Improvements in or relating to the heat treatment of narrow texile fabric

944,607. Drying webs; fluidized beds for heating sheet and filamentary material. COTTON, SILK & MAN-MADE FIBRES RESEARCH ASSOCIATION. May 1, 1962 [Feb. 2, 1961], No. 3921/61. Headings F4G and F4U. [Also in Division D1] A fluid bed machine comprises a fluid bed container 11; means 13 for heating a bed of particles in the container; means 12 for introducing a fluidizing gas to the container; and means for supporting and progressing narrow fabric F through the container 11 which latter means includes a pair of guide rollers 17, 20 to accommodate the fabric F in a plurality of convolutions; the relative position of the container 11 and the rollers 17, 20 being adjustable to alter the length of the fabric F passing through the fluidized bed. The container 11 is loaded with suitable particles, e.g. glass spheres, and a tape F passes through a tension device 37, over a roller 33 and several convolutions are wound around the rollers 17, 20. The tape F then passes between brushes 27, 28 and rollers 24, 32. Elements 13, preferably thermostatically controlled, heat the bed fluidized by air from a perforated tube 12. The container 11 is raised until an appropriate depth of immersion of the fabric F is achieved by chains 38 secured each at one end to a lug 39 and which pass over wheels 40, 41 and have counterweights 42 attached thereto. A motor 18 is started to drive the roller 17 and rods 23, 25 and 28 carrying the roller 24 and the brushes 26 and 28 respectively. The roller 20 may be positively driven or may be free to rotate within polytetrafluoroethylene bearings. The apparatus may be used to dry cotton zipfastener tape which has along one edge a thermoplastic filament, e.g. nylon, which shortens on heat treatment to give the tape a bias. The rollers 17, 20 are formed of a series of frustoconical portions, the smaller diameter end of each portion being relieved to accommodate the nylon filament. In a modification (not shown) more than one roller assembly is provided to treat several tapes simultaneously. According to the Provisional Specification the roller 20 may be fixed. Specifications 773,598 and 800,091 are referred to.