| 摘要 |
A steplessly adjustable pre-stretched film wrapping apparatus includes a downstream film roller driven by a motor through a first shaft and an upstream film roller connected to the downstream roller with a steplessly adjustable mechanical coupling system for unwinding and stretching a film web from a film roll and extending therebetween. The coupling system includes an input disk mounted to an input shaft that is driven by the motor and in turn drives the downstream roller and having a thickness gradually reduced from a center portion to the peripheral edge, and an output disk mounted to an output shaft that drives the upstream roller and having a thickness gradually reduced from a center portion to the peripheral edge thereof. A pair of cramp disks are mounted on a floating shaft which is manually movable between the input disk and the output disk to change the center distance between the floating shaft and both of the input and output shafts. The cramp disks define therebetween a gap which receives and crampingly engages, by being biased by springs, the reduced peripheral edges of the input and output disks to therein so as to transmit the rotation from the input disk to the output disk. Changing the center distance between the floating shaft and the input and output shafts, respectively, provides a stepless adjustment of speed ratio between the input shaft and the output shaft.
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