Folding device

A folding device capable of folding signatures and includes a blade cylinder, which is provided with at least one blade; a counter-pressure cylinder, which is provided with at least two counter-pressure elements which together define an axial gap; and a conveying element which is capable of conveying a signature, and which extends in the axial gap. The blade extends over the axial gap and the conveying element extends in the axial gap with spacing from the blade when the blade co-operates with the counter-pressure elements.

This claims priority to the French patent application number 05 13382, filed Dec. 27,2005, and hereby incorporated by reference herein.

The present invention relates to a folding device, in particular for a rotary press, capable of folding signatures, of the type comprising:a blade cylinder which is provided with at least one blade which is capable of cutting a printed web of material,a counter-pressure cylinder which is provided with at least two counter-pressure elements which together define an axial gap, the blade pressing on the two counter-pressure elements during the cutting operation,a conveying element which extends around the counter-pressure cylinder, which at least partially surrounds the blade cylinder, and which is capable of conveying the web and/or a signature cut from the web at least downstream of the cutting location, and which extends in the axial gap when the blade co-operates with the counter-pressure elements.

BACKGROUND TO THE INVENTION

Document EP-A-1 362 819 discloses a folding device for a rotary press which comprises a blade cylinder or cutting cylinder provided with a blade which is capable of cutting a printed web of material and a plurality of counter-pressure elements which co-operate with the blade and which are arranged so as to form axial gaps between each other.

Web traction belts extend in the axial gaps which serve to guide the printed web or the cut signature. The toothed belts comprise counter-pressure elements which are placed in the axial gaps. The blade also presses on the counter-pressure elements of the belts during the cutting operation.

This folding device has the disadvantage that the belts rapidly become damaged by the blade and must be changed regularly.

SUMMARY OF THE INVENTION

An object of the present invention is to overcome the disadvantage and provide a folding device which has longer maintenance intervals.

The present invention provides a folding device wherein the blade extends over the axial gap and the conveying element extends in the axial gap with spacing from the blade when the blade co-operates with the counter-pressure elements.

According to specific embodiments, the folding device comprises one or more of the following features:the axial width of the axial gap may be sufficiently small for the web to be cut by the blade in the entire zone corresponding to the axial gap;the blade cylinder carries a plurality of blades being distributed over the circumference of the blade cylinder;the blade cylinder including devices for gripping the cut signatures, for example, pincers;the blade cylinder capable of being rotatably driven so that the peripheral speed of the blade cylinder is greater than the travel speed of the printed web of material;the blade cylinder capable of being rotatably driven so that the peripheral speed of the blade cylinder is equal to the travel speed of the printed web of material;the counter-pressure cylinder carries one assembly of counter-pressure elements;the blade being retracted behind the covering surface of the blade cylinder, and the blade being surrounded by protection blocks being of rubber and capable of protecting the conveying element extending around the blade cylinder;the conveying element includes at least a first belt provided with a transport surface being smooth directed towards the printed web of material during operation;the first belt has a round or rectangular cross-section;the first belt extends around the blade cylinder upstream of the cutting location and capable of retaining the web during the cutting operation;a single bank of one or more first belts surrounding the counter-pressure cylinder and extending around the blade cylinder as far as a location for transfer of the signature, and the bank being capable of transporting the signatures from the cutting location to the transfer location;the folding device comprises a first bank of belts constituted by a plurality of first belts surrounding the counter-pressure cylinder and are imbricated with a second bank constituted by second belts, the first and second belt banks capable of transferring a signature from the first belt bank to the second belt bank;the second belt bank extends around the blade cylinder and capable of retaining the cut signatures on the surface of the blade cylinder, the speed of the belts of the second belt bank being identical to the tangential speed of the blade cylinder;the folding device capable of driving each conveying element at a speed equal to or greater than the transport speed of the web; andthe folding device capable of driving each conveying element at a speed greater than the transport speed of the web and less than or equal to the transport speed of the signatures, and less than the transport speed of the signatures.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1illustrates a folding device2according to the invention.

The folding device2is capable of cutting and folding a printed web of material, such as a web of paper4. The web of paper4may have one or more layers. The web4is driven with a web speed V1.

The folding device2is equipped with two pairs of cylinders6and8for traction of the web4. The folding device2includes a blade or fold cylinder10, a counter-pressure cylinder12, a transfer cylinder14and two transfer cylinders16having pincers.

The folding device2is capable of cutting the web4into signatures18or sheets18and transporting the signatures/sheets with a signature speed V2which is preferably greater than the web speed V1.

To this end, the blade cylinder or fold cylinder10and the counter-pressure cylinder12together define a cutting location19which corresponds to the closest location between these two cylinders10,12. Furthermore, the blade cylinder10has a peripheral speed which is equal to the signature speed V2. The rotation speed of the counter-pressure cylinder12is adapted to the speed of the blade cylinder10so that a counter-pressure element26is always present when a blade20presses on the web4in order to cut it.

The blade cylinder10includes three blades20being distributed regularly over the circumference of the cylinder10. The blades20are fixed to the blade cylinder10in a retracted position in which the cutting edge of the blade20is retracted behind the circumference of the cylinder10. Each blade20preferably extends in an uninterrupted manner over the entire axial width of the web4to be cut or the blade cylinder10.

For each blade20, the blade cylinder10is further provided with two protection blocks22of resilient material, such as rubber, which extend at one side and the other of the associated blade20.

Pincers24which are capable of holding cut signatures18are also arranged on the blade cylinder10.

The counter-pressure cylinder12includes one or more counter-pressure assemblies25, each of which is provided with a plurality of counter-pressure elements26which will be explained in greater detail below.

The folding device2is provided with a plurality of first conveying elements, in the form of a first bank of first belts28which extend around the counter-pressure cylinder12, which press on a segment of the surface of the blade cylinder10and on a segment of the surface of the counter-pressure cylinder12. These belts28are capable of conveying the web4and/or a cut signature18downstream of the cutting location19. Each first belt28comprises a round or rectangular cross-section and a smooth or slightly rough transport surface. This smooth surface reduces the soiling of the web. Each first belt28has a speed which is equal to or greater than the web transport speed V1. In a preferred configuration, the first belts28are driven at a speed which is greater than the web speed V1, and equal to or less than the signature speed V2and in particular strictly less than the signature speed V2. In this manner, the traction of the belts28on the web4and on the signatures18is limited and protects the paper.

The folding device2further includes a plurality of second conveying elements, in this instance, belts30which form a second bank of belts. As can be seen inFIG. 7, the belts30of the second belt bank are imbricated between the belts of the first belt bank28so that a signature head18can pass from the first belt bank28to the second belt bank30. The speed of the belts of the second belt bank30being identical to the peripheral speed of the blade cylinder10.

The protection blocks22are capable of contributing to protecting, on the one hand, the first belts28and, on the other hand, the second belts30, against wear by the blades20.

Furthermore, these protection blocks22keep the web4of paper pressed against the counter-pressure elements26at the time of the cutting operation.

FIG. 5is a perspective view of a detail of the counter-pressure cylinder12. As can be seen, the counter-pressure elements26are arranged axially one behind the other in an aligned manner, together forming gaps32in which the first belts28engage during the cutting of the web of paper4.

Each counter-pressure element26comprises a cutting groove34which extends axially and in which the blade20engages during the cutting operation. At each side of the groove34, there is arranged a support surface36which extends parallel with a tangent of the surface of the blade cylinder10and which receives the web of paper4under the action of the protection blocks22at the time of the cutting operation. Furthermore, the support surface36is displaced outwards relative to the surface of the blade cylinder10. Guiding grooves40are arranged in the counter-pressure cylinder12. These grooves40are aligned with the gaps32and extend circumferentially around the cylinder12. The belts28engage in these guiding grooves40.

As illustrated inFIG. 6, when the blade20presses in the bottom of the cutting groove34it extends through each axial gap32and the belt28extends in the gap32with a radial spacing e from the blade. This spacing is preferably 1 mm. In a variant, this spacing is between 0.5 mm and 1.5 mm. In this manner, the blade20is not in contact with the belt28during the entire cutting operation and the belt28is not damaged by this blade20.

Furthermore, the axial dimension of the gap32is selected so that the web4is cut by the blade20in the entire zone corresponding to the gap32. The web4is thus cut over the entire width thereof in a single operation.

FIG. 8illustrates a second embodiment of the folding device according to the invention. This folding device2differs from that described above in the following manner. Elements which are similar have the same reference numerals.

The first belts28extend around a segment of the blade cylinder10upstream of the cutting location19, and are capable of retaining the web4in a zone which extends upstream from the cutting location at the time of the cutting operation. In this manner, the end of the web4that is created by the cutting operation is retained. Furthermore, the first belts28completely surround the counter-pressure cylinder12and are deflected by three deflection rollers50. Consequently, the first belts28are in contact with the counter-pressure cylinder12only in the zone defined by the counter-pressure elements26or are not in contact over the entire circumference of the counter-pressure cylinder12.

This embodiment facilitates the driving of the first belts28at a speed V3which is different from the web speed V1or the signature speed V2.

The second belts30are not illustrated in this Figure.

FIG. 9illustrates a third embodiment of the folding device according to the invention.

This folding device2differs from the folding device described above in the following manner.

The first belts28press, downstream of the cutting location19, against the blade cylinder10on a segment which corresponds to approximately 170°, that is to say, as far as a location for transferring the signature18to the transfer cylinder14. The belts28thus extend around three return rollers50.

Owing to this embodiment, the second belts30may be omitted whilst providing correct guiding of the cut signature18as far as the region of the transfer cylinder14.

In a variant which is not illustrated, the counter-pressure pressure cylinder12carries a plurality of counter-pressure assemblies25or counter-pressure elements26which are distributed over the circumference thereof.

During operation, the blade cylinder10is capable of being rotatably driven so that the peripheral speed thereof is greater than the travel speed V1of the printed web4of material and is equal to the speed V2.

In a variant, the blade cylinder10is capable of being rotatably driven so that the speed thereof is equal to the travel speed V1of the printed web4of material. In this instance, the speed V2is equal to the speed V1.

Preferably, the counter-pressure assembly25and therefore the counter-pressure elements26are produced as a single component, the gap32between two counter-pressure elements being formed by a recess or a groove for guiding the belts28. This variant facilitates the assembly and the production of the folding device.

Furthermore, the cutting groove34may be omitted.

It is self-evident that the belts28may be replaced with another conveying element, for example, a chain.