Filter changing device

Claim 2

A filter changing device for the extrusion of plastic material comprising a filter body having an inlet line adapted to be connected to an extruder and an outlet line adapted to be connected to a die, said filter body having a cylindrical bore disposed with its axis perpendicular to said inlet and to said outlet lines, two cylindrical, axially spaced, coaxial filters lodged in said cylindrical bore, the two filters being provided with adjacent lines of feed and of discharge, permitting the introduction into the flow of plastic material or the removal from it of either of the two filters, characterized in that the two filters are machined in a cylinder of revolution and in that the input sections of the adjacent lines of feed and the output sections of the adjacent lines of discharge have their centers located essentially on the same right-hand section of the said cylinder of rotation, the said sections of input and of output corresponding to each of the filters, being respectively in such a manner as to coincide by angular displacement with the line of the filter body receiving the plastic material issuing from the extruder and, with the discharge line of the filter body, assuring the movement of the plastic material toward the die.

Claim 3

A filter changing device according to claim 1, characterized in that the carrying surfaces of the filter body of the cylinder of revolution comprising the two filters are limited to the end and median portions of the said cylinder, the run of flow of the plastic material having traversed the filters being thus partially delineated by the interior wall of the filter body.

Claim 4

A filter device for extrusion machines, comprising: a body having an inlet portion formed with an inlet line adapted to be connected to an extruder and an outlet portion formed with an outlet line adapted to be connected to a die; said body having a cylindrical bore formed therein, said inlet and outlet lines communicating with said cylindrical bore; a cylindrical filter housing rotatably mounted in said cylindrical bore in slidable sealing contact with said inlet and outlet lines, a pair of axially aligned chambers in said filter housing, said filter housing having a pair of inlet ports and a pair of outlet ports successively registering in sealing contact with said lines in said body upon rotation of said filter housing relative to said body; each chamber communicating with a different one of said inlet and outlet ports, a filter screen in each of said chambers in the path of flow from the inlet to the outlet ports thereof; and means for rotating said filter housing relative to said body between a first position in which only one of said inlet and only one of said outlet ports registers with said inlet and outlet lines respectively and a second position in which only the other one of said inlet and only the other one of said outlet ports registers with said inlet and outlet lines respectively.

Claim 5

A filter device for extrusion machines, comprising: a body having an inlet portion formed with an inlet line adapted to be connected to an extruder and an outlet portion formed with an outlet line adapted to be connected to a die; said body having a cylindrical bore formed therein, said inlet and outlet lines communicating with said cylindrical bore; a cylindrical filter housing rotatably mounted in said cylindrical bore in slidable sealing contact with said inlet and outlet lines, a pair of axially aligned chambers in said filter housing, said filter housing having a pair of inlet ports and a pair of outlet ports successively registering in sealing contact with said lines in said body upon rotation of said filter housing relative to said body; each chamber communicating with a different one of said inlet and outlet ports, a filter screen in each of said chambers in the path of flow from the inlet to the outlet ports thereof; and means for rotating said filter housing relative to said body between a first position in which only one of said inlet and only one of said outlet ports registers with said inlet and outlet lines respectively and a second position in which only the other one of said inlet and only the other one of said outlet ports registers with said inlet and outlet lines respectively.

Claim 6

A filter device according to claim 3 in which said inlet ports and said outlet ports in said filter housing are respectively separated by a relatively narrow land, and said inlet line is in communication with said pair of inlet ports and said outlet line is in communication with said pair of outlet ports during a mid-portion of travel of said filter housing as it is rotated between said first and said second positions.

Claim 7

A filter device according to claim 4 in which the ends of said filter housing are exposed for cleaning the filter device and closure means is removably mounted on the outer end of each of said chambers.

Claim 8

A filter device according to claim 5 in which said chambers are separated by a partition extending across the filter housing intermediate the opposite ends thereof and said inlet ports and said outlet ports are located in said partition.

Claim 9

A filter device according to claim 6 in which said closure means comprises a plug sealingly mounted in a counterbore formed in each end of said filter housing, and fastening means mounted on each end of said filter housing and engaging said plugs for removably holding them sealingly mounted in their respective counterbore.

Claim 10

A filter device according to claim 6 in which the interior wall of each of said axially aligned chambers is cylindrical, said screens are tubular and engage said interior walls and are removable and insertable through opposite ends of said filter housing.