Thermoplastic, flexible tube and method for herstelen of such tubes

摘要

1441573 Flexible hose ALENCO HILYN Ltd 24 Aug 1973 [24 Aug 1972] 39499/72 Heading F2P In manufacturing a reinforced flexible hose a thermoplastic tube is provided with an external reinforcement of braided or spiral form, the assembly is heated whilst applying a positive pressure difference between the inside and the outside of the tube to cause expansion of the tube against the reinforcement such that the outer surface of the tube is deformed to follow the internal contours of the reinforcement and the assembly is then cooled or allowed to cool whilst maintaining the pressure difference whereby the tube is stressed and permanently set in such state. An outer sheath of thermoplastic material may be formed around the deformed tube by extrusion and this may be done before the cooling operation so that the outer sheath is welded or bonded to the softened thermoplastic material of the tube. Alternatively an adhesive or cement may be used. Preferably the pressure difference is created by applying pressure inside the tube whilst the latter is passed continuously through an oven for a time and at a temperature sufficient to soften or melt the outer surface of the tube. The temperature, pressure and heating time may be adjusted so as to soften the inside of the tube sufficiently to cause the bore to assume a true circular shape. The softening or melting of the outer surface of the tube is said to allow any disconformities or tensions in the reinforcement to be relieved thus enhancing the properties of the hose. If desired two or more layers of reinforcement may be provided such layers being separated by thermoplastic material. The material of the tube may comprise a polyolefin, polyamide, polyvinyl chloride, polyester or polytetrafluoroethylene and the reinforcement may be of a natural or synthetic fibre textile or wire.