Patent GB-822706-A (GB)
Title: Improvements relating to the production of slub filaments
Inventor: GIBBINS LESLIE BRISBANE
IPC: D01D5/20
Filed: 1955-09-30
Abstract: <PICT:0822706/IV (a)/1> <PICT:0822706/IV (a)/2> <PICT:0822706/IV (a)/3> Variations in denier are imparted to artificial filaments by drawing the filaments from a point where they are in a stretchable condition along a path from which they are periodically deflected by a moving deflecting surface so as to vary the length of the path, and periodically moving the filaments in a direction which is perpendicular to the plane in which lies the path of travel of the filaments when they are deflected, so that the filaments are disengaged from the deflecting surface and are free to return abruptly to a shorter path.  The process may in particular form part of the dry, wet or melt-spinning of artificial filaments, e.g. the dry-spinning of cellulose acetate.  The process may also be applied to previously spun artificial filaments which have been rendered stretchable by passing them through a heating zone or a zone for applying to them a softening agent such as a solvent in liquid or vapour form, hot water or moist steam.  Alternatively the process may be used for the cold-drawing of filamentary material such as nylon. The process may be carried out in the apparatus shown in Fig. 1 in which a cellulose acetate solution is dry-spun in the conventional metier 7 from which a thread of filaments 8 is passed over a lubricating device 13 adapted to apply a finish to the filaments and to a feed-roller 14 rotating at uniform angular speed and provided with a back guide 15.  The roller 14 forwards the thread 8 to the balloon guide 16 of a ring-spinning device 17 in the usual manner. On their way from the lubricating device 13 to the feed roller 14 the filaments pass over a deflecting roller 19 about 9 inches in diameter.  A series of such rollers is provided along the metier 7, one for each six spinning jets.  Each roller 19 is driven individually through a clutch 21 from a common countershaft 22 extending along the length of the metier 7.  Each roller 19 is in the form of a hollow shell (Figs. 1 and 2) supported at each end on short axles 24 which do not extend internally along the axis of the roller. At intervals along the length of the roller 19 corresponding to the spacing of the six spinning jets along the length of the metier 7 the roller is formed with six slots 25 (Figs. 2 and 3) each extending at right angles to the roller axis round half of the periphery of the roller.  Nearly opposite each slot 25, a pair of stationary thread guides 26, 27 are situated at the level of the roller axis and both offset a short distance to one side of the slot 25.  A hook guide 28, for temporary use during starting operations is disposed above the roller 19.  Alongside each slot 25 and secured to the roller surface is a radially-extending fin 29 reaching circumferentially of the roller from a point at about the middle of the length of the slot 25, to a point a little beyond the end of the slot.  The leading end 31 of the fin is spaced further from the edge 32 of the slot than the plane 30 normal to the roller axis containing the two guides 26, 27. In extending backwards round the roller 19, however, the base of the fin 29 gradually approaches the edge 32 of the slot 25 at an angle of about 5 degrees, and reaches it at the trailing end 33 of the fin. The trailing part of the fin from 33 to 34 is of a uniform height of about 1/2 inch, but the leading part from 34 to 31 where the fin is well clear of the plane 30 diminishes in height and merges into the roller surface.  The face 35 of the fin adjoining the slot 25 is not quite vertical but leans over slightly towards the slot 25 so that, while the base of the fin at its trailing end 33 coincides with the edge 32 of the slot the crest of the fin at this point overhangs the slot.  The countershaft 22 is driven at a variable speed from the shaft 36 which carries the feed rollers 14, by means of a chain 39 and an infinitely-variable gear 37.  The gear ratio is varied through the control lever 38, by means of a multi-node cam 41 which in turn is driven from a second infinitely-variable speed gear 42 similar to the gear 37 and driven through a chain 43 from the main shaft 44 of the metier, from which the shaft 36 is itself driven through a change-speed gear-box 45 and chains 46.  The nodes of the cam 41 are irregular as to both height and angular extent.  The control lever 47 of the gear 42 is in turn actuated by a heart cam 48 driven from the main shaft 44 through a speed reduction gear 49, giving a speed reduction of the order of 1000 : 1, and a chain 51. By means of this assembly of gears and drives the slotted rollers 19 are driven at a speed which varies according to a pattern which is repeated only after a very long period.  When the roller 19 is in the position where the slot 25 extends round its upper half and the ends of the slot lie in a horizontal line, as shown in Fig. 1, the filaments 8 passing through the two stationary guides 26, 27 extend in a straight line through the slot 25 and along a diameter of the roller 19.  As the roller 19 rotates, the unslotted portion 57 of its periphery (Fig. 2) picks up and deflects the filaments from their straight path so that they are caused to pass over the unslotted portion of the roller surface.  As the leading end of the slot 25 comes round, the filaments continue to be carried by the roller surface alongside the slot 25, on account of the disposition of the two stationary guides 26, 27 slightly offset from the slot.  Subsequently the leading end 31 of the raised fin 29 on the roller surface comes abreast of the filaments and at first does not disturb their passage over the roller.  On continued rotation of the roller, however, the fin urges the filaments axially along the roller until they are disengaged from the roller surface and caused to drop into the slot.  This takes place at the moment when the trailing end 33 of the fin 29 reaches the point, indicated at 56 in Fig. 2, where the thread 8 travelling from the guide 26 first meets the surface of the roller.  This is shortly before the ends of the slot 25 are again in a horizontal line.  When the thread 8 drops into the slot 25 it becomes slack, but in a very short time this slack is taken up by the rotation of the feed-roller 14.  The timing of this is determined by the position of the trailing end 33 of the fin 29 with respect to the ends of the slot 25 and should be such that, just as the slack is taken up, the ends of the slot 25 come into a horizontal line so that the filaments on tightening assume a direct path along the diameter of the roller 19, whereupon the cycle is repeated.  The optimum position of the fin end 33 may be abreast of about the mid-point of the slot 25 or a little behind or in front of this point.  While the filaments 8 are being deflected from the straight path from one stationary guide 26 to the other 27, their path is lengthening, and the filaments are drawn from the spinning jets at a rate greater than the peripheral speed of the feed roller 14.  As the filaments drop into the slot 25, however, they cease to be drawn down from the spinning jets and emerge from these at a rate determined by the volumetric rate of extrusion of the spinning solution.  This causes a thick place in the filaments which passes down the spinning cabinet and is hardened by evaporation.  When the roller 19 again deflects the thread, the hardening of the thick place prevents it from being drawn out, the drawing taking place only at the freshly-forming parts of the filaments in the immediate neighbourhood of the spinning jets where the filaments are in an extensible condition. The mean peripheral speed of the deflecting rollers 19 is arranged to be about equal to that of the feed roller 14.  However, the speed of the rollers 19 is caused to fluctuate by, for example \sB 10%, by means of the speed varying or "scrambler" gear 37-51 so as to break up the regularity of the variation in denier along the length of the yarn.  The maximum peripheral speed of the rollers 19 should preferably not at any time much exceed the peripheral speed of the rollers 14 and should preferably for the most part be below that of the rollers 14.  The drawing rollers 14 may be tapered instead of cylindrical and in this case in addition to the back guide 15 there is provided a further guide at the horizontal level of the top of the tapered roller, both guides being mounted on a horizontal traverse-bar extending the length of the metier. The bar is traversed to-and-fro, e.g. at a variable speed, by means of an arrangement of gears similar to that previously described, so that the guides supply the thread 8 to different portions along the length of the tapered roller, thus varying the speed of drawing of the filaments.  The tapered feed roller and its accessories may be used in place of or in addition to the variable speed drive for the roller 19.  A portion of the edge of the slot 25 of the slotted roller 19 may be bevelled, the bevel being wide enough to reach the transverse plane 30 containing the guides 26, 27 and containing the direct path of the thread 8 over the roller.  The fin 29 is in this case omitted.  When the bevelled portion reaches the point 56 (Fig. 2), the thread 8 slips over the bevel and drops into the slot 25.