PURPOSE: To control simply and rapidly the thickness of a sheet-like material by receiving the light passing through between rolls by an image sensor, measuring the clearance between the rolls and adjusting the clearance between the rolls by this measuring value.
CONSTITUTION: When plastic material is prepared by a pair of mutually accessible calender rolls 1a, 1b in the form of sheet, light passing through between the rolls 1a, 1b is irradiated from a light projector 2 arranged on one side of a plane including both axial lines of the rolls 1a, 1b and this light is received by an image sensor 3 arranged on the other side of above said plane. The clearance between the rolls 1a, 1b is measured with an image sensor, this measured value is compared with the object value of the clearance and the clearance between the rolls 1a, 1b is adjusted on the basis of this compared result. Thus, the thickness of the sheetlike material can be controlled simply and rapidly.
YAMASHITA KENJI
TSUKAMOTO KEIICHI
HIRAI TAKAYUKI
