| 摘要 |
A dispenser of stretchable plastic material film and a wrapping machines equipped with such a dispenser are described. The dispenser comprises a bobbin (2) of plastic film, a pre-stretching unit (P1,P2) driven by driving means and a movable controlling roller (B) apt to control said driving means on the basis of the tension applied thereon by the plastic material film, said movable controlling roller being mechanically connected to a friction slipping clutch (10-12) apt to transfer a torque from said driving means to the pre-stretching unit, the torque transferred by said slipping clutch being proportional to the pressure applied thereon through said movable controlling roller. <IMAGE>
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