Patent ID: 10436355

Abstract:
A duct of fiber material and binder agent, at least two fold lines are present lengthwise for providing a foldability of the duct by weakened material along the fold lines. The duct is pushable into a folded state and the material remembers the original shape and return to its original shape when released from a folded state. A method of manufacturing a duct: applying a web of origin fiber material with binder agent to a core and compressing the web by an outside form under the influence of heat against the core, wherein the core and/or the outside form is provided with a number of lengthwise ridges corresponding to the desired number of fold lines, to a third of the original thickness of the sides and at the ridges a tenth to a twentieth of the original thickness, and in that the fiber and binder agent web weighs 1.5-3 kg/m2.