Roll, calender, and process for operating a roll

Details Roll, calender, and process for operating a roll Roll, calender, and process for operating a roll

1999-05-26

2001-04-03

Vo, Peter (Department: 3721)

Presses

With additional treatment of material

Heating, cooling, or drying

C100S331000, C100S334000, C100S336000, C165S089000, C165S299000

Reexamination Certificate

active

06209451

ABSTRACT:

CROSS-REFERENCE TO RELATED APPLICATIONS
The present application claims priority under 35 U.S.C. § 119 of German Patent Application No. 198 24 542.4, filed on Jun. 3, 1998, the disclosure of which is expressly incorporated by reference herein in its entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a roll, a calender and a process for operating a roll, and more particularly, to a roll with a core that has an elastic cover extending over a working width and with roller pins on the end faces of the core.
2. Discussion of Background Information
Calender rolls having an elastic cover have been used as a middle roll in a roll stack of a calender. These rolls are often called a soft or elastic calender roll, because the cover causes the surface of the roll to be elastic to a certain degree. A calender roll of this kind cooperates with a “hard” roll in order to satinate a paper web or another material web.
The hard roll is often heated so that the paper web can be acted on with increased pressure and increased temperature in the nip formed between the soft roll and the hard roll. The elastic cover is used primarily for uniform compression of the paper web.
The working width of such a calender roll corresponds to the width of the material web to be treated. The cover can taper conically outside the working width. This tapering extends over an axial length in the size range of approximately 20 to 100 mm. This length prevents the part of the cover that is not covered by a paper web from coming into contact with the counter roll and being damaged. For future reference, only the working region of the cover is referred to as the working width.
Rolls are often damaged during operation because the cover tears or breaks. This damage occurs even in very temperature-resistant or temperature-proof covers that are actually supposed to withstand the temperatures during operation.
Working with heat-carrying mediums is intrinsically known in the related art, for example, from cooling or heating rolls. However, these rolls do not have an elastic cover. Heretofore, when elastic rolls have been temperature controlled, this control occurred by using air to cool the cover.
SUMMARY OF THE INVENTION
The present invention provides a roll for a paper calender. The roll includes a core having opposed end faces and a barrel intermediate the end faces, the barrel having a barrel region. An elastic cover extends over a working width of the core, and a plurality of roller pins are provided, each roller pin engaging an end face and having a pin region. Also provided is a temperature control device adapted to supply heat to and/or dissipate heat from the pin regions to a first temperature, and further adapted supply heat to and/or dissipate heat from the barrel region to a second temperature, wherein the first and the second temperatures are different.
In another arrangement of the invention, the roll may include a core having opposed end faces and a barrel intermediate the end faces, the barrel having a barrel region. An elastic cover extends over a working width of the core, and a plurality of roller pins are provided, each roller pin engaging an end face and having a pin region. Also provided is a temperature control device adapted to control the temperature of the pin regions to a first temperature, and further adapted to control the temperature of the barrel region to a second temperature, wherein the first and the second temperatures are different.
The temperature control device may include a flow path for transporting a heat-carrying medium into and out of the roll. The temperature control device may further be adapted to adjust the temperature of the heat-carrying medium as a function of line load and roll temperature. Furthermore, the temperature of the heat-carrying medium upon entry into the roll and the temperature of the heat-carrying medium upon exit from the roll may differ by no more than approximately 3° C.
Additionally, the roll may further have a displacement body disposed within the core that forms an annular chamber with the inner surface of the core.
A plurality of peripheral bores evenly disposed about the circumference and along the length of the core may further be provided.
Still further, a first heat exchange surface area present on each the pin region and a second heat exchange surface area present on the barrel region may be provided, wherein the first heat exchange surface area is greater than the second heat exchange surface area.
The flow speed of the heat-carrying medium in the barrel region may be greater than the flow speed of the heat-carrying medium in the pin regions.
Also, a predetermined portion of each pin region may extend beyond the working width of the core, and the temperature control device may internally cool the portion of each pin region that extends beyond the working width of the core.
Additionally, the temperature of the heat-carrying medium may be between the temperature of the pin regions and the temperature of the barrel region.
The present invention also provides a calender comprising a plurality of rolls having any or all of the above-mentioned characteristics.
The process for operating a roll according to the present invention includes adjusting temperature progression in an axial direction of the core, as a function of the temperature in the vicinity of the roll and a line load acting upon the roll.
The process may also include heating the roller pins and the barrel. Further, the process may include charging the roll with a heat-carrying medium having an initial temperature between the temperature at the roll ends and the temperature at the axial center of the roll.
Additionally, the process may include cooling the roller pins more intensely than the cooling of the center of the roll.
The process may still further include performing one of supplying heat to and dissipating heat from the pin regions to a first temperature, and performing one of supplying heat to and dissipating heat from the barrel region to a second temperature, the first and second temperatures being different. Further, the process may alternatively include controlling the temperature of the pin regions to a first temperature and controlling the temperature of the barrel region to a second temperature, the first and second temperatures being different.
The process may also include disposing an annular chamber between a displacement body and an inner surface of the core.
Other exemplary embodiments and advantages of the present invention may be ascertained by reviewing the present disclosure and the accompanying drawings.


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