Paper making and fiber liberation – Apparatus – Running or indefinite length product forming and/or treating...
Reexamination Certificate
1999-05-06
2001-07-03
Silverman, Stanley S. (Department: 1731)
Paper making and fiber liberation
Apparatus
Running or indefinite length product forming and/or treating...
C162S370000, C162S369000, C162S368000, C162S363000, C162S205000, C162S204000, C277S300000, C277S345000, C277S583000, C277S910000, C277S913000
Reexamination Certificate
active
06254732
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method for sealing a vacuum space in a suction roll in a paper machine and a seal therefor. The seal includes a wear surface, side surfaces and a lower surface and is fitted from its holder to a suction box inside the suction roll. The seal essentially covers the whole operating length of the suction roll, extending by its wear surface to the inner face of the mantle of the suction roll. The seal is urged in the direction of the radius of the suction roll in the holder with a loading device that loads the seal.
BACKGROUND OF THE INVENTION
It is known in the art that suction rolls are used in paper machines on the one hand to gather water from a paper web, on the other hand to direct the paper web in the roller groups. By setting a vacuum inside the mantle of the perforated suction roll, the paper web can be maintained on the surface of the suction roll. The necessary vacuum is produced by vacuum chambers, which are confined between the mantle and the suction box with sealing devices that cover the whole of the operating length of the suction roll.
These sealing devices each have a seal that extends to the inner face of the mantle, and there are two or more of them inside one suction roll. The seal is quickly used up when constantly pressed against the inner face of the mantle. Several pressing and regulation devices have been developed primarily for the purpose of reducing seal wear. For example, a sealing construction presented in FI patent application number 955275 includes loading hoses. Therein, the seal is pressed onto the mantle with one loading hose, and it is slightly pressed back with the other hose locking the seal into place. The principle is thus to lock the seal a small distance away from the mantle after the starting of the suction roll, whereby seal wear is reduced.
Due to the bend of the suction box, the elastic limit of the seal comes quickly to an end. One of the problems of the present seals is that they provide for only a small elastic movement length. It has not been possible to reduce the scale of the suction box and therefore the whole suction roll. It has only been possible to allow the suction box a slight bend.
In order to reduce the wearing of seals, the above-mentioned known solution has been carried out in a very complex way. Loading devices that include several components add to the risk of malfunctions. In addition, loading devices need to be manufactured accurately in order to function, which adds to the manufacturing and servicing expenses and further to the risk of malfunctions. The operating distance of loading devices is also limited, whereby they are only suited to seals of a certain height.
SUMMARY OF THE INVENTION
An object of the present invention is to produce a simple suction roll sealing construction that is suitable for different seal heights, the mantle load of which can be regulated and with which it is possible to achieve an essentially wider elastic limit than present constructions.
A sealing construction for loading a seal against a suction roll in a paper machine includes a seal having a wear surface, side surfaces and a lower surface. The seal is fitted from its holder to the structure of a suction box which is inside the suction roll. The seal essentially covers the whole operating length of the suction roll, extending from its wear surface to the inner face of the mantle of the suction roll. The seal is moveable in the direction of the radius of the suction roll in the holder by a pressure effect that is applied directly onto the lower surface of the seal. Negative pressure or vacuum can be applied during operation to draw the seal into its holder to reduce seal wear.
According to the present invention the seal itself operates as part of the loading device, whereby the sealing structure is simplified. Loading hoses and other prior art devices thus can be eliminated when the pressure effect of the pressure medium is applied directly onto the lower surface of the seal. In addition to pressing the seal against the mantle, it can be moved in the way desired in its holder. At the same time, however, the characteristics of the seal stay the same regardless of its wear. Existing seal holders can be used in the installation of a sealing construction according to the invention, and the life of the seal can be lengthened simply by adding to its height.
These and other features and advantages of the invention will be more fully understood from the following detailed description of the invention taken together with the accompanying drawings.
REFERENCES:
patent: 4915787 (1990-04-01), Branyon
patent: 5580424 (1996-12-01), Snellman
Fildes & Outland, P.C.
Halpern Mark
Metso Paper Inc.
Silverman Stanley S.
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