Pressure processing roll

Details Pressure processing roll Pressure processing roll

1999-05-07

2001-03-20

Cuda, I (Department: 3726)

Roll or roller

Rotatable relative to supporting shaft

C492S020000

Reexamination Certificate

active

06203480

ABSTRACT:

CROSS-REFERENCE TO RELATED APPLICATIONS
The present application claims priority under 35 U.S.C. §119 of German Patent Application No. 198 22 144.4, filed on May 16, 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 concerns a pressure processing roll with a roll jacket, the roll jacket being rotatably mounted on a carrier by a bearing arrangement.
2. Description of Background Information
A pressure processing roll in which the bearing arrangement has at least one hydrostatically supported bearing surface, which forms a gap with an opposing surface, is known from German Patent No. DE 33 48 209 C2.
Such rolls are suitable for numerous applications, for example, for calenders; smoothing machines; press sections of paper, pulp, and printing machines; or rolling mills for steel, plastic, and the like. The roll works with an opposing roll such that a material web can be guided through between the two rolls and processed under pressure in the nip between the two rolls.
In this process, the roll jacket may sag. When the roll jacket sags, a nonuniform nip will develop over the axial length of the roll. However, usually, some mechanism is provided in such pressure processing rolls to oppose the sagging of the roll jacket. The mechanism may be, for example, a set of support shoes which are disposed between the roll jacket and the carrier (roll jacket carrier). The roll jacket may be alternatively provided with a hollow interior or cavity, which is subdivided into two or more chambers in the circumferential direction, the chamber adjacent to the nip being placed under the pressure of a hydraulic fluid.
Where the pressurized hydraulic fluid is used to counteract the sagging of the roll jacket, in all cases in which an elevated pressure exists in the interior of the roll jacket, it is necessary to seal the cavity or interior of the roll jacket by transverse seals of the ends of the roll. In these transverse end seals, parts which are movable relative to each other must work together, which causes significant wear. Moreover, the wear increases with the operational speed of the roll. It is not necessary, however, that the transverse end seal completely prevent the escape of hydraulic fluid. The task of the transverse end seals is rather to maintain the pressure in the interior of the roll jacket at a specific level.
SUMMARY OF THE INVENTION
In view of the shortcomings of the prior art, an object of the invention is to provide a transverse end seal for the interior which operates with low wear even at high speeds.
According to one aspect of the present invention, a pressure processing roll, having an axis, includes a carrier and a roll jacket. A bearing arrangement rotatably mounts the roll jacket on the carrier, and has one or more hydrostatically supported bearing surfaces that form a gap with an opposing surface (e.g., within the bearing), a normal force of the hydrostatically supported bearing surface having an axially oriented component. An axial pressure mechanism applies a predetermined, axially oriented force on the bearing arrangement in the direction of the axis to substantially completely close the gap in the absence of hydrostatic pressure in the hydrostatically supported bearing surface or surfaces.
In another aspect of the present invention, a pressure processing roll connectable to a hydraulic system includes a substantially cylindrical roll jacket having a hollow interior; and a carrier within the roll jacket, the carrier extending along a rotational axis of the roll jacket. A first bearing at one end of the roll jacket and a second bearing at the remaining end of the roll jacket connect the carrier and the roll jacket. Each of the first and second bearings have a hydrostatic gap between two internal surfaces of the bearing that are transverse to the rotational axis. The hydrostatic gaps hydrostatically support the ends of the roll jacket when pressurized by the hydraulic system. A gap closing mechanism applies pressure to the second bearing in a direction transverse to the rotational axis, to close the hydrostatic gaps when the hydraulic pressure in the hydrostatic gaps is lower than a predetermined pressure. The gap closing mechanism closes off the hollow interior of the roll jacket by closing the hydrostatic gaps.
That is, the object is accomplished in a pressure processing roll of the type mentioned in the introduction in that the bearing arrangement is acted upon by a predefined, preferably axially oriented force, which substantially completely closes the gap or gaps in the absence of the hydrostatic pressure.
The axially oriented force thus counteracts the hydrostatic pressure which prevails in the gap or gaps. Thus, the gauge of the gap can be set or maintained at a predefined value. When the hydrostatic pressure drops or even disappears, for example, during an interruption in operation (or when shut down), the gaps are closed by the axially acting force such that no hydraulic fluid can leak from the hollow interior of the roll jacket through the nip. Likewise, during operation, no fluid can leak from the interior or cavity since the hydrostatic pressure (which is, as a rule, at least as great as the hydraulic pressure in the interior or cavity of the roll jacket) prevails in the nip. For example, where the hollow interior is pressurized by a hydraulic system, and the hydrostatic gaps connect the hollow interior and an exterior of the roll jacket, the first and second hydrostatic gaps may be pressurized by the hydraulic system to a pressure no less than a pressure of the hollow interior, thereby maintaining the pressure of the hollow interior. To be sure, hydraulic fluid will pass out through the gaps; however, no loss of pressure in the interior of the roll jacket is associated with the passage of the hydraulic fluid through the gaps.
In one modification, the bearing arrangement includes at least one bearing having an inner ring and an outer ring, and the inner or the outer ring is divided in two parts in a radial direction of the pressure processing roll, the two parts being a radially inner part and a radially outer part. The radially inner part has a concave arch on a radial outer side, and the radially outer part has a convex arch on a radially inner side, adapted to the concave arch. The two arches thus work together such that the outer ring can execute a tilting motion on the inner ring; or the inner ring, in the outer ring. Thus, the sag of the carrier (which passes through the roll jacket) under load is taken into account. Under such sag, the carrier has, on the ends where the bearing or bearings are disposed, a certain inclination such that the axis of the carrier at the bearings no longer coincides with the rotational axis of the roll jacket. Based on the modification described, tilting is permitted without the occurrence of additional wear occurring.
In such a case, the concave arch and the convex arch may each have a constant radius. In other words, each of the first and second bearings further includes a spherical journal bearing formed therein for permitting relative tilt of the carrier and the roll jacket. Thus, particularly large tilt angles can be realized without the risk that the pressure in the interior can leak at the contact surface between the inner ring and the outer ring. Further, each spherical journal bearing may include at least one seal at this contact surface, e.g., in an interfacing portion of the spherical journal bearing.
The inner ring may be the ring that is divided in two in the radial direction into the radially inner part and the radially outer part. In this case, when the carrier sags, the inner ring assumes an angle immediately, i.e., the inner ring is tilted relative to the outer ring. Additional movements do not have to occur until there is a change in the sag of the carrier. If the outer ring, instead, is divided, a tilting motion occurs with every revolution of the roll.
The axial pressure mechanism may include a hyd

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