Presses – Methods
Reexamination Certificate
1998-12-17
2001-06-12
Vo, Peter (Department: 3721)
Presses
Methods
C100S15500G, C100S330000, C492S058000, C492S059000
Reexamination Certificate
active
06244171
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
The present applications claims priority under 35 U.S.C. §119 of German Patent Application No. 197 57 185.9, filed on Dec. 22, 1997, 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 an elastic coating for calender rolls, a calender roll equipped with this coating, and a use of this calender roll.
2. Discussion of Background Information
Providing an elastic coating for calender rolls is known in the art of paper finishing. The coating is generally made of compressed fiber rounds and, more recently, of a plastic material. The elasticity of the coating allows compression of the paper to be finished to be evened out, whereby “black glazing” is prevented.
The elastic coatings utilized are often exposed to rather high temperatures, because heat is supplied to the calender rolls as additional deformation energy and because the periodic compression and load alleviation in the coating itself generates heat. If a maximum permissible temperature is exceeded for a certain amount of time, even if only in places, the elastic coating is destroyed and the calender roll becomes unusable. Such overheating arises, e.g., when the compressive strain in the roll nip is set too high or a foreign object, such as a paper strip, adheres to the mating roll.
SUMMARY OF THE INVENTION
The present invention enables better control of problems related to the temperature dependency of the coating.
The present invention the coating may be provided with a color material (colorant) that changes its color depending upon temperature.
The change of color of the color material may almost immediately indicate that a specific temperature has been exceeded. By observing the color material (or the color of the elastic coating with the color material), the operator can draw appropriate conclusions and make countermeasures in a timely manner. Moreover, a control system that monitors the color of the color material can also act automatically.
In this regard, it may be preferable to utilize a color material that changes its color reversibly.
However, advantages may also be realized by utilizing a color material that changes its color irreversibly. The color change may then provide evidence that overheating has occurred, and where the overheating has occurred. This may also be of interest for determining the causes of defects.
In accordance with the present invention, it is not necessary that the color material change its color continuously with temperature. In general, it may be sufficient for the color material to display or exhibit only one color transition that is related to a predetermined temperature.
However, it can be advantageous for the color material to display or exhibit several color transitions, in which each color transition is associated with a predetermined temperature. In this manner, e.g., a critical temperature and/or the approach of the critical temperature can be displayed so that countermeasures can be taken.
In an exemplary embodiment of the instant invention, the color transition may take place or occur at a temperature that lies above a maximum permissible coating temperature. The color transition may be utilized to indicate that the temperature is too high, i.e., that the maximum permissible coating temperature has been exceeded.
Thus, it may be particularly advantageous for the color transition to take place or occur at a temperature that is equal to or somewhat lower than the maximum permissible coating temperature. In this manner, it may be possible to control the calender in such a way so that temperature damage to the coating may be substantially prevented.
The color material may include, e.g., color pigments and/or color crystals. The specific amounts of color pigments and/or color crystals utilized in the color material may be selected so that the color transition occurs at a desired critical temperature and so that the color transition area is compatible with the remaining coating material.
Particularly, the color material may include copper, nickel, cobalt, chrome, vanadium, molybdenum, or uranium salts.
It may be advantageous for the coating to be formed mainly of plastic because plastic may withstand significantly higher temperatures than fibrous materials. Further, plastic may be advantageous because, as a result of the flexing work, the coating may be endangered by localized heating.
Preferably, the color material may be added to the plastic material.
In an alternative embodiment, the color material may be laid onto the surface of the coating.
It may be preferable that the coating be formed, e.g., by an elastic color coat having a relatively thin coating thickness of, e.g., approximately 2 mm or less.
The protection offered by the color material may also extend to protection of a calender roll that is provided with the above-described elastic coating.
In this regard, calender rolls may be protected during use by providing a calender with zone-controlled bending adjustment rolls that are controlled as a function of the color pattern of the coating surface. If the forces exerted by adjacent calender rolls are set to display an even color pattern, it would be apparent that the distribution of force and compressive strain in the roll nip is substantially even.
Accordingly, the present invention is directed to calender apparatus that includes at least one calender roll body, and an elastic coating coupled to the at least one calender roll body. The elastic coating includes a colorant to change a color of the elastic coating depending upon a temperature of the elastic coating.
In accordance with another feature of the present invention, the colorant may be adapted to change color reversibly.
In accordance with another feature of the present invention, the colorant may be adapted change color irreversibly.
In accordance with still another feature of the present invention, the colorant may be adapted to display one color transition related to a predetermined temperature.
In accordance with a further feature of the present invention, the colorant may be adapted to display a plurality of color transitions. Each color transition may be related to a respective predetermined temperature.
In accordance with a still further feature of the present invention, the color transition of the colorant may occur at a temperature above a maximum permissible coating temperature.
In accordance with another feature of the present invention, the color transition of the colorant may occur at a temperature one of equal to and slightly lower than a maximum permissible coating temperature.
In accordance with still another feature of the present invention, the colorant may include color pigments.
In accordance with another feature of the present invention, the colorant may include color crystals.
In accordance with a further feature of the present invention, the colorant may include at least one member selected from the group consisting of copper, nickel, cobalt, chrome, vanadium, molybdenum, and uranium salts.
In accordance with a still further feature of the present invention, the coating may be composed of a plastic material. Further, the colorant may be added to the plastic material.
In accordance with still another feature of the present invention, the colorant may be laid onto the surface of the elastic coating.
In accordance with another feature of the present invention, the elastic coating may be composed of an elastic color coat.
In accordance with a further feature of the present invention, the at least one calender roll may include a deflection adjustment roll having a plurality of press zones, and the plurality of press zones may be controllable as a function of a color pattern of the elastic coating.
The present invention may also be directed to a calender roll that includes an elastic coating with a colorant, the elastic coating is adapted to change color depending upon a temperature of the elastic coating.
The present invention may also be directed t
Greenblum & Bernstein P.L.C.
Huynh Louis
Vo Peter
Voith Sulzer Papiertechnik Patent GmbH
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