Filtering device for molten polymeric materials with counterflow cleaning system

A filtering device (A) for a plastic material in a molten state, said filtering device (A) comprising:

• a hollow body (2.1) provided with a mouth and a cover (2.1) configured to be associated with said mouth to define a filtration chamber (1);
• an inlet way (2.3) for receiving said plastic material in the molten state into said filtration chamber (1) and an outlet way (2.4) for discharging the filtered plastic material in the molten state from said filtration chamber (1);
• two filters (3.1) made up of a metal mesh and arranged side by side in said filtration chamber (1), said two filters (3.1) defining a first compartment (1 a) which communicates directly with said inlet way (2.3) and a second compartment (1 b) which communicates with said outlet way (2.4);
• a first holed support (3.2) and a second holed support (3.3), each of said first holed support and said second holed support (3.2, 3.3) being arranged so as to adhere to one of two sides of each of the said two filters (3.1), holes of said first holed support and said second holed support (3.2, 3.3) being larger than meshes of the two filters made up of the metal mesh (3.1);
• a cleaning device (4) arranged in said first compartment (la) between said two filters (3.1);
• and
• an evacuation device (6, 7) configured to discharge said impurities collected by said cleaning device (4) towards an evacuation outlet (8), said evacuation device (6, 7) being arranged centrally with respect to said cleaning device (4);
• wherein said cleaning device (4) comprises one or more pairs of main hollow bodies (4.1′, 4.1″), one or more pairs of adhering walls (4.2) which adhere to said second holed support (3.3), and a moving system (4.4),
• wherein a first main hollow body of said one or more pairs of main hollow bodies (4.1′, 4.1″) is configured to be coupled with a second main hollow body of said one or more pairs of main hollow bodies (4.1″, 4.1′) in a position diametrically opposite thereto and in such a way that each of the first main hollow body and the second main hollow body rotate integrally with each other and are free to translate along a common axis,
• wherein each of said one or more pairs of main hollow bodies (4.1′, 4.1″) is configured to support each of said one or more pairs of adhering walls (4.2) so as to remain adherent to a surface of a corresponding second holed support (3.3) of one of the two filters (3.1), and
• wherein each of said one or more pairs of adhering walls (4.2) is provided with a slit or an opening (4.2 a) configured to place a surface of said one or more pairs of adhering walls (4.2) that is in contact with the second holed support (3.3) in communication with an inside of said one or more pairs of main hollow bodies (4.1′, 4.1″) to which said one or more pairs of adhering walls (4.2) is joined, and
• wherein said one or more pairs of main hollow bodies (4.1′, 4.1″) are provided with an internal connection duct (4.1 d) configured to connect a seat (4.1 s) of said one or more pairs of adhering walls (4.2), the inside of each said one or more pairs of main hollow bodies (4.1′, 4.1″) and an inside of a central mutual coupling part (4.1 a).