Werkwijze en inrichting voor het vervaardigen van een filterbuis ten behoeve van een TL-buis.

摘要

A strip of film is formed into a roll on a vacuum mandrel (7) and then the transparent tube is placed over the mandrel and the vacuum turned off. A method for making filter tube used to make TL tubes comprises the following steps : (i) cutting or punching a strip from a web of film; (ii) rolling the strip up to form a (partial) roll with a diameter less than that of a transparent plastic tube; (iii) placing the (partial) roll inside the plastic tube to form one or more layers of light filter and/or reflector material; and (iv) fitting flexible caps into both ends of the tube, each cap containing an opening via which a TL tube can be inserted. The (partial) roll is formed by bending the strip around a tubular mandrel with an external diameter less than that of the plastic tube. Perforations (8) are provided in at least one region of the mandrel so that when a vacuum is generated inside the mandrel tube the strip of material is held against the mandrel surface. The plastic tube is slid over the mandrel and the vacuum turned off so that the finished (partial) roll is held inside the plastic tube and prevented from unwinding.