GB941358A - Stretching frame for stretching organic thermoplastic film - Google Patents

Abstract

941,358. Stretching films. LINDAUER DORNIER G.m.b.H. July 20, 1962 [Aug. 10, 1961], No. 27975/62. Heading B5B. [Also in Division D1] In a stretching frame for organic thermoplastic films, incorporating clip chains running in guide rails which are fixed to the web supports of the frame, and in which the width of the stretching zone may be adjusted by moving the web support, the ends of the guide rails, at points of transition between the stretching zone and adjoining heating, fixing or outlet zones in which the clip chains run parallel, are constructed as separate parts. Each part is arranged to be swingable on the web support about a spindle having its axis perpendicular to the chain path, and is arranged to be automatically adjustable. The bend that occurs in each chain path at the point between parallel and non-parallel parts of the guides is thereby rendered less abrupt. In a customary type of stretching frame (Fig. 1), the material B1 is fed into entry zone E, heated in zone A, stretched transversely in zone S, fixed in zone F and finally cooled to room temperature. The width of the stretching zone may be varied by altering the path of the clip chains from U1 K1, U2 to, e.g. U1<SP>1</SP>, K1<SP>1</SP>, U2<SP>1</SP>, in a known manner by use of handles H. According to the invention, the guide rails for the clip chains have the construction shown in Figs. 2 and 3 at the points of transition between parallel and non-parallel sections of the guides, e.g. U in Fig. 1. In one embodiment shown in Fig. 2, and, on larger scale, in Fig. 3, guide rails 1 and 2 of one zone and guide rails 5 and 6 of the next zone are rigidly fixed to the carriers of the stretching frame. The outer ends of these guide rails are constructed as separate swingable transition rails 3, 4, 7 and 8 which may be deflected laterally. The fixed rails 1, 2, 5 and 6 together with closure plates 10 and 11 are swingable about a spindle 9. In Fig. 3, transition rail 3 is shown swingable about spindle 13 whose axis lies in the line of vertical section of the associated rails 1 and 3. Transition rail 3 engages in the associated fixed rail 1 by means of a semicircular portion 16, and is cut off outside the semicircular portion 16 on the inside of the angle formed on deflection, obliquely to the path of the chain, whereas at the opposite side it is cut off perpendicular to the chain path. The arrangement is repeated in mirror image for transition rail 7. To limit deflection of transition rails 3 and 7, slots 15 and 15<SP>1</SP>, through which bolts 14 and 14<SP>1</SP> are inserted and screwed into transition rails 3 and 7, are provided in the support. The two swingable transition rails 3 and 7 automatically adjust to the required angle, and ensure satisfactory guidance and smooth movement of the clip chains over the transition point.