Hybrid tube for industrial and hydraulic hose products and method for manufacturing same

Abstract

A hybrid tube construction for use, for example, an industrial or hydraulic hose is presented, the hybrid tube typically comprising an inner tube layer and an outer tube layer that are co-extruded. The inner tube layer of the mixing tube is a functional layer that is chemically resistant to a fluid to be conveyed within the mixing tube, while the outer tube layer is a modulus layer that imparts strength and flexibility to the mixing tube. The hybrid tube may optionally include a reinforcement layer and / or a cover layer. The hybrid tube is generally fabricated using simultaneous co-extrusion of an inner tube layer material and an outer tube layer material to form a hybrid tube structure. In some embodiments, the hybrid tube formed by co-extrusion has sufficient structural integrity, thereby eliminating the need for a support mandrel and / or a post-extrusion curing step.

Description

Technical Field

[0001] The present application relates to a hybrid tube structure for use in, for example, industrial and / or hydraulic hose products. The hybrid tube includes an inner functional tube layer designed to be chemically resistant to the fluid being conveyed, and a modulus outer tube layer formed over the functional tube layer to provide the hybrid tube with flexibility and strength. Background Art

[0002] Fluid power and fluid transfer applications rely on pipes as an important barrier to retain fluids and pressures. Typical pipes include an inner pipe layer that contacts the fluid to be transferred and may also include reinforcement and / or covering layers wrapped around the inner pipe. The material of the inner pipe must not degrade due to contact with the internal fluid and must be strong enough to withstand pressures and temperatures. Reinforcement layers may be included to help the inner pipe withstand higher pressures.

[0003] In addition to being chemically resistant to the fluid being conveyed and meeting the required pressure and temperature requirements for the fluid and tube application, there are also processing requirements that must be met when forming the tube. For example, the inner tube must be formed in a manner that provides a hollow passage extending therethrough, but also prevents the tube from collapsing during the forming process. Meeting this requirement may require selecting a specific material for the inner tube that is strong enough to withstand collapse during processes such as extrusion, adding reinforcement layers, etc., and / or using a support mandrel during the extrusion process.

[0004] Thermosetting polymer materials are commonly used as materials for inner tubes due to their inherent flexibility, chemical resistance, and compression properties. However, thermosetting materials must be cured in their final product form (after extrusion), which requires a lot of time, plant floor space, and utility costs. In addition, uncured thermosetting materials are ductile, making them prone to collapse in processing steps prior to curing (such as braided reinforcement and additional extruded layers on the inner tube) without the use of a mandrel to support the tube.

[0005] The use of thermoplastic materials for the inner tube (which is rigid after extrusion without curing) eliminates the need for a support mandrel lining and an autoclave curing step. Unfortunately, the processing advantages of the thermoplastic inner tube may be offset by the reduced performance of the pipe (compared to the pipe based on thermosets). For example, hoses using nylon as the inner pipe have been previously manufactured, but these hoses are harder than rubber / thermoset lined hoses and generally require a low hardness friction layer wrapped around the inner pipe to achieve the compression characteristics of the coupling and allow braided or otherwise added reinforcements to be properly placed on the nylon pipe. The flexibility of the final hose product is also lower than that of traditional rubber and thermoset hoses. In a different approach, polyolefins are used as materials for the inner pipe of the hose, but it is found that there is not enough tolerance to the fluids (such as oils) being conveyed.

[0006] Therefore, there is a need for an improved conduit that meets the aforementioned performance and manufacturing requirements. Summary of the invention

[0007] This summary is used to introduce a selection of concepts in a simplified form, which will be further described in the detailed description below. This summary and the foregoing background technology are not intended to determine the key aspects or essential aspects of the claimed subject matter. Moreover, this summary is not intended to help determine the scope of the claimed subject matter.

[0008] In some embodiments, a hybrid tube suitable for use, for example, in industrial and hydraulic hoses is described, the hybrid tube comprising: an inner tube layer having a hollow passage extending therethrough, the inner tube layer being configured to be chemically resistant to fluids transmitted through or present in the hollow passage; and an outer tube layer formed on and coaxially aligned with the inner tube layer, the outer tube layer being used to provide structure and flexibility to the hybrid tube.

[0009] In some embodiments, a method for forming a hybrid tube is described, the method comprising the steps of co-extruding an inner tube layer material and an outer tube layer material through an annular die to form a hybrid tube, the hybrid tube comprising: an inner tube layer having a hollow passage formed therein; and an outer tube layer formed on and coaxially aligned with the inner tube layer. The method may not require the use of a support mandrel to support the hybrid tube after the co-extruded hybrid tube leaves the annular die, because the manufactured hybrid tube has sufficient structural integrity to ensure that the hollow passage does not collapse after extrusion. The method may also be without any post-extrusion curing step, again due to the overall structural integrity of the hybrid tube immediately after extrusion.

[0010] These and other aspects of the technology described herein will become apparent after considering the detailed description and drawings herein. However, it should be understood that the scope of the subject matter claimed should be determined by the issued claims, rather than by whether a given subject matter solves any or all of the problems mentioned in the background technology or includes any features or aspects recorded in the summary of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Non-limiting and non-exhaustive embodiments of the disclosed technology, including preferred embodiments, will be described with reference to the following figures, wherein like reference numerals refer to like parts throughout the various figures unless otherwise specified.

[0012] Figure 1 is a perspective view of a portion of a mixing tube configured in accordance with various embodiments described herein.

[0013] Figure 2 is a perspective view of a portion of a mixing tube configured in accordance with various embodiments described herein.

[0014] Figure 3 is a flow chart detailing a method for manufacturing a mixing tube according to various embodiments described herein. DETAILED DESCRIPTION

[0015] Embodiments will be described more fully below with reference to the accompanying drawings, which form a part of the present invention and illustrate specific example embodiments by way of illustration. These embodiments are disclosed in sufficient detail to enable those skilled in the art to practice the present invention. However, the embodiments may be implemented in many different forms and should not be construed as being limited to the embodiments set forth herein. Therefore, the detailed description below should not be considered to have a limiting meaning.

[0016] Various embodiments of hybrid tube structures and methods of making the same are described herein, which are well suited for use in industrial and / or hydraulic hoses. Embodiments of the hybrid tubes described herein generally include an inner tube layer defining a hollow passage extending through the length of the tube; and an outer tube layer formed on and coaxially aligned with the inner tube layer. The inner tube layer is designed to serve as a functional layer that is chemically resistant to fluids that can be conveyed through the hollow passage of the hybrid tube. The outer tube layer is designed to serve as a modulus layer that provides strength and flexibility to the hybrid tube. The combination of these two layers generally provides the hybrid tube with a chemically resistant inner tube layer material that otherwise may be unsuitable for use in industrial hoses due to its lack of sufficient strength, inability to maintain a hollow passage, and high cost. Moreover, the outer tube layer material provides strength and flexibility to the hybrid tube, and because a chemically resistant inner tube layer is used, the outer tube layer material may be selected from materials that may not be sufficiently chemically resistant to the fluid being conveyed. Providing strength to the hybrid tube through the use of an outer tube layer can provide a variety of benefits, including, but not limited to: eliminating the need for a support mandrel as part of the hybrid tube manufacturing process, eliminating a curing step as part of the hybrid tube manufacturing process, and / or reducing the amount of reinforcement layers required (or even eliminating the need for reinforcement layers).

[0017] refer to Figure 1 , a mixing tube 100 configured in accordance with various embodiments described herein is shown to include an inner tube layer 110 and an outer tube layer 120 formed on and coaxially aligned with the inner tube layer 110. The inner tube layer 110 defines a hollow passage 115 extending through the inner tube layer and providing a passage for conveying a fluid through the mixing tube 100. The specific dimensions of the entire mixing tube 100, the inner tube layer 110, and the outer tube layer 120 are generally not limited, but in some embodiments, the outer diameter of the inner tube layer 110 should be approximately equal to the inner diameter of the outer tube layer 120, so that the outer tube layer 120 is directly located on the inner tube layer 110.

[0018] In some embodiments, the thickness of the inner tube layer 110 is 1% to 99% of the total thickness of the mixing tube 100 (including additional optional layers described in more detail below), such as about 5% to about 50% of the total thickness of the mixing tube 100. In some embodiments, the thickness of the inner tube layer 110 is relatively small, such as about 10% of the total thickness of the mixing tube 100. A relatively thin inner tube layer 110 can provide the desired chemical resistance while minimizing the amount of inner tube layer 110 material used in the mixing tube 100, thereby reducing the cost of the mixing tube 100 (e.g., where the cost of the inner tube layer 110 material is relatively high compared to other materials used in the mixing tube 100).

[0019] In some embodiments, the thickness of the outer tube layer 120 is 1% to 99%, such as about 50% to about 99%, of the total thickness of the hybrid tube 100 (including the additional optional layers discussed in more detail below). In some embodiments, the thickness of the outer tube layer 120 is greater than the thickness of the inner tube layer 110. Together with the specific material selected for the outer tube layer 120, the thickness selected for the outer tube layer 120 can also be used to ensure that the outer tube layer 120 provides the hybrid tube 100 with the appropriate amount of strength and flexibility. In some embodiments, the thickness of the outer tube layer 120 is designed to ensure that the hybrid tube 100 passes through a hose product having a minimum bend radius requirement, while also being sufficiently rigid so that the hybrid tube 100 does not require the use of a support mandrel for handling and can withstand the pressures that may be experienced when the hose product is used.

[0020] As previously mentioned, the main function of the inner tube layer 110 is to provide chemical resistance to the fluid transmitted in the mixing tube 100. Therefore, the material of the inner tube layer 110 should generally be a material with desired chemical resistance. For example, the material of the inner tube layer 110 can be selected to meet the ASTM D543 chemical resistance test standard, but other chemical resistance test standards can be used to select the material of the inner tube layer 110. In some embodiments, the material of the inner tube layer 110 is selected from thermoplastic materials, thermosetting materials, ceramics, metals and carbon. In a more specific embodiment, the material of the inner tube layer 110 is selected from polyamide, high-density polyethylene (HDPE), cross-linked HDPE, cross-linked low-density polyethylene (LDPE), ethylene propylene diene terpolymer (EPDM) / polypropylene (PP) blends, polyethylene terephthalate (PET), polyvinylidene fluoride (PVDF) and fluorinated ethylene propylene (FEP). These materials are all capable of providing at least sufficient chemical resistance, as may be required for the specific application of the mixing tube 100.

[0021] The main function of the outer tube layer 120 is to provide strength and flexibility for the hybrid tube 100. Therefore, the material of the outer tube layer 120 should generally be a material with desired strength and flexibility. In some embodiments, the material of the outer tube layer 120 is selected from thermoplastic materials, thermosetting plastics, ceramics, metals and carbon. In a more specific embodiment, the material of the outer tube layer 120 is selected from polyamide, high-density polyethylene (HDPE), cross-linked HDPE, low-density polyethylene (LDPE), polypropylene (homopolymer or copolymer), polyethylene terephthalate (PET) and polyvinylidene fluoride (PVDF). These materials can provide the hybrid tube 100 with a suitable combination of strength and flexibility.

[0022] Any suitable combination of inner and outer tube layer materials may be used, as long as the hybrid tube has a suitable combination of chemical resistance, improved strength, and flexibility. In some embodiments, the inner tube layer material is nylon 12, while the outer tube layer material may be a blend of one or more polyethylene types (e.g., HDPE, LDPE, LLDPE, etc.) and an adhesive (e.g., EVA, EEA, or grafted polyethylene, etc.). In other embodiments, the inner tube layer material may be a polypropylene functional layer, while the outer tube layer may be an EPDM / PP blend.

[0023] As previously described, the dimensions of the inner tube layer 110 and the outer tube layer 120 can be selected so that the outer tube layer 120 is directly located on / against the inner tube layer 110. In some embodiments, the outer tube layer 120 is attached to the inner tube layer 110 to provide a structurally strong and cohesive hybrid tube. Any type of attachment can be used for the inner tube layer 110 and the outer tube layer 120, including multiple types of attachment. In some embodiments, the outer tube layer 120 is attached to the inner tube layer 110 by one or more of chemical bonding, intermolecular attraction, and mechanical attachment. As described in more detail below, the specific manner of attachment can be due to the co-extrusion process used in the formation of the hybrid tube 100.

[0024] Reference below Figure 2 , shows another embodiment of the hybrid tube 200, wherein the hybrid tube 200 further includes an optional reinforcement layer 230 and / or an optional cover layer 240. The inner tube layer 210 and the outer tube layer 220 are respectively similar to those previously described with reference to FIG. Figure 1 The inner tube layer 110 and the outer tube layer 120 are similar or identical. Figure 2 An additional reinforcement layer 230 is shown formed on and coaxially aligned with the outer tube layer 220. The reinforcement layer 230 is generally included to provide additional strength and / or structural integrity to the hybrid tube 200, and thus, may not be required in embodiments where the outer tube layer 220 provides sufficient strength and structural integrity to the hybrid tube 200. In some embodiments using the reinforcement layer 230, due to the increased strength provided by the outer tube layer 220, the thickness and / or amount of the reinforcement layer 230 is reduced compared to previously known tubes for industrial and / or hydraulic hoses, thereby being able to provide reduced costs and increased ease of manufacturing.

[0025] The specific material of the reinforcement layer 230 is generally not limited, as long as the material of the reinforcement layer 230 provides some amount of additional strength to the hybrid tube 200. In some embodiments, the material of the reinforcement layer 230 is selected from textiles, wires, ceramics, or carbon materials. The reinforcement layer can be formed on the outer tube 220 using any suitable technique, including but not limited to: applying the reinforcement layer 230 in a braided, spirally wound, or linear pattern. The material of the reinforcement layer 230 can be provided in the form of, for example, cords, filaments, yarns, wires, or meshes.

[0026] Figure 2 Also shown is a mixing tube 200 including a cover layer 240. Although Figure 2 The cover layer 240 is shown formed directly on the reinforcement layer 230, but it should be understood that in embodiments where the mixing tube 200 does not include the reinforcement layer 230, the cover layer can be formed directly on the outer layer 220. The material of the cover layer 240 is generally selected based on the environmental conditions in which the mixing tube 200 will be used. In some embodiments, the material of the cover layer 240 is selected from an elastomer or a thermoplastic material. Another suitable material for the cover layer 240 is a thermoplastic vulcanizate (TPV) (a heat-treatable material with elastomeric properties).

[0027] The aforementioned mixing tubes 100, 200 are usually manufactured using a co-extrusion process. Figure 3 , shows a method 300 for making a hybrid tube as described herein, the method 300 generally comprising a step 310 of co-extruding an inner tube layer material and an outer tube layer, thereby forming a hybrid tube as described above and as described above. Figure 1 Generally speaking, the co-extrusion step 310 usually includes using a co-extruder equipped with an annular die, so that the flowable inner tube material and the flowable outer tube material are combined in a layered manner near the annular die (the outer tube layer material is layered on the inner tube layer material), and then the combined material is extruded through the annular die to at least partially harden the material and form a mixed tube structure.

[0028] Because the coextruded layers are laid down as molten or viscous layers, material layers with different thicknesses, moduli, and / or melting temperatures (e.g., within 50°C) can be used with minimal or no compatibility issues. Due to extrusion under pressure, the layers of the coextruded hybrid tube will adhere together by chemical bonding, intermolecular attraction, and / or mechanical adhesion. The adhesion between the inner and outer tube layers is preferably designed to be at least the minimum required to keep the layers together during use of the hybrid tube alone or with a braided reinforcement layer and / or cover layer. If a reinforcement layer is used, the adhesion between the outer tube layer and the reinforcement layer should also be greater than the minimum required for the application.

[0029] Figure 3Optional additional steps for adding a reinforcement layer (step 320) and / or a cover layer (330) to the mixing tube are shown. The reinforcement layer and the cover layer can be the same as previously described with respect to Figure 2 The reinforcement layer and cover layer are similar or identical and may be formed on the hybrid tube using any previously known technique. The step 330 of forming the cover layer may include forming the cover layer on the reinforcement layer or on the outer tube layer (in embodiments where no reinforcement layer is used).

[0030] Figure 3 Step 340 emphasizes that due to the materials used for the inner and outer tube layers and the co-extrusion step 310, the method 300 may not require a support mandrel and / or a curing step after the extrusion step 340. In some previously known processes, the structural integrity of the extruded tube is very weak, so that the hollow channel of the tube will collapse unless the tube is extruded onto a support mandrel. The diameter of the support mandrel is typically approximately equal to the diameter of the hollow channel of the tube, so that when the extruded tube leaves the die and is transferred to the support mandrel, the support mandrel extends through the hollow channel. The need for a support mandrel will generally increase the manufacturing footprint, which may reduce manufacturing capacity and production locations. In an embodiment of the method 300 described herein, the hybrid tube extruded in step 310 has sufficient structural integrity to maintain the hollow channel without the need for a support mandrel.

[0031] Similarly, step 340 highlights that method 300 can be performed without any post-extrusion curing step. This may be due to the materials that can be used for the inner and outer tube layers and the co-extrusion process used to produce the hybrid tube structure. In such an embodiment, the hybrid tube leaving the extruder has sufficient strength so that curing in, for example, an autoclave is not required.

[0032] The mixing tubes described herein (including the methods for manufacturing the mixing tubes described herein) can provide various advantages. For example, the mixing tube construction allows a large number of material combinations to produce mixing tubes that meet various application requirements. In some embodiments, the technology described herein allows the use of chemically resistant materials (for the inner tube layer), which otherwise cannot be used due to undesirable physical properties or their cost-prohibitive properties. Moreover, the outer tube layer material can be made hard enough (while still having a sufficiently high bending modulus), so that the support mandrel is not required for processing, and the mixing tube can withstand higher pressures with less or no reinforcement layer material. Without focusing on chemical resistance (which will be provided by the inner tube layer), the outer tube layer can be very professionally designed to provide the desired bending modulus. This makes the mixing tube flexible enough to allow the tube to pass through the product with the minimum bending radius requirement. Since the mixing tubes described herein show improved structural strength, the mixing tube can be manufactured with materials that do not require a support mandrel or solidify after extrusion in an autoclave. Therefore, the manufacturing process has a smaller equipment footprint, which will allow greater capacity at the production site.

[0033] Mixing tubes as described herein may have potential applications in industrial, food and beverage, hydraulic, chemically corrosive materials, pneumatic, automotive, aerospace, and other fluid transfer or fluid power applications. In some embodiments, the mixing tubes described herein meet the specifications set for SAE100R7 and SAE100R8 hydraulic thermoplastic hoses. Mixing tubes can be configured to carry a variety of materials, including water, steam, corrosive fluids, acidic fluids, solvents, flammable fluids, air, gas, and oil. Although the present invention is generally described as transferring fluids, the embodiments of the mixing tubes described herein are applicable to any internal fluid, whether it is transferred through the tube or generally retained within the tube.

[0034] From the foregoing it will be appreciated that particular embodiments of the invention have been described herein for purposes of illustration, but that various changes may be made without departing from the scope of the invention. Accordingly, the invention is limited only by the appended claims.

[0035] Although the technology has been introduced in language specific to specific structures and materials, it should be understood that the invention defined in the claims is not necessarily limited to the specific structures and materials described. Instead, specific aspects are introduced as forms for implementing the claimed invention. Because many embodiments of the present invention can be practiced without departing from the spirit and scope of the present invention, the present invention is present in the claims appended below.

[0036] Unless otherwise specified, all numbers or expressions (such as expressing dimensions, physical properties, etc.) used in the specification (except for claims) should be understood as being modified by the term "approximately" in all cases. At least without attempting to limit the application of the principle of equivalents to the claims, each numerical parameter modified by the term "approximately" recorded in the specification or claims should be interpreted at least according to the number of significant figures recorded and by applying rounding. Moreover, all ranges disclosed herein should be understood to include and provide support for the claims (the claims record any and all subranges or any and all single values ​​contained therein). For example, the range of 1 to 10 should be considered to include and provide support for claims that state any and all subranges or single values ​​between and / or including the minimum value 1 and the maximum value 10; that is, all subranges starting with a minimum value of 1 or greater and ending with a maximum value of 10 or less (such as 5.5 to 10, 2.34 to 3.56, etc.) or any value from 1 to 10 (such as 3, 5.8, 9.9994, etc.).

Claims

1. A mixing tube for industrial and hydraulic hoses, comprising: an inner tubular layer having a hollow passage extending therethrough, the inner tubular layer being configured to be chemically resistant to a fluid conveyed through or present in the hollow passage; as well as An outer tubing layer is formed on and coaxially aligned with the inner tubing layer, the outer tubing layer being configured to provide structure and flexibility to the hybrid tube.

2. The mixing tube according to claim 1, wherein: The thickness of the outer tube layer is greater than the thickness of the inner tube layer.

3. The mixing tube according to claim 1, wherein: The inner tube layer is from about 5% to about 50% of the thickness of the hybrid tube, and the outer tube layer is from about 50% to about 95% of the thickness of the hybrid tube.

4. The mixing tube according to claim 1, wherein: The inner tube layer is approximately 10% of the thickness of the hybrid tube.

5. The mixing tube according to claim 1, wherein: The material of the inner tube layer is selected from the group consisting of thermoplastics, thermosets, ceramics, metals and carbon.

6. The mixing tube according to claim 1, wherein: The material of the outer tube layer is selected from the group consisting of thermoplastics, thermosets, ceramics, metals and carbon.

7. The mixing tube according to claim 1, wherein: The material of the inner tube layer is selected from the group consisting of polyamide, high density polyethylene (HDPE), cross-linked HDPE, cross-linked low density polyethylene (LDPE), ethylene propylene diene terpolymer (EPDM) / polypropylene (PP) blend, polyethylene terephthalate (PET), polyvinylidene fluoride (PVDF) and fluorinated ethylene propylene (FEP).

8. The mixing tube according to claim 1, wherein: The material of the outer tube layer is selected from the group consisting of polyamide, high density polyethylene (HDPE), cross-linked HDPE, low density polyethylene (LDPE), polypropylene, polyethylene terephthalate (PET) and polyvinylidene fluoride (PVDF).

9. The mixing tube according to claim 1, wherein: The inner tubing layer is attached to the outer tubing layer by one or more of chemical bonding, intermolecular attraction, and mechanical attachment.

10. The mixing tube according to claim 1, further comprising: A reinforcement layer is formed on the outer tubular layer and is coaxially aligned with the outer tubular layer.

11. The mixing tube according to claim 10, wherein: The reinforcement layer is applied to the outer tube layer in a braided, spirally wound or linear pattern.

12. The mixing tube according to claim 10, wherein: The material of the reinforcement layer is selected from the group consisting of textiles, metal wires, ceramics or carbon materials.

13. The mixing tube according to claim 10, further comprising: A cover layer is formed on the reinforcement layer and is coaxially aligned with the reinforcement layer.

14. The mixing tube according to claim 10, wherein: The material of the cover layer is selected from the group consisting of elastomers or thermoplastic materials.

15. The mixing tube according to claim 1, further comprising: A cover layer is formed on the outer tubular layer and is coaxially aligned with the outer tubular layer.

16. The mixing tube according to claim 15, wherein: The material of the cover layer is selected from the group consisting of elastomers and thermoplastic materials.

17. The hybrid tube layer of claim 1, wherein: The mixing tube has no reinforcement layer.

18. A method for forming a mixing tube, comprising: An inner tube layer material and an outer tube layer material are co-extruded through an annular die to form a hybrid tube, the hybrid tube comprising: an inner tube layer having a hollow passage formed therein; and an outer tube layer formed on and coaxially aligned with the inner tube layer.

19. The method of claim 18, wherein: The inner tube layer material is selected from the group consisting of polyamide, high density polyethylene (HDPE), cross-linked HDPE, cross-linked low density polyethylene (LDPE), ethylene propylene diene terpolymer (EPDM) / polypropylene (PP) blend, polyethylene terephthalate (PET), polyvinylidene fluoride (PVDF) and fluorinated ethylene propylene (FEP).

20. The method of claim 18, wherein: The outer tube layer material is selected from the group consisting of polyamide, high density polyethylene (HDPE), cross-linked HDPE, low density polyethylene (LDPE), polypropylene, polyethylene terephthalate (PET) and polyvinylidene fluoride (PVDF).

21. The method of claim 18, wherein: The coextruded mixing tube, after being extruded through the annular die, is transferred to a support mandrel that extends through the hollow passage of the mixing tube.

22. The method of claim 18, wherein: The coextruded mixed tube flows freely from the annular die without being supported by a support mandrel.

23. The method of claim 18, wherein: The coextruded hybrid tube exiting the annular die has sufficient structural integrity such that the hollow passageway does not collapse after exiting the annular die.

24. The method of claim 18, wherein: The method is devoid of any curing step after co-extrusion of the inner tube layer material and the outer tube layer material through an annular die.

25. The method of claim 18, further comprising: A reinforcement layer is added to the coextruded hybrid tube, the reinforcement layer being formed on the outer tube layer and coaxially aligned with the inner and outer tube layers.

26. The method of claim 25, wherein: The material of the reinforcement layer is selected from the group consisting of textiles, metal wires, ceramics or carbon materials.

27. The method of claim 25, further comprising: A cover layer is added to the hybrid tube, the cover layer being formed over the reinforcement layer and coaxially aligned with the inner tube layer, outer tube layer and reinforcement layer.

28. The method of claim 27, wherein: The material of the cover layer is selected from the group consisting of elastomers or thermoplastic materials.

29. The method of claim 18, further comprising: A cover layer is added to the hybrid tube, the cover layer being formed over the outer tube layer and coaxially aligned with the inner and outer tube layers.

30. The method of claim 29, wherein: The material of the cover layer is selected from the group consisting of elastomers and thermoplastic materials.

Images