GB954968A - Stretching machine for thermoplastic films - Google Patents

Abstract

954,968. Film-stretching apparatus. LINDAUER DORNIER G.m.b.H. July 20, 1962 [Sept. 1, 1961], No. 27977/62. Heading B5B. Apparatus for stretching thermoplastic film simultaneously in longitudinal and transverse directions comprises a number of stretching rollers, arranged one behind the other in the stretching zone, and driven at peripheral speeds which increase from roller to roller in the direction of movement of the film. The rollers may be of known Mycock type, and arranged in series of upper and lower stretching rollers, such that the film is stretched biaxially in successive small increments. The rollers may be of equal diameter, rotated at different speeds, or may be of increasing diameters, rotated at the same speed. In one embodiment (Fig. 2) a web 1 is wound from drum 2 and passes via roller 3 to the stretching zone 5 where it is biaxially stretched by upper and lower series 7 and 6, respectively, of curved Mycock rollers. The web is looped alternately over and under the rollers (Fig. 5), the degree of looping being variable by adjustment of the height of rollers 7, individually or together. The stretched web is wound up at 10. Both series 6 and 7 of the rollers may be driven, or driven rollers may alternate with idler rolls. The web may be heated in the stretching zone, e.g. by hot air, hot liquid, heated plates or by heating the stretching rolls. The stretching zone may be preceded or followed by other treating zones. In Fig. 3, web 1 is conveyed by clip chains K<SP>1</SP> from inlet zone E, through a heating zone H, stretching zone R, heat fixation zone T, and cooling zone K to outlet zone A. The web in the zones preceding or following the stretching zone R may be subjected to additional longitudinal and/or transverse stretching.