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1. WO2012068244 - COMPOSITE TUBE AND METHOD THEREFOR

Note: Text based on automatic Optical Character Recognition processes. Please use the PDF version for legal matters

[ EN ]

COMPOSITE TUBE AND METHOD THEREFOR

BACKGROUND

[0001] This disclosure relates to composite tubes that have good resistance to abrasion. Tubes are known and used for transferring fluids, such as automotive fluids, within a vehicle. A conventional tube may include multiple layers of rubber material, and reinforcement fibers for strength.

SUMMARY

[0002] Disclosed is an example method for making a composite tube. The method includes applying a coating material onto an outside surface of a tube and treating the coating material to transform the coating material into a polymeric cover on the tube.

[0003] Also disclosed is a manufacturing system that includes a device operable for continuously forming a tube and at least one coating application device arranged to receive the tube as it is discharged from the device. The coating application device is operable to apply a polymeric coating material onto the outside of the tube. A dryer is arranged downstream from the coating application device. The dryer is operable to transform the polymeric coating material into a polymeric cover on the tube.

[0004] Also disclosed is a composite tube that includes an inner tube extending along an axis and defining a radial thickness R1; and a polymeric cover fixed on the inner tube and defining a radial thickness R2 such that a ratio Ri/R2 is 100-400.

BRIEF DESCRIPTION OF THE DRAWINGS

[0005] Figure 1 illustrates an example composite tube.

[0006] Figure 2 illustrates an example method for making a composite tube.

[0007] Figure 3 illustrates an example apparatus for making a composite tube.

DETAILED DESCRIPTION

[0008] Figure 1 illustrates selected portions of an example composite tube 20. For instance, the composite tube 20 is used in any application where there is a desire to protect the tube from abrasion and/or thermal conditions. As an example, the composite tube 20 is used in a vehicle for conveying a fluid within a heating/cooling system, transmission system, or the like. It is to be understood, however, that the examples disclosed herein are not limited to any particular application and that other applications, in addition to the above, will benefit from this disclosure.

[0009] As shown in the example in Figure 1, the composite tube 20 includes an inner tube 22 and a polymeric sleeve/cover 24 (hereafter polymeric cover 24) fixed on the outer peripheral surface of the inner tube 22. As will be explained in greater detail below, the polymeric cover 24 provides a relatively tough exterior layer that protects the inner tube 22 from abrasion.

[0010] In a further embodiment, the inner tube 22 is a multilayered composite of one or more different materials or layers. For example, the inner tube 22 includes an innermost layer 26, a reinforcement layer 28 disposed on the peripheral surface of the innermost layer 26 and an outer layer 30 disposed on the reinforcement layer 28. It is to be understood that the inner tube 22 can include additional layers to those disclosed above. In another embodiment, the inner tube 22 includes only those layers disclosed above such that the reinforcement layer is in contact with the peripheral surface of the innermost layer 26 and the outer layer 30 is in contact with the reinforcement layer 28.

[0011] In further examples, the innermost layer 26, the outer layer 30 or both are an elastomeric material and the reinforcement layer 28 is a wrap or weave of reinforcement fibers around the innermost layer 26. In additional examples, the elastomeric material of the innermost layer 26 and the outer layer 30 are the same or different chemical compositions.

[0012] Alternatively, the inner tube 22 is a homogenous material instead of a multilayered composite. For instance, the inner tube 22 is a single, monolithic layer of elastomeric material, metallic material, or other type of material. In some embodiments, the inner tube 22 is a metal or metal alloy, such as an aluminum alloy, steel alloy, or other alloy commonly employed as tubing material.

[0013] The polymeric cover 24 is a relatively thin layer located directly on the peripheral surface of the outer layer 30. The polymeric cover 24 is fixed through bonding to the outer layer 30 and thereby does not translate or rotate relative to the inner tube 22. The bonding is chemical bonding, mechanical bonding or a combination thereof.

[0014] The polymeric cover 24 is serves to protect the inner tube 22 from abrasion, such as from contact with foreign debris or movement against a neighboring component. Thus, the polymeric cover 24 need not be very thick but must be thick enough to suitably protect the inner tube 22 from abrasions.

[0015] In a further example, the inner tube 22 has an average radial thickness Ri in a radial direction relative to the central axis of the composite tube 20 and the polymeric cover 24 has an average radial thickness R2 in the radial direction. Ri and R2 are selected with a predetermined ratio Ri/R2 (Ri divided by R2) to provide a balance of tube performance, weight and abrasion resistance. In one example, the ratio Ri/R2 is from 100 to 400. In a further example, the ratio Rx/R2 is from 100 to 200.

[0016] The actual average thicknesses Ri and R2 can be varied to achieve the given ratio and depending on the desired balance of performance, weight and abrasion resistance, for example. In one embodiment, the inner tube 22 is approximately 4 millimeters thick and the polymeric cover 24 is approximately 10-35 micrometers thick. In a further example, the polymeric cover 24 is 15-25 micrometers, or is nominally 20 micrometers.

[0017] In a further example, the polymeric cover 24 is or includes a polymer material with or without additives. In one example, the polymer material is or includes polyurethane, and the polyurethane optionally includes silicon. In a further example, the silicon is incorporated via covalent bonding into the polyurethane chemical structure. The polyurethane- silicon material optionally additionally includes a heat-resisting additive, such as aluminum or fiberglass, which has a relatively low heat transfer co-efficient and/or an additive that has the ability to reflect radiation, such as visible light, to reduce the temperature of the composite tube 20.

[0018] Figure 2 illustrates an example method 40 for making a composite tube, such as the composite tube 20 shown in Figure 1. The description of the composite tube 20 is hereby incorporated into the description of the method 40. The method 40 generally includes an

application step 42 and a treatment step 44. The application step 42 includes applying a coating material onto the inner tube 22. The application of the coating material is conducted by spraying in one example, but in other non-limiting example can include brushing or dipping.

[0019] The coating material is a material that will later form the polymeric cover 24 of the composite tube 20. In some examples, the coating material is a solvent-based mixture that can be applied onto the inner tube 22. In one embodiment utilizing a polyurethane or polyurethane- silicon material as the polymeric cover 24, the coating material is a water-based polyurethane.

[0020] After applying the coating material onto the inner tube 22, the composite tube 20 is treated in the treatment step 44 to transform the coating material into the polymeric material of the polymeric cover 24. For instance, the treatment step 44 includes drying and/or curing the coating material to thereby form the polymer of the cover 24. Drying refers to the substantial removal of any solvent and curing refers to polymerization. As can be appreciated, the treatment times and temperatures may vary depending upon the type of coating material selected.

[0021] In a further embodiment, the application step 42 and the treatment step 44 are conducted in a continuous flow process with extrusion of the inner tube 22. For example, as will be described in more detail below, the inner tube 22 is continuously extruded, coated and treated to form the composite tube 20.

[0022] Regarding the ratio R1/R2, the application step 42 is controlled to apply a controlled amount of the coating material to achieve the proper average radial thickness Ri and thus the given ratio Ri/R2. Given this description, one of ordinary skill would understand how to control the amount of the coating material applied to achieve a target thickness without undue experimentation .

[0023] Figure 3 illustrates an example apparatus or manufacturing system 60 that can be utilized to conduct the method 40 of making the composite tube 20. The description of the composite tube 20 and method 40 are hereby incorporated into the description of the system 60.

The system 60 includes a device 62 for forming the inner tube 22, at least one coating application device 64 arranged to receive the inner tube 22 as it is discharged from the device 62 and a treatment device 66 arranged downstream from the at least one coating application device 64.

The device 62 is operable for continuously forming the inner tube 22 such as by extrusion or other technique. The at least one coating application device 64 is operable to apply the polymeric coating material onto the outside of the inner tube 22, and the treatment device 66 is operable to transform the polymeric coating material into the polymeric cover 24 on the inner tube 22.

[0024] In further examples, the device 62 is an extruder, the at least one coating application device 64 includes one or more sprayers or nozzles and the treatment device 66 is a dryer. Upon exit from the extruder 62, the coating material is sprayed onto the outer surfaces of the inner tube 22. For instance, a plurality of nozzles 64 are arranged circumferentially around the inner tube 22 near the exit from the extruder 62. The nozzles 64 spray the coating material onto the inner tube 22. The number of nozzles 64 selected and the position of the nozzles 64 are arranged such that the coating material completely circumferentially coats onto the inner tube 22.

[0025] The composite tube 20 with the sprayed-on coating material then proceeds to the dryer 66 for the treatment step 44. The dryer 66 may apply heat to the composite tube 20 to dry the coating material and/or cure the coating material to form the cover 24. In this example, the nozzles 64 and dryer 66 are shown in line with the extruder 62 in a continuous flow process such that the inner tube 22 is continuously provided by the extruder 62, the nozzles 64 continuously coat the inner tube 22 and the dryer 66 continuously dries and/or cures the coating material.

[0026] Although it may be less efficient, the composite tube 20 may alternatively be made in a discontinuous process such that the inner tube 22 is separately sprayed from the extrusion and/or separately dried from the spraying. That is, the extruding, the spraying, and the treatment may be separately conducted in time and space.

[0027] Although example embodiments have been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this disclosure.