Paper-machine structure and method for subjecting a web to suction
AssigneeValmet Corporation
InventorMatti Kankaanpaa
Life of this patent
Estimating the term…
Abstract
In a paper-manufacturing machine a web is subjected to suction by placing a space between the web and a suction roll lapped thereby in communication with a region of substantially less than atmospheric pressure which is maintained at a part of the suction roll which is not lapped by the web. The structure includes a jacket which defines with the part of the suction roll which is not lapped by the web a hollow region with which a source of suction communicates. This hollow region of less than atmospheric pressure is situated at the exterior of the suction roll and bounded in part by an exterior surface of the suction roll, so that the hollow interior of the shell of the suction roll need not necessarily be utilized for providing the suction at the web.
Claims18
A method of subjecting a travelling fabric in the press section or web dewatering section of a paper-making machine to a suction effect when travelling over a suction-roll comprising the steps of:
- partially lapping a first sector of a rotary suction roll with a travelling air-permeable fabric means adapted to support a web, said suction-roll comprising a solid, non-perforated inner portion and a circumferentially extending outer portion, said outer portion having circumferentially extending channels formed therein;
- and
- maintaining at a reduced pressure which is substantially less than atmospheric pressure a region situated at the exterior of said suction roll, said region being in sealed communication with a second sector of said suction-roll comprising substantially the entire exterior surface of said suction-roll which is not lapped by said fabric means such that said reduced atmospheric pressure is transmitted through said circumferentially extending channels which extend through said first suction-roll sector.
In the press or web dewatering section of a paper-manufacturing machine, rotary suction-roll means for guiding a travelling fabric means adapted to support a web while being partially lapped thereby over a first sector thereof, said suction roll means comprising a solid, non-perforated inner portion and a circumferentially extending outer portion, said outer portion having circumferentially extending channels formed therein, jacket means situated at the exterior of said suction-roll means and defining with a second sector of said suction-roll means comprising substantially the entire exterior surface thereof which is not lapped by said web a hollow region bounded by an inner surface of said jacket means and said suction-roll means second sector, said jacket means having opposed longitudinal edge regions which extend substantially parallel to the axis of said suction-roll means and opposed end walls which extend between said edge regions, said jacket means carrying along said edge regions and end walls sealing means engaging said suction-roll means to an extent sufficient for maintaining said hollow region substantially closed off from the outer atmosphere while communicating with said circumferentially extending channels, and suction means operatively connected with said jacket means for maintaining said hollow region at a reduced pressure substantially less than atmospheric pressure to provide through said hollow region a pressure in said channels which is sufficiently low to cause air flow through said fabric means inwardly into said channels.
Dependencies are inferred from the claim text.