Spinneret for the production of a plurality of hollow filaments

摘要

A spinneret for the production of a number of hollow filaments comprises three superimposed plates of which the plate 1 (Fig. 1) constituting the base of the spinneret is provided with a number of spinning orifices 6 and with alignment bores 7 for dowels 17. The middle plate 2 has a central opening 8 which is enlarged downward to form a supply chamber 9 of relatively large diameter for the spinning solution or spinning melt. An annular recess 10 is provided in the lower surface of the upper plate 3 from which a gaseous or liquid medium for introduction into the filament axis is distributed to the spinneret orifices. The medium is supplied to the recess 10 by a number of ducts 18 and a number of tapered bores 11 extend from the recess 10 to the chamber 9. Axially drilled tapered pins 12 (Figs 1 and 3) terminating in capillaries 13 are secured in the bores 11 by means of axially drilled screws 14 which are screwed into the threaded upper portions of the bores 11 and bear down upon the pins 12, which are thereby forced into the bores 11 to form gas and liquid tight push fits therein. The gaseous or liquid medium from the recess 10 passes through the central bores 15 in the pins 12 and then through the capillaries 13 into the filaments as they are being extruded from the orifices 13. A thin aluminium gasket 21 is provided between plates 1 and 2 and 2 and 3 to form gas and liquid tight seals between the plates. At least three dowels 17 are firmly fixed in the plate 2 and are an accurate sliding fit in the bores 7 in the plate 1. The upper plate 3 has a central opening 16 through which spinning solution or melt is fed via opening 8 to the supply chamber 9. The lower part of the portion of the pin 12 which projects into the plate 1 is provided with vertical grooves 19 (Figs. 2 and 3) through which the spinning solution or melt is forced to the spinning orifices 6. Vertical ribs 20 between adjacent grooves ensure exact centring of the pin in its bore. The three plates are held together by screws of which four are shown at 21 to 24. In the spinneret of the parent Specification each axially drilled pin 12 instead of being tapered is cylindrical and is provided with a shoulder which is pulled up tightly against the underside of the plate 2 when the screw 14 is screwed into the threaded upper portion of the central bore of the pin, the underside of the head of the screw bearing on the upper surface of the plate 2. The bores 11 in this case are cylindrical and not tapered and the pins are a close sliding fit in the bores.