Patent ID: 7540291

Claim:
A method for cleaning a blowing head for plastic films after completion of production while the blowing head remains installed in an extrusion installation, the blowing head having a region that is in contact with plastic, the plastic having a melting temperature and a decomposition temperature, the method comprising the following steps: in a first cleaning phase, heating the blowing head with a heater contacting the blowing head to a temperature above the melting temperature of the plastic until the plastic runs out; in a second cleaning phase, sealing off at least the region of the blowing head that is in contact with plastic from the ambient atmosphere, purging the region of the blowing head of any oxygen-containing atmosphere, heating the blowing head with the heater above the decomposition temperature of the plastic until any plastic remaining in the blowing head decomposes to produce gaseous products and residual particles, discharging the gaseous products; and in a third cleaning phase, flushing the blowing head with an oxygen-containing gas in order to incinerate the residual particles, thereby cleaning the blowing head while the blowing head remains installed in the extrusion installation.