Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B1/00—Layered products having a non-planar shape
  • B32B1/08—Tubular products
• • D—TEXTILES; PAPER
  • D02—YARNS; MECHANICAL FINISHING OF YARNS OR ROPES; WARPING OR BEAMING
  • D02G—CRIMPING OR CURLING FIBRES, FILAMENTS, THREADS, OR YARNS; YARNS OR THREADS
  • D02G3/00—Yarns or threads, e.g. fancy yarns; Processes or apparatus for the production thereof, not otherwise provided for
  • D02G3/22—Yarns or threads characterised by constructional features, e.g. blending, filament/fibre
  • D02G3/36—Cored or coated yarns or threads
• • D—TEXTILES; PAPER
  • D02—YARNS; MECHANICAL FINISHING OF YARNS OR ROPES; WARPING OR BEAMING
  • D02G—CRIMPING OR CURLING FIBRES, FILAMENTS, THREADS, OR YARNS; YARNS OR THREADS
  • D02G3/00—Yarns or threads, e.g. fancy yarns; Processes or apparatus for the production thereof, not otherwise provided for
  • D02G3/44—Yarns or threads characterised by the purpose for which they are designed
  • D02G3/447—Yarns or threads for specific use in general industrial applications, e.g. as filters or reinforcement
• • D—TEXTILES; PAPER
  • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
  • D04B—KNITTING
  • D04B1/00—Weft knitting processes for the production of fabrics or articles not dependent on the use of particular machines; Fabrics or articles defined by such processes
  • D04B1/14—Other fabrics or articles characterised primarily by the use of particular thread materials
  • D04B1/16—Other fabrics or articles characterised primarily by the use of particular thread materials synthetic threads
• • D—TEXTILES; PAPER
  • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
  • D04B—KNITTING
  • D04B1/00—Weft knitting processes for the production of fabrics or articles not dependent on the use of particular machines; Fabrics or articles defined by such processes
  • D04B1/22—Weft knitting processes for the production of fabrics or articles not dependent on the use of particular machines; Fabrics or articles defined by such processes specially adapted for knitting goods of particular configuration
  • D04B1/225—Elongated tubular articles of small diameter, e.g. coverings or reinforcements for cables or hoses
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
  • F16L11/00—Hoses, i.e. flexible pipes
  • F16L11/04—Hoses, i.e. flexible pipes made of rubber or flexible plastics
  • F16L11/08—Hoses, i.e. flexible pipes made of rubber or flexible plastics with reinforcements embedded in the wall
  • F16L11/085—Hoses, i.e. flexible pipes made of rubber or flexible plastics with reinforcements embedded in the wall comprising one or more braided layers
• • D—TEXTILES; PAPER
  • D10—INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES
  • D10B—INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES
  • D10B2505/00—Industrial
  • D10B2505/02—Reinforcing materials; Prepregs

Definitions

• the present invention relates to a polymeric tubular article comprising a hybrid reinforcing yarn, wherein the reinforcing yarn comprises a high strength core and at least one wrap of a sheath yarn wound about the core for better fatigue resistance at high temperature.
• Low-pressure hoses are generally reinforced with textile yarns to withstand required internal pressures without compromising flexibility.
• Braid, spiral, wrap, and knit reinforcements are well known types of textile yarn reinforcements. But for hoses with complicated shapes, knit reinforcement is often preferred due to its flexibility. Knit reinforcement is accomplished by applying reinforcing yarns over the tube to form loops interlocking with each other. This chain-like structure results in yarns passing over other yarns. However, continuous radial expansion and contraction of the hose because of internal pressure changes cause these yarns to move back and forth and cut each other at knot points. Once a yarn is broken, the knit reinforcement starts to unravel at that point resulting in a local hole in the fabric. As a result, hose may excessively expand in that region and rupture. Thus, abrasion resistance of a reinforcing yarn determines its long-term dynamic fatigue performance, which in turn determines the operating life of the knitted hose.
• l Yarns such as PEN, PBO, para-aramid, para-aramid copolymer, carbon and liquid crystal polyester are known to exhibit high tensile strength.
• long-term dynamic fatigue performance of these yarns at high temperatures is not satisfactory because of yarn on yarn abrasion.
• composite cords composed of two or more yarns.
• a composite or hybrid cord refers to a single yarn comprising strands of two or more kinds with different properties, wherein individual strands are core spun, twisted, commingled, air covered, wrapped etc. to obtain the final cord. The proportion and the orientation of each kind are adjusted according the desired properties of the final cord.
• US Patent Application 20080202618 describes a hose reinforced with a hybrid cord comprising multiple monofilaments and short fibers entangled between them to increase adhesion of the cord to the rubber layers.
• US Patent Application 20100224298 discloses a tire reinforced with a hybrid cord produced by commingling process, which includes two different multifilament yarns having different initial tangent moduli.
• EP2066947 relates to a flexible hose reinforced with a hybrid cord wherein two yarns having different fatigue properties are twisted together in order to increase the fatigue performance.
• the disclosed hybrid yarn comprises a first yarn of co-para-aramid fibers and a second yarn of meta-aramid fibers which are twisted, plied, folded, or commingled together to form a single hybrid reinforcing yarn for the hose.
• the hybrid yarn may have a surface comprising both co-para-aramid fibers and meta-aramid fibers so that the pressure-carrying yarn is not fully isolated and it is still open to yarn-on-yarn abrasion and self-cutting at contact points.
• twisted co-para-aramid and meta-aramid yarns are expensive especially for coolant hoses.
• the object of the invention is to provide an inexpensive polymeric tubular article exhibiting improved fatigue resistance at high temperatures.
• a tubular product which comprises an inner tube, a reinforcement, and an outer tube; wherein said reinforcement comprises a hybrid cord comprising a pressure carrying high strength core and at least one, preferably two wraps wound around the core in opposite directions.
• the term "yarn" within the context of the present invention is to be interpreted broadly to include a continuous strand of textile fibers, filaments or material in a form suitable for knitting, weaving or otherwise intertwining to form a textile fabric.
• “Fiber” refers to an elongate, individual, monolithic unit of matter that forms the basic element of a fabric and the "filament” refers to a continuous fiber of extremely long length.
• the term “strand” refers to an ordered assemblage of textile fibers having a high ratio of length to diameter. For the purpose of this application, it shall be understood to mean a single fiber, filament, monofilament or yarn.
• cord refers to a twisted or formed structure composed of one or more single or plied filaments, strands, or yarns of organic polymer or inorganic materials and "greige” is a descriptive term for yarns that have not received any bleaching, dyeing or finishing treatment after being produced.
• the entire tensional load is carried by the longitudinally extending core.
• Wraps only function to protect and therefore increase the yarn-on-yarn abrasion resistance of the core to improve long term fatigue performance.
• the core is completely covered with the wrappings in such a way that the surface of the hybrid cord comprises only the wrapped sheath yarns. In this way, load carrying core yarns are isolated from each other so that possibility of self-cutting is eliminated.
• This structure also protects the core against yarn to metal abrasion which occurs during knitting, braiding and spiraling operation.
• the inventive tubular article can be used as a fluid transfer hose as well as a bellow, expansion joint or the like. Of particular importance is low-pressure fluid transfer hoses used in automotive applications like turbocharger, radiator, heater or fuel hoses.
• FIG. l is a perspective view of the polymeric tubular article in accordance with the invention.
• FIG. 2 shows a typical knit fabric.
• FIG. 3 is a diagrammatic drawing of a composite cord constructed in accordance with the invention.
• FIG. 4 is a graph showing the burst pressure values of samples before and after the fatigue life test.
• FIG. 5 is a graph showing a single pressure cycle of hose fatigue life test.
• Figure l shows an arrangement of the inventive tubular article (l).
• Article comprises an inner tube (io) onto which a reinforcement (n) is knitted and an outer tube (12) covering the knitting.
• Figure 2 illustrates the details of a typical knit fabric.
• There are different types of knit fabrics called plain stitch, lock stitch etc, but in common, they all have the cord (111) forming loops (110) interlocking with each other and creating contact points (110').
• Figure 3 illustrates a preferred embodiment of a hybrid cord (111) used in the reinforcement (11) of the tubular article (1) in accordance with the invention.
• the hybrid cord (111) comprises an elongated core (115) with at least one strand of a high strength yarn, a first wrap (116) of a sheath yarn wound around the core in one direction, and a second wrap (118) of a sheath yarn wound in opposite direction to the first wrap.
• the load carrying core (115) comprises at least one strand of a high tensile strength material selected from the group consisting of polyester, liquid crystal polyester, polyamide, para-aramid, para-aramid copolymer, polyimide, polyphenylene-2,6-benzobisoxazole (PBO), polyketone (PK), polyetheretherketone (PEEK), glass, carbon, basalt, steel and blends thereof.
• a high tensile strength material selected from the group consisting of polyester, liquid crystal polyester, polyamide, para-aramid, para-aramid copolymer, polyimide, polyphenylene-2,6-benzobisoxazole (PBO), polyketone (PK), polyetheretherketone (PEEK), glass, carbon, basalt, steel and blends thereof.
• Various forms of such para- aramid fibers are available from E.I. duPont de Nemours and Company under trademark Kevlar®, from Teijin Ltd. under trademark Twaron®, from Kolon Industries
• Para-aramid copolymer fibers known under trademark Technora® are available from Teijin Ltd., and liquid crystal polyester, also known as aromatic polyester are sold by Kuraray Co. Ltd. under trademark Vectran®.
• Poly(p- phenylene-2,6-benzobisoxazole) (PBO) known as liquid crystalline polyoxazole fibers are commercially available from Toyobo Co Ltd under trademark Zylon®, and polyetheretherketone fibers made of polyether are sold by Zyex Ltd. under trademark Zyex®.
• Wraps (116, 118) of sheath yarns protect the core (115) to improve its yarn-on-yarn and yarn-to-metal abrasion resistance.
• the core (115) has a total linear density in the range of about 400 to 4000 dtex and sheath yarns of each wrap (116, 118) has about 40 to 400 dtex.
• Preferably linear density of the yarn of the second wrap (118) is equal to the first wrap (116).
• the core (115) is completely covered with the wraps (116, 118) in such a way that the surface of the hybrid cord (111) comprises only the yarns of wrappings.
• the first and second wraps (116,118) are wound at the rate of 200 - 4000 turns per meter depending on the linear density and twist level of the core (115) and wrap (116,118) yarns.
• first wrap (116) is wound in one direction about the core (115) and a second wrap (118) is wound in an opposite direction to the first wrap.
• first wrap (116) is wound in one direction about the core (115)
• second wrap (118) is wound in an opposite direction to the first wrap.
• first wrap (116) is wound in one direction about the core (115)
• second wrap (118) is wound in an opposite direction to the first wrap.
• the possibility of unraveling of the wrappings at high stress contact points is eliminated.
• a single wrap (116) wound in either S or Z direction it is also possible to use a single wrap (116) wound in either S or Z direction.
• more than two wraps can also be employed. In the latter case, each subsequent wrap is wound in a direction opposite to the previous wrap.
• the core (115) comprises a single strand, either composed of a single filament or filaments plied, textured, commingled, twisted or air covered together.
• the wraps (116, 118) may be wound around this bundle.
• greige yarn is used in the core (115) and the wraps (116, 118).
• the core or sheath yarns or the final hybrid cord can be treated with adhesives or bonding elastomers or may comprise plastic resin layers.
• wet lubricants such as synthetic oil or grease, glycerol, polybutane, polymer ester, polyolefines, polyglycols, silicon, soap, natural or synthetic waxes, resins and tars with additives of organic and/or inorganic thickeners, such as, for example, organic polymers, polycarbamide, metal soap, silicates, metal oxides, silicic acid, organophilic betonite or dry lubricant such as Talcum, graphite powder, molybdenum disulfide, polytetrafluorethylene (PTFE), lead (Pb), gold (Au), silver (Ag), boron trioxide (BO3), lead oxide (PbO), zinc oxide (ZnO), copper oxide (Q12O), molybdenum trioxide (M0O3) and titanium dioxide (T1O2) can be applied to the core or sheath yarns prior to wrapping process.
• organic and/or inorganic thickeners such as, for example, organic polymers, poly
• the final hybrid cord (111) can be dipped in lubricants stated above.
• 1-10 cN/tex pre tension is applied to the core (115) before the wraps (116,118) are wound.
• the first wrap (116) is wound around the core (115) with closed coiling
• the second wrap (118) is wound around the first one again with closed coiling.
• Both the first and second wraps must be coiled in precision without any gap to cover the core (115) completely.
• the inventive tubular article (1) can be used as a fluid transfer hose, bellow, expansion joint or the like. Of particular importance is low-pressure fluid transfer hoses used in automotive applications like turbocharger, radiator, heater or fuel hoses.
• the polymeric material used in inner (10) and/or outer tube (12) of the tubular article (1) can be selected among elastomers, termoplastic elastomers or flexible plastics.
• vulcanized rubber compositions comprising any one of ethylene acrylic elastomer, ethylene propylene diene copolymer, ethylene propylene copolymer, chloroprene rubber, chlorinated polyethylene, chlorosulfonated polyethylene, polyepichlorohydrin, nitrile rubber, hydrogenated nitrile rubber, fluoro rubber, natural rubber, styrene-butadiene rubber, isoprene rubber, butyl rubber, bromobutyl rubber, chlorobutyl rubber, butadiene rubber, silicone rubber, acrylate rubber, ethylene-vinyl acetate rubber, and blends thereof.
• the hybrid cord reinforcement (11) may reside between the inner and the outer tube (10, 12) and/or may be embedded in a layer (10, 12) of the product. Also, it should be noted that the invention is not limited to the knit reinforcement. As one skilled in the art will appreciate, disclosed hybrid cord reinforcement (11) may also be provided in the form of braid, spiral, wound or any other type of known textile yarn reinforcements.
• a further object of the invention is to provide a method for producing a polymeric tubular article (1) exhibiting improved fatigue resistance at high temperatures.
• This object is achieved by a method comprising the steps of - forming a hybrid cord (111) by winding a first wrap (116) of a sheath yarn around a core (115) in a first direction, then winding a second wrap (118) around the first wrap in an opposite direction;
• the reinforcement (11) is preferably formed by knitting with plain stitch, lock stitch or any other stitch pattern. However it may also be formed by braiding or spiral winding or wrapping the hybrid cord over the inner tube.
• the method may also include a final step of curing the polymeric tubular article (1) on a linear or curved mandrel. Curing may be accomplished by steam or air vulcanization.
• each yarn construction is also individually tested to measure tensile strength and yarn-on-yarn abrasion resistance.
• Each of the six sample hoses has a 16 mm inner diameter and 3,5 mm wall thickness.
• EPDM composition is used for both inner and outer layers and the reinforcements are knit with a plain stitch on a 1 3/16" knitter head with 8 needles, 4 bobbins, at 3 mm per stitch for all samples.
• Each sample is vulcanized on a L-shaped curved metal mandrel in steam autoclave.
• Sample hose 1 utilizes an example embodiment of the inventive hybrid cord where a 1100 dtex Kevlar continuous filament core yarn having a twist level of 90 tpm is first wrapped by a 167 dtex PES yarn with a twist level of 30 tpm at a rate of 1200 turns per meter. Then a second wrap of PES yarn having same linear density and twist level as the first wrap is wound around the first one again at a rate of 1200 turns per meter.
• Example 2
• Example 2 has the same construction as that of the first embodiment of the reinforced hose except that the wrapping yarns on the Kevlar® 1100 core yarn are 220 dtex PES. This polyester yarn has higher linear density than the first embodiment.
• Example 3
• Example 3 has the same construction as that of the second embodiment of the reinforced hose except that the wrapping yarns on the core Kevlar® 1100 yarn are 220 dtex PPS .
• Example 4 has the same construction as that of the second embodiment of the reinforced hose except that the wrapping yarns on the Kevlar® 1100 core yarn are 220 dtex Nomex® .
• Example 5 has the same construction as that of the first embodiment of the reinforced hose except that reinforcing material is Kevlar® 1100 greige yarn.
• Example 6 has same construction as that of the first embodiment of the reinforced hose except that the reinforcing material is Kevlar® 1100 /PET 1100 twisted hybrid yarn.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Textile Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Rigid Pipes And Flexible Pipes (AREA)

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• 2012
  • 2012-10-05 WO PCT/IB2012/055365 patent/WO2014053884A1/en active Application Filing
  • 2012-10-05 EP EP12815781.5A patent/EP2903812A1/de not_active Withdrawn

Non-Patent Citations (1)

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