A filtering device for filtering molten plastic material that employs a filtration mesh belt that enters and exits a chamber, engaging an outer surface of a hollow perforated cylinder inside of the chamber, without losing any molten plastic material during the replacement of the filtration mesh belt and without tearing even when operating at high pressures inside of the chamber.

A continuous filtration device for molten plastic materials that employs a filtration mesh that enters and exits the filtration chamber, resting against the outer surface of a perforated hollow cylinder, without losing any molten material during the replacement of the mesh and without tearing even when operating at high pressures inside the filtration chamber.

A continuous screen changer, including: an external shell having an internal cavity, and an internal drum. The external shell is provided with a feed port, a screen changing port, and a discharge port. The internal drum is provided with at least four filter screen mounting grooves and material flow passages correspondingly communicating with the filter screen mounting grooves. A sealing wall hermetically connected with the internal cavity is formed between each two adjacent filter screen mounting grooves. Whichever of the filter screen mounting grooves is opposite to the feed port rotates to be opposite to the screen changing port in a rotation process, and whichever of the filter screens is on said filter screen mounting groove opposite to the screen changing port is changed at the screen changing port

Disclosed are a continuous screen changer, a screen changing device, and an extruder. The continuous screen changer includes an external shell with an internal cavity and an internal drum; the external shell is provided with a feed port, a screen changing port and a discharge port. The internal drum is provided with at least four filter screen mounting grooves and material flow passages correspondingly communicating with the filter screen mounting grooves, and a sealing wall hermetically connected with 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 a filter screen, materials flow out of the discharge port along the material flow passages. The filter screen mounting groove rotates to be opposite to the screen changing port, and the filter screen on the filter screen mounting groove is changed at the screen changing port. The continuous screen changer can implement continuous and uninterrupted change of the filter screens, so that the apparatus to which the continuous screen changer is applied can continuously work.

The invention relates to a dirt precipitator (100) for a highly viscous medium, having a housing comprising a front housing element (30; 30) that comprises at least one inlet channel (33) and a rear housing element (20) that comprises at least one outlet channel (23), and having a screen wheel (10; 10) rotatably mounted between the housing elements (20, 30; 30) having a number n of screen positions disposed in a ring zone, on each of which at least one screen opening (11.1, . . . , 11.12) having at least one screen insert element is provided. The inlet channel (33), the outlet channel (23), and the screen opening (11.1, . . . , 11.12) are disposed flush one after the other in at least one working position and form a flow channel. In all positions of the screen wheel (10; 10), more than 50% of the screen openings (11.1, . . . , 11.12) are always able to be permeated, and are impinged by flow from at least one inlet channel and from which at least one outlet channel leads.