EP1291176A2 - Printing machine and method of operating an inking unit - Google Patents

Abstract

A screen roller (5) consisting of a pattern formed of recesses (11) over its periphery which are filled with a printing medium. The screen roller and the roller (7) with which it is driven are coupled so that, each time the screen roller rotates, the printing medium present in the form of piled-up printing medium (15) is placed into the voids (19) formed by the previous revolution and free of printing medium.

Description

The invention relates to a printing press with an inking unit, in particular Short inking unit, according to the preamble of claim 1 and a method for operating a Inking unit, according to the preamble of claim 6.

Printing machines and methods of the type discussed here are known. An acquaintance Printing machine comprises an inking unit, for example an anilox inking unit, which has a Anilox roller for metering one on a cooperating with the anilox roller Inking roller to be transferred printing medium, such as paint or varnish, includes. The anilox roller has recesses on its periphery, for example single cups or lines, formed pattern. The pressure medium is from the Anilox roller on a printing plate, such as plate cylinder, transferred and from this on a substrate. Due to the pattern of the anilox roller are the Solid areas of a print image applied to the substrate are not closed, but you can see the fine anilox structure, which is not desirable.

To prevent the pattern of the anilox roller from being visible on the printed image, For example, additional rider rollers are used on the inking roller, the to rub this pattern. The disadvantage here is the cost-intensive construction of the Printing unit and that the additional rollers cause the inking unit to cease is stencil-free. Furthermore, it is known that the pattern on the anilox roller is so fine training that it no longer perceived as disturbing by the eye of an observer becomes. As the pattern becomes finer, however, the transferable amount of color, that is, the amount of color that can be transferred, increases Creation volume of the depressions in the anilox roller and thus the density of the the printed matter applied printed image. Consequently, the cleaning of designed Anilox roller very difficult. Furthermore, a device is known from DE 44 31 464 A1, the differential circumferential speed between the anilox roller and inking roller allows you to blur the print media pattern on the inking roller. It has however, it has been found that the printing medium film on the inking roller is not can be uniformed in the desired manner and that at Differential peripheral speeds greater than about 5% the pressure medium density easy decreases while the pattern remains visible in the print image.

It is an object of the invention to provide a printing machine of the type mentioned, with the one possible closed solid surface can be printed and the preferably has a simple and inexpensive construction. Another goal is to provide a method of operating an inking unit, wherein a Closed as possible solid surface is preferably generated by simple means.

To solve the problem, a printing press with the features of claim 1 proposed. It has an anilox roller, such as an anilox roller, on its periphery has a pattern formed from recesses. The wells are with a printing medium, such as liquid paint or paint, filled. The anilox roller is in contact with another roller, such as a dye transfer roller the applied in the wells pressure medium is applied. The Printing machine is characterized in that the anilox roller and the roller are drivingly coupled together so that after each revolution of the anilox roller that through the print medium on the roll in the form of print medium clusters pictured patterns opposite one at a previous revolution of Anilox roller on the roller imaged pattern such a small offset in Circumferential direction that the new pressure medium accumulations in the pressure medium-free or substantially pressure medium-free gap in each case adjacent Pressure medium residual accumulations can be positioned on the roller. That in the Wells located pressure medium is thus in between the anilox roller and transferred to the roller nip formed on the roller and forms on the roller Peripheral surface small pressure medium accumulations, which in the circumferential direction of the Roll a corresponding to the pattern of the wells constant distance from each other exhibit. After a part of the piled in the course of a rotation of the roller Pressure medium by cleavage to a cooperating with the roller printing plate, For example, a plate cylinder was dispensed remain in their volume and their height reduced pressure medium residual accumulations on the roller. Between these Pressure medium residual accumulations are virtually pressure medium-free gaps. The Unwinding of the anilox roller and the roller on each other is adjusted such that when the pressure medium-free gaps on the roller are moved past the anilox roller of this the next, fresh pressure medium accumulations in exactly these gaps between the pressure medium residual accumulations are placed on the roller. To the gaps between the pressure medium accumulations to be provided with pressure medium, are - Unlike in known methods - so this is not blurred, but it takes place Controlled filling of the practically pressure medium free gaps between the Media residual buildup on the roll with fresh print media buildup. As a result, a printing medium surface relief is generated on the roller, whose Pressure medium layer thickness comparatively only slightly fluctuates, causing the Increased print quality and a consistent coloration of a printed solid surface is feasible. The pattern formed by the depressions on the anilox roll is thus can not be seen on the printed image applied to a substrate.

The size of the offset between the fresh print media buildup and the Pressure medium residual accumulation is dependent on the distance of the anilox roller provided wells to each other. For example, instructs the anilox roller Cup or line patterns on, for example, up to 50 on a centimeter Be provided lines. The distance between two adjacent lines can be seen here Range from a few hundredths of a millimeter to a few tens of millimeters.

In an equally suitable anilox engraving the anilox roll pattern is through Wells or lines are formed, of which one centimeter can be arranged over 100 can. It becomes clear that the offset must be extremely precise so that the new Media accumulations exactly in the pressure medium free or substantially pressure-medium-free gap of each adjacent pressure medium residual accumulations on the Roller to be set.

In an advantageous embodiment of the printing machine is provided that the anilox roller and the roller are coupled together via a single-stage or multi-stage drive gear. In a particularly advantageous embodiment, the overall gear ratio "i" of the drive gear is selected and the diameter d _{R of} the anilox roller and the diameter d _{W of} the roller coordinated so that the peripheral speed difference is zero, so that the anilox roller and roll roll without slipping together, yet, after each revolution of the anilox roller, the pattern imaged on the roller has such a small offset in the circumferential direction that the new print medium clusters are placed in the virtually pressure medium-free gap of respectively adjacent print medium residual clumps on the roller. This is realized, for example, in that the transmission ratio is 1: 1.999, the diameter d _{W of} the roller is 200 mm, and the diameter d _{R of} the anilox roller is 100.05 mm. Preferably, the diameter d _{W of} the roller is the same size as the diameter of a plate cylinder in contact with the roller.

Further advantageous embodiments will be apparent from the remaining dependent claims.

To solve the problem, a method for operating an inking unit with the Characteristics of claim 6 proposed. The procedure provides that the anilox roller and the roller are rotated so that after each revolution of the Anilox roller that through the printing medium on the roller in the form of pressure medium clusters pictured patterns versus one in a previous revolution The anilox roller and the roller imaged such a small offset in Circumferential direction that the new pressure medium accumulations in the pressure medium-free or substantially pressure medium-free gap in each case adjacent Pressure medium residual accumulations of the roller are positioned. The offset can be both be realized in the direction of rotation of the rollers or against the direction of rotation of the rollers.

Figur 1

einen Ausschnitt aus einem Ausführungsbeispiel einer Druckmaschine, nämlich zwei aneinander abrollende Walzen,

Figur 2

ein Ausführungsbeispiel eines mehrstufigen Antriebsgetriebes für Walzen der Druckmaschine in Seitenansicht,

Figur 3

ein weiteres Ausführungsbeispiel einer Antriebseinrichtung für Walzen der Druckmaschine mit Blick in Maschinenlaufrichtung und

Figur 4

ein drittes Ausführungsbeispiel der Antriebseinrichtung für Walzen in Seitenansicht.

The invention will be explained in more detail below with reference to the drawing. Show it:

FIG. 1

a detail of an embodiment of a printing press, namely two rolls rolling against each other,

FIG. 2

an embodiment of a multi-stage drive gear for rolls of the printing press in side view,

FIG. 3

a further embodiment of a drive device for rolls of the printing machine with a view in the machine direction and

FIG. 4

a third embodiment of the drive device for rollers in side view.

The printing machine 1 described below is generally applicable. Hereinafter is purely exemplary assumed that it is an offset printing press which is operated in wet offset or dry offset. This for printing a Print image on a substrate, for example a sheet or a web of paper, Cardboard, plastic or sheet metal, selected printing medium can be, for example, liquid or be pasty paint or varnish. The following is assumed to be here liquid color is.

Figure 1 shows a section of an embodiment of the printing machine 1, namely an inking unit 3, which is formed here by an anilox inking unit. The inking unit 3 comprises an anilox roller 5, which is in contact with a roller 7 stands, that is, the anilox roller 5 and the roller 7 roll off each other. The roller 7 is here formed by a an elastic jacket having inking roller with a plate cylinder, not shown in Figure 1 cooperates. The diameter of the Roller 7 is preferably the same size as that of the plate cylinder, wherein in this Embodiment of the diameter of the anilox roller 5 is half as large as that of the roller 7th

In the peripheral surface 9 of the anilox roller 5 are at an equal distance from each other arranged recesses 11 are provided, whereby a pattern is formed. The Recesses 11 are formed here as wells, the cell geometry and the Cell distribution determine the cup volume of the anilox roller. The depressions 11 can be filled with paint, wherein a doctor device, not shown in Figure 1, the Scrapers peripheral surface 9 of the anilox roller 5, ensures that the recess 11th be reproducibly filled with color and thus always a predetermined color volume is transferred to the roller 7.

The anilox roller 5 and the roller 7 are not shown in FIG Driven drive means, wherein between the anilox roller 5 and roller 7 is a small Circumferential speed difference is set, that is, there is a slip between the rollers 5, 7, which will be discussed in more detail below. to Setting a desired peripheral speed difference is preferably one not shown control means provided by means of which the drive means is controlled.

From the wells 11 of the anilox roller 5 is color on the peripheral surface 13 of Roll 7 transfers and forms thereon small color clusters 15 (print medium clusters), seen in the circumferential direction of the roller 7 a constant distance to each other. In this case, the recesses 11 on the anilox roller 5 partially emptied. Due to the color clusters 15 forms on the peripheral surface 13 of the roller. 7 the pattern or the structure of the anilox roller 5 from. The on the roller 7 applied color clusters 15 are due to the ongoing color splitting not completely transferred to the plate cylinder, but a part of each of the color clusters 15 remains on the roller 7. These remaining color piles are in the Hereinafter referred to as residual color accumulations 17 (residual pressure accumulations). Between each adjacent color residual accumulations 17 is a colorless Gap 19. As can be seen from FIG. 1, the residual color accumulations 17 have a smaller one Color volume and a lower height than the color clusters 15 on, as by Color splitting each one part of the color clusters 15 delivered to the plate cylinder has been.

The rolling ratios of the anilox roller 5 and the roller 7 are selected so that Moving the gaps 19 on the anilox roller 5 in the region of the nip of the Anilox roller 5 the new color clusters 15 exactly in the gaps 19 between the color residual accumulations 17 are set or transferred to the roller 7. Thereby becomes on the peripheral surface 13 of the roller 7 a continuously colored ink film formed, whose thickness varies only slightly. Due to the continuous coloring can be printed on the substrate a closed solid surface, in which the Pattern on the anilox roller is not recognizable. So there are no additional rollers or other means for smearing or elimination of the color clusters 15 required, as used in known printing machines.

A completely pressure medium-free gap 19 between adjacent residual color clusters 17 is ultimately only after a first revolution of the roller. 7 After the gaps 19 have passed the nip, the previously colorless gaps are 19 provided with color clusters 15, so that a closed color film is formed, such as it in Figure 1 on the nip downstream part of the peripheral surface 13 of the Roller 7 is shown. Because with each revolution of the roller 7 parts of the color clusters 15 and the color residual accumulations 17 are transferred to the plate cylinder, Finally, only the thickness of the color film fluctuates.

FIG. 2 shows a section of a further embodiment of the printing press 1, namely the anilox roller 5 and the roller 7, which via a multi-stage drive gear 21st coupled together. The drive gear 21 is part of the drive device for the rollers 5, 7. The drive gear 21 comprises a first gear stage 23, a second Gear stage 25 and a third gear stage 27. The drive gear 21 has a first Gear 29 and a second gear 31 which rotatably connected to a shaft 33 and a third gear 35 and a fourth gear 37 connected to a shaft 39 are rotatably connected. The drive device 21 further comprises a fifth gear 41, which is rotatably connected to a bearing pin 43 of the anilox roller 5. The first gear 29 and coupled to the roller 7 gear 75 form the first gear stage 23, the meshing with each other engaged gears 33, 35 form the second Gear stage 25 and the gears 39, 41, the third gear 27th The Overall gear ratio of the drive gear 21 is selected so that - As described with reference to Figure 1 - the color clusters 15 in the gaps 19th be positioned between the color residual accumulations 17, wherein the Peripheral speeds of the anilox roller 5 and the roller 7 to each other preferably are the same or slightly different.

FIG. 2 also shows a diagrammatic representation of one of the anilox roller 5 Doctor device 45 indicated, which may be formed for example by a chamber doctor blade can.

In one embodiment, not shown in the figures, the drive gear single-stage, that is, there are only two gears provided, of which a first gear with the roller 7 and a second gear with the anilox roller 5 are coupled, which mesh with each other.

Figure 3 shows a cross section through an embodiment of the printing machine 1 in Area of the inking unit 3. It is here still one of a plate cylinder 47 formed Printing form 49 shown, which is in contact with the roller 7. There is another one Embodiment of the drive device shown. The roller 7 is with a Main drive 51 of the printing press 1 coupled. For this purpose, one with the roller. 7 connected gear 53 and connected to the plate cylinder 47 gear 55th intended. The gear 55 is connected to the gear 53 and one with the Main drive 51 connected gear 57 meshing engaged. In this Embodiment, the gears 53, 55 have the same speeds, so that the Roller 7 and the plate cylinder 47, which have the same diameter, slip-free unroll. The anilox roller 5 is coupled to a separate motor 59, see FIG that a desired peripheral speed difference between the anilox roller 5 and the roller 7 can be made by influencing the engine control. The embodiment of the drive device shown in Figure 3 has the advantage on that the peripheral speed difference for any pattern of Anilox roller 5 can be optimally adjusted. With the help of the separate motor 59 can So an extremely small translation can be realized, so that the anilox roller 5 per Rotation in the circumferential direction, ie in or against its direction of rotation, relative to the Roller 7 has an offset, which is preferably a few 10ths of a millimeter or 100ths Millimeters.

FIG. 4 shows a section of a further embodiment of the printing press 1 in side view, in which the anilox roller 5 via gears with the not closer driven main drive of the printing press is driven. The offset of the fresh Pressurized media builds up to the print media residual buildup is by Superposition gear 61 caused. In this embodiment, the are not illustrated plate cylinder, the roller 7 and the anilox roller 5 via gears in one Level connected with each other. The superposition gear 61 is here of a Planet gear formed, the gear 63 with internal teeth, a ridge 65, on the three planet gears arranged in pairs 67 are rotatably mounted and a rotatably connected to the anilox roller 5 connected gear 69 includes. The gear design is chosen here so that at conceivable stop of a motor 71 and consequently at resting ridge 65 the anilox roller would turn twice when the anilox roller 7 has gone through a revolution. In operation, the web 65 is so by means of the motor 71 slowly twisted that the overall translation of the superposition gear 61 of the Cup and line structure of the respectively used anilox roller 5 accordingly is adjusted and that the coloring of the roller 7 is again such that the color clusters 15 is positioned in the gap 19 between the color residual clusters 17 become.

The motor 71 needs to rotate the web 65 very little power and can therefore be designed to be correspondingly small. Furthermore, a high accuracy for adjustment the peripheral speed difference between the anilox roller 5 and roller 7 easily adjustable, since the motor 71 is a large translation for its slow-running pinion 73rd has, whereby the resolution also multiplies. The described with reference to FIG 4 Ausrührungsform further has the advantage that in case of failure of the engine 71st can still be re-printed, if not more as desired, because then the peripheral speed difference between the anilox roller 5 and roller 7 is zero.

Alternatively to the overlay gear 61 described with reference to FIG Of course, other ways of producing a very small, exact adjustable peripheral speed difference between the anilox roller 5 and roller. 7 be used.

LIST OF REFERENCE NUMBERS

1

press

2 3

inking

4 5

anilox roller

6 7

roller

8th 9

peripheral surface

10 11

wells

12 13

peripheral surface

14 15

Color Pilings

16 17

Color residual accumulations

18 19

colorless gap

20 21

drive gear

22 23

first gear stage

24 25

second gear stage

26 27

third gear stage

28 29

first gear

30 31

second gear

32 33

wave

34 35

third gear

36 37

fourth gear

38 39

wave

40 41

fifth gear

42 43

pivot

44 45

doctor device

46 47

plate cylinder

48 49

printing form

50 51

main drive

52 53

gear

54 55

gear

56 57

gear

58 59

engine

60 61

Superposition gear

62 63

gear

64 65

web

66 67

planetary gears

68 69

gear

70 71

engine

72 73

pinion

74 75

gear

Claims (6)

Printing machine (1) having an inking unit (3), in particular a short inking unit, with an anilox roller (5) having on its circumference a pattern formed by depressions (11), which cooperates with a roller (7), the depressions (11) having a Pressure medium can be filled, and with a drive device,
characterized in that the anilox roller (5) and the roller (7) are drivingly coupled to each other so that after each revolution of the anilox roller (5) through the printing medium on the roller (7) in the form of pressure medium clusters (15) Pattern compared to one in a previous revolution of the anilox roller (5) on the roller (7) imaged pattern has such a small offset in the circumferential direction that the new print medium clusters (15) in the pressure medium-free or substantially pressure medium-free gaps (19) respectively adjacent Druckmedium residual accumulations (17) on the roller (7) are positionable. Printing machine according to claim 1,
characterized in that the anilox roller (5) and the roller (7) via a single-stage or multi-stage drive gear (21) are coupled together. Printing machine according to claim 1,
characterized in that the roller (7) with a main drive (51) of the printing machine (1) and the anilox roller (5) with a separate motor (59) are coupled. Printing machine according to claim 1,
characterized in that the anilox roller (5) and the roller (7) via a superposition gear (61) are interconnected. Printing machine according to one of the preceding claims,
characterized in that the roller (7) is driven at machine speed and that a differential circumferential speed between the screen roller (5) and roller (7) is adjustable by increasing or slowing down the anilox roller peripheral speed. Method for operating an inking unit (3), in particular a short inking unit, which comprises an anilox roller (5) which cooperates with a roller (7) and has on its circumference a pattern formed from depressions (11) which can be filled with a pressure medium,
characterized in that the anilox roller (5) and the roller (7) are rotated so coordinated that after each rotation of the anilox roller (5) by the printing medium on the roller (7) in the form of pressure medium clusters (15) shown Pattern compared to one in a previous revolution of the anilox roller (5) on the roller (7) imaged pattern has such a small offset in the circumferential direction that the new print medium clusters (15) in the pressure medium-free or substantially pressure medium-free gaps (19) respectively adjacent Print medium residual accumulations (17) on the roller (7) are positioned.

Images