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 filters (3.1) defining a first compartment (1a) which communicates directly with said inlet way (2.3) and a second compartment (1b) 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 filter (3.1), holes of said first and said second holed supports (3.2, 3.3) being larger than meshes of the filters made up of a 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 each main hollow body (4.1′, 4.1″) is configured to be coupled with another one of said main hollow bodies (4.1″, 4.1′) in a position diametrically opposite thereto and in such a way that each hollow body and the respective other one of said main hollow bodies rotate integrally with each other and are free to translate along a common axis,
• wherein each of said main hollow bodies (4.1′, 4.1″) is configured to support each of said 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 adhering wall (4.2) is provided with a slit or opening (4.2a) configured to place a surface of said adhering wall (4.2) that is in contact with the second holed support (3.3) in communication with an inside of said one of the main hollow bodies (4.1′, 4.1″) to which said adhering wall (4.2) is joined, and
• wherein said main hollow bodies (4.1′, 4.1″) are provided with an internal connection duct (4.1d) configured to connect a seat (4.1s) of said adhering wall (4.2), the inside of each main hollow body (4.1′, 4.1″) and an inside of their central mutual coupling part (4.1a).