Presses – With additional treatment of material – Heating – cooling – or drying
Patent
1996-10-20
1998-07-21
Gerrity, Stephen F.
Presses
With additional treatment of material
Heating, cooling, or drying
72240, 425 3, 492 8, 100168, 100176, 100917, B30B 304, B30B 1534
Patent
active
057821771
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to an arrangement of rollers with parallel axes which can be adjusted to one another for creating pressing power which is evenly distributed along the length of the rollers for treating web-shaped materials.
2. The Prior Art
Such roller arrangements are known, for example, in the textile industry as foulards and in the paper industry as calenders. Furthermore, they are used in the leather-and plastics-processing industries and the field of metallurgy.
The design and operation of such roller arrangements involve difficulties in the production and maintenance of a pressing power in the roller's working gap which is constant or evenly distributed along the rollers' working width. This is caused primarily in that the entire required force is applied to the rollers at their shaft ends. As a result of the shaft being pressed together, the rollers bulge in opposite directions, the bulge being largest at its center. Therefore, the pressing power between the rollers decreases towards the center if appropriate preventative measures are not taken.
The technique of grinding the roller so that it is convex to compensate for the bulge is known. Apart from the extreme difficulties with regard to engineering which are involved, such a measure can achieve equal distribution of the pressure along the working gap at a certain pressure only. If the pressure is lower, the pressing power decreases near the center, meaning that it increases in the opposite direction.
This disadvantage can be avoided in a known way by constructing the roller as a hollow cylinder and providing it with a stationary shaft, a so-called stationary crosshead, upon which the ends of the hollow cylinder are mounted in such a way that it can rotate. The pressure is applied to the ends of the stationary shaft, whereby it bulges together with the hollow cylinder in the direction opposite to that in which the force is applied.
The bulge in the hollow cylinder is compensated in that the space between the stationary shaft and the hollow cylinder is divided into two longitudinal chambers. The chamber adjacent to the opposing rollers is filled with a pressurized medium which helps to create excess pressure in this chamber. As a result, this area of the hollow chamber bulges against the stationary shaft, thereby compensating the bulge created by the pressing power.
The seal of the pressurized chamber against the adjacent chamber in the circumferential direction, which is not pressurized, causes considerable difficulties during both production and operation of the roller, especially with regard to the seal at the point subject to sliding friction on the inner shell surface of the hollow cylinder. These difficulties are eliminated in a known way by separating the seal and support functions by evenly distributing hydraulic or pneumatic pressurized elements along the roller length between the stationary roller and hollow cylinder and near the pressurized chamber instead of a hydraulic fluid. These elements then act directly at the working gap, and therefore the line which is in contact with the opposing roller.
In this case also, however, the pressurized elements leak and signs of friction appear in the pressurized elements' support bearings on the inner shell surfaces of the rotating hollow cylinder in a number of different designs. As a result, costly and difficult maintenance work is necessary.
Therefore, various roller arrangements have become known which eliminate the disadvantage that the counterforces between the pressurized elements and the inner shell surface of the hollow cylinder are absorbed by a magnetic cushion, i.e., a magnetic field between the two magnets with opposite poles. Such a roller arrangement is described, for example, in the patent claim DE 391 84 13. Permanent magnets are preferably used in this case.
Roller arrangements are also known in which the inner counterforces are produced electromagnetically to compensate the deformation. This eliminates the need for an o
REFERENCES:
patent: 3456582 (1969-07-01), McClenathan
patent: 4062097 (1977-12-01), Riihinen
patent: 4142281 (1979-03-01), Muller
patent: 4290353 (1981-09-01), Pav et al.
patent: 4485540 (1984-12-01), Riihinen
patent: 4985972 (1991-01-01), Sollinger et al.
patent: 5392702 (1995-02-01), Suzuki
EMS Elektromagnetische Systeme GmbH
Gerrity Stephen F.
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