DE102005003836A1 - Device for reducing viscosity of printing ink while printing in offset rotary printing press has electromagnetic wave emitting radiation source which is arranged before first printing column in rotation direction of impression cylinder - Google Patents

Abstract

The device consists of a printing device, an inking system, a plate cylinder (1) and an offset cylinder (4). A printing column (6) is arranged between the offset cylinder and impression cylinder (7). An electromagnetic wave emitting radiation source is arranged before the first printing column in rotation direction of the impression cylinder.

Description

The The invention relates to a device on offset rotary printing machine for reducing the viscosity of inks in printing, such a rotary offset printing machine has at least one printing unit, which contains at least one inking unit, wherein the inking unit over at least one plate cylinder at least one offset cylinder assigned.

at the high-viscosity inks used in offset printing occur sometimes to tearing out of small or larger parts from the surface of the printing material. This occurs when the external adhesion forces are greater than the internal structural strength of the printing material. This is particularly the case with dry offset the lack of moistening is one of the central problems the increase the temperature of the printing inks can counter this as is well known, with increasing temperatures the viscosity the printing ink is reduced. For this purpose, it is necessary, the concerned inkless Cylinder to a processing-technically optimal temperature level to bring and keep there. This is done by the supply of Thermal energy.

A solution for tempering ink-carrying cylinders is from the DE 29 51 436 A1 known. Here, a device is described in which radiant heaters are directed to the blanket cylinder. In a further variant z. B. the blanket cylinder flows through a heated medium.

The in the DE 29 51 436 A1 described solution has the disadvantage that the heat energy of the blanket cylinder is dissipated by the contact with the printing cylinder and the plate cylinder again. In particular, the heating of the printing plate mounted on the plate cylinder leads to disruptions of the printing process, which is particularly noticeable in dry offset. Here are the non-printing image areas covered with a special silicone that keeps them colorless. This silicone loses its color-repellent properties when the temperature exceeds a threshold. This value is usually between 30 and 35 ° C. Therefore, the plate cylinder is usually cooled, which in turn removes heat energy from the blanket. Such a solution is from the EP 1 270 219 A1 known.

task The invention therefore, the ink is effective and non-reactive heat energy supply.

According to the invention Task by a device having the features of the first claim solved.

The Invention has the advantage that it is now possible with little effort, Also to temper the guided on the blanket cylinder ink and in the transfer phase to bring the substrate to a viscosity for a trouble-free Printing is required. The plucking of the printing material can thus be avoided and repercussions on the temperature level of the plate cylinder are largely excluded.

The Invention is intended to an embodiment be explained in more detail. The accompanying drawing shows the structure of a printing unit, as is the case in particular with dry offset is used.

As can be seen from the figure, a plate cylinder 1 an inking roller 2 assigned. The inking roller 2 stands with an anilox roller 31 in contact with the anilox roller 31 a chambered doctor 32 is employed with a Farbzuführeinrichtung not shown here.

The plate cylinder 1 is with a pressure plate 11 covered by the inking roller 2 is colored. In this case it is a dry offset plate.

The plate cylinder 1 is still one with a blanket 41 covered offset cylinder 4 associated with the sheet-guiding impression cylinder 7 in contact. The impression cylinder 7 is a bow-passing transfer drum 8.1 forward and a bow-accepting transfer drum 8.2 downstream.

The offset cylinder 4 is at the printing cylinder 7 hired. It forms a pressure gap 6 , In the direction indicated by the arrow sheet travel direction or rotation direction of the printing cylinder 7 is in front of the printing nip 6 a radiation source in the form of an infrared radiator 5 arranged capable of emitting electromagnetic waves. The infrared radiator 5 emits its heat radiation in the direction of the surface of the printing cylinder occupied during printing with printing material 7 , The infrared radiator 5 extends over the entire width of the printing cylinder 7 or over the entire width of the printing substrate. It is also possible to use several infrared radiators 5 in the axial direction of the printing cylinder 7 to arrange in series. The wavelength of the infrared radiator 5 is on the substrate is adjusted so that the majority of the energy used is stored in the substrate, so that it can influence the viscosity of the subsequently applied ink. It can also optimize the wavelength with respect to the ink of the infrared radiator 5 done, which the pressure columns 6 the printing units following the first printing unit are arranged upstream.

The printing cylinder 7 has a heat-insulating surface to prevent their inadmissible and uncontrollable heating.

In offset rotary printing machines in series or satellite construction several technologically arranged one behind the other printing units in the arrangement described above are available. For the function of the device according to the invention, it is sufficient in most cases, in the order of the printing units technologically first printing unit with an infrared radiator 5 equip. It may also be necessary, one, several or all subsequent printing units with an infrared radiator 5 equip.

For the operation of the device according to the invention:
At the beginning of printing the infrared radiator 5 put into operation and brings the substrate to a higher temperature level. When passing the printing gap 6 will be on the offset cylinder 4 transferred ink to the preheated substrate. In this phase, an increase in temperature of the ink, so that as described above, the viscosity of the ink decreases and the judder can be effectively prevented.

at the arrangement of several printing units is possibly in the first printing unit following printing units by the arranged there infrared radiator the substrate also heated. These infrared heaters have a double function: they hold that for the Rupffestigkeit required temperature level and dry at the same time the applied by the previous printing ink.

1

plate cylinder

11

printing plate

2

Inking roller

31

anilox roller

32

chambered doctor blade

4

offset cylinder

41

blanket

5

infrared Heaters

6

nip

7

pressure cylinder

8.1

Transfer drum

8.2

Transfer drum

Claims (7)

Device for offset rotary printing press for reducing the viscosity of printing inks, wherein such an offset rotary printing machine comprises - at least one printing unit, - which contains at least one inking unit, wherein the inking unit over - at least one plate cylinder ( 1 ) - at least one offset cylinder ( 4 ) and - the offset cylinder ( 4 ) with a printing material-carrying impression cylinder ( 7 ), wherein between the offset cylinder ( 4 ) and the impression cylinder ( 7 ) - pressure gap ( 6 ) is formed and - at least before the first pressure nip ( 6 ) in the direction of rotation of the printing cylinder ( 7 ) Seen at least one electromagnetic wave emitting radiation source is arranged. Device for offset rotary printing press for reducing the viscosity of printing inks according to claim 1, characterized in that the radiation source as infrared radiator ( 5 ) is trained. Device on offset rotary printing machine for Reduction in viscosity Printing inks according to claim 1 or 2, characterized that the radiation source for emitting waves is one for energy storage in the Substrate and / or optimized in the ink wavelength is. Device for offset rotary printing press for reducing the viscosity of printing inks according to claim 1 or 2, characterized in that the infrared radiator ( 5 ) over the entire width of the printing cylinder ( 7 ). Device for offset rotary printing press for reducing the viscosity of printing inks according to claim 1, characterized in that the printing cylinder ( 7 ) is equipped with a heat-insulating surface. Device on offset rotary printing press for reducing the viscosity of printing inks according to claim 1, characterized in that the radiation source when using multiple printing units before the printing nip ( 6 ) is arranged in the processing direction first printing unit. Device for offset rotary printing press for reducing the viscosity of printing inks according to claim 1, characterized in that on the plate cylinder ( 1 ) of pressure a dry offset printing plate is clamped.