Roll or roller – Rotatable relative to supporting shaft
Reexamination Certificate
1999-08-26
2001-03-27
Rosenbaum, I Cuda (Department: 3726)
Roll or roller
Rotatable relative to supporting shaft
C492S007000, C492S020000
Reexamination Certificate
active
06206813
ABSTRACT:
FIELD OF THE INVENTION
The invention concerns an arrangement for prevention of foaming of fluid in a variable-crown roll provided with loading shoes.
BACKGROUND OF THE INVENTION
Variable-crown rolls comprise a stationary axle inside the roll, on which axle the roll mantle is fitted to revolve. The roll mantle is supported in the press direction on the axle of the roll by means of loading shoes acting upon the inner face of the roll mantle, which shoes are pressed against the inner face of the roll mantle by means of the pressure of a fluid.
In paper machines, rolls which form a dewatering press nip are used commonly. It is important that the distribution of the linear load, i.e. the profile, in the axial direction of the rolls can be made invariable and that the profile can be regulated in the desired way, for example, in view of controlling the cross-direction moisture profile and/or thickness profile of the web. Also in supercalenders, the aim is to be able to regulate the calendering nip in the axial direction of the calender rolls so that the cross-direction thickness profile of the web becomes as desired. For this purpose, from the prior art, a number of different variable-crown or adjustable-crown rolls are known, at which attempts are made to act upon the distribution of the linear load in the nip.
In the rolls mentioned above, it has been noticed that foaming of the fluid is a drawback. The rolls comprise a central stationary axle, in which the loading shoes have been fitted, and the loading shoes project from the axle so that their loading members reach contact with the inner face of the roll mantle. When fluid is sprayed onto the inner face of the roll mantle for the purpose of cooling, or when fluid enters onto the inner face of the roll mantle through lubrication of the loading shoes, the fluid strikes against said loading shoe constructions, in which connection the fluid is atomized and is then readily mixed with air. Great changes in the direction of the fluid cause so-called whipping, which further affects the fluid detrimentally and foams it, in which case the fluid must already be replaced after a short period of use. The operation of the hydraulic components of the system is disturbed and their service life becomes shorter.
OBJECTS AND SUMMARY OF THE INVENTION
In the present application, a novel arrangement is suggested for elimination of the drawback mentioned above. In an embodiment of the application, it is suggested that a separate fluid guide is employed, which is fitted to be attached to the displaceable loading shoe by means of an arm. By means of a spring, the guide is pressed into contact with the inner face of the roll mantle. The guide comprises a gently curved face, by whose means the fluid is guided to fall back into a fluid collecting trough before it meets the side face of the loading shoe. Since the guide is attached to the displaceable loading shoe, the guide always follows the shape of the roll mantle and is, thus, in contact with the inner face of the roll mantle in a controlled way irrespective of any deformations of the roll mantle.
In a second preferred embodiment of the invention, a guide is used which comprises a separate loading member, for example a piston operating with fluid pressure, at whose end the guide is fitted. In such a case, the fluid pressure is fitted to be effective at the other side of the piston, and by means of the fluid pressure the guide is kept in contact with the inner face of the roll mantle.
In a third embodiment of the invention, the guide is provided with a through opening, in which connection, by means of a curved face of the guide, the fluid is guided from the inner face of the roll into the through opening and further to fall down into the fluid collecting trough. Also in this embodiment, a separate actuator acts upon the guide, which actuator can be a hydraulic piston actuator, or it can also be a spring actuator, by whose means the guide is kept in contact with the inner face of the roll mantle in connection with any deformations of the roll mantle. Through the through opening in the guide, the doctored fluid can flow through the guide and fall into the fluid collecting trough by the effect of gravity. The embodiment is in particular suitable for press constructions in which the loading shoes are in a lower position.
The invention is characterized in what is stated in the patent claims.
The invention will be described in the following with reference to some preferred embodiments of the invention illustrated in the figures in the accompanying drawings, the invention being, yet, not supposed to be confined to said embodiments alone.
REFERENCES:
patent: 4856154 (1989-08-01), Nikulainen et al.
patent: 5096734 (1992-03-01), Nikulainen et al.
patent: 5170547 (1992-12-01), Nikulainen et al.
patent: 5456645 (1995-10-01), Link
patent: 5846173 (1998-12-01), Grabscheid et al.
patent: 5853359 (1998-12-01), Grabscheid et al.
patent: 5896813 (1999-04-01), Nikulainen et al.
patent: 5980438 (1999-11-01), van Haag et al.
patent: 0340192 (1989-11-01), None
PCT International Search Report (Form PCT/ISA/210), 3 pages.
PCT International Preliminary Examination Report (Form PCT/IPEA/409), 3 pages.
Cuda Rosenbaum I
Steinberg & Raskin, P.C.
Valmet Corporation
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