Paper making and fiber liberation – Processes and products – Running or indefinite length work forming and/or treating...
Reexamination Certificate
1999-04-14
2002-07-30
Hastings, Karen M. (Department: 1731)
Paper making and fiber liberation
Processes and products
Running or indefinite length work forming and/or treating...
C162S358300, C162S360200
Reexamination Certificate
active
06425980
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
The present application claims priority under 35 U.S.C. §119 of German Patent Application No. 298 11 048.2 filed Jun. 19, 1998, German Patent Application No. 198 16 673.7 filed Apr. 15, 1998, and German Patent Application No. 198 48 284.1 filed Oct. 20, 1998, the disclosures of which are expressly incorporated by reference herein in their entireties.
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a press device and process for treating a material web, in particular a paper or a cardboard web.
SUMMARY OF THE INVENTION
The present invention provides a compact press device which is as inexpensive as possible and which has a simple design. Further, the present invention provides a press device requiring low operating costs, which ensures an optimal web guidance and which also ensures, as much as possible, less rewetting of the material web and increased overall efficiency in treating a material web.
The present invention may be related to a calender roll system and provides increased efficiency and lower costs associated with treating a material web. The press device of the present invention includes two separate shoe presses positioned next to each other. The press device of the present invention further includes a transfer suction roll which is disposed between the two shoe presses. The material web, together with a felt, are continuously guided by the transfer suction roll, which is at least partially provided with suction, in a continuous manner. The material web is transported through at least one of the two shoe presses.
According to one embodiment of the invention, the distance between the nips of the two shoe presses may be relatively short. Further, it is possible to guide the web over a completely closed or a continuous, partially suctioned path. This may be particularly advantageous by requiring a low degree of rewetting of the material web, a lower decree of treating the web on both sides, and increased efficiency. The operating costs may be kept relatively low, particularly with respect to the felts, the drive, the vacuum production, the maintenance, and the like. The press device of the present invention is further distinguished by its reasonable manufacturing costs. For example, the vacuum requirement is considerably reduced because the large press suction roll required in the prior art, which included a thick jacket, is no longer necessary.
On the whole, the present invention results in the utilization of considerably lower drive power. Further, because a closed or continuous web guidance system is possible, the corresponding press section is particularly well suited for paper webs which have a low basis weight or which use high machine speeds. The number of felts is reduced to a minimum, which results in lower operating costs. The operating costs are further reduced by the lower vacuum requirement for suction devices as well as the lower drive power. The present invention also decreases initial investment costs, in that fewer guide rolls, regulators, clamps, suction devices, doctors, troughs, and the like are required. Further, a simpler, lever-free, and compact seating is also possible such that three cantilever carriers are sufficient.
According to the present invention, only one base felt is necessary so that there is more space available for certain subassemblies, such as the pulper. Also, the overall maintenance cost is considerably lower. The elimination of press roll mechanics tends to further minimize the initial investment costs. The lack of blade wear, maintenance and replacement decreases the operating costs as well as increases the availability of the machines to treat the material web. The lubricant spray tube may be eliminated. Further, the paper tension after the press section is decreased.
It is generally true that, if the number of the rolls and roll types used is reduced to a minimum, the number of rolls that have to be kept on hand is also correspondingly low, which in turn decreases the investment costs. Because the pick-up rolls, transfer rolls, and transfer suction rolls used in the invention may often be structurally identical, the number of rolls that must be kept on hand is reduced. Thus, the investment costs and maintenance costs can also be kept low.
The lengthy roll service lives also turn out to be advantageous. Thus, the use of a press suction roll is eliminated and hard covers are used practically exclusively. Moreover, because crowns are no longer required, an endless combination of line force regions with varying forces are possible. There is, for example, no line force dependency between the two nips.
Due to the compact embodiment, the space required for the relevant press section is minimal. For example, in a width of 5.5 m, approximately 10 m or less in the longitudinal direction of the press device is sufficient. The low spatial volume results in low investment costs both for the machine and the relevant building space that must be acquired or dedicated for this process.
Moreover, there is good accessibility. In a respective press jacket replacement, oil cannot get into the felt. In addition, the felt does not interfere with the jacket replacement. The relevant shoe press unit can be easily withdrawn for service work. To this end, for example, it is possible for there to be a travel-out carriage on a cantilever carrier. Removing the felt is not necessary for a respective withdrawal of the shoe press unit. The felt and roll replacement is embodied as extremely simple on the whole. One cantilevering per felt is sufficient. There is good accessibility to the rolls for a roll replacement via a crane. The form width can be varied with no trouble. Fundamentally, it is also possible for there to be a closed guidance (draw) of the web from the wire section to the end of the drying section.
Advantageously, the felt that is guided together with the material web over the transfer suction roll, may be routed through both shoe presses.
According to the present invention, each of the two shoe presses may be double felted.
According to another embodiment of the present invention, the press device as a whole may have a closed or continuous web guidance, which produces an increased efficiency and practically eliminates tears in the press device. A manual design is no longer required, which results in a correspondingly higher operational reliability and a high degree of machine availability. Due to the lack of open draws, it is practically impossible for paper stretching or web tearing to occur. In particular, the web does not have to be pulled away from smooth roll surfaces. Between the presses, the paper is no longer subjected to any fluctuations in tension. A corresponding tensile force coupling by way of a respective felt produces the desired synchronism. An ideal web guidance is always assured for both brown and white papers. This results in short rewetting segments and a good web securing between the presses.
In yet another embodiment of the present invention, the press device further includes a web holding box positioned after the transfer suction roll. More particularly, the web holding box may be placed between the suction roll and the subsequent shoe press.
According to one aspect of the invention, a pick-up felt is routed through at least the first shoe press which the material web encounters in the web travel direction.
Moreover, it is possible for one of the two shoe presses to be formed by a shoe press unit disposed on the bottom and a counter roll disposed on top. In one embodiment of the press device, both of the shoe presses are respectively formed by a shoe press unit disposed on the bottom and a counter roll disposed on top. The material web, together with a bottom felt which is routed through both the shoe presses, may be guided over the transfer suction roll.
For example, one of the two shoe presses can also be constituted by a shoe press unit disposed on top and a counter roll disposed on the bottom. In a suitable embodiment of the press device according
Dahl Hans
Meschenmoser Andreas
Mirsberger Peter
Greenblum & Bernstein P.L.C.
Hastings Karen M.
Voith Sulzer Papiertechnik Patent GmbH
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