Air cooling ring for plastic film with independent lubricating air for film guide surface

摘要

Air ring for cooling a hot extruding tube of plastic film in which a lubricating air bleed port communicates with air from the air ring plenum independent of the cooling air flow path. The bleed port communicates with a bleeded air passage that extends to an annular lubricating air outlet positioned in advance of a guide surface that precedes the cooling air outlet. In an exterior air ring a valve arrangement limits the bleeded flow to the minimum desired.