Continuous screen changer, screen changing device, and extruder

A continuous screen changer for changing filter screens, comprising:

• an external shell with an internal cavity and an internal drum accommodated in the internal cavity and rotating relative to the external shell, wherein
• the external shell is provided with a feed port and a screen changing port located at two opposite sidewalls of the external shell and communicating with the internal cavity, as well as a discharge port located at one end of the external shell and communicating with the internal cavity;
• the internal drum is provided with at least four filter screen mounting grooves uniformly distributed at a peripheral surface of the internal drum for mounting the filter screens, and material flow passages corresponding to the filter screen mounting grooves in positions and communicating with the filter screen mounting grooves;
• a sealing wall hermetically connected with an internal wall of the internal cavity is formed between each two adjacent filter screen mounting grooves;
• after entering the internal cavity along the feed port and being filtered by the filter screens, materials flow out of the discharge port along the material flow passages in the filter process;
• and
• one of the filter screen mounting grooves opposite to the feed port rotates to be opposite to the screen changing port in the rotation process, and one of the filter screens on said filter screen mounting groove opposite to the screen changing port is changed at the screen changing port.