GB665114A - Improved process and device for the manufacture of a shrunk artificial thread - Google Patents

Abstract

<PICT:0665114/IV (a)/1> <PICT:0665114/IV (a)/2> A process for the manufacture of a fully shrunk artificial thread comprises leading the thread through a drying device so that the thread can sag exclusively under the influence of its own weight, maintaining the supply speed at a constant value, and passing the thread through a discharge device rotating at constant speed and having a conical supporting face so that the position of the thread on the discharge device controls the discharge speed, the process being characterized by the provision of a guiding surface which makes an angle, preferably of 45 degrees, with the horizontal plane, which controls the position of the thread upon the discharge device and which, if moving, moves only in the direction of the movement of the thread. The thread in the drying device should hang entirely free under a tension of not more than 1 g. per 100 denier and preferably not more than 0.2 g. per 100 denier. The thread may be pre-dried to about 70 per cent moisture calculated on the dry substance before applying the process. The drying device may be heated by hot air or other gases, infra-red radiation or by dielectric heating. After leaving the discharge device the thread may be taken up by a device which can operate independently of its speed such as a ring twister or centrifuge. As shown, the dry thread 1 leaves the drying device and is discharged by a pair of rollers 2, 3, the lower roller 2 having its axis horizontal. A <PICT:0665114/IV (a)/3> <PICT:0665114/IV (a)/4> <PICT:0665114/IV (a)/5> thread guide 4 in the form of a smooth straight-sided fork with prongs 5 and 6 forming a slot open at the top is provided between the rollers and the drying chamber. The slot is disposed in the plane parallel to that containing the roller axes with its open end upwardly inclined toward the smaller end of the rollers, and makes an angle of 45 degrees with the horizontal. The speed of rollers 2, 3 is such that the thread forms a tangent to the edges of the thread guide when it is running in the centre of the pulling-off rollers (the equilibrium position). Increasing shrinkage causes the thread to travel to the smaller side of the rollers and decreasing tension toward the larger side. If desired, the thread may lap the prongs or not even touch them in its equilibrium position. Figs. 4 and 5 show a combined drying chamber and discharge device according to the invention. The wet thread, pre-dried to 70 per cent moisture if desired, is supplied by rollers 7 and 8 at constant speed and sags under its own weight into a vertically-arranged drying channel 9 provided at the bottom with a polished plate 10 arranged preferably at 45 degrees to the horizontal. The sagging thread lightly touches this plate. The rollers 7 and 8 are arranged so that the thread enters the drying channel at the edge nearest to the upper edge of the plate. Conical rollers 2 and 3 take-up the thread, roller 2 having its axis horizontal and being disposed to the left of the supply rollers when seen in the direction of the thread entering the supply device. The dimensions and speed of the discharge rollers are such that the peripheral speed at the middle is equal to the average speed of the fully shrunk thread. If, owing to a decrease in shrinkage the loop lengthens and travels down the plate 10, the position of the thread on the discharge roller 2 is shifted toward the larger end of the rollers, and vice versa. To avoid disturbance of the loop by air currents during drying, a partition extending almost to the plate 10 may be provided, thus dividing the channel into two parts, one for the descending thread and one for the ascending thread. To enable the device to be started up the partition does not extend to the back of the channel but forms a slot therewith. Its lower edge forms a sloping slot with the plate 10. If desired (Fig. 8), the sloping surface may be the surface of one of the take-up rollers. The sagging thread, in a vertical plane, comes from the drying chamber (not shown) and is taken up by rollers 2 and 3, roller 2 having its axis 21 running parallel to the plane of the thread and forming an angle b (preferably 45 degrees) with the horizontal. As before, the speed of the rollers is such that the fully shrunk thread runs over the middle of the discharge device. Guides 11 may be provided in all embodiments to limit the sideways movement of the thread. Specification 369,669, [Group IX], is referred to.