Bank quantity monitoring method and apparatus, sheet forming method and

Abstract

A plastic material, controlled at a desired temperature, is fed on an upstream side of a gap between a pair of rotating forming rolls arrayed almost in parallel and controlled at a desired temperature from a flat die connected to an extruding machine and having a slit outflow portion. The plastic material is pressed and formed into a sheet by the forming rolls therebetween while forming a bank or an accumulation of the plastic material on an upstream side of the gap of the forming rolls and is carried out on a downstream side of the gap. The bank quantity monitoring is performed by measuring a temperature of the sheet carried out through the gap of the forming rolls and estimating the quantity of the bank in accordance with measured temperature information. The sheet formation is performed by measuring a temperature of the sheet carried out through the gap of the forming rolls and controlling various forming conditions according to a measured temperature information. The sheet temperature measurement is performed by measuring a temperature of the sheet by directing said non-contacted temperature measuring means against an inner part of a wedge-shaped space formed by a surface of the sheet carried out of the gap and a surface of the forming roll facing on the surface of the sheet at a slight gap therebetween.