DE102015203909A1 - Method of printing a sheet in a printing system - Google Patents

Abstract

In a method for printing a sheet (15) in a printing system, the sheet (15) is transported by a transport element (5) along an orbit (6) and printed in a first circulation by a printing device (1) and by a dryer ( 12) is dried and printed in a second circulation by a further printing device (4).

Description

The present invention relates to a method for printing a sheet in a printing system, wherein the sheet is transported by a transport element along an orbit and thereby printed in one pass by a printing device.

In the DE10235872A1 There is described a sheet-fed satellite printing system including a central transport drum, ink jet printers and dryers.

In the DE19523378A1 is a sheetfed offset printing machine with a central impression cylinder, two blanket cylinders and two printing forme cylinders each described with two printing plates. In the printing method employed here, each sheet passes once more to the blanket cylinders in a first pass for printing two colors to the blanket cylinders and in a second pass for printing two more colors to the blanket cylinders.

The invention has for its object to provide a further method for printing a sheet.

This object is achieved by a method having the features of claim 1.

In the method according to the invention for printing a sheet in a printing system, the sheet is transported through a transport element along an orbit and thereby printed in a first circulation by a printing device and dried by a dryer and printed in a second circulation by a further printing device.

The method lends itself well to printing two different types of fluids (eg ink and varnish), one of which is printed in the first circulation and the other in the second circulation. In addition, the method is suitable for multilayer printing of large layer thicknesses, wherein in the first circulation a first layer of a fluid is printed on the sheet and in the second circulation a second layer of the same fluid is printed on the first layer.

In the dependent claims further developments of the invention are mentioned. In a further development, the sheet is transported past the printing device, the further printing device and the dryer in the first circulation and the second circulation.

In a further development, the sheet in the first circulation is not printed by the further printing device.

In a further development, the sheet in the second circulation is not printed by the printing device.

In a further development, the transport element is a drum (eg vacuum drum) and the orbit is a circular path. But the transport element could also be an endless conveyor belt, wherein the orbit has an elongated ring shape, so no circular path is.

In a further development, at least one of the two printing devices is a non-impact printing (NIP) print head. It is also possible for one, several or all of the printing devices to be designed as a planographic offset printing device or as a flexographic printing device.

In a further development, the two printing devices are each an inkjet printhead.

In a further development of the sheet is printed by the further printing device with transparent ink or clearcoat in the second round.

In a further development of the arc by one of the two printing devices at successive circulations -. B. the first round and the second round or z. B. the second round and a third round - each printed.

In a further development of the sheet is printed by the two printing devices on one and the same side of the sheet.

In a further development of the sheet is dried by another dryer after the first round.

In a further development of the further dryer is a UV (ultraviolet) dryer.

Further advantageous developments will become apparent from the following description of an embodiment and the accompanying drawings.

The sole figure shows a printing system with a first printing device 1 , a second printing device 2 , a third printing device 3 and a fourth printing device 4 which are inkjet printheads. The printing devices 1 - 4 are consecutive next to an orbit 6 arranged along which a transport element 5 the respective bow 15 transported. With the first, second and third printing device 1 . 2 , and 3 water-based colors are printed and with the fourth printing device 4 a transparent UV color.

The transport element 5 is a multi-sized drum whose peripheral surface is the bow 15 carries and determines the orbit. The transport element 5 has gripper to hold the bow 15 , z. B. clamping gripper for holding the sheet 15 at its front edge and suction pads to hold the bow 15 at its rear edge. The transport element 5 is adjustable to the sheet format, z. B. by an adjustment of the suction pads relative to the clamping grippers. The transport element 5 is tempered by a tempering, z. B. by an integrated water cooling.

A sheet feeder 7 has a investment pile 8th , a sheet singulator, and a sheet feeder that holds the sheet 15 the transport element 5 supplies. The transport element 5 transports the bow 15 at the printing facilities 1 - 4 passing, of which the one on the transport element 5 lying arch 15 is printed. After the bow 15 from the printing devices 1 - 4 has been printed, gives the transport element 5 the bow 5 to a sheet delivery 7 from. The bow boom 9 has a chain conveyor and a delivery stack 8th ,

A first dryer 11 to dry the bow 15 is in the direction of rotation of the transport element 5 seen between the third printing device 3 and the fourth printing device 4 arranged. A second dryer 12 is between the fourth printing device 4 and the bow boom 9 arranged. A third dryer 13 is along the orbit 6 seen the bow boom 9 downstream and the sheet feeder 7 upstream. A fourth dryer 14 is in the bow boom 9 arranged between an upper and a lower chain tower of the chain conveyor. The first, second and third dryer 11 . 12 and 13 are TL (thermo-air) dryer or IR (infrared) dryer and the fourth dryer 14 is a UV dryer.

The printing system works according to the following procedure:
Every bow 15 is during a first revolution of the transport element 5 (Specifically: a first revolution of the drum) of the first and / or second and / or third printing device 1 . 2 , and or 3 printed, but not by the fourth printing device 4 , During the first round, the bow becomes 15 with the first and / or second and / or third dryer 11 . 12 and or 13 dried. After that, the bow becomes 15 from the transport element 5 at the sheet feeder 7 or its feeder transported over and the second round of the bow 15 starts.

During the second cycle, the first, second and third printing devices are 1 . 2 and 3 passive and the bow happens 15 these without being printed by them. During the second round the bow becomes 15 with the fourth printing device 4 printed.

The fourth printing device 4 is thus controlled so that it is passive in the first round and active in the second round. The arc 15 goes through the complete orbit 6 in the first round and in the second round only one section of the orbit 6 , This means in particular the drum and its orbit that the bow 15 is transported in the first circulation over a circumferential angle of 360 ° and in the second circulation over a circumferential angle of less than 360 °. The arc 15 is from the transport element 5 in the first round at the sheet delivery 9 or its chain conveyor transported past and in the second round to the sheet delivery 9 or its chain conveyor delivered.

The second round of the fourth printing device 4 on the bow 15 Applied transparent paint becomes after the second circulation with the fourth dryer 14 dried; if necessary, the second dryer 2 during the second cycle to act on the transparent color to additionally support their drying by heating.

In the manner described are all the bow 15 of the investment pile 8th processed, the sheet feeder 7 successively the transport element 5 supplies.

In a modification, the bow goes through 15 also in the second round the complete orbit 6 , This is followed by the second round a third round at which the arc 15 a second time from the fourth printing device 4 printed with the transparent color. During the third cycle, the first, second and third printing devices are 1 . 2 and 3 passive and the bow happens 15 these without being printed by them.

By taking place in two rounds, double-layered application of the transparent color whose total layer thickness can be particularly large, which is advantageous in many applications. In the third round the bow goes through 15 only a section of the orbit 6 and he is going to the sheet delivery 9 issued.

The third round of the fourth printing device 4 on the bow 15 applied transparent color is with after the third round with the fourth dryer 14 dried; if necessary, the second dryer 2 during the third round, act on the transparent color to further assist in drying by heating.

In the described modification, the second dryer 12 and / or the third dryer 13 a combination dryer in which a TL or IR dryer module and a UV dryer module are combined, wherein the UV dryer module for the second cycle in the intermediate drying of the second circulation of the fourth printing device 4 on the bow 15 applied transparent color.

LIST OF REFERENCE NUMBERS

1

first printing device

2

second printing device

3

third printing device

4

fourth printing device

5

transport element

6

orbit

7

sheet feeder

8th

system stack

9

sheet delivery

10

 delivery pile

11

 first dryer

12

 second dryer

13

 third dryer

14

 fourth dryer

15

 bow

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 10235872 A1 [0002]
• DE 19523378 A1 [0003]

Claims (12)

Method of printing a sheet ( 15 ) in a printing system, the sheet ( 15 ) by a transport element ( 5 ) along an orbit ( 6 ) is transported and in a first round by a printing device ( 1 ) and through a dryer ( 12 ) and in a second circulation through a further printing device ( 4 ) is printed. Method according to claim 1, wherein the sheet ( 15 ) in the first circulation and the second circulation respectively at the printing device ( 1 ), the further printing device ( 4 ) and the dryer ( 12 ) is transported over. Method according to claim 1 or 2, wherein the sheet ( 15 ) in the first circulation not by the further printing device ( 4 ) is printed. Method according to one of claims 1 to 3, wherein the sheet ( 15 ) in the second circulation not by the printing device ( 1 ) is printed. Method according to one of claims 1 to 4, wherein the transport element ( 5 ) a drum and the orbit ( 6 ) is a circular path. Method according to one of claims 1 to 5, wherein at least one of the two pressure devices ( 1 . 4 ) is a non-impact printing (NIP) printhead. Method according to one of claims 1 to 6, wherein the two pressure devices ( 1 . 4 ) are each an inkjet printhead. Method according to one of claims 1 to 7, wherein in the second round the sheet ( 15 ) by the further printing device ( 4 ) is printed with transparent paint or clearcoat. Method according to one of claims 1 to 8, wherein the sheet ( 15 ) by one of the two pressure devices ( 1 . 4 ) in successive rounds -. B. the first round and the second round or z. B. the second round and a third round - each printed. Method according to one of claims 1 to 9, wherein the sheet ( 15 ) by the two pressure devices ( 15 ) is printed on one and the same sheet side. Method according to one of claims 1 to 10, wherein after the first circulation the sheet ( 15 ) through another dryer ( 14 ) is dried. The method of claim 11, wherein the further dryer ( 14 ) is a UV (ultraviolet) dryer.

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