On=line exchangeable or cleanable filter for molten plastics - with successive rectangular openings for constant area to minimise flow fluctuations with venting, prefilling, back-flush and active sealing

摘要

Filter system for plastic melts under pressure, esp. between an extruder and die, consisting of a series of filter elements movable in close succession perpendicularly across the flow channel for exchanging or cleaning. Each filter element consists of a perforated plate with several parallel filter zones arranged so that the last zone of one element is immediately succeeded by the first zone of the following element. The flow channel is pref. square or rectangular immediately adjacent the filter element, which has a number of rectangular filter zones in the flow channel, giving minimum and constant dead area between them. ADVANTAGE - Permits continuous plant operation and constant flow area, minimising flow and pressure variations, during filter changing. Permits air removal (venting) and pre-filling of the cleaned filter element before introduction into the flow channis