Patent GB-1106834-A (GB)
Title: Melt-spinning method and apparatus
IPC: D01D1/09
Filed: 1966-09-12
Abstract: 1,106,834. Melt-spinning apparatus. MONSANTO CO. 12 Sept., 1966 [23 Sept., 1965], No. 40716/66. Heading B5B. A spinning process is characterized by forcing polymer through a filter medium, by means of a meter pump driven by a synchronous motor, selecting said filter medium so that said motor initially consumes power within a predetermined range of wattage, and detecting when said power bears outside said pre-determined range of wattage. Apparatus as shown for the melt spinning of filaments from molten polymer is characterized by a synchronous motor 36 drivably connected to a meter pump 34 for supplying molten polymer 26 through a spinning pack 46 to a spinnerette 40 for extrusion to form filaments 42, and means responsive to variatons of the power consumed by said motor outside a pre-determined range of wattage, (e.g. watt meter 48 and alarm 49), for detecting abnormal operation of said apparatus. In operation, the resistance presented by filter pack 46 slowly increases during spinning, thus increasing pressure in chamber 38, leading in time to production of defective low denier filaments. By the addition of relay contacts to meter 48, an alarm or light 49 may be activated whenever the meter pump wattage varies outside the pre-determined levels of normal operation, so that the filter pack may then be changed. Unacceptable operating pressures may be detected in this way long before this is apparent by actual measurement of filament denier. In the preferred embodiment shown, an alternating current motor 30 is drivably connected to a booster pump 28 which supplies molten polymer to the meter pump 34. Normally, booster pump 28 supplies more polymer to passage 32 than is pumped-by metering pump 34, and booster pump 28 has a relief orifice on its output side, to discharge excess polymer back to melt pool 26. If this relief orifice becomes plugged a sharp increase in pressure in passage 32 results, reducing the pressure difference across meter pump 34 and causing an increase in spun denier. Conversely, if booster pump 32 suffers a loss of polymer supply due to a temporary lowering of the melt rate, the pressure in passage 32 drops or becomes variable. This condition will result in production of low or variable denier filaments. Either of these conditions causes substantial variations in the power consumed by booster motor 30. Similarly to meter 48, relay contacts may be added to meter 50, in order to actuate a light or alarm 52 when the power consumed by motor 30 varies outside a pre-determined range. Alarms 49 and 52 may be combined if desired. Comparison of the readings of watt meters 48 and 50 can usually identify the type of abnormal condition. Thus if meter 50 maintains its normal reading while meter 48 indicates an abnormally high reading, the defective condition is an abnormal increase in the resistance of filter 46. On the other hand, if meter 50 reads an abnormally low wattage while meter 48 indicates a normal or low wattage, the failure is a loss of polymer supply to the booster pump 28. Other defective conditions are similarly indicated by other comparisons of meter readings.