Drying roll for drying a material web

Details Drying roll for drying a material web Drying roll for drying a material web

2001-09-12

2003-02-25

Lazarus, Ira S. (Department: 3749)

Drying and gas or vapor contact with solids

Process

Gas or vapor contact with treated material

C034S452000, C034S122000, C034S128000, C034S636000, C034S110000

Reexamination Certificate

active

06523279

ABSTRACT:

CROSS-REFERENCE TO RELATED APPLICATIONS
The present application claims priority under 35 U.S.C. §119 of German Patent Application No. 100 47 369.5, filed on Sep. 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 present invention relates to a roll to be used in the drying section of a machine for producing a material web, e.g., for guiding and holding a paper web being impacted by a drying gas. The roll has a jacket, which, when in operation, the material web is guided over to partially wrap the roll. The roll also includes gas penetration openings and a device for supplying gas through the roll jacket.
2. Discussion of Background Information
Such rolls are used, e.g., as suction guiding rolls in drying sections in which the material web is dried by jet impingement drying, i.e., blowing the material web with drying air. When the suction guidance roll is provided with suction, the material web is held against the roll and can be guided by the roll in the desired manner.
For this purpose, the interior of the suction guidance roll is embodied in a hollow manner and is normally connected to a suction device by way of the roll bearings. This requires relatively large bearing pins and corresponding bearing support for the suction guidance roll.
Therefore, it is also known to provide the interior of the suction guidance roll with suction by a suction box located outside the roll. However, in this regard, the entire inner chamber of the suction guidance roll is provided with suction. Therefore, the suctioned volume depends on the diameter of the roll and is generally relatively large. This has especially negative effects in the start-up phase because a relatively long time elapses before a desired underpressure is achieved in the roll.
SUMMARY OF THE INVENTION
The present invention provides a roll of the type mentioned at the outset that does not exhibit the above-noted disadvantages. In particular, the start-up phase should be shortened. Moreover, the flow rate of the gas should be optimized and a simple construction of the roll should be attained.
Accordingly, the present invention includes a second, gas-tight jacket in the interior of the roll jacket that forms a ring chamber together with the outer roll jacket. The ring chamber is sealed off from the interior of the inner jacket in a gas-tight manner.
By providing a second, gas-tight jacket in the interior of the roll jacket and, due to the ring chamber formed thereby, which is sealed off from the interior of the inner jacket, the suctioned volume of the roll can be considerably reduced as compared to known rolls. For example, the suctioned space can now include only approximately 10 to approximately 15% of the total volume. A desired underpressure can thus be built up in a shorter time than in the case of known rolls. Moreover, the flow rate of the suctioned air over the size of the intermediate chamber can be brought to a desired amount. In particular, this results in short reaction times upon the introduction of a material web, for example, after the interruption of production due to a web tear or the like.
A further advantage lies in the fact that the roll can thus have a relatively simple construction because the main portion of the roll has only a carrying and support function.
In particular, the roll according to the invention is used as a suction guiding roll for guiding and holding a material web in a drying section in which the material web is dried by jet impingement drying. However, the roll according to the invention can also be used for flow-through drying of a material web, in which a drying gas, e.g., air, is fed through the material web.
It is possible to feed the drying gas through the material web into the intermediate chamber of the roll according to the invention, in particular from outside. Furthermore, the roll is preferably embodied as a suction roll in that a suction device is attached to it. However, instead of this, it is also possible to provide a blowing zone in the region of the wrapping of the outer roll jacket by the material web, e.g., to arrange a blow box there. In this manner, it is also possible to feed a drying gas from the outside through the material web into the intermediate chamber. It is furthermore possible to combine such a blowing zone with a suction device connected to the intermediate-chamber.
If a suction device is used, it is preferably attached to the intermediate chamber on the face end. This simplifies the construction of the roll and prevents a large diameter of the bearings. In this manner, it can be particularly preferred for a suction box to be provided that is aligned with the intermediate chamber. Connective lines between the suction device and the intermediate chamber may therefore be omitted.
In principle, however, the roll according to the invention can also be constructed for the purpose of feeding the drying gas from the intermediate chamber, through the material web, and outwards. In this case, the material web is pressed against the roll by a drying wire.
Preferably, the roll in this case can also be embodied or formed as a blowing roll in that a blowing device is attached to the intermediate chamber. In this case as well, the blowing device is preferably attached to the intermediate chamber on the face side in order to achieve a simple construction of the roll.
It is also particularly preferred for a blow box to be provided that is aligned with the intermediate chamber. This in turn makes it possible for connective lines between the blow box and the intermediate chamber to be omitted.
Instead of a blowing device connected to the intermediate chamber, a suction zone can be provided in the wrapping region of the roll jacket. For example, a suction box can be arranged there. In this manner, it is also possible for drying gas to be supplied from the intermediate chamber, through the material web, and outwards. Such a suction zone can also be combined with a blowing device attached to the intermediate chamber.
In order to prevent waste flows, the blow box and suction box are each sealed off from the outside, e.g., by sealing brushes or doctors. Moreover, covers fixed in the intermediate chamber for the throughput openings of the outer roll jacket can preferably be provided for the region of the roll not wrapped by the material web. This also prevents waste flow and improves the effectiveness of the device.
In order to support the two roll jackets, it is preferable for a central carrier to be provided that extends along the longitudinal axis of the roll, upon which the two roll jackets are supported such that they may be rotated around their longitudinal axes. A particularly advantageous construction results when spoke-like support elements are arranged in the interior of the inner jacket, by way of which the inner jacket is supported on the carrier. Moreover, it is also preferable for the outer jacket to be carried by the internal jacket.
Finally, the size of the intermediate chamber can preferably be selected to correspond to a desired flow rate of the gas. In particular, a greater flow rate and faster reaction time can be achieved by decreasing the size of the inner chamber.
The present invention is directed to a roll for a drying section of a machine for producing a material web. The roll includes a jacket having a plurality of throughput openings, a device for supplying gas through the jacket, and a second jacket located within the jacket being arranged to form a ring chamber with the jacket. The second jacket is gas tight to seal the ring chamber in a gas-tight manner from an interior of the second jacket.
In accordance with a feature of the instant invention, during operation, the material web may at least partially wrap the jacket.
According to another feature of the present invention, the roll can be structured and arranged for guiding and holding the paper web while being impinged by a drying gas,
The material web is guided over at least a portion of the ja

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