 D-4 illustrate in more detail a reinforcing machine of the type schematically illustrated in Figure 1A. In these Figures like reference numerals to those used in Figure 1A indicate similar parts. Hence, the machine 1 shown in Figures 1 D and 2 includes a base 2 at or near each end of which upstanding legs 4 and 6 are provided. A cylindrical drum 8 having end plates 54 and 56 is positioned between and journalled for rotation in upper ends of the legs 6 and 8 by means of bearings 38 and 40 which engage a bearing tube 42 extending centrally from one end of the drum 8 and a drive tube 18 which extends centrally from its opposite end. Inlet and outlet apertures 44 and 46 in the bearing tube 42 and drive tube 18 respectively permit the extruded plastics tube 36, which is to be reinforced, to pass through the machine.

A cylindrical bobbin mount 48 with resilient detents 50 projects centrally into the drum 8 from one end plate 56 and rotatably supports a bobbin 52 of reinforcing filament. Extending between the end plates 54 and 56 is a square section track 58 along which a carriage 60 is siidable between limit switch stops 62 and 64. An accumulator and tensioning device 66 receives filament 68 from the bobbin 52 and delivers it at a constant tension to the guide eyelet 70 on the carriage 60 from wnich the filament passes to and is wound round the tube 36. An outer part of the carriage 60 is connected

by screws to a continuous toothed drive belt 72 supported on a roller 74 near one end of the drum and a drive gear 76 near the other end of the drum. The roller 74 is supported by a bracket 78 on the outer wall of the drum 8 and the drive gear 76 is drivably connected to a carriage drive motor 80 which is also connected to the outer wall of the drum 8. The motor 80 is a stepping motor.

The limit switches 62 and 64 are electrically connected to slip rings 20 and 24 respectively which extend around one end of the drum. A third slip ring 22 is electrically connected to the carriage drive motor 80. The slip rings 20, 22 and 24 are in electrical contact with brushes 26, 28 and 30 respectively which are mounted in a brush mount 32 fixed to a lateral extension of the left hand leg 4 as seen in Figure 1. Each brush is biased by a spring into contact with its respective slip ring and permits the drum 8 to rotate. A brush lead 82 connects each brush to a central processing unit (CPU) 84. A drum rotation transducer 86 positioned to sense the movement of a toothed ring 88 mounted on one end of the drum is connected to the CPU 84 by a wire 90. A tube feed rate sensor 92 and a tube rotation sensor 93 are connected to the CPU by wires 94 and 95 respectively. The CPU is also connected to the drum motor 16

Positioned upstream of the drum 8 is a spraying chamber 98 containing adhesive spraying nozzles 100. The nozzles may alternatively provide hot air for heating the surface of the tube. The actuation of the spraying nozzles may be controlled by the CPU. The operation of the machine will now be described with reference to Figures 6 to 8 which show three important stages in one complete winding cycle. The CPU actuates the drum motor 16 and causes the drum 8 and its associated equipment to rotate about the tube 36 at the same time as the carriage is reciprocated. The slip rings 20, 22 and 24 permit all electrical connections with equipment mounted in the drum to

be maintained in conjunction with the CPU and CNC.

Firstly, parameters concerning the weave required are fed into the CPU and to a CNC (computer numeric control) system. These parameters may concern filament weave density, filament weave pitch angle and circumferential winding requirements.

It will be assumed that the filament 68 is already connected to the tube 36 and the carriage is located at the right hand limit switch 64.

As the tube 36 is fed towards the drum 8 at a speed controlled by the CPU, it passes through the spraying chamber 98 where it is sprayed with adhesive from nozzles 100, possibly under the control of CPU 84, at a rate dependent on the feed rate of the tube 36 sensed by the feed rate sensor 32. The CPU also uses feed rate sensor data and tube rotation sensor data to determine the rate V _L at which the carriage 60 must be moved towards limit switch 62 to create a first helical winding 102 (see Fig. 6) of the required pitch angle a ⁰ on the tube 36. The signal sent to the carriage motor 80 controls its speed appropriately. Once the carriage 60 reaches limit switch 62 the signal is sent to the CPU which causes the carnage motor 80 to halt. Such halting may alternatively be controlled by the CPU on the basis of the amount of rotation of the carriage motor 80. If a substantially circumferential winding 104 (see Fig. 7) is to be included, then the carriage is either held stationary or moved at the same speed as the tube feed rate V back towards the limit switch 64. Once the required number of circumferential windings has been applied to the tube, the speed of the carnage towards the limit switch 64 is increased to the level required to create a second helical winding 106 (see Fig. 8) with an equal but oppositely directed pitch angle a ^α to the first winding 102. The required rate of movement V _q of the carriage is given by

V _R = V _^ + 2V

where V is the feed rate of the tube 36. Movement of the carriage to the right continues until it reaches limit switch 64 at which point the cycle described above will be repeated.

A modified form of the machine described above for braiding a non-rotating tubular extrusion with reinforcing filament is shown in Figure 5. In Figure 5, the single centrally mounted bobbin 52 is replaced by two (or more) separate bobbins 108 mounted on bobbin mounts 110 projecting outwardly from the end plate 56. The filaments 112 from the bobbins pass into the drum 8 through holes 114, into accumulators 66 and 67 and then to separate carriages driven along rails 58 and 59 respectively. The carriage, carriage motor etc. associated with the rail 59 may be identical to those associated with the rail 58 and are accordingly not described in detail.

As an alternative to driving the or each carriage 60 by a carriage drive belt 72, it may alternatively engage a spiral track in a rotatable drive shaft. The track may possibly be a continuous track including intersecting oppositely directed spirals in order that the drive shaft will only have to be rotated in an single direction.

Figures 9 and 10 show, in greater detail than Figures 6, 7 and 8. the first helical windings 102, second helical windings 106, circumferential windings 104 and longitudinal reinforcement 105.

Utilising the same rotary machine as described with reference to Figures 1 D to 5 it would also be possible to produce, on a continuous basis, a fibre reinforced pipe or tube which is advanced over a steel mandrel (not shown) which takes the place of the tube 36. The mandrel would be lubricated with PTFE or lubricant forced through perforations in the hollow mandrel. The mandrel would be continuously wound with a suitable plastics strip (for example 50mm to 75mm wide) to which the filament reinforcement is applied. Alternatively, a spool of 50mm to 75mm wide plastic film 57 is

mounted on a tubular support (not shown) projecting into the drum 8 from the end plate 54. Such a spool 55 is shown schematically in broken lines in Figure 1 D. The plastic film is wound onto the lubricated mandrel in an overlapping arrangement and heated by elements inside the mandrel. The internal diameter of the reinforced pipe or tube is determined by the external diameter of the mandrel. The plastic film 57 wound onto the mandrel could be oil or acid resistant, PTFE or a high performance plastic reinforced material. A caterpillar haul-off is provided to control the longitudinal movement of the pipe or tube produced and a circular saw is positioned downstream of the reinforcing machine for cutting the pipe or tube to length.

Figure 1 shows how the reinforcing method of the present invention can be applied to a continuously produced helically wound hose, such as that described in EP-A-0 046 080. The body of the hose comprises inner and outer tubular layers 134,136 of plastics material formed by helically winding strips 116 of the material extruded from successive nozzles 118 onto a rotating mandrel 120 which is adapted to advance the wound layers axiaily along the mandrel to be discharged from the free end of the mandrel. A steel wire 132 is wound onto the body between the inner and outer layers 134, 136 of lap-wound plastic strips 116. It is guided into position on the body by means of power dnve rollers 124, coil forming rollers 126 and a coil forming guide 128 mounted on a support plate 122. A coil engaging fork 130 engages each coil immediately after it has been deposited on the body. A carriage 60, which is reciprocated along a track 58 in the same way as the carriage shown in Figure 1 D, guides a filament 68 through a carriage eyelet 70. Since the hose rotates as it is produced, there is no need to rotate the carriage 60 about the hose and the filament 68 can be applied to the hose in accordance with the invention simply by reciprocating the carriage at the required rate. The fiiament deposited on the hose has

been omitted from Figure 11 for reasons of clarity. A hot air jet 140 is provided to soften the hose materials and assist their adhesion to one another.

Where the hose produced by the apparatus illustrated in Figure 11 is only required to have enhanced burst resistant characteristics and not burst and crush resistant characteristics, the station for winding the steel wire 132 is omitted and the hose is simply braided with the reinforcing filament 68 as described with reference to Figure 11.

Figure 12 schematically illustrates the application of the invention to the simultaneous manufacture of two reinforced hoses having tubular layers of plastics material formed by helically winding strips of the material on to rotating mandrels, as described in EP-A-0 046 080 and Figure 11 hereof. Hence, plastics material is extruded from a first extruder 150 in the form of two strips 151 ,152 of appropriate profile and helically wound about the two rotating mandrels 153,154. Downstream of the winding positions reinforcing filaments are supplied to the external surfaces of both tubular layers or bodies 155,156 via one or more suitable guide eyelets 157 supported by a carriage 158 which is reciprocated along a guide rod 159 parallel to the axes of the mandrels 153,154 and relatively to both tubular layers 155,156 in accordance with the method of this invention. The two tubular layers having the resulting braided reinforcement may be covered with another wound helical layer of plastics material formed by strips 160,161 of the material extruded from a second extruder 162 and bonded to the surface of the inner tubular layers. To facilitate this, the outer surface of the inner tubular layers may be heated and softened by hot air jets (not shown). Appropriate pressure rollers may be provided as necessary to ensure good bonding.