Roll or roller – With heating – cooling – or heat transfer means
Reexamination Certificate
2001-05-30
2003-04-29
Rosenbaum, I Cuda (Department: 3726)
Roll or roller
With heating, cooling, or heat transfer means
Reexamination Certificate
active
06554755
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a roller device that is designed to maintain and improve concentricity.
BACKGROUND OF THE RELATED ART
It is often crucial that rollers used in a variety of machining processes have working circumferences that are highly concentric. A “rolling device” need not only include devices whereby a web-shaped product is treated in interaction with a counter-roller, i.e., between two rollers. There are also cases where only one roller interacts with a fixed counter-element For example, in a system for ultrasound treatment of a web, a moving roller works together with a sonotrode that is radially directed towards it, and the web, which is to be bonded or cut is passed between the two. An example of such an arrangement is described in DE 198 13 121 C1.
An example of a typical roller device, with a heated roller, is known from European Patent 813 632. A heating device is arranged in a cylindrical recess of the roller body, which device serves to increase the temperature at the working roller circumference and thereby to directly influence the treatment of a web that is conducted using the roller. The goal of the known heated roller is to achieve the most uniform possible heating crosswise to the web, i.e., over the length of the roller. For this reason, so-called “peripheral” bores are provided in the roller body, parallel to the axis, located radially outside of the recess. The bores are partially filled with heat carrier fluid and connected with one another at the ends by annular chambers. The heat carrier fluid condenses at colder spots of the peripheral bores making the temperature in the channel system more uniform. Heating takes place in order to bring the roller to a certain temperature that deviates from the ambient temperature, which temperature is practical for the treatment to be conducted.
It is known in the art for it to be possible to adhere to a concentricity tolerance of 5 &mgr;m at roller lengths of 2 to 3 m. However, even this accuracy is sometimes not sufficient for a uniform bonding process, and can be the cause for the variations in properties of the finished product. Furthermore, any irregularity that is present tends to become more pronounced in operation. In an ultrasound treatment, when a beat defect moves past the sonotrode, the output transferred to the nonwoven increases at this point on the circumference of the roller, and results in a greater amount of heat introduced into the nonwoven. This results in the non-uniform bonding effect and also results in an increase in the amount of heat transferred to the roller in this circumference region. This in turn results in a preferential temperature increase of the roller in the direction determined by the location of the beat defect, and thereby in an increase in the non-concentricity. The variation in the bonding effect therefore increases on its own over the course of operation.
Non-concentricity on the order of 5 &mgr;m, as indicated, is not only attributable to tolerances that exist from the start. Such non-concentricity can also occur later, for example if the roller is given a non-uniform temperature in production, due to some external cause. Even the mere influence of the roller weight itself, when the roller is not moving, can be the cause of slight structural changes that are initiated as a result, leading to non-concentricity on the order indicated, which will increase and build up under the influence of the ultrasound energy transfer.
Thus, in the case of ultrasound treatment systems, the requirements concerning concentricity of the roller are particularly high. This holds especially true for ultrasound bonding of nonwovens made of thermoplastic fibers. Here the ultrasound generator works via the fixed sonotrode, i.e., the ultrasound transmitter, radially against a roller that forms the so-called counter-roller, which carries the bonding pattern in the form of a surface engraving. At the raised parts of the surface engraving, the transfer of ultrasound energy to the nonwoven is particularly intensive, so that here, a preferential temperature increase and preferential melting of the fibers occurs, and in this manner, bonding of the individual threads or fibers of the nonwoven takes place at certain points or along certain lines, in accordance with the pattern, thereby bonding the nonwoven layer.
Even the slightest variations in the distance between the fixed face surface of the sonotrode and the circumference of the moving counter-roller result in a difference in bonding effect. Such a nonwoven demonstrates varying properties that vary with the rhythm of rotation of the counter-roller. For example, this can result in a finished product with a differing feel.
The irregularities as described exist in the circumference direction of the roller, not in the lengthwise direction. If there are temperature differences over the length, these can be combated with the device according to European Patent 813 632, for example, but this device is ineffectual when there are differences in the circumference direction.
The present invention, on the other hand, deals with those deviations that result in bending of the roller body in a plane that passes through the axis, in that the roller body has a slightly higher temperature on one lengthwise side than on the opposite lengthwise side; in this case, it bends like a bimetallic strip, in that the one lengthwise side expands, but the other does not.
However, the effect is not tied to the fact that different temperatures prevail at the opposite lengthwise sides, right from the start. The starting situation for bending that causes non-concentricity can also be a finishing inaccuracy or a structural change, as already mentioned.
The effect to be combated with the invention must also be kept separate from the question whether or not this is a heated roller. The problem according to the present invention can occur both in a heated roller, where any slight temperature differences in the circumference direction are superimposed on the general heating of the roller, and in entirely unheated rollers, where the differences come about as a result of the non-uniform energy introduction of an ultrasound system, for example.
SUMMARY OF THE INVENTION
Proceeding from the problems in the ultrasound bonding of nonwovens as described, the present invention is based on the task of maintaining the greatest possible concentricity of a roller in operation.
This task is accomplished by the present invention which provides a roller device that has a roller. The roller has a cylindrical roller body that forms a working roller circumference of the roller. The roller is rotatably mounted at its end. Also provided is a tempering system assigned to the roller body. The tempering mechanism extends over the length of the roller body and configured to adjust the basic temperature of the roller. An equalization system is provided for preferentially tempering the roller body in a narrow circumference angle region adjacent to a plane that passes through an axis of the roller body.
The means of equalization can fundamentally be a heating means or a cooling means. It is preferred that heat transfer to the roller takes place in a certain direction, seen in the circumference direction, so that the moving roller is non-uniformly heated or cooled, in targeted manner, but not over its length, rather in the circumference direction. With this heat transfer, which takes place only in one direction, i.e., in a zone that is essentially flat or maintains a narrow circumference angle, undesirable lengthwise bending of the roller and the non-concentricity that results from it can be counteracted via the corresponding thermal expansion that is achieved. The bimetallic effect should be canceled out. Therefore, if there is a certain “beat defect,” its effect on the circumference of the roller can be reduced, according to the present invention, by heating the opposite side or by cooling the same side. The temperature differences that must be brought about for this purpose amount to on
Cuda Rosenbaum I
Eduard Kusters Maschinenfabrik GmbH & Co. KG
Kenyon & Kenyon
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