Patent GB-1188173-A (GB)
Title: Apparatus for Heat Setting Synthetic Fibre Yarns
IPC: D01D10/04
Filed: 1967-07-11
Abstract: 1,188,173. Apparatus for heat setting synthetic fibre yarns. N. KODAIRA, and N. MOTEGI. 11 July, 1967 [18 July, 1966], No. 31809/67. Heading B5B. [Also in Division F4] An apparatus for heat setting in a continuous manner travelling synthetic fibre yarns comprises an assembly of vertical heating units 1 arranged in parallel, Fig. 1. In the embodiment of the apparatus of the invention shown in Fig. 2 each unit comprises a curved generally vertical closed chamber 3 the convexly curved surface of which is provided with one or more longitudinal guide channels 2 of small crosssection through each of which travels a yarn 2<SP>1</SP> to be heat set. The chamber 3 is enclosed in a housing 14, 16 containing heat insulating material 15, 17. The lower portions of adjacent chambers 3 communicate with one another via horizontal ducts, the end of one of which is shown at 5. A tubular electric heater 6 extends through the lower parts of all the chambers 3 and the lower portion of each duct and each chamber 3 are filled with sufficient of a liquid heat exchange medium 7, such as Dowtherm E to cover the heater to a suitable depth. The upper part of each chamber 3 communicates via a pipe 8 with the upper portion of a chamber 9<SP>1</SP> of a horizontal separating vessel 9 which extends through all the heating units and is provided through its length with a partition 10 which divides the vessel 9 into two chambers 9<SP>1</SP> and 9<SP>11</SP> but does not extend to the bottom of the separating chamber. The upper end of a return pipe 11 projects upwards into the chamber 9<SP>11</SP> to a level above the lower edge of the partition 10 and the lower end of the pipe 11 projects into the lower part of the chamber 3 a sufficient distance to submerge the open bottom of the pipe in the liquid 7 in the bottom of the chamber 3. The vapourfilled portion of the chamber 3 communicates via a pipe 12<SP>1</SP> with a syphon bellows 12 which actuates a microswitch by means of which the power supply to the heater 6 is switched on and off in accordance with the pressure of the vapour in the chamber 3. The temperature in the chamber 3 is thereby maintained constant at a predetermined level. The space between the separating vessel 9 and the housing 14 is not occupied by any of the insulating material 15 so that the temperature of the vessel 9 is below that of the vapour in the upper part of the chamber 3. Consequently vapour enters the vessel 9 and condenses therein, the liquid thereby formed collecting in the lower parts of the compartment 9<SP>1</SP> and 9<SP>11</SP> of the separating chamber until it reaches the top of the return pipe 11 and overflows down this pipe and returns to the liquid 7 in the lower part of the chamber 3. After the apparatus has been in use for some time, steam formed by decomposition of some of the heat exchange medium tends to collect in the upper part of the chamber 3 and unless continuously removed from the upper part of the chamber would lower the temperature therein. This is prevented in the apparatus of the invention since the steam with the vapour of the heat exchange liquid enters the separating vessel 9 and collects as an upper layer on the surface of the layer of the condensed heat exchange liquid in the compartment 9<SP>1</SP> of the separating vessel, from whence it can be periodically withdrawn. In a second embodiment of the apparatus of the invention shown in Figs. 4 and 8 the separating vessel 29 is housed in a heat exchanger 40 through which cooling air or a cooling vapour is passed from inlet 44 to the header 43<SP>1</SP> which communicates via branch pipes 43 with the outlet ends of the ducts 22 through which the yarn travels downwardly. The inlet ends of ducts 22 communicate via pipes 46 with the upper header 46<SP>1</SP> which is maintained under reduced pressure, so that part of the heated air or vapour which has passed over the separator 29 is drawn upwards through the yarn ducts 22 in countercurrent to the yarn 22<SP>1</SP> travelling down the ducts. Additional heat is thereby furnished to the yarn. The flow of heated air or vapour through the yarn ducts 22 also serves to carry away undesirable vapours which may be evolved from oily substances with which the yarn may be impregnated. A third embodiment of the apparatus of the invention differs from the second embodiment only in that the yarn travels through a curved pipe extending throughout the length of the vertical heating chamber.