Patent ID: 7968036
Filing Date: 2011-06-28
Classification: A61F,B29C,B29L,F15D,F16L

Abstract:
1. A method for introducing an internal helical formation into a flexible tubular material such that the internal helical formation is capable of conferring a helical flow on liquid flowing through the tubular material, the method comprising the steps of: i) placing the flexible tubular material on a non-grooved mandrel, winding a thread around the material, pushing the ends of the material together so as to deform the material to have a concertinaed configuration, setting the material in that configuration, and removing the thread and the mandrel, wherein the thread is removed either before or after the material is set; and ii) supporting the material on a mandrel having a groove, placing a helical former corresponding to the groove around the material so as to deform the material to have an internal helical formation corresponding to the shape of the groove, setting the material in that configuration in a second setting operation, and removing the former and the mandrel.