Process for exchanging an intermediate roll in a calender

Details Process for exchanging an intermediate roll in a calender Process for exchanging an intermediate roll in a calender

2001-08-21

2003-11-25

Bryant, David P. (Department: 3726)

Metal working

Method of mechanical manufacture

Roller making

C029S402080, C029S426100, C162S199000

Reexamination Certificate

active

06651337

ABSTRACT:

CROSS-REFERENCE TO RELATED APPLICATIONS
The present application claims priority under 35 U.S.C. §119 of German Patent Application No. 100 41 887.2, filed on Aug. 25, 2000, the disclosure of which is expressly incorporated by reference herein in its entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a process for exchanging an intermediate roll in a calender having more than three rolls, whose pressing plane is inclined at a predetermined angle to the vertical. The invention also relates to a calender with a roll stack having more than three rolls whose pressing plane is inclined at a predetermined angle to the vertical.
2. Discussion of Background Information
Such a calender is known from EP 0 979 896 A2. It is used for glazing webs of paper or similar material. The arrangement of the rolls in a plane inclined to the vertical has several advantages. For example, an arrangement which occurs at an angle of about 45° to the vertical allows the influence of weight forces of the rolls on the material web to be glazed to be somewhat reduced. Moreover, the rolls are at least somewhat more accessible than in a calender with a vertical roll stack.
However, in a calender with an inclined roll stack, it is necessary from time to time to exchange a roll. This is the case, for example, when the roll in question has markings or has been otherwise damaged.
In the known case, the roll in question is then pushed out of the roll stack essentially perpendicular to the pressing plane. It can then be picked up and removed by an indoor crane. The installation occurs in the reverse order, i.e., the indoor crane lays the roll onto the ejection device. Then the roll is placed back in its working position in the roll stack in an essentially perpendicular manner.
Such a process has essentially proven itself. However, it is relatively expensive because a device must be present for each roll, at least for each intermediate roll, with which the roll in question can be displaced perpendicular to the pressing plane. This results in a considerable expense.
SUMMARY OF THE INVENTION
The present invention, therefore, facilitates a roll change in calenders arranged diagonally.
Accordingly, the instant invention is directed to a process of the type mentioned at the outset which also includes that at least the rolls located below the intermediate roll are lowered, with the neighboring roll below the intermediate roll forming a maneuvering gap with the intermediate roll and the neighboring roll additionally being lowered by an amount h that is defined by the equation:
h=(r
1
+r
2
)(1−cos &agr;)
where
r
1
is the radius of the intermediate roll,
r
2
is the radius of the neighboring roll, and
&agr; is the angle of the roll stack.
With this embodiment, it becomes possible for the intermediate roll to be exchanged to be moved horizontally without colliding with the lower neighboring roll. Therefore, it is possible during an exchange to simply grip the intermediate roll and remove it from the calender with the aid of the indoor crane without hitting the neighboring roll located beneath it. When the intermediate roll has covered a predetermined distance in the horizontal direction, it can be lifted. However, this lifting occurs at a distance from the rolls located above the intermediate roll, thus excluding the possibility of a collision. This process does indeed require that the rolls located below the intermediate roll to be exchanged be lowered over a relatively large distance. At an incline angle of 45°, the lower rolls must be lowered by approximately 30% of the sum of the radii of the intermediate roll and the neighboring roll. However, the savings in time is considerable. Above all, however, the danger of damage during removal and installation of the intermediate rolls is quite drastically reduced. Because it is no longer necessary to provide each intermediate roll with its own device for ejection of the roll, the calender can be constructed in a substantially more cost-effective fashion than before. The large lowering movement must only be performed when the intermediate rolls are exchanged. If the opening of nips should become necessary for another reason, for example, in the case of a web tear or for the purpose of threading a material web, this can occur using nip openings like before, i.e., using nip openings on an order of magnitude of approximately 10 mm.
Preferably, the neighboring roll is moved laterally at the same time by an amount s, which is defined by the equation:
s=h·
tan &agr;.
With this construction, it is achieved that, upon lowering the neighboring roll, a relatively large lateral distance from between the neighboring roll and the intermediate roll is achieved, such that the further movement of the intermediate roll can occur with even greater freedom of movement.
Preferably, gaps between the rolls below the intermediate roll are adjusted to a size that corresponds to that of the maneuvering gap. Thus, when the rolls located below the intermediate roll are lowered, distances between these rolls are maintained, such that the danger of accidental damage remains small.
Preferably, the size of the maneuvering gaps is set to about 8 to 15 mm. This size has proven itself. A preferred measurement in this connection is about 10 mm.
Preferably, the rolls below the intermediate roll are moved essentially in the pressing plane. In this type of process, it is possible to move the rolls along a lateral edge of the frame such that no additional directions in which the rolls are moved must be added to the adjustment. Here, the rolls need not move precisely in the pressing direction. For example, they can also be mounted on levers that are pivoted. The movement of the rolls therefore corresponds to a small arch. In the present case, however, this arch is seen as still lying in the pressing plane.
Preferably, stops are adjusted for the rolls located below the intermediate roll in order to select the intermediate roll. Depending on which intermediate roll must be exchanged, it is necessary to lower a larger or smaller number of rolls located below it. This can be determined in a simple manner using stops that are adjusted accordingly.
Here, it is preferred for nuts on spindles to be used for adjusting the stops. Thus, a relatively precise adjustment of the stops can be achieved and a sufficiently high speed can be achieved as well.
Moreover, the present invention is directed to a calender of the type mentioned at the outset which also includes that the rolls under an intermediate roll to be exchanged may be lowered by an amount h that is defined by the equation:
h=
(r
1
+r
2
)(1−cos &agr;)
where
r
1
is the radius of the intermediate roll,
r
2
is the radius of the neighboring roll, and
&agr; is the angle of the roll stack.
In such a calender, the rolls neighboring one intermediate roll to be exchanged can be lowered sufficiently far that the intermediate roll can be moved horizontally for installation and removal with the aid of, e.g., an indoor crane. However, such horizontal movement is relatively easy to control. Because that neighboring roll and naturally the rolls located under it as well may be lowered by the corresponding amount, i.e., the above-mentioned distance, they are no longer in the way of the horizontal movement of the intermediate roll. The removal and installation of the intermediate roll are therefore simplified even though the rolls located below it must be lowered by a relatively large distance.
Preferably, the rolls can be moved during lowering in a manner that is essentially parallel to the pressing plane. The devices used for mounting of the rolls, for example, the seating or the frame, can now also be used for guiding the rolls during lowering. This keeps the additional expense low.
Preferably, the rolls, with the optional exception of one upper roll and one lower roll, are mounted on levers that are arranged in a frame in a pivotable fashion, with an adjustable stop being assigned to each lever. When t

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