Paper making and fiber liberation – Processes and products – Lead strip forming and/or guiding
Reexamination Certificate
2000-02-02
2002-06-11
Chin, Peter (Department: 1731)
Paper making and fiber liberation
Processes and products
Lead strip forming and/or guiding
C100S16200R, C100S173000, C226S092000
Reexamination Certificate
active
06402889
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method and device for threading a web through a calender with a roll stack having several rolls which form nips between one another for treating a material web.
While the exemplary embodiment of the invention describes a paper web as an example of a material web, it is noted that the invention is analogously applicable to other material webs that have to be treated in a calender.
The design of the rolls themselves is not significant to the present invention. Both “hard” as well as “soft” rolls can be used which alternate and these so-called “soft” nips or roll slits can therefore be formed. However, the calender can also have exclusively or predominantly hard rolls.
2. Discussion of Background Information
One type of calender is known from EP 0 232 689 A2.
Treating a paper web in a calender, known as glazing, takes place in many cases in off-line operation, i.e., the paper web is typically unwound by a reel spool, guided through the calender and then wound onto a new reel spool. Even if a so-called flying splice, i.e., a flying change between a used and new reel spool, is performed, from time to time it is necessary to guide the beginning of the paper web through the roll stack, for example, after the web has torn. This threading can take place manually which, as a rule, normally requires two members of the operating crew standing on either side of the roll stack. In this process, the paper web is folded together at its tip into an arrow shape and slid through the first nip. The operating crew member receives the paper web on the other side, guides it around reversing devices, as the case may be, such as guide rollers, and again inserts it into the next desired nip. This manual threading process is relatively time-consuming, laborintensive, and raises safety concerns. Even if the web of paper is moved in this case only at a relatively low speed of 10 to 20 m per minute, it can easily result in dangerous situations or even accidents.
In an effort to address these concerns, EP 0 232 689 A2 discloses the possibility of automating the insertion of the paper web. To do this, a web guidance device having a guide surface as well as a blower device is always arranged between two nips, i.e., always on one roll. The web hitting the guide surface is then slid along the guide surface in the desired direction with the aid of the blower device.
A calender structured in this way can be operated automatically in a certain respect. The danger that accidents to persons will occur during threading is also considerably less. However, the effort and thus the costs for the web guidance device are very high. Complicating this further is that the accessibility of the calender during operation is dramatically restricted. If a web tears, something which cannot reliably be avoided in practice, the web guidance device can cause dangerous paper jams which can cause resulting damage to rolls and other devices. Moreover, this design obstructs the view of the running paper web and makes changing the roll more difficult.
SUMMARY OF THE INVENTION
The present invention reduces the possibility of malfunction in operation by utilizing a threading device.
In particular, the present invention provides a calender of the type mentioned at the outset that also includes a movable web guidance device, which can be fixed in at least one insertion position, arranged on at least one side of a roll stack.
“Side” in this case does not refer to the face, but rather to the front or rear side of the roll stack on which the material web must be reversed in order to be guided into the next desired nip.
Thus, the advantages of a mechanized system are exploited without having to accept its disadvantages. The web guidance device is available for threading the beginning of the material web into the calender. In this threading process, however, it is possible to make do with a far lower constructive cost because the web guidance device can be moved from one insertion position to the next one. If the tip of the material web has been inserted into a nip, the web guidance device has performed its function at this point and is no longer required there. In the time that the paper web on the other side of the roll stack needs to be reversed and inserted into the next nip, the web guidance device can be shifted or moved to the next nip in order to receive the tip of the material web and again transport itself to the next desired nip. Based on this movement of the paper guidance device, it is clear that in operation most of the nips are free from the web guidance device so that it cannot cause malfunctions in operation. Nevertheless, threading or inserting the material web can be widely automated or at least mechanized so that the danger of accidents to the operating personnel remains low.
In one embodiment the web guidance device is initially fixed in a parked position where no nip is covered by the web guidance device. In operation, the material web can be observed just like in a calender which has been threaded by hand. That is, the device should not obstrict the view of the web travel through the nips. As a result, monitoring possibilities are improved quite significantly and the possibility of malfunctions is reduced still further.
The invention incorporates a traverser which is arranged advantageously on the side of the roll stack and the web insertion device is fastened to the traverser. Traversers are present in many calenders at any rate, and they are typically used for maintenance purposes, for example, to detach or fasten bearings of rolls being replaced. They can also be used to assist in manually operated threading of paper webs. Thus, using a conventional traverser makes a transport medium for the web guidance device available without greater additional expense.
In another embodiment, position switches are provided along the path of movement, each of which is assigned to an insertion position wherein these switches. are connected with a drive control. As a result of this design, the movement of the web guidance device can be controlled automatically or at least semi-automatically. In operation, the web guidance device is moved into the position where it receives the tip of the material web and/or can pass it on to the next desired nip. The position is determined, for example, by the position switch. If the web guidance device is moved into the next position, it also actuates the position switch there and thus reports the arrival to the drive control. On the other hand, provisions can be made in the drive control so that the web guidance device does not have to stop at every position, such as when some nips are supposed to be skipped when treating the paper web.
The web guidance device may advantageously have a guide surface arrangement. The tip of the paper web impacts the guide surface arrangement and is. guided in the desired direction thereby. The structural expense in this connection is relatively low.
Here, it is preferred for the guide surface arrangement in this connection to have a modifiable form. The guide surface arrangement can then also be used as “soft.” Thus, it is possible to guide the paper web either immediately into the next nip of the roll stack or to jump over several nips and guide the. paper web parallel to the roll stack if this is desired for the treatment of the paper web.
In this connection, it is particularly preferred for the guide surface arrangement to have an evenly formed surface running essentially parallel to the direction of movement of the traverser and a reversing surface that can be moved out of the evenly formed surface. As long as the reversing surface does not project beyond the evenly formed surface, the paper web will be guided essentially parallel to the roll stack, i.e., will be able to skip several nips. If, on the other hand, the reversing surface is moved out of the evenly formed surface, the paper web will be diverted in order to be inserted into the next nip.
Another embodiment is provided
Gwosdz-Kaupmann Michael
Hermsen Thomas
Kayser Franz
Wenzel Reinhard
Chin Peter
Greenblum & Bernstein P.L.C.
Hug Eric
Voith Sulzer Papiertechnik Patent GmbH
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