EP2829402A2 - Offset printing unit and under-packing for the blanket - Google Patents

Abstract

Printing unit (10) of a printing press with an inking unit (11), a transfer cylinder (14) and a forme cylinder (13), wherein the inking unit (11) applies printing ink to at least one printing plate (15) positioned on the forme cylinder (13), wherein the Printing ink starting from the or each printing plate (15) via at least one on the transfer cylinder (14) positioned, formed as a blanket (23) transfer form on a substrate to be printed (22) can be applied, and wherein between the transfer cylinder (14) and the or each blanket (23) is positioned a contact structure (24) which is connected to the transfer cylinder (14). In the circumferential direction of the transfer cylinder (14), the radial thickness of the contact structure (24) changes, wherein the contact structure (24) at those peripheral portions of the transfer cylinder (14), at which in printing operation leading and trailing ends of the or each pressure plate (15) on the or roll each blanket (23), has a smaller radial thickness.

Description

The invention relates to a printing unit according to the preamble of claim 1. Furthermore, the invention relates to a contact structure for a printing unit.

Fig. 1 shows a schematic view of a known from the prior art printing unit of a printing machine, namely an offset printing unit of a web press. This in Fig. 1 shown printing unit 11 includes an inking unit 11, alternatively a dampening unit 12, a forme cylinder 13 and a transfer cylinder 14. On an outer periphery of the forme cylinder 13 at least one printing plate 15 is arranged. With the help of the inking unit 11 printing ink and with the help of the alternative dampening 12 fountain solution can be applied to the or each positioned on the forme cylinder 13 printing form 15. From the inking unit 11, an ink fountain 16, a fountain roller 17 and a plurality of other inking rollers 18 are shown. From the alternative dampening unit 12 a Feuchtdosiersystem 19 and a plurality of dampening rollers 20 are shown. At the periphery of the transfer cylinder 14 at least one transfer mold 23 is positioned, which can be designed as a blanket or as a blanket plate. Printing ink, which is applied with the aid of the inking unit 11 to the or each printing plate 15 positioned on the forme cylinder 13, can be applied to a printing substrate 21 starting from the or each printing form 15 via the or each transfer mold 23 positioned on the transfer cylinder 14. In the illustrated embodiment of the Fig. 1 the printing material 21 is printed in a printing nip 22 which is formed between the transfer cylinder 14 of the printing unit 10 shown and an adjacent transfer cylinder 14 of an adjacent printing unit. The printing nip 22 for printing on the printing material 21 may alternatively be arranged between the transfer cylinder 14 of the printing unit 10 and another impression cylinder, for example a satellite cylinder. be educated. The embodiment shown of inking unit 11 and dampening unit 12 is purely exemplary nature.

As already stated, at least one transfer mold 23 is positioned on the transfer cylinder 14 of the printing unit 10, which can be designed as a blanket or as a blanket plate. The invention relates to a printing unit in which at least one blanket is positioned on the transfer cylinder 14 as a transfer mold and at least one printing plate is positioned on the forme cylinder 13 as a printing forme.

Blankets have in contrast to blanket plates on no metallic support structure, wherein the setting of a required for ink transfer pressure via a contact structure 24 which is applied to the outer surface of the transfer cylinder 14 and thus with positioned on the transfer cylinder 14 blanket between the blanket and the transfer cylinder 14 is arranged. The contact structure 24 serves not only to set defined compression ratios on the transfer cylinder 14, but also to protect the cylinder surface of the transfer cylinder 14.

In such known from the prior art printing units in which printing plates 15 are positioned on the forme cylinders 13 as printing plates, which have bevelled leading ends and bevelled trailing ends, printing problems can occur during operation. Such printing problems can be caused by the fact that the printing plates are damaged by the bending or bending process at the leading end and trailing end so that the printing plates at the leading and trailing ends unintentionally tend to ink acceptance. The ink taken up by the printing plates in the region of their leading and trailing ends is then unintentionally transferred to the printing substrate 22 via the or each blanket, which is positioned on the transfer cylinder 14. This then leads to an unwanted Mitdrucken plate edges of the printing plates, whereby the print quality is impaired. This is a disadvantage.

To counteract the printing of printing plate edges, it is out of the DE 10 2008 004 892 A1 already known, formed as blankets or blankets transfer forms such that the same in sections, with which the same roll over the forme cylinder in the region of the or each clamping channel and thus in the region of the leading and trailing ends of the printing plates, a reduced wetting ability to ink, so then the respective transmission form which does not accept in the region of the leading and trailing ends of the respective printing plate accumulating ink and thus can not transfer to the substrate. Due to the frictional forces occurring in the printing operation, however, such changes in wettability have only a short service life and can not permanently prevent the pressure of the printing plate edges. In DE 10 2004 011 882 Alternatively, a depression of the lateral surface of the blanket is proposed. But since the position of the blanket and the recess on its surface with respect to the surface of the transfer cylinder is not clearly defined, such a recess must be very wide in order to effectively prevent the pressure of the plate edges. As a result, a cylinder oscillation can be excited, which is disadvantageous for the printing result.

On this basis, the present invention seeks to provide a novel printing unit of a printing press and a novel contact structure for a printing unit.

This object is achieved by a printing unit according to claim 1. According to the invention changes in the circumferential direction of the transfer cylinder, the radial thickness of the contact structure. The contact structure has at those peripheral portions a smaller radial thickness, at which in the printing operation leading and trailing ends of the or each pressure plate on the or each Roll off the blanket. With the present invention, it is proposed to design a contact structure, which is arranged between the transfer cylinder and the or each on the transfer cylinder to be positioned blanket and which is connected to the transfer cylinder, such that the contact structure, at least in those peripheral portions has a smaller radial thickness on which in operation run ends and trailing ends of the or each pressure plate unroll. Due to the reduced radial thickness of the contact structure in these peripheral sections, pressure conditions on the transfer cylinder can be influenced in such a way that in the region of the leading ends and trailing ends of the or each printing plate collecting printing ink can not be transferred to the respective blanket. Therefore, printing problems, namely the unwanted printing of plate edges, can be avoided.

The contact structure according to the invention is defined in claim 3.

According to a first advantageous development, the contact structure of a plurality of films is formed, which are applied to the transfer cylinder such that seen in the circumferential direction of the transfer cylinder a plurality of films or film sections are positioned one behind the other on the transfer cylinder, namely with formation of at least one gap between the circumferentially consecutively positioned slides or foil sections. This embodiment of the contact structure is easy to prepare and can also be easily applied to the transfer cylinder.

Preferably, seen in the radial direction of the transfer cylinder a plurality of films one above the other on the transfer cylinder such that at least a plurality of radially outer films are present, which are seen forming the or each gap between them in the circumferential direction of the transfer cylinder successively positioned together on a radially inner film over which the contact structure on a transfer cylinder can be applied as a unit. Alternatively, in the radial direction of the transfer cylinder Seen several films one above the other on the transfer cylinder can be applied so that on a radially inner film over which the contact structure is applied to a transfer cylinder as a unit, at least one radially outer film is positioned with at least one peelable strip, wherein by separating the or each strippable strip the or each gap between film sections of the or each radially outer film can be formed.

According to a second alternative advantageous development, the contact structure is formed by a single foil which can be applied to the transfer cylinder, wherein the foil has at least one depression on one side, on which the or each blanket comes to rest. This embodiment of the contact structure is easy to prepare and easy to apply to a transfer cylinder.

Fig. 1

einen aus dem Stand der Technik bekannten Aufbau eines Druckwerks;

Fig. 2

ein erstes Ausführungsbeispiel einer erfindungsgemäßen Kontaktstruktur für ein Druckwerk;

Fig. 3

ein Detail der Kontaktstruktur der Fig. 2;

Fig. 4

ein zweites Ausführungsbeispiel einer erfindungsgemäßen Kontaktstruktur für ein Druckwerk;

Fig. 5

ein Detail der Kontaktstruktur der Fig. 4;

Fig. 6

ein weiteres Ausführungsbeispiel einer erfindungsgemäßen Kontaktstruktur für ein Druckwerk;

Fig. 7

ein Detail der Kontaktstruktur der Fig. 6; und

Fig. 8

ein weiteres Detail der Kontaktstruktur der Fig. 6.

Preferred embodiments of the invention will become apparent from the dependent claims and the description below. Embodiments of the invention will be described, without being limited thereto, with reference to the drawings. Showing:

Fig. 1

a known from the prior art construction of a printing unit;

Fig. 2

a first embodiment of a contact structure according to the invention for a printing unit;

Fig. 3

a detail of the contact structure of Fig. 2 ;

Fig. 4

A second embodiment of a contact structure according to the invention for a printing unit;

Fig. 5

a detail of the contact structure of Fig. 4 ;

Fig. 6

a further embodiment of a contact structure according to the invention for a printing unit;

Fig. 7

a detail of the contact structure of Fig. 6 ; and

Fig. 8

another detail of the contact structure of Fig. 6 ,

The present invention relates to a printing unit of a printing press, in particular an offset printing unit of a web-fed printing press. The basic structure of such a printing unit has already been described with reference to Fig. 1 described. Furthermore, the invention relates to a contact structure for at least one on a transfer cylinder of a printing unit to be positioned blanket.

FIGS. 2 and 3 show details of a first contact structure 24 according to the invention, which is to be applied to a transfer cylinder 14 of a printing unit 10 of a printing press, namely in the unwound state.

The contact structure 24 is formed such that it has in the mounted state on the transfer cylinder 14 in the circumferential direction of the transfer cylinder 14 has a varying thickness, namely a varying radial thickness, namely at least in such peripheral portions of the transfer cylinder 14, at which in operation leading and trailing ends of or roll each on the form cylinder 13 positioned pressure plate 15 on the or each also positioned on the transfer cylinder 14 blanket 23. As a result, a color transfer of printing ink, which can collect in the region of the leading and trailing ends of the or each printing plate 15, be avoided on the blanket 23 and thus on the printed material 22 to be printed.

In the embodiment of FIGS. 2 and 3 the contact structure 24 is formed by a single film 25 which can be applied to the transfer cylinder 14, wherein the film 25 has at least one recess 27 on a first side 26 against which the respective blanket 23 abuts. In the illustrated embodiment, the film 25 has such a recess 27 which extends in the mounted on the transfer cylinder 14 state of the film 25 at a circumferential position of the transfer cylinder 14 in the axial direction thereof, namely at such a circumferential position at which the leading ends in the printing operation and trailing ends of the or each positioned on the forme cylinder 13 pressure plate 15 roll. In the embodiment shown, therefore, the leading ends and the trailing ends of the or each pressure plate 15 roll on the same circumferential position of the transfer cylinder 14 on the same, so that such a recess 27 is sufficient.

If, seen in the circumferential direction of the forme cylinder 13, two printing plates are positioned one behind the other on the same, then two such depressions 27 are formed on the film 25, which are then spaced apart in the circumferential direction of the transfer cylinder 14 and are preferably diametrically opposed.

In the embodiment of FIGS. 2 and 3 is, as already stated, the contact structure 24 formed by a single film 25, wherein the in FIGS. 2 and 3 shown recess 27 is formed by the fact that in the region of the first side 26 of the film 25 is removed from the film 25 material, for example by grinding, planing or other material-removing method.

According to Fig. 3 For example, the film 25 has a thickness x in such areas which serve to set a color transfer surface pressure. In order to form the recess 27 and form the pressure conditions on the transfer cylinder 14 in the region of the recess 27 such that a blanket 23 to be placed on the contact structure 24 or film 25 assumes no printing ink in the region of the recess 27 the side 26 of the film 25 material removed, namely by the dimension y. The recess 27, which extends in the axial direction of the transfer cylinder 14, thus has in the radial direction of the transfer cylinder 14 over the depth y.

On one of the first side 26 opposite second side 28, the film 25 is preferably carried out self-adhesive, so that the film 25 for forming the contact structure 24 on the transfer cylinder 14 with the self-adhesive side 28 can be positioned or fixed on the surface of the transfer cylinder 14.

A second embodiment of a contact structure 24 according to the invention in unwound state show 4 and 5 , In 4 and 5 For example, the contact structure 24 is formed by a plurality of films. Thus, in the embodiment of the 4 and 5 two outer films 29, 30 are applied to an inner film 32 to form a gap 31 therebetween, wherein in a state of the contact structure 24 mounted on the transfer cylinder 14, the two outer films 29, 30 are positioned one behind the other as viewed in the circumferential direction of the transfer cylinder 14, namely forming the gap 31, in which the transmission structure 24 has the reduced radial thickness.

Because the two radially outer foils 29, 30 are applied together on a radially inner foil 32, the contact structure 24 formed by the foils 29, 30 and 32 can be easily applied together or as a unit on the outer circumference of the transfer cylinder 14, Preferably, characterized in that the radially inner film 32 of the contact structure 24 on one side 33 thereof is made self-adhesive, so that accordingly the contact structure 24 with the self-adhesive side 33 of the inner film 32 applied to the surface of the transfer cylinder 14, namely glued, can be.

In the illustrated embodiment of the 4 and 5 has the radially inner film 32, which serves as a common carrier film for the two outer films 29, 30, over a radial thickness y. The radially outer foils 29, 30 have radial thicknesses x or z, wherein these radial thicknesses x, z of the two radially outer foils 29, 30 may be different. However, it is also possible that the two radially outer foils 29, 30 have identical thicknesses x = z.

In the embodiment of 4 and 5 the two radially outer foils 29, 30, which define the gap 31, seen in the axial direction of the peripheral cylinder 14, over equal widths and in the circumferential direction of the transfer cylinder 14 seen over equal lengths.

A further embodiment of a contact structure 24 according to the invention FIGS. 6, 7 and 8 , Also in the embodiment of Fig. 6 to 8 the contact structure 24 is formed by a plurality of films, namely by a radially inner film 34 and a radially outer film 35. The radially inner film 34 has according to FIGS. 7 and 8 over a radial thickness y and the radially outer foil 35 applied to the radially inner foil 34 has a radial thickness x.

Via a self-adhesive side 33 of the radially inner film 34, the contact structure 24 can be applied as a unit to the surface of the transfer cylinder 14, namely glued, become.

In the embodiment of Fig. 6 to 8 the radially outer film 35 has a peelable strip 36 which is detachable in particular after application of the contact structure 24 on the surface of the transfer cylinder 14 from the contact structure 24 by peeling, namely forming a recess 37 between then adjacent, after formation of the gap 37th adjacent film sections 38, 39 of the radially outer film 35. Then, when the contact structure 24 of Fig. 6 to 8 Applied over the radially inner film 34 on the transfer cylinder 14 and the strip 36 was separated from the radially outer film 35 by peeling it, the film sections 38 and 39 of the radially outer film 35 are positioned in the circumferential direction of the transfer cylinder 14 successively positioned, namely under training of the gap 37 between the film sections 38 and 39, in which case a blanket which is positioned on the contact structure 24 in the areas which cover the gap 37, receives no ink due to the reduced surface pressure.

According to the invention, a contact structure 24 is thus used on a transfer cylinder 14 of a printing unit which is positioned between the cylinder surface of the transfer cylinder 14 and the or each blanket 23 positioned thereon, the contact structure 24 being provided by at least one film. The contact structure 24 reduces in those areas of the transfer cylinder 14 at which the or each positioned on the same blanket 23 of trailing and leading ends of the or each positioned on the forme cylinder 13 printing plate 15, the surface pressure, so as to ensure that in Area of the leading and trailing ends of the or each printing plate 15 collecting ink is not transferred to the respective blanket 23.

LIST OF REFERENCE NUMBERS

10

printing unit

11

inking

12

dampening

13

form cylinder

14

transfer cylinder

15

printing form

16

paintbox

17

duct roller

18

Inking rollers

19

Feuchtdosiersystem

20

Dampening rollers

21

substrate

22

nip

23

blanket

24

Contact structure

25

foil

26

page

27

deepening

28

page

29

foil

30

foil

31

gap

32

foil

33

page

34

foil

35

foil

36

strip

37

deepening

38

film section

39

film section

Claims (11)

Printing unit of a printing press, with an inking unit (11), a transfer cylinder (14) and a forme cylinder (13), wherein the inking unit (11) applies printing ink to at least one printing plate (15) positioned on the forme cylinder (13), wherein the printing ink proceeds from the or each printing plate (15) via at least one on the transfer cylinder (14) positioned, formed as a blanket (23) transfer form to a substrate to be printed (22) can be applied, and wherein between the transfer cylinder (14) and the or each blanket (23) a contact structure (24) is positioned, which is connected to the transfer cylinder (14), characterized in that seen in the circumferential direction of the transfer cylinder (14) changes the radial thickness of the contact structure (24), wherein the contact structure (24) at those peripheral portions of the transfer cylinder (14) at which in printing operation leading and trailing ends of the or each pressure plate ( 15) roll on the or each blanket (23), has a smaller radial thickness. Printing unit according to claim 1, characterized in that the contact structure (24) is formed according to one of claims 3 to 11. Contact structure (24) for at least one rubber blanket to be positioned on a transfer cylinder, characterized in that the contact structure (24) has a thickness that changes in the circumferential direction of the transfer cylinder (14) such that the contact structure (24) at such peripheral portions, at which roll in the printing operation leading and trailing ends of the or each pressure plate, has a smaller radial thickness. Contact structure according to claim 3, characterized in that the contact structure (24) of a plurality of films (29, 30, 32, 34, 35) is formed, which can be applied to the transfer cylinder (14), that in the circumferential direction of the transfer cylinder (14). seen several films (29, 30) or film sections (38, 39) are successively positioned on the transfer cylinder (14), namely forming at least one gap (31, 37) between the in the circumferential direction of the transfer cylinder (14) successively positioned films ( 29, 30) or foil sections (38, 39). Contact structure according to claim 4, characterized in that the foils (29, 30) or foil sections (38, 39), between which the or each gap (31, 37) is formed, seen in the axial direction of the transfer cylinder (14) equal widths and / or in the circumferential direction of the transfer cylinder (14) have the same lengths. Contact structure according to claim 4 or 5, characterized in that the films (29, 30) or film sections (38, 39), between which the or each gap (31, 37) is formed, in the radial direction of the transfer cylinder (14) seen different thicknesses exhibit. Contact structure according to one of claims 4 to 6, characterized in that seen in the radial direction of the transfer cylinder (14) a plurality of films one above the other on the transfer cylinder (14) can be applied, wherein at least a plurality of radially outer foils (29, 30) are present, the training the or each gap (31) between the same in the circumferential direction of the transfer cylinder (14) are successively positioned together on a radially inner film (32) over which the contact structure (24) on a transfer cylinder (14) can be applied as a unit. Contact structure according to one of claims 4 to 6, characterized in that seen in the radial direction of the transfer cylinder (14) a plurality of films one above the other on the transfer cylinder (14) can be applied, wherein on a radially inner film (34) via which the contact structure (24) at least one radially outer sheet (35) is positioned with at least one peelable strip (36), wherein by separating the or each peelable strip (36), the or each gap (37) between the Film sections (38, 39) of the or each radially outer film (35) can be formed. Contact structure according to Claim 3, characterized in that the contact structure (24) is formed by a single foil (25) which can be applied to the transfer cylinder (14), the foil (25) being attached to a side (26) on which the or each blanket comes to rest, having at least one recess (27). Contact structure according to claim 9, characterized in that the or each recess (27) is formed by removal of material on the side (26) of the film on which the or each blanket comes to rest. Contact structure according to one of claims 3 to 10, characterized in that the same on one side (28, 33) self-adhesive and with the self-adhesive side (28, 33) on a surface of a transfer cylinder (14) can be applied.

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