Sealing device in a polymer filtration device

摘要

A sealing device for sealing a slide plate in a polymer filtration apparatus where the slide plate is translatable across an extrusion bore extending through a housing of the polymer filtration apparatus. A spring device can be positioned around the outer periphery surfaces of the seal for axially biasing the sealing surface of the seal against the slide plate with a preload bias. Increasing pressure of polymer in the extrusion bore can enter a region in the seal cavity upstream of the thrust surface of the seal and can provide polymer pressure in the axial direction for exerting axial force against the thrust surface of the seal for causing the sealing surface to be further biased against the slide plate.

主权项

1. A sealing device for sealing a slide plate in a polymer filtration apparatus where the slide plate is translatable across an extrusion bore extending through a housing of the polymer filtration apparatus, the extrusion bore extending along an axial direction, the sealing device comprising:
a periphery seal having inner periphery surfaces, outer periphery surfaces, an axial periphery sealing surface at a downstream axial end for contacting and sealing against the slide plate, and a periphery thrust surface located at an upstream axial end of the seal, the seal being seated in a seal cavity surrounding the extrusion bore; a spring device positioned around the outer periphery surfaces of the seal for axially biasing the sealing surface of the seal against the slide plate with a preload bias; and a periphery axial gap regulating member having upstream and downstream axial end surfaces positioned within the seal cavity between the thrust surface at the upstream axial end of the seal and an upstream axial end surface of the seal cavity, the axial gap regulating member being sized to provide a generally annular periphery polymer pressure gap between the upstream axial end surface of the seal cavity and the upstream axial end surface of the axial gap regulating member, that is sized for permitting entry into said gap of a generally annular thin periphery film of polymer extending circumferentially from the extrusion bore for exerting a generally annular periphery polymer pressure force in the axial direction against the upstream axial end surface of the axial gap regulating member that is transmitted by the axial gap regulating member axially against the thrust surface of the seal, increasing pressure of polymer in the extrusion bore causing the sealing surface to be further biased against the slide plate, while at the same time minimizing an amount of polymer trapped and heat degraded in the polymer pressure gap, the axial gap regulating member being formed of a material having a higher coefficient of expansion than the seal and the housing, for expanding and minimizing the size of the polymer pressure gap as heat increases.