Patent ID: 7752961
Filing Date: 2010-07-13
Classification: B29B,B29C,B65H

Abstract:
1. A device for driving a preheating roll assembly in a heating or preheating stage of a unit for producing films, the heating or preheating stages comprising a plurality of rolls with an entry roll, an exit roll and a plurality of intermediate rolls arranged between the entry and exit rolls and the device comprising an electrical motor assembly with which the rolls are driven, wherein: the motor assembly comprises at least one individual drive that drives at least one of the entry and exit rolls, the motor assembly comprises at least one asynchronous motor, each asynchronous motor controlling a surface speed and a torque of one of the intermediate rolls, and a common frequency converter is provided with which at least one asynchronous motor is driven, wherein a frequency of the frequency converter is adjusted such that for a predefined temperature profile of the preheating roll assembly and a desired conveying speed of the film a friction of the rolls and elongation of the film are compensated in the preheating assembly.