Paper making and fiber liberation – Apparatus – Running or indefinite length product forming and/or treating...
Reexamination Certificate
1999-10-04
2001-07-17
Hastings, Karen M. (Department: 1731)
Paper making and fiber liberation
Apparatus
Running or indefinite length product forming and/or treating...
C162S344000
Reexamination Certificate
active
06261418
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
The present application claims priority under 35 U.S.C. §119 of German Patent Application Nos. 199 27 241.7, filed Jun. 15, 1999, and 298 23 639.7, filed Oct. 5, 1998, the disclosures of which are expressly incorporated by reference herein in their entirety. The present application further claims priority under 35 U.S.C. §119 of German Patent Application No. 198 45 722.7, filed Oct. 5, 1998.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a headbox for a paper-making machine with a nozzle extending transverse to the machine running direction across the machine width. The headbox has a lower and an upper continuous wall each extending across the machine width.
2. Discussion of Background Information
In conventional headboxes of the type mentioned above, the lower nozzle wall is normally supported by a run-in table provided as a continuous weldment. However, deviations from the desired parallelism in the outlet gap can occur due to the effect of thermal expansion caused by the temperature of the material.
In a headbox as described in German patent DE 41 06 764 A1, the upper nozzle wall is connected to a rigid girder by rods that are flexible to bending.
SUMMARY OF THE INVENTION
The invention resides in creating a headbox of the type mentioned above which continuously guarantees as parallel an outlet gap as possible practically independently of the respective operating conditions, having the most cost-effective design possible, simple operation, and minimal maintenance expense.
In a headbox according to the invention, the lower nozzle wall is supported by several separate supporting elements distributed across the machine width on a foundation. These supporting elements are designed to be non-rigid or flexible to bending transverse to the machine running direction.
As a result, a transverse bar provided directly on the lower nozzle wall is eliminated. This also prevents the lower nozzle wall from bending with a non-uniform change in temperature. The supporting elements essentially carry the entire headbox. In the case of a temperature-induced change in length of the lower nozzle wall, these supporting elements give way correspondingly in a direction transverse to the machine running direction. The lower nozzle wall remains sufficiently even in the case of a change in temperature and/or pressure. Therefore, the heating system that compensates for the thermal bending of the lower nozzle wall that has been conventional until now can be eliminated.
The individual supporting elements can extend at least to some degree in a generally vertical manner, i.e., perpendicular to the lower nozzle wall.
According to the invention, the individual supporting elements are formed at least partially by disks, i.e., stud bolts or the like, extending parallel to the machine running direction.
The individual supporting elements can be connected directly to the foundation by a base plate and/or a pedestal.
In addition, the supporting elements can be connected to the lower nozzle wall, for example.
In another suitable embodiment, in which the lower nozzle wall can be displaced on a stationary supporting plate in the machine running direction, the supporting elements are connected to the supporting plate.
In order to guarantee the most stable positioning of the lower nozzle wall possible and to prevent undesired lateral oscillations, at least one diagonal or transverse brace is provided suitably in a center area, as viewed transverse to the machine running direction, between successive supporting elements.
Another alternative solution according to the invention or one in combination with the preceding solution of the above objective includes a headbox of the type mentioned previously in which the upper nozzle wall can be swiveled around an axis extending transverse to the machine running direction and is connected by several separate supporting members, distributed across the machine width, with a transverse bar attached above the swivel axis. These supporting members are to be non-rigid or flexible to bending transverse to the machine running direction (see claim
10
).
As a result, no transverse bar is provided directly on the upper nozzle wall. Regardless of the respective changes in temperature and/or pressure, it is thus assured that the upper nozzle wall remains sufficiently even.
The headbox can be provided in particular with a central component which includes a lower arm formed by the lower nozzle wall or the supporting plate allocated to the nozzle, an upper arm that is preferably parallel to the nozzle, an inlet-side first central part and a second central part behind the first central part in the machine running direction. The upper arm and the two central parts are arranged between this upper arm and the lower arm preferably forming supporting members of a turbulence generator. In this connection, it is conceivable, for example, that the transverse bar be connected to the central component by at least one stroke element and no more than three stroke elements, and in particular by only one stroke element or by two stroke elements.
In a suitable practical embodiment of the headbox according to the invention, the individual supporting members extend at least to some extent in a generally vertical manner, i.e., perpendicular to the upper nozzle wall.
The individual supporting members are preferably formed at least partially by disks parallel to the machine running direction.
The transverse bar can be formed by sheet metal standing on edge or by a hollow beam.
In a headbox according to the invention, provisions are made for the upper arm and the rear or downstream second central part of the central component to each be segmented transverse to the machine running direction. The inlet-side first central part of the central component and the lower nozzle wall are each designed to be continuous transverse to the machine running direction.
The central component is thus formed by a partially segmented C-shaped clamp, where basically only those parts bordering the material guiding areas are not segmented, i.e., are formed continuously in the crosswise direction.
This third solution according to the invention can also be provided alternatively or in combination with the two previous solutions according to the invention. If in combination with the two previous solutions, both a combination with the first or second solution as well as a combination of all three solutions are conceivable.
If the lower nozzle wall is displaced on a stationary supporting plate in the machine running direction, then it is preferred that the stationary supporting plate also be segmented transverse to the machine running direction.
If, for example, the upper nozzle wall is swiveled by a hinge around an axis extending transverse to the machine running direction, then preferably a continuous hinge bearing is provided extending transverse to the machine running direction on the rear or downstream end of the upper arm of the central component in the machine running direction. This hinge bearing can always have a material reduction in the area between the individual segments of the adjacent upper arm.
In a practical embodiment, the division of the segments of the upper arm of the central component defined by the distances from segment center to segment center is equal to the division of the segments of the rear or downstream second central part of the central component.
It is also advantageous for the division of the supporting elements and the supporting members defined by the distances from element or member center to element or member center to be equal to the division of the segments of the central component.
According to the invention, the parallelism of the outlet gap can be assured under substantially all operating conditions that are possible in practice. Accordingly, deformations of the upper and the lower nozzle wall under varying pressure in the nozzle and/or under varying material temperature are at least essentially excluded. If the nozzle wal
Banning Jurgen
Dietz Thomas
Frey Josef
Juhas Simon
Krägeloch Eckart
Greenblum & Bernstein P.L.C.
Hastings Karen M.
Voith Sulzer Papiertechnik Patent GmbH
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