GB870194A - Improvements in or relating to apparatus for the heat-treatment of synthetic fibers - Google Patents

Abstract

870,194. Heating synthetic fibres by electric resistances. MULLER, G. W. Nov. 26, 1957 [Nov. 27, 1956], No. 36855/57. Class 39(3). [Also in Group IX] Apparatus for the heat treatment of moving synthetic fibres with a base of thermoplastic materials comprises several heating elements each with independent means to modify part only of the thermal output of the element so that all the fibres passing through the elements can be heat-treated to the same temperature. Each heater comprises a main resistance wire preferably wound on a former and in circuit therewith an adjustable regulating auxiliary wire resistor preferably wound on a former both adjacent a tube through which the synthetic fibre passes. Thus in Figs. 2 and 3, a metal heat storage block 20 is formed with three passages, the central one containing a replaceable tube 17 through which the synthetic filament passes and the lower one containing a fixed heating resistor 21 supplying 80% of the required heat and connected in parallel with an adjustable resistor 23 wound on an insulating former 23 lying in the upper passage. Brushes 24, 26 are pressed by springs on to the resistor 23, which is adjusted by axial movement of the former 22, which may be rotated by a knob 31 on a threaded rod 30 made rigid with the former and moved axially by the engagement of threads on the knob with threads on an insulating plate 32; or the threaded rod 30 is screwed as shown into the former 22 which is prevented from rotating by a square end 28 held in a square hole in an insulating support 29 so that on rotation of the rod 30, the former is moved axially to adjust the resistor. The end part of the former 22 on which the brush 24 bears is conducting. The block 20 is mounted in glass wool which may be agglomerated by a thermosetting resin in a tin case 16. Alternatively the heating resistor is wound on an insulating sleeve around a metal mass with a central passage housing a central tube for the filament, and the end turns of the heating resistor, which may be more widely spaced or of different resistivity are tapped to regulate the current. The tapped regulating resistor may in a modification be wound on an insulating sleeve extending around the heating resistor, which may be in series with the regulating resistor. The metal mass may be omitted. The tube for the filament may be of metal, glass or a ceramic and may have at each end a nozzle of tempered or nitrated steel of smaller diameter than the tube to reduce heat loss therefrom. The inlet nozzle is flared. In Fig. 5, the tube 47 for the filament is mounted in a metal mass 48 grooved externally to receive eight resistors incorporated in ceramic cylinders. The heating resistors 49, 50 are diametrically opposite and any of the six auxiliary resistors which may be of unequal value are inserted in circuit as required. The resistors are covered by a ceramic envelope 54 and glass wool 52 all enclosed in a metal casing 53.