Paper making and fiber liberation – Apparatus – Running or indefinite length product forming and/or treating...
Reexamination Certificate
1998-12-17
2001-05-22
Silverman, Stanley S. (Department: 1731)
Paper making and fiber liberation
Apparatus
Running or indefinite length product forming and/or treating...
C162S281000, C162S361000, C162S358300
Reexamination Certificate
active
06235160
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
The present application claims priority under 35 U.S.C. § 119 of German Patent Application No. 197 56 422.4, filed on Dec. 18, 1997, 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 machine for producing a fiber material web, e.g., a tissue paper web. The machine includes at least one press having a shoe press unit and a drying drum that form an elongated press gap.
2. Discussion of Background Information
German patent document DE-OS 42 24 730, e.g., discloses a machine similar in general to the machine discussed above in which a fiber material web is guided over at least one additional upstream press gap for draining. In this manner, the fiber material web is guided, together with a water resistant or waterproof belt, between two press gaps.
In this regard, shoe press units offer the advantage of effective and volume-preserving drainage, which is of particular significance in the manufacture of tissue papers. While the degree of draining depends on the press impulse as an integral of press pressure over press time, the influence on volume is determined by the maximum pressure in the press zone. In this process, transport from the wire former of the machine through the two press locations is performed with the waterproof belt. While this belt does prevent remoistening of the fiber material web, because of its lack of water absorption capacity, the belt cannot contribute to drainage in the press locations. For this reason, a water-absorbent felt is guided through the upstream press gap. Thus, drainage primarily occurs in this press gap. Therefore, these machines are unsatisfactory not only with respect to their draining performance, but also with respect to cost.
SUMMARY OF THE INVENTION
The present invention provides a machine for producing a fiber material web, e.g., a tissue paper web. The machine may be simply designed while enabling as intense and volume-preserving drainage as possible.
The present invention provides a machine that includes at least one water-permeable and water-absorbent belt, e.g., a sieve or screen, a felt, or similar material, that is guided through a press nip or gap with the fiber material web, and over at least one suction device located ahead of the press nip.
Via the suction device, it is possible to remove enough water from the belt and, if applicable, from the fiber material web so that the water absorption capacity of the belt may be sufficient to absorb the water pressed out of the fiber material web in the press nip. Moreover, remoistening of the fiber material web may be reduced.
Thus, the machine in accordance with the present invention may be a simply designed machine that operates efficiently even with only one press nip. Moreover, the belt may be utilized in a former part of the machine for taking up or receiving a fiber material suspension from a material feed device. In this manner, transferring of the fiber material web between different belts may be avoided. Further, a drying drum, e.g., a tissue drying drum, may be provided, and the fiber material web may scraped off the surface of the tissue drying drum, i.e., after drying, with, e.g., a crepe scraper.
The belt may be guided with the fiber material web across or over the suction device such that the fiber material web is located on an outside surface of the belt, i.e., a surface of the belt not in contact with the suction device. The suction device may be composed of a suction roll, however, one or more suction boxes may also be utilized.
Suction rolls may generally include a perforated roll sleeve having a negative pressure created within the roll sleeve either by direct connection to a suction (vacuum) source or by suctioning an area of the roll not covered by the belt. The suction rolls in accordance with the present invention may be more simply constructed than the suction press rolls generally utilized in the prior art arrangement because the prior art suciton rolls are constructed to be more stable and generally require support elements.
It may be particularly advantageous for the shoe press unit to include a plurality of press zones extending laterally to a web travel direction. Further, the plurality of press zones may be controlled independently of each other. In this manner, a desired cross directional profile of the press pressure, i.e., transverse to the web travel direction, may be set independently of any deflection of the drying drum. Consequently, it is not necessary to camber the drying drum, which simplifies its manufacture.
Moreover, an increased temperature of the drying drum may ensure that the viscosity of the water is reduced in the press gap, thereby improving drainage.
The present invention is directed to a machine for producing a fiber material web that includes at least one press device having a shoe press unit and a drying drum, such that the shoe press unit and the drying drum are positioned to form an elongated press nip. The machine also includes at least one belt that is water-permeable and water-absorbent and that is adapted to guide the fiber material web through the press nip, and at least one suction device located ahead of the elongated press nip, relative to a belt travel direction. The at least one belt is guided over the at least one suction device.
In accordance with another feature of the present invention, the at least one belt may be further adapted to guide the fiber material web over the at least one suction device on a belt surface that is directed away from the at least one suction device.
In accordance with another feature of the present invention, the shoe press unit may be composed of a plurality of press zones that extend transversely to the belt travel direction, and the plurality of press zones may be independently controllable independently of each other.
In accordance with another feature of the present invention, the at least one suction device may include a suction roll.
In accordance with another feature of the present invention, a former section including a material feed device may be provided, and the at least one belt may be guided through the former section and may be adapted to receive a fiber material suspension from the material feed device.
In accordance with another feature of the present invention, a crepe scraper may be provided, and the drying drum may be a tissue drying drum. The crepe scraper may be positioned against the tissue drying drum and be adapted to remove the fiber material web from the tissue drying drum after drying. Further, the tissue drying drum may include a dryer hood.
In accordance with another feature of the present invention, the material web may include a tissue paper web.
In accordance with another feature of the present invention, the at least one suction device may include at least one suction box.
In accordance with another feature of the present invention, the at least one belt may be composed of one of a sieve and a felt.
The present invention may also be directed to a process for producing a fiber material web in a machine that includes at least one press device having an extended press nip formed between a shoe press unit and a drying drum, at least one belt that is water-permeable and water-absorbent, and at least one suction device located in front of the elongated press nip, relative to a belt travel direction. The process includes guiding the at least one belt over the at least one suction device and suctioning the at least one belt, such that moisture is removed from the at least one belt, and guiding the fiber material web and the suctioned at least one belt through the extended press nip.
In accordance with another feature of the present invention, the process may include guiding the fiber material web and the at least one belt over the at least one suction device before being guided through the extended press nip. Further, the process may include guiding the fiber material web on a surface of the at least one
Schmidt-Hebbel Harald
Tietz Martin
Greenblum & Bernstein P.L.C.
Silverman Stanley S.
Voith Sulzer Papiertechnik Patent GmbH
Walls Dionne A.
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