Paper making and fiber liberation – Apparatus – Running or indefinite length product forming and/or treating...
Reexamination Certificate
1999-04-14
2001-12-25
Hastings, Karen M. (Department: 1731)
Paper making and fiber liberation
Apparatus
Running or indefinite length product forming and/or treating...
C162S358300
Reexamination Certificate
active
06332955
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
The present application claims priority under 35 U.S.C. §119 of German Patent Application No. 198 16 673.7 filed Apr. 15, 1998, of German Patent Application No. 198 27 483.1 filed Jun. 19, 1998, and of German Patent Application No. 298 11 048.2 filed Jun. 19, 1998, the disclosures of which are expressly incorporated by reference herein in their entireties.
BACKGROUND OF THE INVENTION
Field of the Invention
The invention concerns a press arrangement for the treatment of a fibrous material web, in particular a paper or cardboard web and a method for treating a fibra as material web.
SUMMARY OF THE INVENTION
The invention resides in creating a press arrangement of the type mentioned in the Background of the Invention, whose structure is as simple and compact as possible and whose vacuum requirement as well as whose drive power is as low as possible. In addition, in particular, a closed web path is also possible.
According to the invention, two upper press rolls are associated with one lower shoe press roll, and, in each case, the shoe press roll forms with the two upper press rolls a press nip elongated in the direction of travel of the web. Additionally, the first elongated press nip viewed in the direction of travel of the web is double felted.
Because of this design, the formerly customary large press suction roll provided with a thick jacket is eliminated, whereby the vacuum requirement is clearly reduced. Overall, a clearly reduced drive power results. In particular, a closed web path is also readily possible, such that the corresponding press section is also conformed, in particular for liners with a white top. Additionally, because of the use of a double-acting shoe press roll, the number of necessary press rolls is reduced to a minimum, i.e., only three press rolls are needed as a maximum. Accordingly, the number of necessary press filters is also reduced. Lower overall operating costs also result from the reduced use of felt. These operating costs are also reduced by the lower vacuum requirement for tubular suction devices as well as the lower drive power. Also favorably affecting operating costs is the fact that fewer guide rolls, regulators, voltages, tubular suction devices, doctor blades, channels, etc. are necessary and, in particular a simpler, leverless, and compact support is possible. Thus, as a rule, as few as three cantilever carriers suffice. Only a Keller felt is required, such that more space is available for specific aggregates such as the pulper. The maintenance outlay is also clearly lower overall. With the elimination of press roll doctors, the investment costs are further minimized. The absence of blade wear has a favorable effect on the operating costs as well as availability. Roll wear from doctor action no longer occurs. The lubricant spray pipe can be eliminated. Paper draw downstream from the press section is negligible. Since the number of rolls and types of rolls is reduced to a minimum, the number of reserve rolls to be stocked is also accordingly low, which in turn has a favorable effect on operating costs. Thus, as a rule, only three reserve rolls must be stocked, i.e., a press roll, for example, an internally supported sag compensation roll or a solid roll, a transfer-suction roll, and a felt guide roll. It should be taken into account that, as a rule, pickup, transfer, and transport suction rolls have the same structure. For that reason, operating and maintenance costs can be kept low. The long roll service lives also are advantageous. Thus, the use of a press suction roll is eliminated. Virtually only hard coatings are still used. Moreover, convexing is no longer necessary. Consequently, linear force regions without restrictions are possible. There is no linear force dependency between the two press nips. Because of the compact design, the space requirement for the relevant press section is minimal. Thus, for example, with a width of 5.5 meters, approximately 10 meters or less suffice in the longitudinal direction of the press arrangement. As a result of the low space volume, there are low operating costs both for the machine and for the associated structure. No web stabilizers are necessary between the press nips. A single press jacket suffices for the double-acting shoe press roll. Press jacket replacement is easier to schedule. Since the shoe press roll is on the bottom, this press jacket replacement is, in particular, also significantly simpler to execute. There is good accessibility from both sides. During press jacket replacement, no oil can reach the associated felt. Moreover, the felt does not interfere with the jacket replacement. The double-acting shoe press roll can readily be retracted for service work. For this, for example, a retraction cart on a cantilever carrier is possible. No felt removal is necessary for such a retraction. Felt and roll replacement is designed extremely simple overall. One cantilever device per felt suffices. There is good accessibility to the rolls for roll replacement by means of a crane. A variation in format width is possible with no problem. In principle, closed leading of the web from the wire section through the end of the drying section is possible.
In a practical embodiment of the press arrangement according to the invention, the second elongated press nip viewed in the direction of travel of the web is single felted, such that a low remoisturizing drainage is guaranteed with this press nip. The fibrous material web is preferably guided between the relevant felt and the back upper press roll through the second elongated press nip. The second elongated press damp is thus felted on the bottom. The upper back roll can in this case have an at least substantially closed surface, i.e., be smooth. Thus, in particular a discharge favorable roll coating is possible, such as, in particular, a so-called peeler.
In an alternative embodiment of the press arrangement according to the invention, the second elongated press nip viewed in the direction of travel is double felted. This yields overall space-saving and symmetrical drainage. In paper production, in particular, the two-sidedness of the paper is also improved, a fact which is advantageous in particular with regard to smoothness and printability.
In the preferred practical embodiment of the press arrangement according to the invention, a total of three felts at most is provided. One felt can be guided through both elongated press nips. If the second elongated press nip is only single felted, two felts suffice as a result. If the second elongated press nip is double felted, three felts suffice, in principle.
With a closed web path from the wire to the drying section, high runability is achieved. Breaks inside the press arrangement are virtually excluded. In addition, manual leading of the fibrous material web is eliminated, a fact which brings with it higher operational safety and high machine availability. Because of the absence of open stretches, it is possible to achieve virtually no paper stretching and no tears in the web. Also, no fluctuations in tension acting on the paper occur between the presses. Synchronism is achieved by the coupling of the tractive force via the press jacket and felt.
Between the two elongated press nips formed with the shoe press roll, the fibrous material web can preferably be guided together with a felt around a deflecting roll preferably designed as a suction roll.
In a particular practical embodiment, a felt guided through at least the first elongated press nip is simultaneously provided as a pickup felt. The pickup felt can be guided preferably together with the fibrous material web, in particular along a rising intake path into the first elongated press nip, whereby, among other things, ideal web guidance for brown and white papers results. In principle, closed and open operation are possible. Downstream from the second elongated press nip, the fibrous material web can be guided by a deflecting roll, designed preferably as a suction roll, to a subsequent drying section.
Downst
Greenblum & Bernstein P.L.C.
Hastings Karen M.
Voith Sulzer Papiertechnik Patent GmbH
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