Machine for cutting a paper web into sheets with simultaneous cu

Cutting – With means to convey work relative to tool station – Cut made parallel to direction of and during work movement

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Details

83 98, 83152, 83343, 83349, B26D 718, B26D 726

Patent

active

056090846

DESCRIPTION:

BRIEF SUMMARY
The invention concerns a machine for cutting a paper web or a similar material into sheets with simultaneous cutting of a transverse strip for each sheet, comprising a stationary bottom knife arranged transversely to the paper web and a rotatable knife cylinder arranged over said bottom knife and likewise transversely to the paper web and having at least one set of mutually associated knife cutting edges which, by close passage of the bottom knife during the rotation of the knife cylinder, successively cut a sheet and a strip, respectively, from the paper web while said paper web is advanced continuously between the bottom knife and the knife cylinder.
The electronic data processing technology has its origin in the USA where the inch system is used for measuring lengths. From the outset electronic data processing machinery as well as EDP related external printing machines have therefore been designed for advancing and printing endless lists with modules in inches. In countries using the metric system this has caused problems of e.g. filing, and the inch modules do not fit the new generations of modern laser printers which can only work with formats based on the metric system. In countries using the metric system paper webs divided into inch modules must therefore be cut into sheets to a great extend, which are standardized within the metric system, a narrow strip being cut for each sheet. Paper webs which e.g. have a module of 12 inches are thus cut down to 297 mm, i.e. A4 format, with simultaneous cutting of a strip of about 7.8 mm from each sheet.
The patent publication WO 82/00970 describes an apparatus capable of performing such an operation. This construction has a stationary bottom knife and an overlying knife cylinder having two knives arranged on their respective sides of a relatively wide slot, which is cut along the knife cylinder and extends into a bore which is provided centrally in the cylinder and extends out to one of the ends of the cylinder where it communicates with a source of vacuum. This arrangement serves to remove the strips as soon as they have been cut from the paper web, the strips being immediately sucked up into the central bore of the knife cylinder via the space between the knives and the longitudinal slot, following which the strips continue axially out through the bore to a collection point. Cutting does not take place as a cutting operation proper, but is more in the nature of a linear compression of the paper of a magnitude such that the fibres of the paper are crushed and torn across. This process requires very big forces which the knife cylinder must be capable of absorbing. However, the knife cylinder is greatly weakened by the longitudinal slot and the central bore and therefore tends to bend at the center during cutting, which will thus tend to be deficient so that some of the strips are not cut cleanly, but are still partly connected to the sheets to the detriment of the following operations. The weak and unstable construction moreover entails that the knives are worn relatively quickly, and that their cutting edges are liable to be crushed, because it is difficult to adjust the knife distance with the necessary accuracy.
With a view to overcoming the above-mentioned drawbacks, the object of the invention is to provide a machine of the type mentioned in the opening paragraph, which has a knife cylinder offering greater resistance to bending than known before, and a knife arrangement permitting quick and extremely accurate adjustment of the knife distance so that the machine is capable of cutting strips and sheets from a continuous paper web with clean and perfect cuts, continuously and without heavy wear of the knives.
This is achieved by means of the novel and unique features of the invention, wherein the knife cylinder is substantially solid, and the knife cutting edges of a mutually associated set are present on a cross-sectionally substantially rectangular knife device which, with one of its faces, is fixed against a chord face provided on the knife cylinder.
To

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