Method and apparatus for drawing off a yarn at a spinning station

摘要

A yarn being spun in a spinning station of a spinning machine is drawn off with an apparatus which includes a pair of rollers for clamping the spun yarn in a gap between the rollers and transporting the spun yarn. The rollers include a draw-off roller being driven continuously in a draw-off direction at a given circumferential speed and a switchable feed roller for contacting the draw-off roller and for being driven through friction by the draw-off roller when contacting the draw-off roller. A method for drawing off the spun yarn includes positioning the yarn to be drawn off between the rollers while the feed roller is not contacting the draw-off roller. The feed roller is driven with a fluid in a circumferential direction and accelerated to a circumferential speed being at most the given circumferential speed. The feed roller is then placed in contact with the draw-off roller. In an apparatus for drawing off the yarn, the feed roller is driven at a predeterminable circumferential speed when the gap between the rollers is opened, it is movable into a raised state and it has one end surface with vane-like protrusions. A compressed air nozzle is to be positioned toward the one end surface of the feed roller while in the raised state. The nozzle is controlled for accelerating the feed roller to a circumferential speed being at most the given circumferential speed, prior to contact with the draw-off roller.