Presses – Concurrent pressing and conveying – Roll type
Reexamination Certificate
1998-12-18
2001-05-08
Vo, Peter (Department: 3721)
Presses
Concurrent pressing and conveying
Roll type
C100S076000, C100S16200R, C100S16300R, C100S172000
Reexamination Certificate
active
06227105
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is related to a calender for a web, e.g., a paper web. The calender includes a stack of rolls having axes that are located in a horizontal plane.
2. Discussion of Background Information
Conventional type calenders, which include a stack of rolls having horizontal axes that are located one above the other in a vertical plane, are used for treating paper, paperboard, plastic foils, and similar material. The nips are either formed by adjacent hard rolls or, particularly in paper refining, are formed by an adjacent hard roll and soft roll. The line load in the nips is provided by hydraulic force transmitters that engage an end roll of the roll stack and by the weight of the rolls. Thus, the line load, and, therefore, the compressive strain, increases from the top to the bottom of the roll stack. In this regard, the variation range of the forces that can be exerted by the force transmitters is relatively small. Further, a limitation of force toward the top of the roll stack must be produced to avoid too intensely stressing the web material in the bottom nip, and to ensure that the web material experiences no further deformation in the top nip.
A calender similar in general to the above described calender is disclosed in WO 95/14813, in which the end rolls are formed with deflection adjustment rolls and the middle rolls are supported on levers engaged by devices for exerting a force. The rolls are designed so that natural deflection lines produced by the weight of the rolls is essentially the same. Further, the nip load generated by the masses of the middle rolls and the associated auxiliary devices is essentially completely canceled out by the devices for exerting force. Theoretically, the entire influence of gravity can be eliminated in this manner, however, in practical terms, extreme difficulties are caused in fulfilling the above-mentioned conditions. In particular, if not all rolls have a same deflection due to their weight, then during operation, higher pressure loads occur on either the edges or in the middle of the roll.
Another calender similar to the above-described calender is disclosed in DE 26 03 484 A1 or DE 26 03 485 A1, substantially avoids the above-noted problems associated with the roll weight. In this calender, the horizontal axes of the rolls are located next to one another so that the weight influence of the rolls on the line load is completely eliminated. The rolls are secured in bearing blocks that can be slid along a guide. One end roll is fixed in place and the other end roll is loaded in the direction of the one end roll by force transmitters in the form of piston/cylinder units. With this calender, the same line load prevails in all of the nips.
SUMMARY OF THE INVENTION
The present invention provides a calender of the type generally discussed above which can be operated with different line loads in the individual nips.
The present invention provides end rolls composed of deflection adjustment rolls and middle rolls supported on levers engaged by devices for exerting force.
With the arrangement of the calender in accordance with the features of the present invention, the desired line load may be adjustable in each nip by levers that are loaded by the devices for exerting force. In the present invention, the levers and devices for exerting force are utilized even though they are not necessary for their conventionally known purpose of weight relief. The deflection adjustment rolls on the ends of the roll stack may support the adjustment of the line load and, in particular, permit an evening out of the line load in the direction of the web width.
It may be particularly advantageous to generate a fundamental line load that is substantially the same in all nips, to load the one end roll, e.g., by force transmitters, in a direction of the other end roll. Since roll weight has no effect on the line load in this arrangement, the fundamental line load that is exerted by the force transmitters can be freely selected within a large range. In particular, a relatively large line load can be provided at the first nip. Since the devices for exerting force only have to exert auxiliary forces, they can be embodied as comparatively small.
The devices for exerting force may be, preferably, operational in two directions. In a first direction, the line load may be generated or increased; and in a second direction, the line load may be reduced, if necessary, to rapidly separate the rolls.
It may also be advantageous to provide separate drives for the rolls, which substantially prevents lateral deflections of the rolls. Lateral deflections may occur when a single driven roll causes the other rolls to move via friction.
In a preferable embodiment, a frame supporting the rolls may be moved from an operating position, in which the roll axes are located in a horizontal plane, into a rest position, in which the roll axes are located in a vertical plane, i.e., one above the other. In the rest position, the material web may be introduced into the nip of the calender in the conventional manner. For operation, the calender may be pivoted into the operating position.
In an exemplary embodiment, a horizontal pivot axis may be provided, around which, the frame can be pivoted by approximately 90°.
It may be preferable to couple at least one winding station to the frame through a common support. In this manner, the winding station and the calender may be jointly pivoted.
In an alternative embodiment of the present invention, at least one fixed winding station may includes a roll with a horizontal axis and at least one guide roll with a horizontal axis. The at least one guide roll may be arranged between the winding station and the roll stack. The at least one guide roll may be contacted by the web only when the frame is moved out of the rest position and into the operating position. In this instance, it may only be necessary to pivot the calender.
Accordingly, the present invention is directed to a calender for a web that includes rolls having rotational axes and a roll stack composed of the rolls. The rolls of the roll stack are arranged such that the rotational axes are positionable in a horizontal plane. The calender also includes levers. The rolls include end rolls and middle rolls, and the middle rolls are coupled to the levers. The calender also includes force devices positioned to exert a force on the levers.
In accordance with another feature of the present invention, force transmitters may be provided to load one of the end rolls in a direction of the other of the end rolls. In this manner, a uniform fundamental line load may be exerted in all of the nips.
In accordance with another feature of the present invention, the force devices may be operable for exerting force in two directions.
In accordance with still another feature of the present invention, separate drives associated with each of the rolls may be provided. In this manner, lateral deflections of the rolls are substantially prevented.
In accordance with a further feature of the present invention, a frame that supports the rolls may be provided. The frame may be movable from an operating position, in which the roll axes are located in the horizontal plane, into a rest position, in which the roll axes are located in a vertical plane. Further, the frame may include a horizontal pivot axis and the frame may be pivotable around the horizontal pivot axis through an angle of approximately 90°.
In accordance with a still further feature of the present invention, at least one winding station and a frame that supports the rolls may be included. The at least one winding station may be coupled to the frame.
In accordance with another feature of the present invention, at least one fixed winding station may be provided having a roll with a horizontal axis. At least one guide roll with a horizontal axis may be arranged between the at least one fixed winding station and the roll stack. In this manner, the at least one guide roll may be contacted by the web when t
Greenblum & Bernstein P.L.C.
Huynh Louis
Vo Peter
Voith Sulzer Papiertechnik Patent GmbH
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