Paper making and fiber liberation – Processes and products – Running or indefinite length work forming and/or treating...
Reexamination Certificate
1998-01-23
2001-07-03
Silverman, Stanley S. (Department: 1731)
Paper making and fiber liberation
Processes and products
Running or indefinite length work forming and/or treating...
C162S204000, C162S203000
Reexamination Certificate
active
06254728
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
The present invention claims the priority under 35 U.S.C. §119 of German Application No. 197 02 575.7 filed Jan. 24, 1997, the disclosure of which is expressly incorporated by reference herein in its entirety.
BACKGROUND INFORMATION
1. Field of the Invention
The invention relates to a machine for manufacturing a fibrous pulp web, in particular for a paper or cardboard web.
2. Discussion of Background Information
At higher drainage rates, the formation of a thickened boundary layer on the surface of a web may occur, and it may prevent water from further penetrating the web's surface. In the screen section or press section of the paper machine, for example, this not only may cause undesirable effects, such as slight re-moistening of the web, but it also may crush the web. The same relationship essentially exists for the screen and press sections of a web manufacturing machine.
SUMMARY OF THE INVENTION
The present invention provides a machine for manufacturing a fibrous pulp web which, in particular, is optimized to achieve the highest possible level of dry content, as well as the most gentle handling of the web. According to the invention, the web manufacturing machine includes at least two sequentially positioned draining zones, where the sides of the fibrous pulp web are drained due to a pressure imparted on the web which increases from an initial pressure to a final pressure in the web run direction, where one side of the fibrous pulp web is drained in the first draining zone, where the second side of the fibrous pulp web is drained in the second draining zone, and where the initial pressure in the second draining zone is lower than the final pressure in the first draining zone.
In web run direction before the first and second draining zones, each of which causes one side of the web to be drained, a further draining zone can be provided, where the fibrous pulp web can be drained simultaneously on both sides. In this further draining zone, the web is drained preferably between two screen belts (or sieve belts), between two felt belts and/or between one screen belt (or sieve belt) and one felt belt.
It is advantageous if the pressure acting on the fibrous pulp web in at least one draining zones is created by stretching the web with at least one screen belt and/or felt belt. To increase the stretching of the web, several screen/sieve or felt belts can be provided.
According to another aspect of the invention, a pressure-inducing screen belt and/or felt belt is guided over a roll with a stiff sleeve, or a shoe press device, which may be grooved or sectioned.
A screen belt (sieve belt) is preferably guided over a suction apparatus.
According to another aspect of the invention, drainage of the web occurs in at least one draining zone due to applied differential pressure.
The increase in pressure in the second draining zone is for practical purposes somewhat greater than or equal to the increase in pressure in the first draining zone. Fundamentally, it is also possible to selectively compress the surface of the web with a high final pressure.
The fibrous pulp web is preferably guided through at least one press opening of a mechanical press in at least one draining zone. It is advantageous if at least one press opening is formed by a shoe press elongated in the web run direction.
According to still another aspect of the invention, at least one single-felted press opening is provided, and it is advantageous if the fibrous pulp web is guided through this press opening between the felt and smooth surface which is created, in particular, by a roll, a sleeve of a shoe press device, and/or a belt.
The final pressure in the further draining zone that which is arranged before the first draining zone in web run direction is preferably lower than or equal to the initial pressure in the first draining zone.
According to another aspect of the invention, the initial pressure in the first or second draining zone causing single-sided draining is essentially at least as great as the final pressure in the preceding draining zone which effects single-sided draining on the same side of the web.
The final pressure in the last draining zone causing single-sided draining from one side of the web is at least essentially equal to the final pressure in the last draining zone causing single-sided draining from the other side of the web.
For the production of a multi-layered fibrous pulp web, a machine according to the invention may include a multi-level head box. It thus becomes possible to utilize different types of materials.
The material for making fibrous web sheets may or may not contain hydrogen peroxide. In particular, with hydrogen-peroxide-free paper, thickening of the surface occurs frequently in the press opening, which hinders water from draining out of the web in subsequent press openings. This disadvantage is avoided in accordance with the invention because the linear pressure in the press opening of the first shoe press, as seen in web run direction, may be less than or equal to 15 bar. The maximum pressure lies in the vicinity of approximately 2 bar to approximately 15 bar, and for practical use from approximately 2 bar to 8 bar, where 8 bar is preferred.
According to another aspect of the invention, the linear force produced by the press opening of the first shoe press is less than about 300 kN/m, and preferably is less than or equal to about 150 kN/m.
It is advantageous if the length of the press shoe assigned to the first shoe press, as seen in web run direction, lies within the range of approximately 200 mm to approximately 350 mm.
The mating roll assigned to the press shoe unit of the first press shoe can be a suction roll. This roll can be additionally equipped with blind holes and/or can be grooved. In place of a suction roll, however, a simple roll with dry holes may be provided. The mating roll, however, may also be a grooved roll.
According to another aspect of the invention, a second shoe press is provided behind the first shoe press in the web run direction, such that the linear pressure in the press opening of this second shoe press is approximately three times as great as that in the press opening of the first shoe press. Preferably, the pressure lies in the vicinity of approximately 15 bar to approximately 30 bar. It is preferred if the linear force produced in the press opening of the second shoe press is about approximately 450 kN/m.
A roll press with a press opening located between two stiff roll sleeves can be provided behind the first shoe press, such that the maximum pressure in this press opening lies in the vicinity of approximately 8 bar to approximately 20 bar, particularly from 8 bar to 15 bar, and preferably amounts to approximately 10 bar.
The linear force produced during processing in the press opening of the roll press preferably lies in the vicinity of approximately 10 kN/m to approximately 30 kN/m, preferably approximately 20 kN/m.
A further shoe press can be provided in web run direction behind the first shoe press and, respectively, behind the second shoe press and the roll press, such that the maximum linear force produced in the elongated press opening of the further shoe press lies in the vicinity of approximately 600 kN/m to 1200 kN/m and, optimally, can run to approximately 800 kN/m.
An additional press also can be provided behind the further shoe press in the web run direction. According to another aspect of the invention, the openings of the other shoe press and of the additional press can be felted on different sides of the web. The maximum pressure of the press opening in the additional press can be about equal to that of the press opening of the further shoe press. The additional press can, for example, be a shoe press or also a simple roll press.
The press opening of the first shoe press is preferably double-felted.
According to another aspect of the invention, the paper making machine includes at least one shoe press with a press opening elongated in web run direction, in which the linear force is less t
Bauder Albrecht
Henssler Joachim
Loser Hans
Steiner Karl
Greenblum & Bernstein P.L.C.
Loith Sulzer Papiermaschinen GmbH
Silverman Stanley S.
Walls Dionne A.
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