Process and apparatus for continuously producing webs of plastic

摘要

According to the invention, in the production of webs of extrusion-expanded plastic, regulated pressurised-water cooling and lubrication are used to reduce the high frictional forces between the web of plastic and the calibrating means, the regulation being based on directly measured expanding or foaming pressures in the calibrating device or measured taking-off (hauling-off) forces or moments. Allowance is made for the locally varying expanding pressures and the low shape-changing resistance (dimensional stability) of the expanded material by subdividing the calibrating means into two or more regulating zones. Fed-in firm outer layers produce a homogeneous temperature distribution and flawless surfaces.