초록 ▼

Apparatus for continuously filtering a flow of melted plastic which includes means for purging the filter without interrupting continuous operation. A filter assembly consists of a trap plate and breaker plate between which filters are disposed. The trap and breaker plates each defines triangularly

Apparatus for continuously filtering a flow of melted plastic which includes means for purging the filter without interrupting continuous operation. A filter assembly consists of a trap plate and breaker plate between which filters are disposed. The trap and breaker plates each defines triangularly shaped openings diposed in a circular array, each of which is subdivided into smaller passages for filtering larger contaminants. Individual filters also of triangular configuration are sandwiched between registering openings between the trap and breaker plates, each filter consisting of a fine and coarse screen. A collector head is rotatably disposed for selective registration with each of the openings of the trap plate, and an indexing mechanism is included for stepping the collector head for stationary registration with each opening. The collector head communicates with a contaminant discharge passage that is open and closed in timed sequence with movement of the collector head. When the contaminant discharge passage is opened, a part of the filtered plastic downstream of the filter assembly reverses its flow through the opening registering with the collector head, purging the filter screens by carrying collected contaminants. The contaminant-filled flow initially passes into a purge chamber of predetermined volume having a pressurized piston. After a predetermined volume has entered the chamber forcing the piston to retract, a valve breaks communication between the discharge passage and purge chamber, simultaneously establishing communication between the purge chamber and a contaminant discharge outlet, enabling the piston to evacuate the purge chamber and discharge the contaminants.

대표청구항 ▼

Apparatus for filtering a flow of melted plastic, comprising: housing means; filter means in the housing means having upstream and downstream sides; inlet means for supplying unfiltered plastic to the upstream side of the filter means; first outlet means communicating with the downstream side of the

Apparatus for filtering a flow of melted plastic, comprising: housing means; filter means in the housing means having upstream and downstream sides; inlet means for supplying unfiltered plastic to the upstream side of the filter means; first outlet means communicating with the downstream side of the filter means for discharging filtered plastic; purging means for causing a reverse purge flow of a portion of the filtrate through the filtering means from the downstream to the upstream side thereof to purge contaminants therefrom; second outlet means for discharging the contaminant-filled purge flow from the housing; purge chamber means defining a chamber for receiving a finite quantity of the contaminant-filled purge flow from the purging means; discharge means associated with the purge chamber means for causing said finite quantity to be discharged from the purge chamber means into said second outlet; and valve means for selectively establishing exclusive communication between the purging means and the purge chamber means, and between the purge chamber means and the second outlet means. A segmented filter assembly for filtering a flow of melted plastic, comprising: a trap plate having means defining a plurality of openings therethrough arranged in a generally circular array, each opening defining a segment of a circle, and a plurality of spaced bars disposed in and traversing each segmented opening to define a plurality of passages through which larger contaminants cannot pass; a breaker plate having means defining a like plurality of openings of segmented circular configuration registrable with the openings of the trap plate, and further comprising a plurality of spaced bars in each segmented opening to define a plurality of passages therethrough; and a plurality of filter means each having a segmented configuration corresponding in size to the segmented openings of the trap and breaker plates and disposed between opposed registering segmented openings of the trap and breaker plates.