Continuous widening of plastic sheet tubing, is achieved by floating units inserted during initial lacing of production plant

When the sheet tubing is laced initially into the production line, widening units (8-10) are inserted through the open end of the tubing. Each is held back in a section of the line, against the direction of tubing advance (3) by non-contacting means. An independent claim is included for the corresponding widening- or transverse stretching unit. Preferred features: One or more widening units are held back by: inherent weight, magnetic attraction, change(s) in direction (4-7) or constrictions. The unit(s) are held back by external rollers on either side of edges of the unit or at one of its ends. A pair of rollers flattens the tubing, holding back the unit. The sheet is opened over its entire internal circumference by the widening unit(s). Through the widening unit, a long flexible material is unwound and runs in the conveying direction. The widening unit corresponds approximately with the inner circumference of the sheet tubing. It is rotationally symmetrical at right angles to the conveying direction of the sheet tubing. The outer surface of the widening unit working with the sheet tubing, is free of edges, especially being rounded. At least one widening unit (9) is a supply roll. From this unwinds a long flexible material (11) during tubing advance. The widening unit has guide openings for this (11). It also has a stop preventing rotation inside the tubing. The unit is longer than the maximum opening width of the tubing, when inside it. A production line including such widening unit(s), is also claimed. Bei einem Verfahren zum Aufweiten eines insbesondere flachen Folienschlauchs (2), der in axialer Richtung (3) kontinuierlich gefördert wird, wird beim anfänglichen Einfädeln des Folienschlauchs (2) in eine Förderstrecke mindestens ein Aufweitungselement (8, 9, 10) durch das offene Schlauchende in den Folienschlauch (2) eingelegt und auf einem Förderstreckenabschnitt berührungslos in Förderrichtung (3) zurückgehalten. So kann ein Folienschlauch beliebiger Länge durch das einmal eingelegte Aufweitungselement aufgeweitet werden, wodurch eine kontinuierliche Be- bzw. Weiterverarbeitung des Folienschlauchs möglich ist.