Method for continuously controlling the shrinkage of an amorphous film,

Abstract

The shrinkage of a calendered amorphous film is continuously controlled during the taking off from a calender, the shrinkage being measured over the film width and the film length with the aid of the dichroism of the film. For this purpose, a shrinkage measuring instrument 51 supplies measured data concerning shrinkage of the film to a connected measured-data computer 52 which is connected, on the one hand, via an interface to a master computer 53, and, on the other hand, to a screen display 54. Characteristic calibration curve parameters of different film types and shrinkage deviations and/or of shrinkage limits are stored in the master computer and are, upon request, fed into the measured-data computer. The measured anisotropy of the film is converted into the respective shrinkage by means of a calibration curve, which is based on the calibration curve parameters. If the shrinkage is not within the prescribed limits, the master computer applies signals to the actuators for the purpose of controlling the friction and the rotational speed between the last calender roll and first take-off roll, for the purpose of temperature control or cooling the take-off and chill rolls, for the purpose of controlling the rotational speeds of the take-off rolls and for the purpose of the temperature control of the last calender roll.