| 摘要 |
1,013,980. Stretching films. MARSHALL & WILLIAMS CORPORATION. June 22, 1964 [April 28, 1964], No. 25679/64. Heading B5B. In a machine for stretching webs of film longitudinally a web W (Fig. 5) is drawn from a supply source (not shown), passes over freely rotatable guide rollers 142 and 148 and then in succession over driven feed rolls 41 and 40 which are provided with associated pinch rollers 154 and 170 which may be urged into contact with the feed rolls or spaced therefrom (for threading up) by means of hydraulic cylinders 162 and 182 respectively. The web W then spans the stretching zone " Z," passes over in succession the driven draw rolls 38 and 37 and leaves the machine after passing over the freely rotatable guide roll 97. Pinch roll 98 can be urged against draw roll 38 by means of the hydraulic cylinder 102. The distance between the feed roll 40 and the draw roll 38 (and hence the length of the unsupported portion of the film web at any moment being stretched can be adjusted by pivoting the arms 30 (on which the draw rolls 37 and 38 are rotatably mounted) about shaft 44 by means of the double acting air cylinder 50. The extent to which the arms 30 are pivoted is controlled by rotating cross-shaft 214 which through bevel gears 234 rotates a shaft within tubes 241 and thereby positions a nut in selected position within each tube 241. The nuts function as stops for rods 246 which are slidable within tubes 241 and are attached to the arms 30 by yokes 248 and cross-pin 50. The draw rolls 37 and 38 are driven at higher peripheral speeds than the feed rolls 40 and 41. The temperatures of all four rolls may be controlled by circulating a heat-exchange fluid through them. The film web in leaving the roll 40 may be heated by means of the radiant heater 290 the distance of which from the film is adjustable. |
