Paper making and fiber liberation – Apparatus – Running or indefinite length product forming and/or treating...
Reexamination Certificate
2000-08-30
2001-10-23
Chin, Peter (Department: 1731)
Paper making and fiber liberation
Apparatus
Running or indefinite length product forming and/or treating...
C162S206000, C162S358300
Reexamination Certificate
active
06306261
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
The present application claims priority under 35 U.S.C. §119 of German Patent Application No. 199 41 336.3, filed on Aug. 31, 1999, the disclosure of which is expressly incorporated by reference herein in its entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a dewatering device of a machine for the production and/or processing of a material web, e.g., a paper web or a cardboard web, in which the material web is guided together with at least one screen through a nip which is elongated in the web travel direction. The nip is formed between a circulating flexible continuous belt, which is supported by a saddle, and an opposite surface. The present invention is also related to a glazing device of a machine for the production and/or processing of a material web, e.g., a paper web or a cardboard web, in which the material web is guided between a nip formed between a heated roller and a mating roller.
2. Discussion of Background Information
A dewatering device of the above mentioned type is known, e.g., from DE 197 23 163 A1. It is also known to perform the dewatering between two metal belts of which one is heated and the other is cooled. Moreover, originating from the heated belt, a paper web, a fine screen, and a coarse screen are arranged toward the cooled belt. Arrangements are also known in which the paper web and the screens are guided over a cooled or heated cylinder. Around the cylinder a metal belt is looped which is heated in the case of a cooled cylinder and is cooled in the case of a heated cylinder. The paper web always sits close to the heated surface. Between the paper web and the cooled surface there is at least one screen, usually a fine screen, which is provided close to the paper web and a coarse screen which is located close to the cooled surface. In all of these arrangements, pressure is transmitted during the dewatering process by a pressurized cooling and/or heating medium in the form of a gas or a liquid through an airtight surface such as, e.g., a metal belt to a sandwich formed by the two surfaces of paper, fine screen, and coarse screen (see, e.g., DE-A-26 57 041, FIG. 10; DE-A-32 03 571, FIG. 11; DE-A-35 32 853, FIG. 12).
However, the pressurized liquid requires very expensive constructions concerning the sealing and due to uncompensated forces. A change in the structure pressure applied can only be accomplished with several pressure chambers, which again increase the constructive expense.
Also there are arrangements known in which, during the dewatering process, the pressure is produced mechanically by one or more saddle presses which are pressed against a heated cylinder. In this way, it is possible to reduce the constructive expense necessary for production of the structure pressure and the pressure profile can be predetermined, within certain limits, by the selection of the form of the saddles (see, e.g., EP-A-0 890 675, FIG. 13). However, if only one saddle is used it results in a length of only about 200-300 mm, which is very short. If several saddles are used, the paper is always relieved of pressure between each saddle. This does not allow the construction of a continuous process because the steam pressure inside of the paper must be reduced to the outside pressure after each nip in order to avoid destruction of the paper.
Furthermore, there are also solutions known in which the structure pressure is produced by several pressure rollers against a heated cylinder. Here, too, a continuous process of a structure pressure cannot be created over a longer period of time (cf., e.g., U.S. Pat. No. 5,787,603, FIG. 14).
SUMMARY OF THE INVENTION
The present invention provides a dewatering device of the above mentioned type which enables a continuous process of the structure pressure in the web travel direction over a significantly longer distance during the dewatering process. Furthermore, a coordinating glazing device can be created.
Concerning the dewatering device, the invention includes a saddle segmented in the web travel direction, in which, at least partially, separate pressurization of the saddle segments connected with each other is enabled.
Due to this design, a continuous process of the structure pressure in the web travel direction can be produced over a significantly longer distance during the dewatering process than, e.g., about 300 mm. It is possible, e.g., to monitor the profile of the pressure forces by pressure sensors even during processing and to adjust them in such a way that, especially in the exit area of the pressured area, the steam pressure is small enough to avoid destruction of the paper by the expanding steam still contained in the paper. To this end, appropriate force sensors can be provided, e.g., in the saddle. If the circulating flexible continuous belt is formed, for instance, by a flexible roller jacket, correlating pressure sensors and force sensors can be provided, e.g., in the rotating saddle roller or in the mating roller to the saddle pressure roller.
The saddle can be pressed mechanically against an opposite (opposing) surface in order to apply structure pressure to the material web. Over the sum of the saddle segments a continuous pressure profile is produced which preferably is adjustable during the process. The pressure of the segments can occur on the connection points and/or in between, for instance, with hydraulic stamps.
In a particular embodiment, the saddle segments can at least be partially hinged to one another. In this case the segments can be pressurized at the hinge points and/or in between, accordingly.
In another embodiment, the saddle segments can at least be partially formed by areas of reduced material thickness of the saddle at each point. Thus, the saddle can have, on the side facing away from the nip, several consecutive cuts in the web travel direction.
In a preferable embodiment of the dewatering device according to the invention, different pressure profiles in the nip can be adjusted by appropriate pressurizing of the saddle segments.
The pressure in the nip can also be produced by two saddles facing each other in which at least one of the saddles is segmented.
It is also advantageous when the surface of the flexible continuous belt and/or the opposite surface is structured accordingly, for instance ribbed, to support the pressure equalization in the area of the nip exit.
In another embodiment of the dewatering device according to the invention, the circulating flexible continuous belt is formed by a flexible roller jacket of a saddle roller.
The opposite surface can be formed by a mating roller, e.g., a roller that is supported on the inside, especially a sag (deflection) compensation roller.
In certain cases, it can be useful when the flexible continuous belt that is guided over the saddle is cooled and the opposite surface is heated. In this case, the segmented saddle can have a coolant, e.g., cooling water, flow through it. Alternatively, or additionally, the flexible continuous belt supported by the saddle can also be cooled from the outside and/or inside.
Advantageously, the flexible continuous belt is at least partially cooled on the inside by the lubricant that is used to lubricate the area between the saddle and the continuous belt.
In certain cases, it can also be practical for the screen to be cooled before the nip in the web travel direction.
To increase the heat transfer, the flexible continuous belt can be formed, in particular, by a steel belt.
In another embodiment of the dewatering device according to the invention, the flexible continuous belt guided over the saddle is heated and the opposite surface is cooled.
In an advantageous practical embodiment, the flexible continuous belt and the opposite surface are each formed by a steel belt. Further, the segmented saddle is opposed, preferably, by a saddle that is not segmented and, upon which, the steel belt that forms the opposite surface is supported. Each of the two steel belts is guided, preferably, around two floating idle rollers, prefera
Henssler Joachim
Holzer Walter
Meschenmoser Andreas
Chin Peter
Greenblum & Bernstein P.L.C.
Hug Eric
Voith Sulzer Papiertechnik GmbH
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