Method and device for folding sheet piles

Details Method and device for folding sheet piles Method and device for folding sheet piles

1999-02-18

2001-03-06

Gerrity, Stephen F. (Department: 3721)

Manufacturing container or tube from paper; or other manufacturi

Control means energized in response to activator stimulated...

Responsive to work material, the product or means engaging...

C493S029000, C493S033000, C493S036000, C493S416000

Reexamination Certificate

active

06196959

ABSTRACT:

FIELD OF THE INVENTION
The present invention refers to methods and an apparatuses for folding stacks of sheets making use of folding devices of the type used e.g. in a paper handling device.
BACKGROUND ART
Paper handling devices are primarily used by large enterprises, banks, insurance companies, service-rendering enterprises, etc. In these enterprises, the paper handling devices serve to process large amounts of paper, such as in voices, reminders, statements of account, insurance policies, or cheques. For obtaining at the end of the paper handling device an appropriate combination of various necessary papers, it is necessary that, after having been printed, the various papers are correctly processed by the paper handling device. This processing takes place at successive stations of the paper handling device and comprises e.g. separating, sorting, collecting, folding and stapling of the various papers as well as subsequent enveloping of the assorted material, and stamping of the finished letter so that letters ready for dispatch are discharged at the output of the paper handling device.
The present invention refers to methods and apparatuses for folding stacks of sheets, which are adapted to be used e.g. in paper handling devices of the kind described hereinbefore. In such paper handling devices, stacks of sheets, which may comprise different numbers of sheets, are combined for the respective letters. The expression stack of sheets as used in the present context is intended to comprise an individual sheet as well as a plurality of sheets.
Depending on the fibre orientation, the kind of fibres, the basis weight, the thickness etc., a sheet of paper has a varying ease of folding, i.e. a varying folding resistance. The folding resistance of a stack of sheets is therefore defined by the ease of folding of the individual sheets forming the stack of sheets and by the number of sheets forming said stack of sheets. This folding resistance of a stack of sheets means that the folding speed used can only be a speed that is adapted to one of the above-mentioned characteristic values, viz. fibre orientation, kind of fibres, basis weight, thickness as well as the number of sheets folded at a time.
If pieces of paper which differ with regard to their ease of folding, i.e. with regard to their folding resistance, are to be processed in known devices, the folding speed must be chosen such that also the material having the least ease of folding, i.e. the highest folding resistance, can still be processed. This means that the device must always be operated at the lowest necessary speed; this will, of course, result in performance losses within the respective cycle. Modern folding mechanisms are therefore often equipped with a mechanical or an electrical adjustment mechanism with the aid of which the speed is adjusted by the operator of a device prior to a job. The expression job refers here to a production cycle in which a plurality of stacks of sheets, which may differ with regard to their ease of folding, are folded.
If, however, varying numbers of sheets are collected prior to the folding operation in a job in which paper with identical characteristic values is processed, it will be necessary to adjust also in the case of the above-mentioned operator adjustment for a job the lowest necessary speed for the whole job, and this will again result in losses within the respective cycle.
DESCRIPTION OF PRIOR ART
DE 4446206 A1 describes an apparatus for preparing consignments or the like, which consist of different numbers of pages, for enveloping. The known apparatus is provided with a device for successively transporting individual pages of the consignments to be prepared and with means for separating the pages of a respective consignment to be prepared from the pages of the subsequent consignment and for combining the respective pages associated with a consignment to be prepared. The apparatus is additionally equipped with a limit value counter used for counting the pages of the respective consignment to be prepared. As long as the number of pages counted by the limit value counter for one consignment is below a limit value, the consignment will be folded by means of a folding unit arranged in the transport path of the consignments. If the number of pages for a consignment which has been registered by the limit value counter is, however, equal to or larger than the limit value, the consignment will not be folded, but it will be advanced without having been folded. The apparatus described in DE 4446206 A1, does, however, not provide a solution for the above-described problem, since, for a job to be executed, it is still necessary to adjust the folding speed to the maximum stack height that still has to be processed. Furthermore, consignments whose number of sheets exceeds a predetermined limit value are not folded at all.
DE 39 34 623 A1 discloses a device for determining the folding force of single-layer or multi-layer paper samples of different thicknesses to be folded, said device being adapted to be used for measuring the paper height and the compressibility during folding.
DE 31 20 526 A1 discloses a folding device where the belt speed of a feed belt and the cycle rate of the folding machine are determined by a computing unit in dependence upon parameters of the paper, such as format length, format width, paper properties, weighting factors etc. The parameters are inputted in a computer via an input means, and the computer outputs e.g. the belt speed and the cycle rate, which are converted into analog control variables.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a method of folding a plurality of temporally successive stacks of sheets, which permits an optimized control of the folding speed of the folding device.
In accordance with a first aspect of the present invention, this object is achieved by a method of folding stacks of sheets, which can consist of one or of a plurality of sheets that may have different folding resistances, by supplying a plurality of stacks of sheets to a folding device by means of a temporally successive, cyclic supply which comprises phases of movement and pauses in movement, said method comprising the following steps: determining a stack folding resistance for a respective stack of sheets on the basis of at least the number and/or the folding resistance of the individual sheets forming a stack of sheets; and folding a respective stack of sheets, the folding speed used by the folding device for folding said stack of sheets being controlled in dependence upon the stack folding resistance that has been determined for this stack of sheets, the control of the folding speed of the folding device being carried out during respective pauses in movement of the cyclic supply in such a way that, in the case of a reduction of the folding speed for the folding of the next stack of sheets to be folded, the pause in movement is extended, if the necessary folding-speed reduction is not achieved during the normal pause in movement of the cyclic supply; that, in the case of an increase in the folding speed for the folding of the next stack of sheets to be folded, the pause in movement is, depending on the time required, either extended, if the necessary increase in the folding speed is not achieved during the normal pause in movement of the cyclic supply, or not extended, although the necessary increase in the folding speed is not achieved during the normal pause in movement.
Thus, the present invention provides a method of folding stacks of sheets, which can consist of one or of a plurality of sheets that may have different folding resistances, by supplying a plurality of stacks of sheets to a folding device by means of a temporally successive, cyclic supply which comprises phases of movement and pauses in movement, said method comprising the steps of first determining a stack folding resistance for a respective stack of sheets on the basis of at least the number and/or the folding resistance of the individual sheets forming a stack of sheets, and

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