Paper making and fiber liberation – Apparatus – Running or indefinite length product forming and/or treating...
Reexamination Certificate
1999-03-29
2001-04-24
Silverman, Stanley S. (Department: 1731)
Paper making and fiber liberation
Apparatus
Running or indefinite length product forming and/or treating...
C162S352000, C162S217000, C162S363000, C162S354000, C162S351000, C162S366000
Reexamination Certificate
active
06221215
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a suction device and process for conditioning and/or drainage of an endless felt in web producing machine, e.g., a paper and/or cardboard machine. The suction device includes a housing having at least one vacuum chamber, and the at least one vacuum chamber includes, on a side facing the endless felt, at least one suction slit. Further, the endless felt is guided over the at least one suction slit.
2. Discussion of Background Information
A suction device similar to the device generally discussed above is disclosed in DE-A-43 05 493, in which a continuous suction slit is provided that extends crosswise to the direction of travel of the felt. While this known suction device has proven itself in practice in many respects, it is disadvantageous in that only a limited slit width is possible. Further, even with relatively small slit widths, an unwanted drawing-in of the felt may occur. Also, with the limited slit width, the conditioning length over which, or a dwelling time during which, a respective felt region can be exposed to suction or conditioned is limited.
SUMMARY OF THE INVENTION
The present invention provides a suction device of the type generally discussed above in which the danger of an unwanted drawing-in of the felt is reduced to a minimum and, at the same time, longer dwelling times are possible for the felt conditioning and/or drainage.
In this regard, the present invention provides a housing having a suction surface adapted to face the felt, and a plurality of suction slits formed in the suction surface that extend in at least one of in and obliquely to a travel direction of the felt.
In accordance with the features of the present invention, optimum support of the felt is substantially always guaranteed, even with relatively long slit lengths. In particular, the felt rests on a support surface formed by regions lying between individual suction slits. Since the suction slits do not extend crosswise to the felt travel direction, but rather generally in the direction of travel of the felt, the resultant suction region may be lengthened in the direction of travel of the felt without consequently increasing the danger of an unwanted drawing-in of the felt. In this manner, substantially longer dwelling times are possible for the felt conditioning and/or drainage. Because a large number of separate suction slits are utilized, the slit width may be selected to be virtually as small as desired without negatively affecting the suction capability. An appropriate number of slits must merely be provided. In accordance with the arrangement of the present invention, virtually every section of the felt that is exposed to a respective suction slit is supported on the suction surface of the vacuum chamber. Thus, even with a relatively large number of slits, the danger of a drawing-in of the felt is virtually eliminated. Moreover, generally, only one suction device is necessary for one felt. Thus, the number of vacuum lines, of bearing blocks, and/or the like may be reduced. Thus, space requirement is also correspondingly smaller. Preferably, the surfaces in contact with the felt may be manufactured from a wear-resistant material, e.g., ceramic, of non-wear-resistant material, e.g., plastic, or combinations thereof.
It may be preferable to provide at least some suction slits that have a variably adjustable length. In this manner, the lengths of at least some of the suction slits may be separately adjustable. With adjustable slit lengths, the dwelling times for felt conditioning and/or draining may also be adjustable. Accordingly, effective conditioning and/or draining length of the suction slits may be adjustable during operation and/or while the machine is shut off.
The suction slits may be oriented in the direction of travel of the felt. However, it is also conceivable that at least some of the suction slits may be arranged to run obliquely to the direction of travel of the felt. Further, the obliquely extending suction slits may be arranged in mirror symmetry with a median plane of the felt extending in the direction of travel of the felt. With such an arrangement of the suction slits, a broad-drawing effect may be simultaneously obtained. Further, with such oblique suction slits, care must be taken that the various felt regions are adequately and uniformly conditioned so as to avoid streak formation.
In an exemplary embodiment, at least some of the suction slits may be located near each other in at least one group that extends at least substantially straight over at least a part of a width of the felt. Alternatively or additionally, at least some of the suction slits may also be located in at least one group which extends obliquely over at least a part of the width of the felt.
In another exemplary embodiment of the suction device of the present invention, at least some of the suction slits may be located in at least two groups successively arranged with respect to each other in the direction of travel of the felt.
In particular, two groups of successively located slits may be arranged such that each group extends at least substantially straight over at least substantially an entire width of the felt.
In another embodiment, at least some of the suction slits may be located into at least one pair of groups, in which the groups of slits extend obliquely over at least substantially one-half the width of the felt and are arranged in mirror symmetry relative to a median plane perpendicular to the felt and extending in the direction of travel of the felt. In this case, at least two pairs of groups of slits successively arranged relative to each other in the direction of travel of the felt are provided, i.e., one pair on each side of the median plane. Further, the respective groups of slits extending obliquely on a same side of the median plane may be arranged parallel to each other.
It may be preferable if the suction slits of groups of slits successive to each other are offset relative to the adjacent group generally crosswise to the direction of travel of the felt. Further, it may be preferable to locate the suction slits in gaps between toothed elements.
According to another exemplary embodiment of the present invention, at least two groups of slits may be successively (consecutively) arranged in the felt travel direction. The suction slits may be positioned in gaps defined between two comb-like diaphragms whose teeth extend in the felt travel direction, and which are offset from each other generally crosswise to the felt travel direction so as to preferably mesh with each other. At least one of the comb-like diaphragms can be adjustable in the direction of travel of the felt and relative to a stationary part of the housing. It may also be preferable if at least one comb-like diaphragm is subdivided crosswise to the felt travel direction into a plurality of segments composed of one or a plurality of teeth. Further, at least some of these diaphragm segments may be adjustable in the felt travel direction relative to the stationery part of the housing, and the diaphragm segments may be at least partially separately adjustable.
The housing containing at least one vacuum chamber may be generally formed, e.g., as tube-shaped and extend crosswise to the direction of travel of the felt at least substantially over the entire width of the felt.
In another exemplary embodiment, the housing may include only one vacuum chamber. In this manner, the vacuum chamber may extend at least substantially over the entire width of the felt.
The present invention is directed to a suction device for at least one of conditioning and drainage of an endless felt. The device includes a housing having at least one vacuum chamber, and a plurality of suction slits located on a suction surface of the housing that is adapted to face the endless felt. The plurality of suction slits are oriented to extend at least one of in and obliquely to a travel direction of the endless felt.
The present invention is directed to a process for at l
Haider Peter
Halmschlager Gunter
Stelzhammer Franz
Greenblum & Bernstein P.L.C.
Silverman Stanley S.
Voith Sulzer Papiertechnik Patent GmbH
Walls Dionne A.
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