Roll or roller – Concentric layered annulus – Specific composition
Reexamination Certificate
2000-10-27
2004-02-24
Kelly, Cynthia H. (Department: 1774)
Roll or roller
Concentric layered annulus
Specific composition
C492S053000, C492S050000, C428S375000, C428S036200, C428S036300, C428S900000
Reexamination Certificate
active
06695756
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for the manufacture of an elastic roll having a hard roll core including in particular of metal and an elastic covering layer, wherein, to form the elastic covering layer, a fiber bundle including of a plurality of fibers is wound onto the roll core to form fiber layers lying on top of one another, with the direction of winding of the fibers being essentially parallel to one another and at an angle to the peripheral direction of the roll core. The invention is further directed to a roll, in particular for the smoothing of paper webs, having a hard roll core including in particular of metal and being provided on its outside with an elastic covering layer which comprises a plurality of fiber layers lying radially on top of one another and comprising of a soft matrix material with fibers embedded therein.
2. Discussion of Background Information
Elastic rolls of this kind are used, for example, in the satining of paper webs. Here, one elastic roll forms, in each case together with a hard roll, a press gap through which the paper web to be treated is guided. While the hard roll has a very smooth surface including, for example, of steel or chilled cast iron and is responsible for the smoothing of that side of the paper web facing it, the elastic roll acting on the opposite side of the paper web effects a homogenizing and compacting of the paper web in the nip. The order of magnitude of the rolls ranges from lengths of about 3 to 12 m and diameters from about 450 to 1500 mm. They can withstand line forces of up to about 600 N/mm and compressive stresses of up about to 130 N/mm
2
.
As the trend in paper manufacturing is towards performing satining in an online operation, i.e. towards guiding the paper web exiting the paper machine or coating machine directly through the paper smoothing apparatus (calender), higher demands than previously are made on the rolls of the smoothing apparatus, particularly on the elastic covering layers of the rolls. As a result of the high transportation speeds of the paper web required in online operation and the high rotation speeds of the calender rolls associated with this, nip frequencies, that is the frequencies with which the covering is compressed and relieved of its load again, are achieved, which lead to resonances in the roll jacket or in the rolls.
These resonances lead to vibrations of the calender rolls which lead to transverse stripes perpendicular to the production direction, so-called “barrings” in the surface of the elastic covering of the rolls after a certain running time. These transverse stripes can typically have a width of about 3 to 10 mm in the peripheral direction and a spacing of about 5 to 10 mm.
The vibrations are caused by irregularities which can be caused, for example, by an uneven breast box, irregularities in the roll drive or by other irregularities in the running of the roll. The transverse stripes in the covering layer can occur both due to plastic deformation of the matrix material and to irregular wear. These transverse stripes in the covering layer finally lead to corresponding pressure marks on the calendered paper web so that the quality of the paper web is not sufficient.
The transverse stripes in the covering layer of the roll have to be eliminated by grinding the covering layer which results in a much lower service life of the roll coverings.
SUMMARY OF THE INVENTION
It is an aspect of the invention to provide a method for the manufacture of an elastic roll and to provide such an elastic roll where the occurrence of barrings is avoided.
The part of the aspect relating to the method is satisfied in accordance with the invention, starting from a method of the kind initially mentioned, by at least two fiber layers lying on top of one another being wound alternately in an identical but opposite manner to form a cross-composite layer, i.e. by the angular positions relative to the longitudinal axis of the roll of the fiber bundles of two fiber layers wound in an identical but opposite manner being symmetrical to the cross-sectional surface of the roll, by a damping fiber layer with fiber bundles being wound onto the cross-composite layer, with the angular position of this fiber bundle being substantially flatter than the angular positions of the fiber bundles of the cross-composite layer and by a cross-composite layer again being wound onto the damping fiber layer.
A roll made in accordance with the invention is characterized by the fibers of the fiber layers each, extending at an angle to the longitudinal axis and essentially parallel to one another, by at least two fiber layers lying on top of one another forming in each case a cross-composite layer, with the fibers of the individual fiber layers each extending alternately in an identical but opposite manner, i.e. by the angular positions of the fibers relative to the longitudinal axis of the roll being symmetrical to the cross-sectional surface of the roll, by the covering layer including at least two cross-composite layers, and by a damping fiber layer with fibers of a uniform angular position being provided between the cross-composite layers, with the angular position of these fibers being substantially flatter than the angular positions of the fibers of the cross-composite layers.
The occurrence of barrings is therefore avoided in accordance with the invention by a special winding technique. The rolls manufactured using the winding technique in accordance with the invention have the property of a vibration of the roll being avoided by special damping fiber layers inside the covering layer. While the cross-composite layers including in each case fiber layers wound in an identical but opposite manner have a relatively low E modulus, the damping fiber layers wound in each case in a uniform angular position have a very high stiffness, with pressure forces acting on the covering layer being transferred to the covering layer as torsion due to the very flat angular position of the fiber bundles. In this way, when pressure is applied, minimum torsion of the covering layer occurs, whereby vibrations in the covering layer and so the occurrence of barrings is avoided. The impacts which occur during operation due, for example, to irregularities in the breast box or to irregularities in the drive, are thus taken up by the specially designed damping fiber layers.
In accordance with an advantageous embodiment of the invention, the fiber bundle is wound onto the roll core in a multi-layer design with an essentially uniform angular position to form in each case one of the fiber layers of the cross-composite layers. The fiber layers of the cross-composite layers are thus made in a multi-layer design in each case, i.e. they comprise in each case several layers of fibers of an essentially uniform angular position wound over one another. The required thickness and so the required elasticity of the covering layer is achieved in this way.
At least two or more of these preferably multi-layer fiber layers having a uniform angular position are then put together to form one cross-composite layer in each case. A high stiffness of the covering layer is achieved due to the winding of the individual fiber layers within one cross-composite layer in an identical but opposite manner.
The fiber bundle is preferably wound onto the roll core in one layer to form the damping fiber layer. The damping fiber layers are in this way made substantially thinner than the cross-composite layers so that the stiffness of the covering layer is not disadvantageously reduced. Nevertheless, when pressure is exerted, it is achieved by the thin damping fiber layers, which are not wound in a cross-composite, but in a uniform angular position, that the vibrations in the covering layer and so the occurrence of barrings are avoided.
Within the meaning of the present invention, one-layer defines that when the damping fiber layer is wound, the fiber bundle is wound onto the roll core until the cross-composite layer underneath
Ferguson Lawrenc
Greenblum & Bernstein P.L.C.
Kelly Cynthia H.
Voith Paper Patent GmbH
LandOfFree
Elastic roll and a method for the manufacture of such a roll does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Elastic roll and a method for the manufacture of such a roll, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Elastic roll and a method for the manufacture of such a roll will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3340639