As long as the melt is produced, a screen changer will be used to filter impurities in the melt. The screen changer is a manual or automatic switching device including one or more screens, which is used to filter out foreign particles and impurities when plasticizing the polymer melt flow filter screen. For example, there are non-woven fabrics, chemical fiber spinning, petrochemical granulation, rubber, industrial ceramics, expanded food, transparent soap, hot melt rubber, tape, protective net a