GB972226A - Apparatus for longitudinally stretching thermoplastic film webs - Google Patents

Abstract

972,226. Film stretching apparatus. KALLE A.G. Jan. 18, 1963 [Jan. 18, 1962], No. 2359/63. Drawings to Specification. Heading B5B. An apparatus for longitudinally stretching a travelling continuous web of organic thermoplastic polymeric film comprises a series of spaced parallel rollers each rotatable about an axis at a right angle to the longitudinal axis of the web, the series of rollers having operative positions such that the web can follow a sinuous path over and under consecutive rollers of the series, the series of rollers including one or more positively driven feed rollers and one or more positively driven output rollers, the peripheral speeds of which are higher than those of the feed rollers, alternate rollers being bodily displaceable from their operative positions to provide a straight passage for the web between the displaced and the remaining rollers during the initial threading up of the rollers prior to the commencement of a stretching operation and being returnable to their operative positions with the web in place. The apparatus may include a group of an odd number of three or more feed rollers and a group of an odd number of three or more delivery rollers, each group having at least two alternate, non- displaceable driven rollers and the two groups being separated by an odd number of other rollers. The displaceable rollers may be idler guide rollers. The bearings of the displaceable rollers may be held in their operative positions under hydraulic pressure. The means for displacing the displaceable rollers from the operative position may be actuable by release of the tension in the film web, such as would occur in the event of breakage of the web of film, damage to the apparatus due to the wrapping of the broken ends of the web round the rolls and filling up the clearances between adjacent rolls thus being automatically prevented.