Paper making and fiber liberation – Processes and products – Running or indefinite length work forming and/or treating...
Reexamination Certificate
1999-11-09
2001-11-20
Hastings, Karen M. (Department: 1731)
Paper making and fiber liberation
Processes and products
Running or indefinite length work forming and/or treating...
C162S212000, C162S301000, C162S315000, C162S336000, C162S344000
Reexamination Certificate
active
06319363
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is directed to a sheet forming system of a paper or cardboard machine, More specifically, the present invention is directed to a sheet forming system having a headbox with a nozzle and at least two guide mechanisms that guide screens in the region of the headbox nozzle over a guide surface.
2. Discussion of Background Information
A sheet forming system is disclosed in U.S. Pat. No. 4,358,342. This patent discloses the beginning of a sheet forming system of a papermaking machine with a twin wire former in the region of the headbox nozzle and the necked inlet gap of two screens. In the outlet region, the headbox nozzle has sectionally adjustable headbox lips that can influence or even out a base weight cross-direction profile of the paper web. Holding the upper and lower walls of the headbox nozzle in place requires a heavy and large support structure. To adjust the deformable upper or lower lip of the headbox, the relevant lip is supported on the heavily built base of die nozzle upper wall or nozzle lower wall.
Since this design requires a stable construction of the headbox up to the forward most region of the headbox nozzle, it is quite expensive. In addition, if the first two rolls of the screen section (that form the necked inlet gap) have large diameters, the headbox nozzle cannot be inserted far enough into the necked inlet gap. This results in a free jet that is too long, which decreases the quality of the manufacturing process.
German patent DE 41 05 215 C2 also discloses a sheet forming system in the region of the necked inlet gap of a twin screen section. In this system, the two rolls that form the necked inlet gap of the twin screen section are supported hydrostatically. The hydrostatic bearing across the width of the machine allows for compensation for deflection of the rolls. This uniformly maintains the inlet geometry of the necked gap over the entire width of the papermaking machine, even when small roll diameters are used.
SUMMARY OF THE INVENTION
The present invention provides a sheet forming system of a paper or cardboard machine with a headbox nozzle that is lighter than the prior art, yet which minimizes bending of the headbox nozzle.
According to an embodiment of the invention, a headbox nozzle includes two laterally arranged nozzle side panels, and first and second nozzle walls running the width of the machine. Two screens converge in the region of the output of the headbox nozzle. At least two guide mechanisms glide the screens in the region of the headbox nozzle over a guide surface. At least one support mechanism has at least one support element for supporting at least a portion of a nozzle wall against at least one guide surface.
The above embodiment may include various features At least one of the guide surfaces can be a roll surface and/or the surface of a guide shoe. At least one of the guide mechanisms can be a forming roll or a breast roll. The support elements of the support mechanism can be a roll or a shoe that slides or rolls over the roll surface. At least one of the support elements can haste at least one hydrostatic bearing or support. The support mechanism facing the nozzle wall may have at least one pressure chamber.
The support mechanism may be broken up into individual sections along the width of the machine that can be individually adjusted and controlled. Such a sectioned support may include a mechanism that controls the degree of support for each individual section. For example, control valves can individually control individual pressure chambers of the support mechanism. In the alternative, the support mechanism can also have a number of support elements (for example, individual spindles or hydraulic stamps), whose support action can be adjusted individually as needed.
The deflection of at least one of the guide mechanisms can be adjustable. A deflection compensation device, known per se for rolls, can be provided.
At least one supporting table with at least one pressure-producing device between the supporting table and the nozzle wall may be provided in the region of at least one nozzle wall. The pressure-producing device can have a single pressure chamber, or several individually controlled pressure chambers. Different pressure can be applied by the individual pressure chamber segments to produce a desired pressure cross-direction profile. The pressure-producing device is preferably upstream of the support mechanism between the nozzle wall and guide surface. In this arrangement, the supporting table is located relatively far from the necked inlet gap so that it has adequate space for a stable lower structure, unhindered by the rolls of the necked inlet gap.
According to an embodiment of the invention, a sheet forming system of a paper or cardboard machine is provided. A headbox had a headbox nozzle including two laterally extending side panels and first and second nozzle walls extending along a width of the machine. First and second screens converge in a region adjacent the headbox nozzle. At least two guide mechanisms, each having a guide surface, guide the first and second screens in the region. At least one support mechanism supports at least a portion of one of the first and second nozzle walls against the guide surface of at least one of the at least two guide mechanisms.
The above embodiment may have various features. At least one of the guide surfaces of the at least two guide mechanisms may be a roll surface or a surface of a guide shoe At least one of the at least two guide mechanisms can be one of a forming roll and a breast roll. At least one of the at least one support mechanism may be a roll or a shoe, and may have at least one of a hydrostatic bearing and support. The shoe may face the one of the first and second nozzle walls, and includes at least one pressure chamber.
The at least one support mechanism may be separated into a plurality of individual support mechanisms along a width of the machine. A control system may control the plurality of individual support mechanisms to adjust a degree of support provided along the width of the machine. The control system may individually control individual ones of the plurality of individual support mechanisms.
A deflection of at least one of the guide mechanisms may be adjustable.
The sheet forming system may her include at least one supporting table disposed in the one of the first and second nozzle walls, and at least one pressure-producing device between the supporting table and the one of the first and second nozzle walls. The pressure-producing device may include at least one pressure chamber, The at least one pressure chamber may include a plurality of pressure chambers along a width of the machine that can be individually controlled to apply different pressure. The pressure-producing device may be arranged upstream of the at least one support mechanism.
According to another embodiment of the invention, a sheet forming system of a paper or cardboard machine is provided. A headbox has a headbox nozzle including first and second nozzle walls extending along a width of the machine. First and second screens converge in a region adjacent the headbox nozzle. First and second guide rolls have first and second guide surfaces, respectively, that guide the first and second screens in the region. A support mechanism supports at least a part of the second nozzle wall against the second guide surface, the support mechanism being one of a roll and a shoe.
The above embodiment may have various features. The system may further include at least one supporting table disposed in the second nozzle wall, and at least one pressure chamber defined between the supporting table and the second nozzle wall. The one of roll and a shoe may include one of a plurality of individually elements, along a width of the machine that can be individually controlled to apply different pressure. The at least one pressure chamber may include a plurality of individually controlled pressure chambers along a width of the machine that can
Humberg Holger
Mirsberger Peter
Ruf Wolfgang
Greenblum & Bernstein P.L.C.
Hastings Karen M.
Voith Sulzer Papiertechnik Patent GmbH
LandOfFree
Sheet forming system and method for controlling the same does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Sheet forming system and method for controlling the same, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Sheet forming system and method for controlling the same will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2585254