Continuous screen changer: mostly double-column-based, single-column, single-plate can also be designed as a continuous type (duplex), but its performance is not as good as double-column type screen changer. Continuous type screen changer from the screen shape can also be divided into round, long, curved, cylindrical, rectangular, etc., and its screen changing process pressure and process is relatively stable, the main areas of application are: 1, direct extrusion: film, profiles, sheets, tubes,