Patent GB-983650-A (GB)
Title: Film stretching apparatus
Inventor: ZINK JULIUS
IPC: B29C55/08
Filed: 1962-05-14
Abstract: 983,650. Film stretching apparatus. AVISUN CORPORATION. May 14, 1962, No. 18504/62. Heading B5B. An apparatus for stretching a thermoplastic polymeric film 11 (Fig. 1) having a web 13 and beaded longitudinal edges 15 comprises a metering device 17 (Fig. 2), a number of guide or stretching units or assemblies 19 (Figs. 1 and 2), pull rolls 21 and a chamber 23 which encloses at least a portion of the apparatus. The metering device 17 serves to advance the film 11 at a uniform and predetermined speed and includes a pair of feed rolls 27 and 29, a supporting frame 31 on which roll 27 is rotatably mounted, a carriage 33 which supports the roll 29 and an hydraulic cylinder 35 and piston 37 for vertical adjustment of the carriage 33. The units 19 are positioned in two spaced rows along the path of the film and serve to guide the beaded edges thereof along predetermined diverging paths. The units 19 are mounted on pairs of opposed slide blocks 51 which can be moved towards or away from one another by rotation by means of a hand wheel 59 of a screw 57 rotatably mounted in frames 55 and extending an aligned pair of slide blocks 51. Each unit 19 includes a pair of similar arms in the form of crank levers 65 and 67 (Figs. 3 and 4) which are mounted for free rotation in unison about a post 69 secured to a slide block 51. The crank lever 65 includes arms 71 and 73 which carry at their outermost ends discs 75 and 77. The crank lever 67 is similarly formed with arms 79 and 81 carrying at their outermost ends discs 83 and 85 disposed in opposed and aligned relationship with discs 75 and 77. Each of the discs is supported on its respective lever arm by ball bearings, a shaft 89 on which the disc is fixed, a sleeve 91, and a locking-ring 93. The shaft 89 is threaded within the sleeve 91 at 95 to permit fine adjustment of the spacing between opposing discs. Each pair of co-operating discs are provided with opposed circular projections 101, the peripheral surfaces of which are adapted to engage with the beaded edges 15 of the film. The hub 111 of the lever 67 is mounted for movement up and down the post 69 to permit the lever 67 to be moved relatively to the lever 65, as for example during film lacing operations. The hub 111 of each of the levers 67 contains a cylinder 123 provided with a fluidtight piston 127 so that axial movement of the hub 111 along the post 69 can be effected by the introduction of a fluid under pressure into the portion of the cylinder above or below the piston 127. The film 11 may be stretched longitudinally by rotating the pull rolls 21 at a higher peripheral speed than that of feed rolls 27 and 29. Alternatively, the pairs of discs of the two rows of discs may be individually driven in such a manner that corresponding pairs of discs are rotated at the same speed but one which is higher than that of the preceding pairs of corresponding discs to effect a sequential longitudinal stretching of the film concomitantly with its advancement. To achieve this result the rings 93, which are secured to shafts 89 of each pair of co-operating discs are formed with annular grooves 151 (Fig. 3) to receive belts from individual drive motors mounted on the respective slide blocks. The means for feeding the film into the apparatus and withdrawing it therefrom may be other than feed and draw rolls. Specifications 746,386 and 969,005 are referred to.