Apparatus for monitoring lap formation on a roll for guiding a textile sliver

摘要

The apparatus monitors lap formation at a pair of rolls guiding a slubbing or sliver in a drafting arrangement for spinning machines. In the event of a lap or coil forming, for example, on a pressure roll, a piston rod of a piston is shifted away until a switching element touches a contact edge or region of a switching sleeve. A cylinder housing encircling the switching sleeve and otherwise electrically separated from the piston is thus short-circuited with the piston. Since the switching sleeve and piston are separately connected to a control unit, a switching function is effected in the control unit by this short-circuit and the drafting arrangement is thereby stopped. The switching sleeve is slidably guided on a guide rod mounted at an upper part in such a manner that the frictional resistance is greater than the weight of the switching sleeve. The electrical separation between the cylinder housing and the piston is rendered possible in that a slide bush and a lid-shaped end or closure part each consist of electrically insulating material. If for some reason the pressure roll must be reground so that its diameter is reduced the switching sleeve is automatically shifted further by the lid-shaped end or closure part so that the switching distance or travel always remains essentially constant.