EP1880846B1 - Sheet-fed offset printing press - Google Patents

Description

The invention relates to a sheet-fed offset printing machine for two-sided multi-color printing preferably on paper sheets, with a first row directly successively arranged printing units for printing the first page of the sheet, a subsequent turning device, then a second series of successively arranged printing units for printing the other sheet side and one or more subsequent coating plants. Such sheet-fed presses in a row construction with one or more arranged at the end of the machine coating units for painting the last printed sheet side are known and are offered by several manufacturers.

It's already in the DE 42 13 024 A1 has been proposed, in machines of the type mentioned, the printed sheets in a machine passage, ie inline to paint on both sides. For this purpose, the printing press has a coating unit and a drying device before the turning device. Thus, there is the recto-print side of the sheet painted and dried before it is turned for the purpose of perfecting.

Since the recto printing side of the sheet is already painted here, before the sheet then passes through the printing column of the perfecting, the gloss of the sheet surface produced by painting decreases again, and that more, the more back pressure or pressure column he goes through. In addition, problems occur in particular when the paint applied to the recto printing side is not completely dried by the drying device. Because optimized for the contact with the oil-based offset inks surfaces of the impression cylinders in the printing unit can be contaminated by paint residues, thus glued paper dust, etc., and would then be laboriously cleaned.

There are also known printing presses, for example from the EP 0 976 555 in which the sheet alternately successively from one above and below the Printed paper transport paths arranged printing unit printed with offset inks and then coated on both sides by a arranged above and below the paper path coating unit. Apart from the fact that this type of printing press has not prevailed because of the poor accessibility of the underlying printing units, the following problem occurs here: When the last color of the reverse side is printed, the sheet has already passed through all printing gaps. Compared to a machine in which only the straight printing side and then the reverse side is completely printed, the printed image is more widened due to the double number of continuous printing gaps ("wider print"), whereby it is not possible to compensate for this effect by a register control.

In addition, separate painting machines are known in which finished printed sheets are painted on both sides. A disadvantage of separate painting machines, however, is the fact that once a stack is formed, which must then be created again afterwards. At the time, the sheets coming from the delivery pile of the press are already powdered, which reduces gloss during subsequent painting and can otherwise lead to problems. In addition, the mechanical engineering effort is higher because it requires two feeders and two outriggers compared to an inline solution.

From the DE 10 2004 058 596 A1 a device for the two-sided finishing of printed products is known, in which the sheets are each painted by a coating unit arranged above and below the sheet transport path ( Fig. 5 ). Apart from the fact that the sheets are printed on the device described there only on one side, the two coating units are constructed differently.

It is the object of the present invention to provide a sheetfed offset printing machine of the type mentioned in the inline printed on both sides and printed on both sides in high quality inline sheets are obtained.
This object is achieved by a sheet-fed press with the features specified in the characterizing part of claim 1 or by a method according to
Claim 30. According to the invention, therefore, the sheets are first printed on one side, turned over and printed on the other side before they are painted, wherein the coating units are of the same type and are arranged above and below the sheet transport path. In this way, you get a sheet-fed press on which the inline production of double-coated sheets is possible, without the problems described above. It can be achieved on both sides of the sheet a higher gloss level and cleaning operations for the cylinder surfaces or cylinder lifts in the perfecting, which can now be optimized for contact with oil-based paint, are unnecessary.

Figur 1a

ist eine schematische Darstellung des Schöndruckteils einer Bogenoffsetdruckmaschine in Reihenbauweise,

Figur 1b

ist eine schematische Darstellung des Widerdruckteils einer Bogenoffsetdruckmaschine in Reihenbauweise,

Figur 2

zeigt den Widerdruckteil der Druckmaschine nach Figur 1b gemäß einem zweiten Ausführungsbeispiel, und

Figur 3

zeigt den Widerdruckteil der Druckmaschine nach Figur 1b gemäß einem dritten Ausführungsbeispiel.

Figur 4

zeigt den auf das letzte Druckwerk des Widerdruckteils der Druckmaschine nach Figur 1b folgende Ende der Maschine gemäß einem vierten Ausführungsbeispiel.

Figur 5

zeigt den auf das letzte Druckwerk des Widerdruckteils der Druckmaschine nach Figur 1b folgende Ende der Maschine gemäß einem fünften Ausführungsbeispiel.

Figur 6

zeigt den auf das letzte Druckwerk des Widerdruckteils der Druckmaschine nach Figur 1b folgende Ende der Maschine gemäß einem sechsten Ausführungsbeispiel.

Figur 7

zeigt den auf das letzte Druckwerk des Widerdruckteils der Druckmaschine nach Figur 1b folgende Ende der Maschine gemäß einem siebten Ausführungsbeispiel.

Figur 8

zeigt den auf das letzte Druckwerk des Widerdruckteils der Druckmaschine nach Figur 1b folgende Ende der Maschine gemäß einem achten Ausführungsbeispiel.

Further advantages of the invention will become apparent from the following with reference to the FIGS. 1 to 3 of the accompanying drawings.

FIG. 1a

is a schematic representation of the straight printing part of a sheet-fed offset printing machine in a row construction,

FIG. 1b

is a schematic representation of the counter-pressure part of a sheet-fed offset printing machine in a row construction,

FIG. 2

shows the counterpressure part of the printing press FIG. 1b according to a second embodiment, and

FIG. 3

shows the counterpressure part of the printing press FIG. 1b according to a third embodiment.

FIG. 4

indicates the last printing unit of the counterpressure part of the printing press FIG. 1b following end of the machine according to a fourth embodiment.

FIG. 5

indicates the last printing unit of the counterpressure part of the printing press FIG. 1b following end of the machine according to a fifth embodiment.

FIG. 6

indicates the last printing unit of the counterpressure part of the printing press FIG. 1b following end of the machine according to a sixth embodiment.

FIG. 7

indicates the last printing unit of the counterpressure part of the printing press FIG. 1b following end of the machine according to a seventh embodiment.

FIG. 8

indicates the last printing unit of the counterpressure part of the printing press FIG. 1b following end of the machine according to an eighth embodiment.

FIG. 1a shows an offset printing machine 1 in a row construction with a feeder 2, in which the unprinted paper stack 3 is located, and four printing units 7a to 7d for the four primary colors, which form the straight printing part of the machine 1. On the fourth printing unit 7d followed by a turning device 4, which operates on the principle of three-drum turn. It consists of a feed drum 4a, a storage drum 4b and a turning drum 4c. The drum 4c is mounted in the side walls 18a of the first printing unit 8a following the turning device 4. At the counter-pressure cylinder 108 a of the turned arc is passed. The second part of the machine is in the FIG. 1b shown. On the four perfecting 8a to 8d follows a coating unit 9a of the type "chamber doctor blade", ie, it has a Reubenfüpfchenwalze 19a and a chambered doctor blade 20a, in which there is aqueous dispersion varnish. 22a designates a so-called "anilox roll star" which contains three further anilox rolls with different cup sizes, against which the anilox roller 19a can be exchanged in order to determine the amount of lacquer to be applied on the way. In the coating unit 9a, the counterpressure side of the sheet is coated over its entire area by the varnish application cylinder 17a with an aqueous dispersion varnish.

The coating unit 9a is followed by a drying tower 10a. In this drying tower, the sheet transported through is dried in the area of the cylinder 110a on the counterpressure side by hot air and infrared radiation.

In the direction of sheet travel behind the drying tower 10a, a second coating unit 9b is arranged, which is of the same type as the coating unit 9a and with respect to anilox roller 19b, paint application cylinder 17b and chamber doctor blade 20b substantially identical to the first coating unit 9a, but the paint application cylinder 17b below the sheet transport path which is formed as a paint impression cylinder trained sheet transport drum 109 b is employed. The coating unit 9b serves to cover the straight printing side of the sheet also with an aqueous dispersion coating over the entire surface.

The coating unit 9b is adjoined by a second dryer 10b, which dries the lacquered recto printing side of the sheets with infrared radiation and / or hot air. This dryer 10b contains an IR emitter 113, which is arranged in the interior of the sheet transport drum 120 and thus, like the coating unit 9b, is located below the sheet transport path.

On the dryer 10b follows the boom 5 of the printing press. In it grabber bridges run by means of a chain guide 15. These gripper bars 16 take over the sheets painted on both sides and guide them under dryer inserts 11a-h through, where both sides of the sheets are again dried with infrared radiation and / or hot air and the dispersion coating is solidified. The so dried on both sides dried sheets are then stored in the boom 5 on the sheet pile 6.

During its transport through the printing units 7a to 7d and 8a to 8d, the printed sheets do not come into contact with paint. The surfaces of the sheet-guiding impression cylinders 108a-d in the printing units 8a-d and the guide plates of the transferters arranged therebetween can therefore be coated with color-repellent layers which are matched or optimized to the properties of the oil-based offset inks. The sticky dispersion paint, which causes soiling effects, is introduced only at the end of the machine when the process of printing with offset printing inks is completed. In this way, the life of the Cylinder lifts and the cleaning intervals compared to configurations in which the coating unit is located in front of the first turning device 4, significantly increase.

At the in FIG. 2 illustrated embodiment of the following to the last printing unit 8 d part of the basis of FIG. 1a and 1b modified above-described printing machine. Here is the drying tower 10a off FIG. 1b dropped, ie the coming of the coating unit 9a sheet is fed directly to the second coating unit 9b. After passing through the second coating unit 9b, in which the recto printing side is painted, a dryer 110b is arranged. In this dryer, a first infrared drier 112 is disposed above the sheet transporting drum 111, and a second infrared drier 113 is fixedly arranged inside the skeletonized drum 111. Thereafter, the sheet painted on both sides in the chain boom 5 passes through four dryer modules 1 1a-h, in which the sheet is dried on both sides, ie from above and from below, with the aid of infrared radiation and hot air. Here, for example, in the sheet guide of the boom 5 integrated dryer 21 e to h are used, as in the DE 10 2005 042 956 A1 are described.

As a result of the omission of a transferor and the separate drying tower behind the first coating unit 9a, the machine builds correspondingly shorter and requires less footprint than that of the embodiment of the FIG. 1b ,

In the embodiment according to FIG. 3 is behind the last printing unit 8d of the counterpressure part of the printing press 1, a coating unit 29a arranged. This differs from the coating unit 9a from the Figures 1b and 2 insofar as the anilox roller 19a with the chambered doctor blade 20a and the paint applicator roll 17a are combined to form a replaceable and removable unit 18a which, moreover, is mounted so as to be vertically displaceable in the coating unit 29a for the purpose of positioning against the ink counterpressure cylinder 109a, as indicated by the arrow.

On the coating unit 29a follows, as already based on FIG. 1 described, a drying tower 10 a, in which the painted on the reverse side sheet with hot air and / or Infrared radiation is dried before it is transferred from the transport cylinder 110 to the impression cylinder of the coating unit 29b.

The coating unit 29b, like the coating unit 29a, has a removable and exchangeable unit 18b in which the coating application roller 17b, the anilox roller 19b and the chamber doctor blade 20b are accommodated. The unit 18b, however, is mirror-inverted to the unit 18a and positioned below the sheet transport path to the impression cylinder 109b to paint the recto printing side of the continuous sheets.

The coating unit 29b is followed by a transfer machine and a second dryer 10b, below which a sheet guiding drum 125 an infrared radiator 126 and a hot air box 127 are arranged to dry the straight printing side of the sheet before it is fed to another sheet transport drum 128. The sheet transport drum 128 is arranged with its axis well above the axis of the transport cylinder 125. The connecting line of the two axes of these cylinders encloses an angle α> 30 ° with the horizontal. In this way, the transported sheets are conveyed upwards to the level of the horizontally rotating gripper bars 116 on the guide chains 115, which can now be made relatively simple and inexpensive, since a deflection of the chain from an inclined to a horizontal guide area is not required here.

Over the side of the transport drum 128, on which the transported sheets rest, an inspection camera 141 and a powder device 142 are arranged. Since the sheets lie here in a defined position on the transporting cylinder 128, the sheet surface can be inspected well with the camera 141. Because the focus distance is constant and is not disturbed by flapping movements of the sheet to be inspected. In addition, the powder jet emitted from the powder dispenser 142 can impinge on the sheet resting on the cylinder 128 at high speed without fear of any smearing effects. For the already dried in the dryer 10a on the reverse side of the sheet is without relative movement on the corresponding color or paint-repellent surface of the cylinder 128.

In the embodiment according to FIG. 4 Following on the last perfecting unit 8d is a painting unit 209, in which the sheets leaving the printing unit 8d are fed by a transferor 207 to a half-finished varnish cloth cylinder 208. This half-speed varnish cloth cylinder 208 in turn carries gripper strips 218a and 218b, which are arranged sunk below the radius of the varnish surface. The grippers fastened to the gripper bars only rise above the radius of the surface of the varnish cloth when it is opened in order to grip the sheet leading edge and lie underneath again after closing.

The sheet transported by the varnish cloth cylinder 208 is painted over its entire surface on its counterpressure side by a second varnish blanket cylinder 218, wherein an anilox roller 219a with a chambered doctor blade 220a of the varnish application roller 218 carries the z. B. Disperse paint. At the same time, the paint wipes, which are not shown in more detail on the first paint blanket cylinder 208, are provided by a second anilox roller 219b in conjunction with a chambered doctor blade 220b with a lacquer layer onto which are held by the grippers 218a or 218b and through the printing nip or lacquer gap Place 221 bows.

After passing through the lacquer gap 221, the sheets simultaneously painted on both sides in this way are taken over by a transfer fabric 217, which removes the sheets from the lacquer wipes on the cylinder 208 and transfers them to a dryer 210. This is like the dryer 110b in FIG. 2 constructed, ie it has two dryer units 212 outside and 213 within the transport drum 211, so that the simultaneously coated on both sides of the sheets can also be dried simultaneously before they are transferred to the gripper bridges of the chain guide 215 in the boom 205. In the boom 205 itself, two further dryer modules 21a and 21b are arranged, similar to the dryer modules 11a-h in the embodiments according to FIG. 1 and FIG. 2 finally dry the sheets before they are deposited on the stack 206.

The embodiment according to FIG. 5 is different from that FIG. 4 in that the boom 305 with the chain guide 315 follows directly after the last printing unit 8d of the counterpressure part of the printing machine 1. The sheets that the printing unit 8d So far, therefore, they are only printed with color when they are taken over by the gripper bridges 316 on the circulating chains 307.
On both sides of the plane, which is formed by the circulating chain pairs, a double-coating unit 309 consisting of two varnish cylinder 309a and 309b is stored, which are each coated by an associated anilox roller 319a and 319b in conjunction with chambered doctor blades 320a and 320b with paint.

The blanket cylinders 309a and 309b have chutes designed to allow the gripper bars 316 to pass without touching the cylinders 309. For this purpose, the cylinders 309 are synchronized with the drives of the sprocket 317 by means of unillustrated gears.

The sheets, which are pulled through the lacquer wipes on the lacquer wiper cylinders 309a and b by the lacquer wipes and thus lacquered simultaneously on the front and rear side, are then dried again on both sides in dryer modules 21a and 21b, as described with reference to FIGS FIG. 4 or described in the other embodiments.

According to the embodiment according to FIG. 4 can be in the after FIG. 5 to achieve a significantly better result in terms of painting, since due to the symmetry of the coating rollers on both sides of the continuous sheets are the same conditions.

The lacquer application cylinders 309a and 309b can be mounted movable apart with respect to their axes, as symbolized by the two double arrows. In this way, it is possible to form the parts carrying the varnish cloth as interchangeable sleeves, which can be replaced with sleeves of different thickness and outside diameter. The sleeves can also be exchanged for those having a particularly long channel recess, so that optionally at Doppelgreiferbrücken at the front and rear edges simultaneously held sheets can be painted, ie even at different format intervals or lengths the arches can accommodate both the leading edge bridge and the trailing edge bridge in the channel of the varnish cloth cylinder.

The embodiment according to FIG. 6 is different from that FIG. 5 on the one hand, that the boom 405 with a similar as in FIG. 3 simple, only horizontally extending chain guide 415 is provided. Instead of the ascending part of the chain guide FIG. 5 Here, a sheet transport drum 425 is provided, the skeletal structure three gripper bars 416a, b, and c carries. The sheets leaving the printing unit 8d are transferred from a transferer 407 to the gripper bridges 416 of the drum 425. The drum 425 conveys the sheets to the height level of the chain guide 415 in the boom 405 and, similar to the chain 307 in FIG FIG. 5 through the paint gap 422 between the varnish cloth cylinders 409a and 409b.

The chamber doctor blade 420b and the anilox roller 419b of the second coating unit are located inside the drum 425, which, however, is easily accessible from the side of the sheet stack 406. In addition, the space between the gripper bars 416 is open so that the painted sheets of combined infrared and hot air dryers 421a and 421b disposed above and below the paper transport path can be dried after painting.

Underneath the drum 425, a waste sheet container 426 is disposed. By a corresponding control of the opening time of the gripper on the three gripper bars 416a-c can be achieved that the bills are passed to the chain guide 415 of the boom 405 and the bad bows are released only on the container 426. For example, inline inspection systems in the sheet transport path behind the last printing unit 8d of the machine 1 are suitable for detecting good sheets or bad sheets.

For the varnish blanket cylinder 409, what has already been said for the varnish blanket cylinders 309 applies, ie they can be used as in connection with FIG. 5 described be provided with sleeves of different thickness and diameter and different channel length.

Two further particularly advantageous embodiments of the invention are in the FIGS. 7 and 8th shown. Both have in common that the last printing unit 8d in the counterpressure part of the printing press is followed by the coating unit 9b, in which the varnish sheet cylinder 17b and the anilox roller 19b are arranged with the chambered doctor blade 20b below the counterpressure cylinder 109b and thus also below the sheet transport path. In the embodiment according to FIG. 7 follow on the impression cylinder 109b of the first coating unit, with which the sheet front side, so the straight printing side of the sheet is painted, two dryers. These dryers each consist of a sheet transport cylinder 111a or 111b, below which, ie also below the sheet transport path, a respective dryer 112a or 112b is arranged. This may be, for example, infrared or hot air dryer. Between the counter-pressure cylinder 109b of the first coating unit and the transport cylinder 11a of the first dryer, a transfer conveyor 119a is inserted and a second transfer conveyor 119b is located between the two sheet transport cylinders 111a and 111b of the driers. On the dryer follows the second coating unit 9a, in which the reverse side of the sheets is painted. It should also be noted that in this embodiment, the transport cylinder 111b of the second dryer passes directly to the impression cylinder 109a of the second, here now "upright" coating unit.

On the second coating unit 9a then follows a boom, as already based on FIG. 1b described, but with the proviso that here only the back pressure side of the sheet needs to be dried by the dryer modules 11a to 11d, since the recto printing side has already been dried by the dryers 112a and 112b.

In the embodiment according to FIG. 8 are compared to the after FIG. 7 the two transferters 119a and 119b as well as the two transport cylinders 111a and 111b omitted. On the counter-pressure cylinder 109b of the first, the recto printing side "varnishing from below" coating unit 9b follows directly the impression cylinder 109a, the second, "upright" coating unit 9a, viewed in the sheet running direction. Here intermediate deck dryers 113 below the sheet run and 112 above the sheet run provide for drying of the sheets before they are transferred to the boom 5. The two dryers 113 and 112 are directly below or above the impression cylinders 109b and 109a of the two coating plants arranged. Not shown in each case is a hot air or radiation barrier in the coating units, which prevents heat or radiation from the dryer 112 or 113 enters the coating unit and there excessively heats the components.

By painting from below directly after the last printing unit 8d, a very compact design can be realized. Especially in the embodiment according to FIG. 8 The number of components used for two-sided painting is minimal. It is not necessary to dry the sheets from the inside of a rotating drum, so that it is also possible to work with already existing components as far as the dryer is concerned.

Thus, by painting the sheets after the last printing unit 8d "from the bottom", favorable configurations result once with respect to the parking space of the machine, but also with regard to the development effort and the costs of the machine.

In addition to the described embodiments, further modifications and variations are possible. Thus, depending on the used paint instead of the coating units with chamber doctor blade and coating units with scoop roller can be used. Furthermore, it is of course possible from the outset instead of the four printing units for the four primary colors in the perfecting part of the printing press additional printing units for two-sided printing with z. B. 2 x 2 special colors provide. Instead of the gripper bars 316, 416, of which the sheets are held in the delivery of the printing press at its leading edge, also Greiferleistenanordnungen can be used in which the sheets are gripped at the two lateral edges, such as the z. B. in the U.S. Patent 6,923,119 is described. In that case, no channels are required in the varnish sheet cylinders 309a, b or 409a, b, and when using sleeves which are mounted on the varnish blanket cylinders 409, they can be made seamless and thin-walled.

reference numeral

1

Offset

2

investor

3

stack of paper

4

turning device

4a, 14a, 24a

feed drum

4b, 14b, 24b

storage drum

4c, 14c, 24c

beater

5, 105, 205, 305, 405

boom

6, 206, 406

sheet pile

7a-d

printing units

8a-d

printing units

9a, b

Lackwerke

10a, b

dryer units

11a-h

dryer Bays

15, 115, 215, 315, 415

chain guide

16, 116, 316

gripper bars

17a, b

Coating blanket cylinder

18a, b

removable paint module

19a, b

Rasternäpfchenwalzen

20a, b

chambered doctor blade

21a-h

drier modules

22a, b

Anilox roll star

29a, b

Lackwerke

31 a, b

Steerage dryer

39a, b

coating unit

49a

applicator roll

59a, b

Impression cylinder

106

transferters

108a-d

Impression cylinder

109a, b

Impression cylinder

110a, b

dryer

111, 111a, 111b

transport cylinder

112, 112a, 112b

dryer unit

113

dryer unit

119a, 119b

transferters

120

transport cylinder

124a

transport cylinder

125a

dryer

126

infrared dryer

127

Hot air dryer

128

transport cylinder

129a, b

Impression cylinder

141

inspection camera

142

powder sprayer

207, 407

transferters

208.218

Coating blanket cylinder

209, 309, 409

Double coating unit

210

dryer

211

transport cylinder

212.213

Infrared dryer units

217

transferters

218a, b

gripper strips

219a, b

anilox rolls

220a, b

chambered doctor blade

221

paint gap

307

Chain

309a, b

Coating blanket cylinder

317

Sprocket

318ab, 418a, b

anilox rolls

320a, b, 420a, b

chambered doctor blade

416a-c

gripper bars

417a-c

carrier

418

journal

421a, b

dryer units

422

paint gap

425

drum

426

Container for waste paper

Claims (36)

1. Sheet-fed offset printing press for printing multiple colours on both sides of sheets, preferably of sheets of paper, including a first row of successive printing units (7a-d) for printing on the first side of the sheets, followed by a reversing device (4), followed by a second row of successive printing units (8a-d) for printing on the other side of the sheets, followed by one or more varnishing units (9a, b, 29a, b, 39a, b)
   characterized in
   that at least two varnishing units (9a, b; 18a, 18b; 219a, b; 319a, b; 419a, b) of the same type follow the last printing units (8d) and that the varnishing units and their varnishing blanket cylinders (17a, b; 208/218; 309a, b; 409a, b), respectively, are arranged in such a way that the front sides and the rear sides of the passing sheets are varnished, with one of the varnishing units and its varnishing blanket cylinder, respectively, arranged below the path of sheet transport, and that at least two infrared or hot-air driers (10a, b; 11a-h; 112/113; 212, 213; 21 a, b; 42 1 a, b) are provided, at least one of which is likewise arranged below the path of sheet transport.
2. Printing press according to Claim 1,
   wherein two sheet transport cylinders (109a, 109b) are provided downstream of the last printing unit (8d) in the path of sheet transport and each of the two cylinders (109a, b) is assigned its own varnishing unit, the varnishing blanket cylinders (17a, b) of the two varnishing units (9a, b) being respectively arranged above and below the path of sheet transport.
3. Printing press according to Claim 2,
   characterized in
   that at least one of the varnishing units assigned to the two transport cylinders (109a, b) is designed in the form of a removable insertion unit (18a, b).
4. Printing press according to Claim 1,
   characterized in
   that the connecting line between the axes of two successive transport drums (125, 128) of the printing press is inclined at an angle >30° relative to the horizontal.
5. Printing press according to Claim 2,
   characterized in
   that further transport cylinders follow the transport cylinders (109a, b) assigned to the varnishing units and that a drier (10a, 10b, 112a, 112b; 113) is assigned to two (111; 111a, 111b; 120; 125) of the further transport cylinders.
6. Printing press according to Claim 2,
   wherein the two sheet transport cylinders (109a, b) assigned to the varnishing units (9a, 9b) directly follow each other.
7. Printing press according to Claim 2,
   wherein a drier unit (10a, 112a, 112b) is arranged between the two transport cylinders (109a, b) of the two varnishing units (9a, b).
8. Printing press according to Claim 7,
   wherein precisely two or precisely four sheet transport drums and transfer drums (106, 110a), respectively, are arranged between the impression cylinders of the successive varnishing units (9a, b).
9. Printing press according to Claim 8,
   wherein a drier (10a, 112a, 112b) is assigned to at least one (110a) of the two or four sheet transport drums (106, 110a, 111a, 111b).
10. Printing press according to Claim 8,
    wherein at least one of the sheet transport drums is a transfer drum (106; 119a, 119b).
11. Printing press according to Claim 1,
    wherein at least two of the varnishing units are arranged in such a way that their varnishing blanket cylinders (208, 218; 309a, b, 409a, b) form a nip (221, 422) through which the sheets to be varnished on both sides are passed.
12. Printing press according to Claim 11,
    wherein one (208) of the two varnishing blanket cylinders includes grippers (218a, b) for transporting the sheets to be varnished.
13. Printing press according to Claim 11,
    wherein the sheets to be varnished on both sides are moved/conveyed through the nip (422) between the two varnishing blanket cylinders by gripper bars (316; 416).
14. Printing press according to Claim 13,
    wherein the grippers on the gripper bars hold the sheets on the two lateral edges.
15. Printing press according to Claim 13,
    wherein the grippers on the gripper bars (316, 416) hold the sheets at their leading edges and convey them through the nip between the two varnishing blanket cylinders (309a, b; 409a, b), and wherein one or both of the varnishing blanket cylinders are provided with an axial gap into which the grippers and gripper bars (316, 416), respectively, dip.
16. Printing press according to Claim 15,
    wherein pairs of gripper bars are provided that include grippers that grip the leading and trailing edges of the sheets conveyed through the nip between the varnishing blanket cylinders.
17. Printing press according to Claim 13,
    wherein the gripper bars (416a-c) are part of a drum (425) whose diameter is a multiple of the diameter of the forme cylinders of the printing units (7a-d, 8a-d), and wherein the drum is open in the region of the sheet surface and a varnishing unit (409b, 419b, 420b) is arranged in the interior of the drum (425).
18. Printing press according to Claim 17,
    wherein a container (426) for waste sheets is assigned to the multiple-size transport drum (425).
19. Printing press according to Claim 17,
    wherein a drier device (421a, b) is assigned to the multiple-size transport drum (425).
20. Printing press according to Claim 19,
    wherein a drier device that is arranged partly inside and partly outside the drum (425) is assigned to the multiple-size transport drum (425).
21. Printing press according to one of Claims 13 to 20,
    wherein the varnishing blankets received on the varnishing blanket cylinders (309, 409) are tubular sleeves or are mounted on tubular sleeves.
22. Printing press according to Claim 21,
    wherein the distance of the two varnishing blanket cylinders (309a, b; 409a, b) is adjustable or settable to receive sleeves of varying thickness.
23. Printing press according to one of Claims 1 to 22,
    wherein downstream of the last varnishing unit as viewed in the direction of sheet travel, infrared and/or hot-air drier devices (11a-h, 21a, b; 212, 213, 112, 113) are provided for drying both sides of the sheets that have been varnished on both sides.
24. Printing press according to one of Claims 1 to 23,
    wherein a drier unit (113, 213, 421b) that is arranged inside a drum (111, 220, 425) transporting the sheets is assigned to at least one of the varnishing units (39a).
25. Printing press according to one of Claims 1 to 24,
    wherein one or more of the varnishing units are designed to apply water-based varnishes and dispersion varnishes, respectively.
26. Printing press according to one of Claims 1 to 25,
    wherein two or more of the varnishing units (9a, b) include a screen roller (19a, 19b) with a doctor blade (20a, 20b).
27. Printing press according to one of Claims 1 to 25,
    wherein the two varnishing units are of the dipping-roller type.
28. Printing press according to Claims 14 and 21,
    wherein the sleeves are gapless.
29. Printing press according to Claims 15 and 21,
    wherein the sleeves are provided with a gap.
30. Method for printing multiple colours on both sides of sheets, preferably sheets of paper, comprising the following steps:

    a) the stacked sheets and individually fed to multiple successive printing units (7a-d) to be printed on the front side of the sheet,

    b) the sheets that have been printed in this way are turned and multiple colours are printed on their rear sides in a number of further successive printing units (8a-d),

    c) the printed front and/or rear sides of the sheets are provided with one or more layers of varnish by varnishing units of the same type arranged above and below the path of sheet transport and are dried by infrared radiation and/or hot air by means of driers arranged above and below the path of sheet transport,

    d) the sheets that have been printed and varnished on both sides are deposited on a stack (6) or are further processed.
31. Method according to Claim 30,
    wherein the side of the sheets that has been printed first is dried before the second side of the sheets is varnished.
32. Method according to one of Claims 30 or 31,
    wherein having been varnished on both sides, the sheets are dried on both sides.
33. Method according to one of Claims 30 to 32,
    wherein in the drying step, radiation and/or hot air is applied to that side of the sheets that concavely faces a transport cylinder (111, 220, 425).
34. Method according to one of Claims 30 to 32,
    wherein in the drying step, radiation and/or hot air is applied to that side of the sheets that convexly faces away from a transport cylinder by means of a drier device arranged below the path of sheet transport.
35. Method according to one of Claims 30 to 34,
    wherein firstly the printed front sides of the sheets and then the rear sides of the sheets are varnished.
36. Printing press according to one of Claims 1 to 10,
    wherein the impression cylinder (108d) of the last printing unit (8d) is followed by the impression cylinder (109a) of the first varnishing unit (9a).

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