| 摘要 |
PURPOSE:To obtain the film having uniform thickness and less uneven thickness by a method in which the thickness of a completed film is measured by a film thickness-measuring device, and on the basis of said film thickness-measured value, the corresponding relation between the uneven thickness part of the film and the heating element adjacent to a die lip, is obtained by computing, and then the generated heat by the corresponding heating element is controlled corresponding to the unevenness amount of the uneven thickness part. CONSTITUTION:The film thickness after forming is measured through a film thickness- measuring device 8, and said measured value is inputted into an arithmetic unit 7. In the arithmetic unit 7, the necessary measuring position wherein measuring position is caused to correspond with the film thickness in the measured data of film thickness, is caused to correspond with the necessary position of a die lip 2a, and a plurality of heating elements 5 provided on the peripheral edge of the die lip is caused to correspond with the data of the necessary film thickness in the measured data of film thickness. The electrically controlled value controlling the generated heat of each heating element 5 correspondingly to each heating element 5 is computed so that the uniform film thickness data in said measured data of film thickness is obtained, based on the film thickness data corresponding to each heating means. A film 3 is formed by drawing out molten resin from the die 2 in which each heating element 5 is controlled by the electrically controlled value thus obtained, whereby the synthetic resin film with uniform thickness is obtained. |
