Device for sheathing pipes with fiber-reinforced plastic

Abstract

Sheathing device (10) for sheathing a tube (12) with fibers (14) embedded in a plastic matrix, the sheathing device (10) comprising: - a tube holder (20) configured to hold a tube (12) to be sheathed during the sheathing process such that the tube is rotatable about its longitudinal axis; - a fiber feeder (30) configured to feed fiber webs formed from textile glass fibers in the form of rovings or fiber bundles to a tube to be sheathed such that the fed fibers are wound helically around the tube while the tube (12) rotates about its longitudinal axis, the fiber feeder being continuously movable along the longitudinal axis such that the fed textile glass fibers are wound helically around the tube such that webs of the fed fibers overlap by at least 50% in the longitudinal direction of the tube; - a displacement drive (50) configured to is,the fiber feed (30) is displaced along the longitudinal axis of the tube to be sheathed such that, during each rotation of the tube, the fiber feed is displaced by a distance which corresponds to a maximum of half the width of a fiber tape to be supplied, and a resin feed (40) which is configured to impregnate fibers to be supplied to the tube with a liquid, curable resin, so that the tube to be sheathed is wrapped with fibers (14) impregnated in liquid, curable resin during operation of the sheathing device (10).

Description

The invention relates to a device for sheathing pipes with fiber-reinforced plastic. Another aspect relates to the use of such a device for sheathing pipes.Pipes, in particular steel pipes, for open or trenchless laying are frequently provided on their outer side with a corrosion protection layer, which can be formed, for example, by a thermoplastic. It is also known to provide a steel pipe with a corrosion protection layer made of fusion-bonded epoxy (FBE), possibly additionally with an adhesion-promoting layer and a thermoplastic layer. A thermoplastic layer is often made of polyethylene (PE) or polypropylene (PP). On the outer side of the pipe or-if present-of the corrosion protection layer, a sheathing of fiber-reinforced plastic can be applied. This sheathing serves for the mechanical protection of the corrosion protection layer or the corrosion protection layers or the corrosion protection of the pipe or for improving other, e.g. static, properties of the pipe.The present invention relates to applying the fiber reinforced protective jacket to a pipe.An apparatus for sheathing a tube with fibers embedded in a plastic matrix comprises a tube holder configured to hold a tube to be sheathed during the sheathing such that the tube is rotatable about its longitudinal axis.The sheathing device also comprises a fiber feed which is designed to feed fibers, in particular textile glass fibers in the form of rovings or fiber strands, to a tube to be sheathed in such a way that the fed fibers are wound helically around the tube while the tube rotates about its longitudinal axis, the fiber feed is in this case moved continuously along the longitudinal axis in such a way that the fed textile glass fibers are wound helically around the tube, wherein webs of the fed fibers overlap by at least 50% in the longitudinal direction of the tube. For this purpose, the sheathing device is preferably configured such that the fiber feed together with the resin feed are uniformly displaced along the tube to be sheathed, while the tube rotates uniformly about its longitudinal axis of the tube, wherein the rotational speed of the tube and the feed speed of the fiber feed together with the resin feed are matched to one another and the width of the respective fiber sliver is matched such that an overlap degree of the successive turns of the fiber sliver of at least 50%, preferably more than 70%, up to 95% is produced.For this purpose, the feeding device has a displacement drive which is designed to displace the fiber feed along the longitudinal axis of the tube to be sheathed, namely in such a way that the fiber feed is displaced during a respective revolution of the tube by a distance which corresponds at most to half a width of a fiber sliver to be fed.A fiber sliver can be formed by a plurality of rovings running parallel or else by fiber fabrics or fiber mats.The fiber feed is further designed to keep the fed fibers under tension, wherein the tensile force causing the tension is preferably 2 to 5 Newtons per yarn, wherein a yarn is, for example, a roving. If a sliver is formed, for example, from 100 rovings running parallel to one another, the tensile force is, for example, 200 N to 500 N. Since the fibers to be supplied are pulled off from the fiber supply during the sheathing from the rotating tube, the fiber supply has a braking device and / or one or more deflecting rollers which bring about the desired tensile stress for tensioning the fibers during the winding.The sheathing device also has a resin feed which is designed to impregnate fibers to be fed to the tube with a liquid, curable resin, so that the tube to be sheathed is wound around with fibers impregnated in liquid, curable resin. The resin can be, for example, a polyester resin (UP) or a vinyl ester resin (VE). In exceptional cases, the resin may also be an epoxy resin. Preferably, the resin is a styrene-free UV curable resin. The resin feed may comprise a resin bath through which the fibers to be fed to the tube are passed. Alternatively or additionally, the resin feed can be or contain a resin spray in which liquid resin drips or flows onto the fibers from a resin dispenser, for example a line or a container, above the fibers to be impregnated. Below the fibers to be impregnated, a catcher may be provided which catches the liquid resin that does not remain on the fibers. The liquid resin flows through the air, so that a curtain of liquid resin is formed, through which the fibers to be supplied to the tube are guided. The resin dispenser can also be placed above the tube where the fibers meet the outer surface of the tube. In this case, a collecting device is superfluous.The sheathing device preferably has at least one UV emitter which is designed to irradiate fibers wound onto the tube and impregnated with initially liquid resin with UV light, in order in this way to effect UV curing of the resin. For this purpose, the UV emitter is likewise arranged displaceably and can move, during operation, for example at the same speed along the longitudinal direction of the tube as the fiber feed. The UV emitter is preferably arranged in such a way that it is directed at a circumferential position of the tube at which the angle of wrap of freshly wound fibers onto the tube is a maximum of 180°. The angle of wrap is here an angle which originates from the location at which the fibers are fed tangentially to the circumference of the tube and touch the tube for the first time. Preferably, the UV emitter is arranged such that no UV light impinges on the resin-impregnated fibers before they lie on the tube. A shielding bell can also be provided for the UV emitter, which shielding bell ensures that the UV radiation only impinges on a defined sector of the tube, which sector can comprise, for example, 25% to 5 0% of the tube circumference.According to an alternative embodiment, the UV emitter is arranged on that side of the tube to be sheathed from which the fiber sliver is also fed.While fiber feeding and resin feeding are preferably moved by a single sliding drive-and thus synchronously-the UV emitter can also be movable independently of fiber feeding and resin feeding. This makes it possible, for example, to initially completely cover a tube and to cure the resin in which the fibers are embedded only subsequently by means of the UV emitter. In particular, the curing of the resin can then take place on a first sheathed tube by means of the UV radiator, while a second tube is simultaneously sheathed by means of the fiber feed and resin feed.The sheathing device allows fiber webs to be wound around a tube to be sheathed with a high degree of overlap. A high degree of overlap provides a sufficient thickness of the finished sheathing. For example, if the overlap rate is 80%, the thickness of the cladding will be less than the thickness of a single fiber web because, as a result, five layers of fiber webs are superposed. In this case, there is the problem in principle that, in particular in the case of resins which cure by means of UV light, it must be ensured that the intensity of the UV light must be sufficiently high. With large layer thicknesses, there is the risk that the intensity of the UV light is sufficiently high only on an outer side of the layer and the UV light cannot penetrate with sufficient intensity to deeper layer depths. Because, according to the invention, the UV emitter always acts directly on the freshly wound fibers impregnated in initially liquid resin, only a single layer has to be cured at all times. It is therefore advantageous if the UV emitter is displaced synchronously with the fiber feed and the resin feed and is arranged in such a way that the resin is always irradiated with UV light and is thus cured by fibers freshly applied to the circumferential surface of the tube.In an advantageous embodiment variant, the fiber feed of the sheathing device has a plurality of supply spools with textile glass fibers in the form of rovings or fiber bonds and is designed to bring textile glass fibers from the plurality of supply spools together to form a fiber sliver. This makes it possible to assemble a fiber band in one pass for a final laminate thickness from identical or different fiber, bundle or fabric types and to wind it onto the tube to be sheathed. The fiber band then effects a single multilayer layer. For a thickness of the sheathing of, for example, 5 mm and a degree of overlap of 80%, the gathered fiber sliver can have, for example, a thickness of 1 mm.In this embodiment variant, the fiber feed and the resin feed are preferably arranged in such a way that the resin feed is impregnated into the fiber band during operation of the sheathing device after the bringing together with the liquid, curable resin.The sheathing device is preferably designed to carry out a method with the following steps:providing textile glass fibers, preferably on one or more supply spoolsguiding the textile glass fibers to a tube to be sheathedimpregnating the textile glass fibers with a liquid, curing or curable resin,wrapping a tube to be sheathed with the textile glass fibers impregnated in resin,wherein the tube to be sheathed rotates about its longitudinal tube axis and the location of the impingement of the textile glass fibers is shifted in the longitudinal tube direction while rotating during the tube, so that the textile glass fibers are wound onto the tube along a helical path.Preferably, the textile glass fibers are kept under tension during the winding. This can be done by pulling the textile glass fibers from the rotating tube from the supply reel or the supply reels and braking them, so that a defined tensile force results.Preferably, a plurality of textile glass fibers are drawn from a plurality of supply spools and brought together to form a fiber sliver. The impregnation of the textile glass fibers preferably takes place after the textile glass fibers have been brought together to form the fiber sliver.The method carried out by the sheathing device preferably also comprises curing the initially liquid resin after the textile glass fibers are applied to the circumferential surface of the tube. For curing the resin, the resin-impregnated textile glass fibers applied to the circumferential surface of the tube are preferably irradiated with UV light.The invention will now be explained in more detail on the basis of exemplary embodiments with reference to the figures. The latter show in FIG. 1 : a first variant of a sheathing device in a diagrammatic view along a longitudinal pipe axis of a pipe to be sheathed; FIG. 2 : a second variant of a sheathing device in a diagrammatic view along a longitudinal tube axis of a tube to be sheathed; FIG. 3 : a third variant of a sheathing device in a diagrammatic view along a longitudinal pipe axis of a pipe to be sheathed; FIG. 4 : shows a diagrammatic plan view of a sheathing device according to FIG. 1 or FIG. 2 ; FIG. 5 : a third variant of a sheathing device in a diagrammatic plan view; FIG. 6 : shows the third variant of a sheathing device with a tube wound around further in comparison to FIG. 5 in a diagrammatic plan view; and FIG. 7 is a schematic illustration for explaining the degree of overlap.The variants of a sheathing device 10 for winding a pipe 12 to be sheathed with resin-impregnated fibre strips 14, which are preferably formed by glass fibres, depicted in FIGS. 1 to 6, each comprise, as main components, a pipe holder 20, a fibre feed 30, a resin feed 40, a displacement drive 50 and a UV emitter 60.The tube holder 20 is configured such that the tube 12 to be sheathed can be driven in rotation about its longitudinal tube axis. Preferably, the tube holder 20 holds the respective tube 12 to be sheathed at its two free longitudinal ends. In the exemplary embodiment shown, the tube holder 20 has support rollers 20.1 and 20.2.The fiber feed 30 comprises one or more supply spools 30.1 with glass fibers 14 or fiber bands 14.1 wound thereon in the form of fiber fabrics or fiber laids, which are unwound from the supply spool 30.1 in the course of a tube sheathing. FIGS. 1 and 2 illustrate an embodiment with a supply reel 30.1, onto which a fiber sliver is wound. FIG. 3 illustrates an embodiment in which the fibers are present in the form of rovings which are brought together in the form of a ribbon, wound from a plurality of supply spools 30.1 on individual winding stands, via a grid.In addition, the fiber feed 30 between the supply reel 30.1 or the supply reels and the tube 12 to be sheathed has guide and brake rollers 30.2, between which the fibers 14 are guided. The guiding and braking rollers 30.2 serve to adjust a tension in the fibers in order to wind the fibers 14 under slight tension around the tube to be sheathed. In the case of a sliver formed by 100 rovings running parallel to one another, the braking force and thus the tensile force acting on the sliver is, for example, between 200 N and 500 N.The resin feed 40 serves to soak the fibers 14 with resin before they are wound onto the pipe 12 to be sheathed. The resin feed 40 is preferably arranged between the supply spool 30.1 and the guide and brake rollers 30.2, because then the guide and brake rollers 30.2 can squeeze excess resin onto the resin-impregnated fibers 14.In the embodiment variant shown in FIG. 1, the resin feed 40 has a resin bath 40.1 containing liquid resin 40.2, through which the fibers 14 are passed.In the embodiments shown in FIGS. 2 and 3, the resin feed 40 has a resin spray in which liquid resin 40.2 drips or flows onto the fibers from a resin dispenser 40.3 above the fibers 14 to be impregnated.In the embodiment variant shown in FIG. 2, a collecting device 40.4 is arranged below the fibers 14 to be impregnated, which collecting device collects liquid resin that does not remain on the fibers. In this embodiment variant, the liquid resin flows from the resin dispenser 40.3 through the air into the collecting device 40.4, so that a curtain 40.5 of liquid resin is formed, through which the fibers 14 to be supplied to the tube 12 to be sheathed are guided. The catcher 40.4 and the resin dispenser 40.3 can be fluidly connected to each other such that the liquid resin circulates between the catcher 40.4 and the resin dispenser 40.3.In the embodiment variant shown in FIG. 3, the resin dispenser is placed above the tube where the fibers meet the lateral surface of the tube. In this case, a collecting device is superfluous.In order to wind the fibers 14 in the form of fiber bands helically around the tube 12 to be sheathed, the fiber feed 30 and the resin feed 40 are displaced continuously along the tube longitudinal axis of the tube 12 to be sheathed, while the tube 12 likewise rotates continuously about its tube longitudinal axis and draws the fibers 14 from the supply reel 30.1. This results in the sliver being wound helically around the tube 12. In FIGS. 3 to 5, the pitch of the helix is not visible for graphic reasons.The rotational speed of the tube and the feed speed of the fiber feed 30 together with the resin feed 40 are matched to one another and the width of the respective fiber sliver are matched in such a way that an overlap degree of the successive turns of the fiber sliver of at least 50%, preferably more than 70%, up to 95%, is obtained; see FIG. 7. This means that the pitch of the helix formed by the fiber sliver is 14.1 between half and one twentieth of the width B of the fiber sliver.Due to the high degree of overlap, slightly greater layer thicknesses D of the sheathing 70 can be produced, so that tubes can be produced in one pass-i.e. during a single displacement of the fiber feed 30 together with the resin feed 40 along the tube 12-with a sufficiently thick sheathing 70 of, for example, 5 mm to 15 mm thickness or more.For the uniform displacement of the fiber feed 30 together with the resin feed 40 along the longitudinal axis of the tube 12, a displacement drive 50 is provided.The resin used is a vinyl ester (DI) or polyester resin (UP) which preferably cures under UV light.For curing the resin, a UV emitter 60 is therefore provided, with which the initially liquid resin surrounding the fibre strips wound onto the tube can be UV illuminated and thus cured. The UV emitter 60 is arranged such that the UV light emitted by it does not strike the resin-impregnated fiber 14 before they rest on the circumferential surface of the tube 12.According to preferred embodiment variants, the UV emitter 60 is displaced along the tube 12 as is the fiber feed 30 together with the resin feed 40.In operation, the sheathing device performs a method comprising the following steps:providing textile glass fibers 14, preferably on one or more supply spools 30.1guiding the textile glass fibers 14 to the tube 12 to be sheathed,impregnating the textile glass fibers 14 with a liquid, curing or curable resin,wrapping a tube 12 with the textile glass fibers 14 impregnated in resin,wherein the tube 12 to be sheathed rotates about its longitudinal axis of the tube and the location of the impingement of the textile glass fibers 12 on the circumferential surface of the tube 12 is shifted in the longitudinal direction of the tube while the tube 12 rotates, so that the textile glass fibers 14 are wound onto the tube 12 along a helical path.Preferably, the textile glass fibers 14 are kept under tension during the winding. This can be done by pulling the textile glass fibers 14 from the rotating tube 12 from the supply reel 30.1 or the supply reels and braking them so that a defined tensile force results.Preferably, a plurality of textile glass fibers are drawn off from a plurality of supply spools 30.1 and brought together to form a fiber sliver, as is shown in FIG. 3. The impregnation of the textile glass fibers 14 is preferably carried out after the textile glass fibers have been brought together to form the fiber sliver 14.1.The method performed by the sheathing device 10 preferably also comprises curing the initially liquid resin after the textile glass fibers 14 are applied to the circumferential surface of the tube 12. For curing the resin, the resin-impregnated textile glass fibers applied to the circumferential surface of the tube are preferably irradiated with UV light. For this purpose, the UV emitter 60 is preferably provided.List of reference characters10 Sheathing device 12 for sheathing pipe 14 fibers, glass fibers, 14.1 fiber sliver 20 pipe holder 20.1, 20.2 support rollers 30 fiber feed 30.1 supply spool with a fiber sliver 30-2 guide and brake rollers 40 resin feed 40.1 resin bath 40.2 resin dispenser 40.3 collecting device 40.4 curtain of liquid resin 50 displacement drive 60 UV emitter 70 sheathing

Claims

Sheathing device (10) for sheathing a tube (12) with fibers (14) embedded in a plastic matrix, the sheathing device (10) comprising: - a tube holder (20) configured to hold a tube (12) to be sheathed during the sheathing in such a way that the tube is rotatable about its longitudinal axis, - a fiber feed (30) configured to feed fiber webs formed by textile glass fibers in the form of rovings or fiber bonds to a tube to be sheathed in such a way that the fed fibers are wound helically about the tube while the tube (12) rotates about its longitudinal axis, wherein the fiber feed is continuously movable along the longitudinal axis in such a way that the fed textile glass fibers are wound helically about the tube in such a way that the fed textile glass fibers are wound helically about the tube, wherein webs of the supplied fibers overlap in the longitudinal direction of the tube by at least 50%, - a displacement drive (50) which is designed to displace the fiber feed (30) along the longitudinal axis of the tube to be sheathed in such a way that the fiber feed is displaced during a respective revolution of the tube by a distance which corresponds at most to half a width of a fiber sliver to be supplied, and - a resin feed (40) which is designed to impregnate fibers to be supplied to the tube with a liquid, curable resin, such that the tube to be sheathed is wound around during operation of the sheathing device (10) with fibers (14) impregnated with liquid, curable resin.Sheathing device (10) according to claim 1, comprising a UV emitter (60) configured to irradiate UV light onto fibers wound onto the tube, impregnated with initially liquid resin, in order to thereby effect UV curing of the resin, wherein the UV emitter is also arranged displaceably and moves along the longitudinal direction of the tube.Sheathing device (10) according to claim 1 or 2, wherein the resin feed (40) has a resin dispenser arranged above a fibre band (14.1) to be fed to the pipe to be sheathed, from which resin liquid during operation drips or flows through the air in a curtain-like manner onto the fibres to be impregnated.Sheathing device (10) according to claim 3, wherein the resin feed (40) comprises a collecting device arranged below a fibre band (14.1) to be supplied to the pipe to be sheathed, which collecting device are configured such that, in operation, liquid resin flows from the resin dispenser through the air in a curtain-like manner into the collecting device and thus forms a resin curtain through which the fibre band (14.1) to be supplied to the pipe to be sheathed passes.Sheathing device (10) according to at least one of claims 1 to 4, which is configured such that the fiber feed (30) together with the resin feed (40) are displaced uniformly along the tube (12) to be sheathed, while the tube (12) rotates uniformly about its longitudinal axis of the tube, wherein the rotational speed of the tube (12) and the feed speed of the fiber feed (30) together with the resin feed (40) are matched to one another and the width of the respective fiber sliver (14.1) such that an overlap degree of the successive windings of the fiber sliver (14.1) of at least 50%, preferably more than 70%, up to 95%, results.Sheathing device (10) according to at least one of claims 1 to 5, wherein the fiber feed (30) has a plurality of supply spools (30.1) with textile glass fibers in the form of rovings or fiber strands, wherein the fiber feed (30) is designed to bring textile glass fibers from the plurality of supply spools (30.1) together to form a fiber sliver (14.1).Sheathing device (10) according to claim 6, wherein the fiber feed (30) and the resin feed (40) are arranged such that the resin feed (40) impregnates the fiber sliver (14.1) with the liquid, curable resin after being combined during operation of the sheathing device (10).Sheathing device (10) according to at least one of Claims 1 to 7, which is configured to produce a layer thickness of the sheathing of at least 5 mm in a winding pass from one longitudinal end of the tube (12) to be sheathed to the other longitudinal end thereof.Sheathing device (10) according to at least one of claims 1 to 8, wherein the resin feed is designed for impregnating the fibre sliver with a vinyl ester or polyester resin that cures under UV light.The sheathing device (10) according to any one of claims 1 to 9, which is configured to carry out a method with the following steps: - providing textile glass fibres (14), preferably on one or more supply spools, - guiding the textile glass fibres to a tube (12) to be sheathed, - impregnating the textile glass fibres (14, 14.1) with a liquid, curing or curable resin, - winding a tube (12) to be sheathed with the textile glass fibres (14, 14.1) impregnated in resin, wherein the tube (12) to be sheathed rotates about its longitudinal axis of the tube and the location of the incidence of the textile glass fibres (14.1) is displaced in the longitudinal direction of the tube while the tube (12) rotates, such that the textile glass fibres (14) are wound about the tube (12) along a helical path.

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