Patent GB-656093-A (GB)
Title: Improvements in apparatus for the production of artificial filaments
IPC: D01D5/04
Filed: 1948-07-02
Abstract: <PICT:0656093/IV (a)/1> An apparatus for the production by dry-spinning of a heavy bundle or tow of continuous filaments comprises a vertical spinning cell, a plurality of ranks of multi-orifice jets in the upper part of the cell, one rank within another, each rank consisting of a number of jets arranged round the middle of the cell, the jets of each inner rank being at a higher level than those of the rank immediately outside it, and the top of the cell being stepped back so that all the jets are accessible through openings in the sides of the cell, the cell being formed at the bottom with a space common to the filaments from all said jets, and means for collecting all said filaments in tow form.  The tow so obtained may be cut into staple fibre.  As shown, a vertical spinning cell 1 has a number of multi-orifice jets 2 in the upper part thereof, the jets being arranged in two ranks 4, 5 around the middle of the cell 3, and the inner rank 4 being within and at a higher level than the outer 5.  The top of the cell is stepped back at 6 to allow access to all jets from the outside.  At the bottom is a space 8, 9 common to all filaments and collecting means are provided beneath a common outlet 13 for collecting the filaments 10 in tow form.  The upper part of the cell is divided into sub-cells 20 by metal partitions 21, the cell and sub-cells being conveniently but not necessarily of square cross-section.  This division into sub-cells reduces the possibility of different jets receiving substantially different supplies of evaporative medium and also minimizes the effect of cross-draughts near the jets. The spinning solution may be supplied to each jet by its own pump and filter or the jets may be supplied in groups, pipes 23 connecting the jets to the supply system.  The pipes 23 serving the outer rank pass through passages formed in the partitions 21 dividing the sub-cells.  Heating means such as a steam coil 25 may be disposed in the central space 3 in the top of the cell.  The outside of the top of the cell may be lagged.  If preferred, the pumps and/or filter may be immersed in heated baths or jackets. It is essential that the cell be long enough for the filaments to set so that they do not stick together when they meet at the common outlet 13.  The bottom part 9 of the cell is formed as an inverted truncated pyramid, the angle of the walls to the horizontal being such that the filaments automatically find their way to the outlet under gravity.  The common outlet may be provided with swing doors 29 which can be opened to allow the initial emergence of filaments and subsequently closed.  Springs 30 hold these doors in the open or closed position.  The gaseous setting medium (e.g. air) may enter at the top of the cell and be withdrawn through draw-off pipes 31 in an enlarged part 32 of the cell communicating with a suction duct 33 and a suction main. Gauze-covered openings 35 communicating with pipes 36, 37 may also be provided at the bottom of the cell so that air can be sucked from or introduced to the truncated part of the cell.  The middle of the cell may be provided with a hollow closed shell 38 in order to reduce the volume and, if desired, provision may be made for drawing off air centrally by a suction pipe extending up the middle of the shell. The apparatus is particularly useful in the spinning of cellulose acetate, but it may be used for the spinning of any filaments that can set by the action of a gaseous setting medium, such as cellulose propionate, butyrate, acetate-propionate, acetate-stearate, and ethyl and benzyl celluloses.