Abstract: Improved yarn spinning-in process and apparatus in open-end rotor spinning units which raises the quality of the spun-in point in the yarn to a level comparable with the quality of the entire yarn length. The yarn open end is pieced on to high-quality fibers while low-grade fibers are separated from the high-quality fibers and do not participate in the spinning-in process.

Abstract: The invention relates to an apparatus for the spinning-in of yarns in an open-end rotor spinning unit. The apparatus includes a spinning-in device for returning yarn end through a take-off duct into the spinning rotor, a severing device for shortening the yarn end to a predetermined length, and a withdrawing duct which communicates with the take-off duct and which is designed, on the one hand, for holding the yarn end by the action of a vacuum which, in the contact region of the two ducts, exceeds the working vacuum in the take-off duct, and, on the other hand, for withdrawing the severed yarn end. In accordance with an essential feature of the invention, at least one air nozzle opens into the withdrawing duct which during both spinning and spinning-in processes is connected to a subatmospheric pressure source, which nozzle is designed for introducing a fresh yarn end into the take-off duct by a controlled air outflow in a particular phase of the spinning-in process.

Abstract: A method of and an apparatus for piecing yarn in open end rotor spinning units. The returning of the yarn end into the spinning rotor for piecing is performed in two stages, in the first of which the yarn is stopped immediately upon breakage within the sucking range of the spinning rotor, and is brought immediately thereafter into a withdrawal chamber in which the yarn end is retained. In the second stage the yarn end is separated and deposited in said withdrawal chamber, and the new yarn end is introduced by further reverse motion into the spinning rotor. The apparatus has a withdrawal chamber interposed between the inlet of the withdrawing channel and a cutting mechanism. In one embodiment said chamber is connected to the withdrawing channel, opposite which there is mounted a nozzle connected to a controlled pressure air source. In another embodiment there is provided a nozzle communicating with the withdrawal chamber, said nozzle being connected to a controlled source of underpressure.

Abstract: An improved technique for stopping the advance of spun yarn through the draw-off rollers and distributing cylinder of an open-end spinning machine in response to a detected yarn breakage condition is described. A reversible clutch is selectively interposed between first and second oppositely rotating drive shafts and the cylinder, which in turn is coupled to the draw-off rollers. The clutch is operated from a normal forward advance condition to an operated reverse condition for a duration corresponding to a variable-duration control pulse generated in response to a yarn breakage condition upstream of the discharge end of the machine withdrawal tube. The duration of the control pulse is adjusted to dynamically brake the forward motion of the advancing yarn to a stop. The control pulse is removed soon enough to prevent reverse movement of the yarn.

Abstract: An arrangement for timing the initiation of a spinning-in operation of an open-end textile machine is described. A sequencer is coupled to the take-up bobbin to provide an indication proportional to the increase in diameter of the yarn package during the take-up operation. The sequencer converts changes in such indication to a variable delay of signals to be applied to at least the take-up rollers and yarn-distributing rollers of the machine. The thus-delayed signals, whose delay is continually updated as the diameter of the yarn package increases, are applied to the appropriate rollers upon the detection of yarn breakage or other suitable initiation signal for the spinning-in mode.

Abstract: A method and an apparatus for conveying empty bobbin tubes through a channel member which extends longitudinally along a plurality of working units of an open-end spinning, winding, yarn texturing or similar machine. The apparatus of the invention includes a transporting member which is operatively mounted on the machine so as to move in a stepwise manner along the plurality of working units of the machine. The machine includes a bobbin supply and withdrawing station opposite each working unit. The transporting member is adapted to move in a stepwise manner from one bobbin withdrawing and supply station to the next adjacent one. The apparatus further includes a channel member extending longitudinally along the plurality of working units. A plurality of empty bobbin tubes are disposed in the channel member end-to-end so as to form a column. The transporting member has a carrier member extending therefrom towards the channel member.