PURPOSE: To make the cost of plant and equipment inexpensive and improve an yield by a method wherein the whole pass is rolled without applying tensile force to the title material and specific pressure is applied to a sheet plane in the heat after rolling.
CONSTITUTION: A rolled material having a fixed thickness is obtained with a tensionless rolling process from a condition where the middle part of a longitu dinal direction of the material is forced down beforehand with a roll. Then when pressure is applied to a sheet plane in the heat after rolling of the thin rolled sheet whose form is changed for the worse, the thin rolled sheet whose form is changed for the worse can be reformed into a sufficiently-satisficable form. When pressure, for example, of 0.003kgf/cm2 is applied to polypropylene, a flat sheet is obtained, in relation between a form (steepness) and the pressure in the polypropylene. Since it is unnecessary to make use of tension, there is no omission of a joining part at all and a rolled sheet superior in flatness becomes manufacturable at yield of 100%.
WATANABE KAZUO
TSUKASAKI HIDEYUKI
