EP0455782A1

EP0455782A1 - Rotary sheet offset printing machine

Info

Publication number: EP0455782A1
Application number: EP19900917491
Authority: EP
Inventors: Hermann Fischer
Original assignee: PRINT ASSIST AG
Current assignee: PRINT ASSIST AG
Priority date: 1989-12-04
Filing date: 1990-12-03
Publication date: 1991-11-13
Also published as: WO1991008109A1; JPH04503781A; DE3940019A1; DE3940019C2

Abstract

Afin de pouvoir produire des impressions en offset sur des produits multicouches, un groupe d'impression d'une imprimante offset rotative à feuilles est réalisé sous la forme d'un ensemble d'impression (2), dans lequel au moins un groupe d'impression est formé par un ensemble d'impression (2) chargeable avec des produits multicouches (1), dans lequel le bord arrière de la partie excavée cylindrique (7) du cylindre caoutchouté (4) suit le bord arrière de la partie excavée cylindrique (8) du cylindre de pression (5), dans la mesure requise pour éviter toute rencontre avec les pinces de prise (13), dans lequel un dispositif de maintien à un faible écartement (24) agissant dans la zone d'amenée vers la zone de pression entre le cylindre de pression (5) et le cylindre caoutchouté (6) est associé au cylindre de pression (5), et dans lequel la périphérie du cylindre de pression (5) présente à partir du cylindre caoutchouté (4) un intervalle (23) qui est fonction de l'épaisseur du produit multicouche (1).In order to be able to produce offset prints on multilayer products, a printing group of a rotary sheet-fed offset printer is produced in the form of a printing assembly (2), in which at least one group of impression is formed by a printing assembly (2) loadable with multilayer products (1), in which the rear edge of the cylindrical excavated part (7) of the rubberized cylinder (4) follows the rear edge of the cylindrical excavated part ( 8) of the pressure cylinder (5), to the extent required to avoid any encounter with the grippers (13), in which a device for maintaining a small distance (24) acting in the zone of supply towards the zone pressure between the pressure cylinder (5) and the rubberized cylinder (6) is associated with the pressure cylinder (5), and in which the periphery of the pressure cylinder (5) has an interval from the rubberized cylinder (4) (23) which is a function of the thickness of the mult product icon (1).

Description

Sheet-fed offset printing machine

The invention relates to a sheet-fed rotary offset printing press with at least one printing unit, which contains a rubber cylinder provided with a cylinder pit, with which, on the one hand, a plate cylinder which can be acted upon with ink and dampening solution and also provided with a cylinder pit, and on the other hand, also a cylinder pit in which Grippers are arranged, interacting counter-pressure cylinders.

The known arrangements of this type are used for printing individual sheets. Thicker products, e.g. in the form of multilayer, folded booklets etc., cannot be printed with the known arrangements. If multilayer, thicker products were printed with this, there would be a risk of bulging. In this context it can be assumed that there are air accumulations between the individual layers of such products.

REPLACEMENT LEAF find that can lead to the aforementioned bulge. ^"" The consequence of this would be the risk of so-called greasing, since the bead can come into contact with the rubber cylinder outside the pressure area. In addition, there could be severe wrinkling. In this context, it can be assumed that slight folds cannot be avoided in the folded area of folded products. In the known arrangement in which printing is carried out close to the edge, these folds would be rolled out and thus enlarged.

For the reasons mentioned, it has not hitherto been possible to subsequently provide multilayered products, such as booklets, folded semi-finished products and the like, with a so-called impression using the offset printing process. When it comes to providing such products with an impression, other printing methods, for example the flexographic printing method, still have to be used. The consequence of this, however, is that the quality of the impressions lags behind the other print quality, which is also undesirable. This results in a strong need that has so far not been met.

Proceeding from this, it is therefore the object of the present invention to enable the production of impressions on multilayer products using the offset printing process using simple and inexpensive means.

Starting from a conventional sheet-fed offset printing machine of the type mentioned at the outset, this object is achieved in that at least one printing unit - as with

REPLACEMENT LEAF Multi-layer products feedable impression mechanism is formed, in which the rear edge of the cylinder pit of the rubber cylinder follows the rear edge of the cylinder pit of the impression cylinder more than is necessary to avoid a collision with the grippers, in which the impression cylinder in the inlet area effective hold-down device is assigned to the pressure zone between the blanket cylinder and counter-pressure cylinder, and in which the circumference of the counter-pressure cylinder is spaced from the circumference of the blanket cylinder depending on the thickness of the multi-layer products.

For the first time, these measures enable an impression to be made of multi-layer products in the offset printing process while avoiding the difficulties described at the outset. With the measures according to the invention, therefore, a long-existing need is satisfied for the first time. As a result of the comparatively large wake of the rubber cylinder compared to the impression cylinder, there is advantageously no need to fear wrinkling etc. This results in a larger, non-printable edge area. However, this is not a disadvantage when producing impressions, since experience has shown that the impressions have a larger edge spacing anyway. At the same time, this wake ensures an easy escape of the “air trapped between the individual layers, which is stripped out with the aid of the hold-down device assigned to the counter-pressure cylinder. This results in an elongation of the products and a clean, wrinkle-free system on the circumference of the impression cylinder, which is also necessary to achieve a clean pressure. The foregoing demonstrates that the invention is the one it presented

REPLACEMENT LEAF Solves the task with simple and inexpensive means.

In an advantageous embodiment of the superordinate measures, the rear edge of the cylinder pit of the rubber cylinder can follow the rear edge of the cylinder pit of the impression cylinder by at least 12 mm, preferably by 15 mm to 20 mm. On the one hand, this wake ensures that wrinkles do not roll out reliably and, on the other hand, also results in a pressure application which is within the scope of what is useful in the case of impressions.

A further expedient further development of the superordinate measures can consist in the fact that the hold-down device is designed as a spring-loaded pressure element. In an advantageous manner, this can simply go over the grippers of the counter-pressure cylinder, so that no air pockets can form.

In a further development of the higher-level measures, the size of the distance between the blanket cylinder and the counterpressure cylinder can be below, preferably 5% to 15% below, the thickness of the multi-layer products. On the one hand, this ensures that there are no constraining forces between the cylinders. Nevertheless, the products are reliably pressed, which is advantageous for achieving quality printing.

A particularly simple measure for achieving the relieving Zy¬ distance ^'may be that the diameter of the impression cylinder relative to the diameter of the blanket cylinder simply reduced to the desired level

_REPLACEMENT SHEET is. This measure is particularly recommended when converting existing machines to impression machines, since the cylinder bearing can be retained.

The rubber cylinder can also expediently be covered with a film which has a rubber covering which is preferably glued on only in the indentation area. With this measure, undesired lubrication can be further prevented. At the same time, this results in easier control of the dye and dampening solution. In this context, it can also be advantageous to adapt the effective width of the inking unit and the dampening unit to the width of the impression.

A further, particularly preferred measure can consist in that the counter-pressure cylinder is preceded by a stretching device which comes into engagement with the bottom sheet of the product being fed. It is hereby achieved that the multilayer products are also stretched in the area of their underside, which comes into contact with the cylinder circumference of the impression cylinder, which further prevents wrinkling. This measure can be used in a particularly advantageous manner in the production of a perfecting print.

Further advantageous refinements and expedient further developments of the higher-level measures result from the remaining subclaims and from the following description of an exemplary embodiment with reference to the drawing.

REPLACEMENT LEAF The only figure in the drawing shows a vertical section of a sheet-fed rotary offset impression machine according to the invention in schematic representation.

The impression machine on which the drawing is based for multilayer products 1, such as booklets, folded semifinished products, etc., contains an impression mechanism 2 designed as a sheet-fed rotary offset printing unit. This consists, in a manner known per se, of a PJatten cylinder 3, a Guπi cylinder 4 and one Counter pressure cylinder 5. These cylinders are provided with cylinder pits 6, 7, 8. In the cylinder pit 6 and 7 of the plate cylinder 3 and the rubber cylinder 4 there are tensioning devices 9, 10 for the printing plate 11 and the rubber blanket 12. In the cylinder pit 8 of the impression cylinder 5 there are controlled grippers 13 for holding the front edge of the products 1 provided.

The plate cylinder 3 is supplied by an inking unit 14 with ink and a dampening unit 15 with dampening solution. The impression cylinder 5 interacts with a delivery drum 16, which here is gripped by a delivery belt 17. This can be with ^"a separate drive to be equipped ^•! Therefore be selectively driven so as to be a Schup¬ designed from egten products in the form penstroms or L .izelexe plare.

The impression unit 2 is connected via a feed table 18, which is designed here as a belt table.

REPLACEMENT LEAF upstream ner investor 19. In the exemplary embodiment shown, this is a so-called cassette feeder which has a shaft 21 which can be loaded from above and holds a stack 20 of products 1, the bottom of which is designed as a removal belt 22 through which products 1 can be removed individually and the feed table 18 can be fed. In the area of the feed table 18, the sides and front marks, not shown here, and pre-grippers or infeed rollers can be provided, of which the grippers 13 of the counter-pressure cylinder 5 take over the products 1 and through the gap between the rubber cylinder 4 and Guide impression cylinder 5 through.

The plate cylinder 3 and the blanket cylinder 4 have the same effective diameter D. In the exemplary embodiment shown, the extension drum 16 also has this diameter. In normal sheet-fed rotary offset printing machines for printing on individual sheets, the impression cylinder generally also has approximately the same diameter and its circumference lies against the blanket cylinder. As the products 1, but considerably thicker than ein¬ zelne sheet are _/, in the present imprinter the circumference of the impression cylinder 5 is the cylinder 4 distanced so far from the periphery of the Gummi¬ that a relative to the thickness of the products 1 slight undersize having Direction gap 23 results . The clear width of the gap 23 can decrease the thickness of the products 1 by about 5% to 15%. An undersize of 10% should be provided here. In the exemplary embodiment shown, the counter-pressure cylinder 5 is simply with a correspondingly smaller diameter than the rubber cylinder 4 and the plate cylinder. linder 3 provided. This can be achieved, for example, by turning the impression cylinder of a normal sheet-fed rotary offset printing machine accordingly. This is particularly recommended when converting existing sheet-fed rotary offset printing presses to impression presses according to the invention, since the cylinder bearing can be retained. However, it would also be conceivable for the impression cylinder 5 to be detachable from the blanket cylinder 4 while maintaining its engagement with the delivery drum 16 and / or for the blanket cylinder 4 to be detachable from the impression cylinder 5 while maintaining its position relative to the plate cylinder 3. In such a case, an individual adjustment of the size of the gap 23 would be possible. In contrast, in the exemplary embodiment shown, there is a fixed gap setting, which is sufficient for many applications in which products of known thickness are processed.

With their holding claws which come into engagement with the products 1, the grippers 13 project beyond the circumference of the counter-pressure cylinder 5 by the thickness of the products 1, so that they can be reliably detected. In the case of a rotated counter-pressure cylinder, this can be achieved simply while maintaining the grippers.

Air can be located between the individual layers of the multi-layer products 1. This must be removed to create a clean print. For this purpose, the products 1 are pressed onto the counter-pressure cylinder 5 by means of a hold-down device 24 arranged in the inlet area to the pressure zone between the material cylinder 4 and the counter-pressure cylinder 5. In simple cases

REPLACEMENT LEAF len, the hold-down device 24 can have a spring-loaded pressure plate that extends over the entire length of the cylinder and under which the grippers 4 can pass. In the exemplary embodiment shown, the hold-down device 24 is provided with a gap for the resilient comb plate 25 forming the grippers 13. This can be arranged stationary. In the exemplary embodiment shown, the comb plate 25 is arranged pivotably and can be brought into and out of holding engagement in cycles by means of a cam control 27 cooperating with a spring 26. This cyclical actuation of the hold-down device 24 results in a particularly gentle operation. With the help of the holding-down device 24, the products 1, as can be clearly seen in the drawing, are not only stripped and pressed against the counter-pressure cylinder 5, but at the same time also kept away from the rubber cylinder 4, thus eliminating the risk of lubrication.

The hold-down device 24 also causes the upper layers of the products 1 to be stretched. In order to stretch the lower position of the products 1, which comes to rest on the impression cylinder 5, a stretching device is provided in the area of the contact table 18, which extends to the lower one Able to apply a braking force. In the exemplary embodiment shown, blowing nozzles 28, which are inserted into the feed table 18 and are provided against the transport direction of the products 1, are provided for this purpose and are supplied with compressed air via a supply line 29, whereby the hydrodynamic paradox can develop. Instead of blowing nozzles could of course also on

REPLACEMENT3LATT a vacuum source connectable suction nozzles can be provided. In any case, the stretching device is controlled in such a way that the braking force is only effective when the products 1 are transported by the grippers 13.

In order to avoid collisions of the rubber cylinder 4 with the grippers reaching into the circumferential region on the rubber cylinder side, the cylinder pits 7 and 8 of the rubber cylinder 4 and the impression cylinder 5 do not run with their edge edges on one another. Rather, the rubber cylinder 4 runs after the impression cylinder, as indicated by the caster angle N. This caster dimension is greater than would be absolutely necessary to avoid a collision with the grippers 13 in order to prevent the products 1 from rolling out in the region of the fold edge detected by the grippers 13. In this context, it can be assumed that multilayered folding products have certain folds in the folding area, which would be rolled out in the event of the rubber cylinder 4 running too little in relation to the impression cylinder 5. At the same time, the provided wake ensures an undisturbed escape of the air stripped from the products 1.

The caster angle depends on the product thickness, which means that a weaker caster is required for weaker products than for thicker products. For as universal a use as possible, the caster angle can be selected so that a caster of the rear edge of the cylinder groove 7 of the rubber cylinder 7 in the direction of rotation

REPLACEMENT LEAF - 1 1

4 relative to the rear edge of the cylinder pit 8 of the impression cylinder 5 results in from 15 mm to 20 mm. In the exemplary embodiment shown, this overrun should be 20 mm. This results in a somewhat later use of pressure. However, this is not disadvantageous in the production of impressions, because impressions do not reach the edge of the product anyway. However, the folds of the fold area are prevented from spreading out even with thicker products. In order to accomplish the desired caster, the rubber cylinder 4 is reset by the angle N while maintaining its relation to the plate cylinder 3 with respect to the impression cylinder 5. This can take place in the state or during operation.

The rubber blanket 12 received on the rubber cylinder 4 can correspond to a normal rubber blanket. In the illustrated embodiment, the effective area of the rubber blanket 12 is limited to the printing area. For this purpose, the rubber blanket 12 consists of a carrier film which has a rubber sticker 12a indicated in the indentation area by a dashed line. With this measure, the risk of lubrication can be further reduced. In addition, this has an advantageous effect on the control of the ink and dampening solution supply.

In order to achieve a good ink / fountain solution balance at the same time, the width of the inking unit 14 and the dampening unit 15 is also reduced to the impression area. It would be conceivable to do this by simply reducing the ink and dampening units that are correspondingly narrower over the entire length of the cylinder.

REPLACEMENT LEAF and dampening systems. In the exemplary embodiment shown, this is simply achieved by lateral stripping devices in the form of stripping knives which can be adjusted to a dyeing or dampening agent transfer cylinder. This has the advantage that ^" continuous dyeing and dampening units can be used over the entire length of the cylinder.

In the case of impression works, a quick plate change is often desired. In order to accelerate the plate change, an automatic plate changing device 31, which is assigned to the plate cylinder 3 and is provided with cassettes 32 for the plates that are used or used one after the other, is provided in the exemplary embodiment shown. To achieve a flying plate change, two impression mechanisms could be provided, one of which is activated and the other is passivated for the plate change.

REPLACEMENT LEAF

Claims

- 1 3 -patent claims

1. Sheet-fed rotary offset printing press with at least one printing unit which contains a rubber cylinder (4) provided with a cylinder pit (7), with which on the one hand a plate cylinder provided with ink and fountain solution and provided with a cylinder pit (6) (3) and, on the other hand, a counterpressure cylinder (5), which also has a cylinder pit (8) in which grippers (13) are arranged, cooperate, characterized in that at least one printing unit can be used as an impression unit which can be loaded with multilayer products (1) (2) is designed in which the rear edge of the cylinder pit (7) of the rubber cylinder (4) follows the rear edge of the cylinder pit (8) of the counter-pressure cylinder (5) more than to avoid a collision with the grippers ( 13) is necessary in which the counter-pressure cylinder (5) is assigned a hold-down device (24) which is effective in the inlet area to the pressure zone between the counter-pressure cylinder (5) and the rubber cylinder (4) nd in which the circumference of the impression cylinder (5) is at a distance (23) from the circumference of the rubber cylinder (4) as a function of the thickness of the multilayer products (1).

REPLACEMENT LEAF 14 -

2. Sheet-fed rotary offset printing machine according to claim 1, characterized in that the rear edge of the cylinder pit (7) of the blanket cylinder (4) traces the rear edge of the cylinder pit (8) of the impression cylinder (5) by at least 12 mm, preferably by 15 mm to 20 mm .

3. Sheet-fed rotary offset printing machine according to one of the preceding claims, characterized in that the hold-down device (24) has a spring-loaded, preferably designed as a comb plate ^' pressing member (25).

4. sheet-fed offset printing machine according to claim 3, characterized in that the pressing member (25) via a cam control (27) is controllable.

5. sheet-fed offset printing machine according to one of the preceding claims, characterized in that the size-e of the distance between the blanket cylinder (4) and impression cylinder (5) is below, preferably 5% to 15% below the thickness of the multi-layer products.

6. Sheet-fed rotary offset printing machine according to one of the preceding claims, characterized in that the diameter of the impression cylinder (5) compared to the diameter of the blanket cylinder (4) is reduced to form the distance (23).

REPLACEMENT LEAF

7. sheet-fed rotary offset printing machine according to one of the preceding claims, characterized in that the impression cylinder (5) relative to the rubber cylinder (4) is adjustable, preferably displaceable, is arranged.

8. Sheet-fed rotary offset printing machine according to one of the preceding claims, characterized in that the rubber cylinder (4) is adjustable, preferably pivotable, relative to the counter-pressure cylinder (5).

Sheet-fed rotary offset printing machine according to one of the preceding claims, characterized in that the rubber blanket (12) received on the rubber cylinder (4) consists of a film which has a preferably glued-on rubber pad (12a) in the impression area.

10. sheet-fed rotary offset printing machine according to one of the preceding claims, characterized in that the effective width of the inking unit (14) is adapted to the width of the impression-S.

11. Sheet-fed offset printing press according to one of the preceding claims, characterized in that the effective width of the dampening unit (15) is adapted to the width of the impression.

12. Sheet-fed rotary offset printing machine according to one of the preceding claims, characterized in that the impression cylinder (5) has a loading side

REPLACEMENT LEAF The stretching device (28) which is preferably arranged in the area of a feed table (18) and which engages with the lowest position of the supplied products (1) is arranged upstream.

13. Sheet-fed rotary offset printing machine according to claim 12, characterized in that the stretching device has nozzles (28) which can be acted upon by air.

14. Sheet-fed rotary offset printing machine according to one of the preceding claims, characterized in that a feeder (19) is provided for deduction from below.

That a rive with its own ⁵ provided delivery belt (17) is provided 15th sheet-fed rotary offset printing machine according to one of vor¬ reciprocating claims, characterized in that a "f the indicated with an impression products (1) by means of a pressure cylinder with the Gegen¬ ( 5) interacting delivery drum (16) can be deposited.

16. Sheet-fed rotary offset printing machine according to one of the preceding claims, characterized in that the plate cylinder (3) is associated with a plate changing device (31).

REPLACEMENT LEAF