METHOD OF MANUFACTURING SHEET, DEVICE AND PROGRAM FOR CONTROLLING SHEET THICKNESS, AND SHEET

摘要

A sheet (1) obtained by extruding and molding a raw material using a die (4) with plural thickness adjusting means (10), characterized in that the power spectrum (90) of the thickness profile of the sheet (1) in the transverse direction expressed by the following formula P = F É �¢ F �¢ É ° F É = ˆ« - ˆž ˆž f x �¢ e - jÉx �¢ dx (where f(x) is the thickness profile of the sheet in the transverse direction (in ¼ m), F(É) is the Fourier transform of f(x), x is a position in the transverse direction of the sheet (in m), É is a wave number (in m -1 ) , and F(É)* is the conjugate complex number of F(É) ; and j is an imaginary number, and j 2 = -1) and the mean sheet thickness T (¼ m) satisfy the following relation:
The mean value X1 of the powers of smaller than a predetermined wave number a is 0.2 x T 2 or less and is smaller than the mean value X2 of the powers of wave number a and larger.