GB1129324A - Improvements relating to the stretching of yarns of man-made fibres - Google Patents

Abstract

1,129,324. Stretching filaments. BARMAG BARMER MASCHINENFABRIK A.G. 11 Feb., 1966 [16 Feb., 1965; 19 March, 1965], No. 6180/66. Heading B5B. [Also in Division D1] A device for stretching synthetic yarns especially of polyamides, comprises a stretching roller 1 rotatable at different peripheral speeds and spaced behind a delivery roller 2 in the path followed by the yarn, wherein at least one of the said rollers is associated with an endless feed belt, (e.g. 5 in Fig. 1) which can be brought into contact with the periphery of the roller under a variable pressure and is looped around axially parallel, free friction-driven rollers, (e.g. 3 and 4) which are mounted in a pivotally or displaceably mounted frame (e.g. 7) which is connected to an engaging and disengaging gear (e.g. 14). Preferably, pressure means (e.g. spring 8) act on the feed belt when the belt is in its engaged position and are arranged so that they can be disconnected when the belt is shifted into its disengaged position (Fig. 2). Desirably, the belt 36 (Fig. 5), travels around rollers 43 which each have a generally cylnidrical periphery which is rounded spherically at their ends (44, 45). This prevents the feed belt from shifting axially on the friction-driven rollers, especially when overhung. Suitably, one of the friction driven rollers has a main cylindrical section which occupies at least 80% of the total axial length of the roller, the width of the belt being smaller than the total axial length of the friction-driven roller, but up to 15% greater than the axial length of the main cylindrical section. As shown in Fig. 1, the rollers are overhanging rollers mounted on a supporting arm 7 and a tensioning member under spring pressure for maintaining the belt under tension and guiding it laterally, (e.g. 30, Fig. 2) is arranged between the overhung rollers. A yarn guide 25, or 24 may be arranged to reciprocate parallel to the axis of the delivery or stretching roller above a yarn inlet between the roller and the belt. As in Fig. 1, the feed belt may be engaged and disengaged by means 18, 19, 13, 15, coupled with a spindle clutch or brake and/or yarn-breaking stopper associated with a following twisting or winding unit 22. A heating plate 23, may be arranged between rollers 1 and 2. In Fig. 1, the engaging and disengaging gear comprises a shift lever system 14 driven hydraulically or pneumatically through a piston 13, and is engaged by the free ends of supporting arms 7, which project into the longitudinal slots 15 and 16, by a forked brake-lever 18 pivoting about an axis of rotation 17 for applying and releasing the spindle brake between plates 19. Movement of piston 13 is initiated by movement of control lever 20 of a control valve shown diagrammatically. In the case of the two rollers shown in Figs. 2 and 3 with their engagable and disengageable feed belt unit, supporting arms 7 can also be shifted by means of a Bowden cable 26 or 27 which in Fig. 2, is attached to the free end of supporting arm 7, and in Fig. 3, to a spring anchor 28 which in this case is not fixed but is so mounted as to be displaceable, e.g. in a slot guide 29. In the arrangement shown in Figure 4, a swinging arm 31 is loaded by means of a tension spring 32 and pivotally mounted on a machine frame 33. Rollers 34 and 35 which carry belt 36 (Fig. 5), are freely mounted on bearing pins 37 and 38 provided on the swinging supporting arm 31, and are held in position e.g. by spring washers. In the working position shown in Fig. 4 the belt 36 is in firm contact with the periphery of the rotating delivery roller 40 under the action of tension spring 32. The yarn, shown in dot and dash lines, is thus guided, without slipping, between delivery roller 40 and belt 36. In the rest position, shown in broken lines, a projection 41 of arm 31 rests on the machine frame 33. The tension spring 32 is also effective in this position. When arm 31 is in its rest position, the belt 36 is no longer in contact with the periphery of delivery roller 40, and is therefore kept under tension by means of a spring-wire tension spring 42 fixed to the arm 31, to such an extent that it cannot accidentally slide off the rollers 34 and 35. By the use of the apparatus the stretch point can be kept by the feed belt to within a very small area of a clearly defined point, i.e. near the surface of contact between 'the feed belt, and the roller driven at the lower speed, thus maintaining high uniformity of denier.