| 摘要 |
954,420. Stretching films. ASAHI KASEI KOGYO KABUSHIKI KAISHA. June 29, 1962 [June 30, 1961], No. 25053/62. Heading B5B. Apparatus for stretching flat thermoplastic film of substantially uniform thickness throughout comprises a pair of circuitous guide means between sets of feed and take-up rolls. The guide means comprise endless rails for guiding two sets of clips adapted to grip opposite edges of the film, and include driven wheels adjacent feed and take up rolls for delivering clips to and removing clips from the film. The clips in each set are interconnected so that the spacing between adjacent clips, while variable, cannot increase beyond a predetermined amount. Means for heating the film during stretching may be provided. In one embodiment (Fig. 1) a film B is fed from rolls f, longitudinally stretched by passing to take-up rolls g rotating at higher peripheral speed, and simultaneously transversely stretched by guide means A, A 1 carrying sets of clips J, J 1 . Each set of clips in eludes a series of clip elements a connected by folding links b. Wheel c opens the clips and delivers them to the film, wheel d opens and removes the clips from the film and wheel e is provided with pawls for folding the clip linkage. Each clip body 1 (Fig. 2) carries a pin 4 which in turn carries links 6 and a bearing 5 on which the clip moves along guide rail 7. The film is gripped by finger 2 and holding spring 3. Wheel c includes a sprocket-wheel 8 (Fig. 3) having recesses for receiving pins 4 and moving them forward and a disc 9 adapted to constrain gripping finger 2 so as to provide a film-receiving space. Wheel d is of similar construction. Wheel e includes a disc 12 (Fig. 5) having pawls 13 pivoted thereto and springs 14 anchored at one end to disc 12 and secured at the other to pawls 13. Each spring holds its associated pawl outwards so that it engages with clip pins 4. In operation, clips a are carried by sprocket-wheel 8 to a point where, with fingers opened by disc 9, they can grip the unstretched film B. As the guide rails are straight beyond the film gripping point, the clips are then disengaged from the sprocketwheel, and the fingers 2 are released from disc 9 so as to grip the film. As the film is advanced, the clips in each series are carried forward by the film and become increasingly spaced apart in accordance with the longitudinal stretching. At the point where the film is completely stretched by a predetermined amount the interconnecting clip linkages are fully extended, and thereafter, the clips are pulled forward by the wheel d. As the clips reach the removal point, clip pins 4 engage a sprocket-wheel 10 and the clips are opened by disc 11. The clips are returned to their starting position under the pull of wheel e, which pulls the clips forward and folds the links. As the clips reach wheel c, the clip pins 4 are again engaged by sprocket-wheel 9 and carried to the film gripping point. |
