Roll or roller – With antideflection means – Rotatable relative to supporting shaft
Reexamination Certificate
1998-11-17
2001-01-16
Cuda, I (Department: 3726)
Roll or roller
With antideflection means
Rotatable relative to supporting shaft
C492S016000, C492S020000
Reexamination Certificate
active
06174272
ABSTRACT:
FIELD OF THE INVENTION
The invention concerns a roll, comprising a frame beam, at each of whose ends there are axle journals, the revolving roll mantle being mounted by means of bearings on support of said axle journals, in which roll a glide shoe has been provided in connection with the frame beam in order to produce a loading pressure in the nip between the roll and its backup roll.
BACKGROUND OF THE INVENTION
From the prior art, a number of different variable-crown rolls are known, which are in many cases provided with a possibility of profiling in the longitudinal direction of the roll. In certain applications, such a possibility of profiling is unnecessary, in which case a roll provided with a profiling arrangement is a complicated and expensive solution.
In respect of the prior art, U.S. Pat. No. 3,853,698 can be referred to, from which patent a large hydraulic press roll is known. In accordance with an embodiment described in said publication (FIG.
4
), the roll arrangement is composed of a piston and of a pressurized duct as well as of an articulated shoe, in which way a possibility of inclining the shoe is provided. This arrangement is quite complicated and requires pressurizing devices for the duct, regulation arrangements, etc., which makes an arrangement in accordance with said application expensive.
OBJECTS AND SUMMARY OF THE INVENTION
It is an object of the present invention to provide a roll, which has simple construction and is therefore advantageous, for a number of different applications in which a possibility for profiling of the nip pressure in the longitudinal direction of the roll is not required.
It is an object of the invention to provide a roll by whose means occurrence of bending in the longitudinal direction of the nip is compensated for.
In view of achieving the objectives stated above and those that will come out later, the roll in accordance with the invention is mainly characterized in that a hose filled with fluid has been fitted between the glide shoe and the frame beam in order to equalize the loading pressure transferred through the glide shoe in the longitudinal direction of the roll.
In a particular embodiment of the invention, the roll is a variable-crown roll.
In accordance with the basic idea of the invention, the bending is compensated for by means of a hose or equivalent filled with fluid so that the fluid pressure produced by the loading force, which fluid pressure is uniform over the entire length of the roll, produces a uniform nip pressure likewise over the entire length of the roll. In the arrangement in accordance with the invention, the roll consists of a thin mantle and of a frame beam fitted inside the mantle, onto which frame beam a fluid-filled hose of preferably flat shape has been fitted, onto which hose a glide shoe that operates as a bearing face has been fitted. In the loaded state, when the frame beam bends, the force that supports the glide shoe remains substantially invariable in the cross direction of the machine, because the pressure in the interior of the hose is invariable across the entire area. In the arrangement in accordance with the invention, the support force produced by the pressure in the hose becomes, in a loading situation, equal to the effective loading force.
In accordance with an embodiment of the invention, the possible error that is produced by flattening of the hose at the roll ends and by bulging of the hose in the middle area has been eliminated by shaping the hose so that the effective width of the hose remains invariable irrespective of bending of the frame.
In accordance with an embodiment of the invention, variation in the effective width of the hose can also be reduced by fitting two or more hoses one above the other, and in view of possible situations of oblique loading the hose can be divided into two parts in the middle in the cross direction of the machine, whereby “floating” of the glide shoe on support of the fluid pressure is maintained over the entire length in the longitudinal direction in spite of an oblique load, which might otherwise cause gathering of the fluid in one end of the hose while the other end is emptied of fluid.
A possible variation in the effective width of the hose can also be compensated for by making the frame beam appropriately curved.
The arrangement in accordance with the invention is of simple construction and, therefore, advantageous to carry into effect. Also, the invention permits making of the roll mantle quite thin, because the mantle is not subjected to a significant strain since the glide shoe, the hose and the frame beam receive the loads.
In an arrangement in accordance with the invention, the lubrication of the glide shoe can be made hydrodynamic or hydrostatic, as required. The mantle of the roll is journalled from its ends by means of guiding bearings, which permit a slight movement in the direction of the loading force as a result of bending and of compression of the hose. However, it should be noticed that significant forces are not applied to the bearings, because the roll mantle rests on support of the glide shoe over its entire loaded length.
In the arrangement in accordance with the invention, the pressure in the hose that is used is set in compliance with the area of the hose and with the loading situation so that the support force is equal to the loading force, in which case, in a situation with no load, the pressure in the hose is very close to zero.
Since, in the arrangement in accordance with the invention, the loading pressure is applied to the shoe and is transferred through the hose to the frame beam, flattening of the diameter of the roll mantle in the loading direction, which occurs in prior-art applications, does not occur in the present arrangement.
A roll in accordance with the invention, in particular a variable-crown roll, is suitable for use in a number of different applications in paper and/or board machines and in their finishing machines, for example, as a roll in press nips in which no rolls that can be profiled are needed, as a backup roll for a shoe press, as a roll in an extended-nip press in situations in which the backup roll must be profiled, as an upper and/or lower roll in calenders with one or several nips, etc.
In an arrangement in accordance with the invention, in connection with the roll, if desired, it is possible to fit arrangements by whose means the pressure present in the hose is regulated depending on the loading situation, in which case the ends of the roll mantle are journalled so that the movement in the direction of the loading force, mentioned above, is prevented and the curve form of the roll can be set.
In accordance with the invention, the curve form of the roll can be regulated by setting the pressure inside the hose. In such a case, the journalling of the roll must be fixed, i.e. the movement in the direction of the loading force be prevented. By setting the pressure in the hose, it is also possible to close and to open the nip between the variable-crown roll and its backup roll by means of a system fitted in the interior of the roll. In such a case, the journalling of the variable-crown roll must, however, be floating, i.e. it permits a movement of the necessary extent in the loading direction, and the backup roll must be provided with fixed journalling. Regulation of the curve form, i.e. of the nip pressure profile, and so also closing and opening of the nip, require that an outside source of pressure with a regulation system is arranged in connection with the hose of the roll. When the movements of closing and opening the nip are carried out in this way, loading means fitted outside the roll are not needed at all, which means considerable economies. In some applications, a second glide shoe and a second hose are needed in the roll for opening of the nip if the roll has to be raised in order to open the nip.
REFERENCES:
patent: 3543366 (1970-12-01), Collet
patent: 3853698 (1974-12-01), Mohr
patent: 4455727 (1984-06-01), Tschirner
patent: 4685183 (1987-08-01), Justus
patent: 4747195 (198
Cuda I
Steinberg & Raskin, P.C.
Valmet Corporation
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