Patent GB-872807-A (GB)
Title: A method and an apparatus for stretching filaments, particularly those consisting of synthetic linear organic polymers
IPC: D01H1/30
Filed: 1959-10-23
Abstract: <PICT:0872807/IV (a)/1> <PICT:0872807/IV (a)/2> In stretching filaments by a method in which the filaments engage and are stretched between a driven feed roller and a driven draw roller and are collected from the draw roller by a winding device, the filaments are threaded-up while the feed roller, the draw roller and the winding device are idle, the draw roller and the winding device are then driven so that the filaments are taken up by the winding device while the feed roller rotates freely so that substantially no stretching of the filaments occurs, and finally the feed roller is driven so that its rate of rotation is gradually reduced until the filaments are stretched as desired. The filaments may pass through a heating zone between the feed roller and the draw roller.  The filaments are guided outside the heating zone during the initial threading-up operation and introduced into the heating zone after the draw roller and the winding device have been caused to be driven but before the rate of rotation of the feed roller has been reduced to the desired value.  As shown in Fig. 1, a yarn 18 from a package of unstretched yarn 17 travels through an eyelet 19 to a feed roller 5 and passes in a few helical turns round this roller and a guide roller 6 before travelling towards and around a snubbing pin 7 en route to the draw roller 9 and its guide roller 10.  Between the pin 7 and the roller 9 the yarn may pass over and in contact with a heated plate (not shown) and two guides so pivotally mounted that the yarn running over the guides may be guided against the heated plate or away therefrom as required.  After leaving the rollers 9 and 10 the stretched yarn is fed through the balloon guide 21 to a conventional belt-driven twisting spindle 12 carrying the take-up bobbin 13.  The rollers 5 and 9 and the spindle 12 may be started and brought to rest independently of each other, the rollers 5 and 9 by means of switches 22 and 23 respectively (Figs. 1 and 2), and the spindle 12 by means of a knee-operated brake 24.  The feed roller 5 is driven by an induction motor 4 through a speed reduction gear 4a.  The draw roller 9 is driven direct by the motor 8.  When the machine is to be threaded-up, the motors 4 and 8 are switched off, the spindle 12 is braked and the thread is kept away from the heating plate (when fitted) by manipulation of the thread guides in the heating zone. The machine is then threadedup with thread drawn from the bobbin 17, the knee brake 24 is released and at the same time the motor 8 is switched on, thus causing the yarn 18 to travel along its normal path and to begin to be wound on the bobbin 13.  Since the motor 4 is non-energized at this stage, the feed roller 5 will be freely rotatable and the yarn, therefore, unstretched. Finally, the motor 4 is switched on and the feed roller 5 thereby slowed down to its normal operational speed, so that the yarn is stretched.  If the apparatus is provided with a yarn-heating plate, the yarn is brought into contact with the plate before the motor 4 is switched on.  An electrical system for adjusting the peripheral speed of the feed rollers and the stretch ratio to predetermined values is described.