Roll or roller – With antideflection means – Rotatable relative to supporting shaft
Patent
1996-06-24
1998-03-10
Cuda, Irene
Roll or roller
With antideflection means
Rotatable relative to supporting shaft
492 6, B23P 1500
Patent
active
057254656
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for operating a roller, and a corresponding roller.
2. Description of the Prior Art
A roller is shown in DE-PS 34 45 890. This known roller is intended for operation with hydraulic oil, i.e., the two longitudinal chambers are filled with hydraulic oil. The longitudinal chamber located on the side of the roller nip has the higher pressure.
SUMMARY OF THE INVENTION
A disadvantage not only of the roller of DE-PS 34 45 890 but also of other deflection equalization rollers, is that at high speeds, they demonstrate a high internal consumption of drive power. Internal consumption of power refers to portions of the drive power which do not go into deformation of the product but instead are used up by the roller itself, i.e. would come about if the roller were rotating without product.
In so-called floating rollers, the power loss due to friction at the longitudinal seals and end cross-seals is comparably slight. The main portion of power loss lies in the losses due to internal fluid friction, which comes about due to the deflection, at the longitudinal seals, of the oil film entrained at the inside circumference of the hollow roller. Particularly at higher speeds, these losses due to fluid friction make up by far the major portion of the power demand.
The present invention is designed in such a way that the internal power losses are reduced.
This task is accomplished, in its method aspects, by the invention as described below according to a preferred embodiment. By using a gaseous pressure medium in the longitudinal chambers, the internal friction which occurs when the pressure medium layer entrained at the inside circumference of the hollow roller is deflected, and the resulting turbulence, are significantly reduced. The gaseous pressure medium, however, sets higher demands with regard to sealing of the longitudinal chambers, which are met by filling the spaces between the longitudinal seals and the end cross-seals with a sealing fluid. In order to make it impossible for the compressed gas to penetrate into these spaces, the pressure of the sealing fluid is higher than the pressure of the compressed gas, i.e., particularly higher than the pressure in the pressure-active longitudinal chamber on the side of the roller nip. Because of this condition, a small portion of the sealing fluid will constantly enter into the longitudinal chambers, going underneath the longitudinal seals and the end cross-seals, on the inside circumference of the hollow roller. If not corrected, this would result in filling the longitudinal chambers with sealing fluid over time. To prevent this from occurring, the penetrating sealing fluid is continuously removed, so that the pure gas filling of the longitudinal chambers is maintained.
The use of compressed gas as a pressure medium is known in deflection-controlled rollers. An example of this type of roller is shown in DE-PS 36 25 801, which shows a rotating hollow roller with a non-rotating cross-beam. The entire space between the cross-beam and the inside circumference of the hollow roller can be filled all around, i.e. without longitudinal seals, with a compressed gas; and zones can be created at individual points, by radial pressure punches, at which the gas pressure does not prevail. In this way, a unilateral force effect comes about. However, since no longitudinal seals are used here, which would seal off longitudinal chambers demonstrating different pressures from one another, the sealing problem does not exist, or does not exist to a comparable degree.
Another example of an air-supported roller is shown in DE-OS 41 03 799, which has a punch-supported deflection-controlled roller as the pressure roller of a film winder. No details of the formation of the air support are described in that patent.
In accordance with an embodiment of the present invention the compressed gas supplied to the pressure-active longitudinal chamber may be tempered, i.e., heated or, particularly, cooled. The latt
REFERENCES:
patent: 4941247 (1990-07-01), Kubik
patent: 5224448 (1993-07-01), Niskanen et al.
patent: 5338279 (1994-08-01), Scheil
Cuda Irene
Eduard Kusters Maschinenfabrik GmbH & Co. KG
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