Abstract
The quality of a wide film manufactured is determined by the flatness of the film thickness along the width of the film. To control the film thickness in the lip-heater method, an uniform distribution of melted polymer flow velocity in the gap between die lips is required, which is realized by making use of one hundred or more regulating heaters.
In this paper, the following technical proposals of the film thickness control system design are described in order to overcome the difficulties of thickness control.
(a) A “fundamental control system” is introduced.
A “fundamental model” consisting of five thickness measurement points and five heaters is assumed. A fundamental control system which can control the thickness of the location corresponding to the position of the central heater at the specified value by using the five heaters is designed. This is based on the idea that in order to effect thickness control along the total width of the film, this fundamental control system is applied to every thickness control point.
(b) The predictive control method is applied to design the fundamental control system design.
Finally, the evaluation of the proposals is conducted by the simulation calculation.
