Method and apparatus for production of a flexible duct

摘要

Abstract A method of and apparatus for forming a flexible duct including helically winding a tube containing insulating material, wherein the tube is delivered into its initial winding at a rate of delivery so that at the outer periphery of the winding the tube remains substantially unstretched and uncompressed circumferentially while at the inner periphery the tube is allowed to pucker circumferentially. Also a method of forming a flexible duct, including the steps of drawing a strip of flexible material relatively laterally of and into a forming head that delivers the strip forwardly from the forming head as a tubular casing in the direction of the axis of the casing, and delivering fibrous insulating material into said casing at the forming head as a gas entrained stream of the material, wherein the tube is delivered into its initial winding at a rate so that at the outer periphery of the winding the tube remains substantially unstretched and uncompressed circumferentially, while at the inner periphery the tube is allowed to pucker circumferentially.