EP2718104B1 - Printing unit of a gravure printing machine having a pivotable ink pan and method for inking and cleaning a gravure printing cylinder - Google Patents

Description

The invention relates to a printing unit of a gravure printing machine according to the preamble of patent claim 1 and to a method for cleaning ink-bearing parts of a printing unit of a gravure printing press according to the preamble of patent claim 13.

A printing unit of a gravure printing machine comprises a gravure cylinder, which carries the print motif, so that the printing ink is transferable in terms of format to a printing substrate. The printing material runs via a so-called impression roller, which can be adjusted to the gravure cylinder, which is displaceably mounted, for example, in the side walls of the machine frame.

To apply ink to the gravure cylinder, this usually immersed in a paint tray, which is filled with the ink. The ink is thereby taken from the introduced into the gravure cylinder depressions, which represent the print motif. The part of the ink, which is taken from the raised areas of the gravure cylinder, is usually removed from an arranged between the ink pan and the printing material doctor blade from the surface of the gravure cylinder, so that ink remains only in the wells.

After a completed print job, it is now often necessary, the ink-carrying parts of the printing unit or at least the gravure cylinder, too clean. This is necessary because for a follow-up order usually a new gravure cylinder is used in the printing unit. Often, it is additionally desired that a different color is used in this printing unit for the next job.

The publication US 3,896,730 discloses a system for cleaning a flexographic printing unit. In this system, the ink used in the print job is pumped out of the ink tray via a front side arranged drain. A cleaning fluid is now applied to a inking roller via the line system, via which ink is supplied in the printing operation. By rotation of these inking roller and the engageable with the inking roller metering these two rollers are cleaned. In addition, a spray nozzle strip is provided with which pressurized cleaning fluid can be added to the inking roller. Since only one or more printing plates are inked in a printing roller which operates on the flexographic printing principle and these plates are removed from the printing drum when the printing job is finished, it is not necessary to clean the printing drum.

Even with known gravure printing works, the ink-carrying parts, so primarily the ink pan and the gravure cylinder, thereby cleaned that pumped in the ink pan ink pumped through a frontal drain and that the pressure cylinder is cleaned with a spray of a spray bar on the printing cylinder applied cleaning fluid.

This process takes a relatively long time, so that time that could be used for production is lost.

The publication US 2,201,452 discloses, therefore, a paint trough which in use is suspended at two fixed points on a wall of the machine frame. The gravure cylinder is also mounted at a fixed point in the machine frame. A relative adjustment of the position of the ink pan depending on the diameter of the gravure cylinder is not given. To drain the paint, the paint tray must now be detached from one of the two fixed points and be panned around the second point. The ink runs through a gutter of the paint tray. This structure and procedure require a lot of space and also a lot of time since the ink tray has to be swiveled manually. The downtime is extended accordingly.

The object of the present invention is therefore to propose an apparatus and a method with which the unproductive downtime required for cleaning can be shortened.

This object is achieved by a printing unit according to claim 1. First, it is provided that the ink tray - like that in the US 2,201,452 - a gutter includes, over which the ink can be removed. The gutter may extend in the longitudinal direction of the ink pan, wherein the extension direction of the ink pan is parallel to the axis of the gravure cylinder. Furthermore, the invention provides that the ink pan is at least as far pivotable that the ink is transferred into the gutter the pivot axis of the ink pan should run parallel to the extension direction of the ink pan.

Proceeding from this, the invention provides that the ink pan comprises an end wall, which has a U-shaped recess, wherein the pin of the gravure cylinder pierces the recess, so that the end wall and ink tray is vertically displaceable relative to the gravure cylinder and pivotable about the axis of rotation of the gravure cylinder.

Due to these design features, it is now possible, instead of pumping the ink over the front side of the paint tray to transfer the ink in a very short time in the gutter. From this gutter, the ink can be removed via a connection piece. The gutter can be greatly inclined in the direction of the connection piece, so that the ink flows quickly.

In gravure printing machines, which are used for example in packaging printing, it is often desired. To use pressure cylinders of different diameters. Therefore, the other structural features have the goal to be able to use in a printing unit according to the invention also pressure cylinder of different diameters.

It is therefore advantageous if the pivot axis of the ink pan and the axis of rotation of the printing cylinder coincide or at least close to each other. In a first embodiment of the invention, it is therefore provided that the ink tray is attached to holding elements, which in turn are attached to a ring, said ring being rotatable about the journal carrying the gravure cylinder.

In a particularly preferred embodiment of the invention, side plates are provided on which the color pan or the color pan supporting pivot lever are supported, wherein the ink pan or the pivot lever are movable together with the ink pan relative to the side plates. In this embodiment, the elements necessary for pivoting the ink tray have no points of contact the printing cylinder or its attachments. Thus, the printing cylinder can be conveniently removed from the printing unit, without having to first dismantle holding means for the ink tray.

In a further embodiment of the invention, it is provided that the side plates comprise sliding elements or rolling elements and the ink pan or the pivot lever comprise recesses in which the sliding elements or rolling elements can be guided. The rolling elements may be, for example, conventional rollers which revolve around pins which are fastened in the component to be guided.

In an alternative embodiment, it is provided that the ink pan or the pivot levers comprise the sliding elements or the rolling elements. In this case, the side plates comprise recesses in which the sliding elements or the rolling elements are feasible. With the two embodiments described above kinematics have been found that realize the inventive idea in a simple manner.

In an advantageous embodiment, the recesses are circular arc-shaped and extend concentrically about the axis of rotation of the gravure cylinder. In this way it is ensured that the pivot axis of the ink pan coincides with the axis of rotation of the printing cylinder or that pivot axis and axis of rotation are close to each other.

It is particularly advantageous if a force delivery element acts on the ink pan or the pivot levers to make a manual intervention for pivoting the ink pan unnecessary.

It is particularly cost effective if the power delivery element is a compressed air cylinder.

A particularly preferred embodiment of the invention includes that the side plates are displaceable relative to the machine frame. For this purpose, suitable devices should be provided. A preferred embodiment of this is disclosed in the instant specification. A displacement of the side plates is advantageous if gravure cylinders of different diameters are to be used in the printing unit.

Furthermore, it is advantageous if at least one lever arm which supports a inking roller is articulated in the side plates, by which means the inking roller can be set against the gravure cylinder. A storage of the inking roller in a lever arm is particularly advantageous in the use of pressure rollers of different diameters.

In a further embodiment, it is provided that the inking roller is partially surrounded by an enclosure, in which a fluid inlet nozzle is introduced. About this fluid inlet nozzle printing ink or a cleaning liquid can be introduced into the printing unit in a simple manner.

In a further embodiment, it is provided that the ink tray comprises end walls, in which recesses are introduced. Through these recesses, the inking roller or at least its pin can reach through the end walls. This allows lever arms to be located outside the inkwell, but still allows the position of the inking roller to be adapted to the diameter of the impression cylinder.

A further component of the invention is a method for cleaning color-guiding parts of a printing unit of a gravure printing machine, wherein printing ink or a cleaning fluid are provided or collected in a paint trough and a gravure cylinder in the ink or cleaning fluid is immersed. According to the invention, it is provided that the ink tray is pivoted so far that the printing ink or the cleaning fluid is transferred into the gutter enclosed by the ink tray.

In this way, the method for cleaning color-leading parts of a printing unit of a gravure printing machine is accelerated because now no longer the Printing ink must be pumped through a - usually frontal - connection to the ink tray.

1. 1. Schwenken der Farbwanne. Hierbei fließt die Druckfarbe über die Ablaufrinne zurück in den Farbtank. Anschließend erfolgt ein Zurückschwenken in die Ausgangsposition.
2. 2. Füllen der Farbwanne mit frischem Reinigungsfluid, beispielsweise Lösemittel. Dabei wird das Reinigungsfluid über den Zulaufstutzen der Einhausung auf die Einfärbewalze gegeben, so dass das Reinigungsfluid auf die Druckwalze aufgetragen wird und schließlich in die Farbwanne gelangt.
3. 3. Waschzyklus: Der Druckzylinder wird mit maximal möglicher Drehgeschwindigkeit gedreht. Durch das Eintauchen des Druckzylinders in das Reinigungsfluid und durch die hohe Geschwindigkeit werden alle Farbe führenden Teile des Druckwerks gereinigt, wobei die Reste der Druckfarbe durch das Reinigungsfluid stark verdünnt werden. Mit farbführenden Teilen sind hier solche Teile gemeint, deren Kontakt mit der Farbe beabsichtigt und notwendig für den Druckprozess ist. Hierzu gehören beispielsweise nicht Spritzschutze oder ähnliches, die nur eine übermäßige Umgebungsverschmutzung verhindern sollen, aber nicht zwingend für den Druckprozess benötigt werden.
4. 4. Schwenken der Farbwanne. Das nunmehr verschmutzte Reinigungsfluid wird über die Ablaufrinne aus der Farbwanne abgeführt und einem Schmutztank zugeführt.
5. 5. Die Verfahrensschritte 2. bis 4. werden zumindest einmal wiederholt. Wenn jedoch beispielsweise von einer helleren zu einer dunkleren Druckfarbe gewechselt wird, kann dieser Verfahrensschritt, also die Wiederholung, auch unterbleiben.
6. 6. Über den Zulaufstutzen der Einhausung wird wiederum Reinigungsfluid auf die Einfärbewalze gegeben. Dabei wird die Einfärbewalze in berührendem Kontakt mit der Druckwalze gehalten. Die Umfangsgeschwindigkeiten der Einfärbewalze und der Druckwalze können leicht unterschiedlich sein, so dass mithilfe der Einfärbewalze die Druckwalze gereinigt wird.
7. 7. Schwenken der Farbwanne, so dass das Reinigungsfluid über die Ablaufrinne abgeführt werden kann.

An embodiment of a cleaning process comprising the process step according to the invention could be as follows:

1. 1. Panning the ink tray. The ink flows through the gutter back into the paint tank. Subsequently, a swing back to the starting position.
2. 2. Fill the ink tray with fresh cleaning fluid, for example solvent. In this case, the cleaning fluid is added via the inlet nozzle of the housing to the inking roller, so that the cleaning fluid is applied to the pressure roller and finally passes into the paint tray.
3. 3. Washing cycle: The printing cylinder is rotated at the maximum possible rotational speed. By immersing the printing cylinder in the cleaning fluid and the high speed of all ink-carrying parts of the printing unit are cleaned, the remains of the ink are greatly diluted by the cleaning fluid. By color-guiding parts are meant here those parts whose contact with the color is intended and necessary for the printing process. These include, for example, not splash guards or the like, which should only prevent excessive environmental contamination, but not necessarily required for the printing process.
4. 4. Panning the ink tray. The now contaminated cleaning fluid is removed via the gutter from the paint tray and fed to a dirt tank.
5. 5. The process steps 2 to 4 are repeated at least once. If, however, for example, from a lighter to a darker ink is changed, this step, so the repetition, also be omitted.
6. 6. Cleaning fluid is in turn added to the inking roller via the inlet nozzle of the housing. The inking roller is held in touching contact with the pressure roller. The peripheral speeds of the inking roller and the pressure roller may be slightly different, so that using the inking roller, the pressure roller is cleaned.
7. 7. Swiveling the ink tray, so that the cleaning fluid can be discharged through the gutter.

Further embodiments of the invention will become apparent from the subject description.

Fig. 1

Schematische Ansicht einer Mehrfarben-Tiefdruckmaschine

Fig. 2

Detailansicht eines erfindungsgemäßen Druckwerks

Fig. 3

Detailansicht eines erfindungsgemäßen Druckwerks, bei dem die Farbwanne abgeschwenkt wurde.

Fig. 4

Eine weitere Ausführungsform eines erfindungsgemäßen Druckwerks

Fig. 5

wie Figur 4, jedoch mit abgeschwenkter Farbwanne

The individual figures show:

Fig. 1

Schematic view of a multicolor gravure printing machine

Fig. 2

Detail view of a printing unit according to the invention

Fig. 3

Detail view of a printing unit according to the invention, in which the ink tray has been swung.

Fig. 4

Another embodiment of a printing unit according to the invention

Fig. 5

as FIG. 4 , but with swiveled ink tray

Fig. 1 shows a schematic view of a multi-color gravure printing machine 1, which is designed in the so-called stator construction. This gravure printing machine 1 shown by way of example is shown with four printing units D1 to D4. However, a gravure printing press is not limited to this number of printing units. Stand-mounted printing machines can even be expanded in a modular manner, so that a user of such a printing press can use as many printing stands as he wishes. In each individual printing unit, a printing ink is printed.

Starting from an unwinding device 2, the material web 4 is fed to the printing machine. About different guide rollers 3, the material web 4 enters the printing unit D1. There, the material web 4 is guided over a impression roller P1. This impression roller P1 is adjustable in the direction of the double arrow y in its height position and thus adjustable to the gravure cylinder T1. In this case, the material web passes through the nip between the impression roller P1 and the gravure cylinder T1. The material web is now printed with the print motif of a printing ink. About further guide rollers 3, the material web 4 enters the printing unit D2. On the Way to the printing unit D2 passes through the web 4 a plurality of drying devices, not shown, so that the printed in the printing unit D1 printing ink can dry sufficiently.

After printing in the printing unit D2, the material web 4 in turn passes through further guide rollers 3 in the printing unit D3, where a third color can be printed. The last illustrated printing unit D4 is not printed, d. h., The impression roller P4 has been moved upwards, so that the material web does not touch the gravure cylinder T4. In this printing unit D4, for example, a cleaning of all ink-carrying parts can be made. After leaving the printing unit D4, the web 4 passes through further guide rollers 3 to a preferred device 5, which comprises a tension roller 6 and a pressure roller 7. Finally, the material web 4 passes to a winding device 8, where it is wound up into a winding.

The FIG. 2 now shows a detailed view of the printing unit D4. This printing unit D4 initially comprises a machine frame 10, in which the gravure cylinder T4 is rotatably mounted in a manner not shown. Furthermore, a side plate 11 can be seen, which in the direction of the double arrow y 'in height is mobile. For this purpose, a driven gear 12 is rotatably mounted in the machine frame 10, which meshes with the rack 13, which is fixed to the side plate 11. With this height-adjustable side plate 11, it is possible to position the ink tray 14 so that gravure cylinder T4 different diameter always deep enough in the ink 15, which is absorbed by the ink tray 14, immerse.

In the side plate 11, two circular arc-shaped recesses 16, 17 are introduced, whose non-visible, hidden by the pivot lever 18 areas are shown with a dashed line. On the pivot lever 18, two pins are attached, each extending into a recess. Each pin carries a roller 19, which can roll on the edge of the recess 16, 17, respectively.

The pivot lever 18 - a pivot lever is provided at each end of the ink tray 14 - continue to wear on their inner sides support members 20, which may be configured, for example, as screws. The ink tray 14 may simply be placed on these support members 20. However, it is also conceivable that the ink tray is locked by means not shown closure elements on the support members 20.

The pivot lever 18 has at one of its ends a semicircular course 21, with which the bearing 22 of the lever arm 23 is rebuilt in a simple manner.

In the lever arm 23, which is mounted on the side facing away from the viewer side of the side plate, a inking roller 24 is mounted, which rotates in the direction of arrow 25 in the rule. The inking roller 24 is surrounded by a housing 26, which is also supported by the lever arm 23. In this housing 26 an inlet nozzle 27 is integrated, can be given to the inking roller 24 via the ink or a cleaning fluid. In printing or cleaning operation, the inking roller 24 can be set close to the printing cylinder T4, but without touching it. Above the resulting nip remains a majority of the ink or the cleaning fluid. However, a narrow film is taken through the nip by the gravure cylinder T4. The inking roller 24 can also be employed on the printing cylinder. In the cleaning operation, this may be advantageous since the inking roller 24 pushes the cleaning fluid into the depressions (wells), so that as complete a cleaning of these depressions takes place. In principle, however, the cleaning operation is also possible without the use of the inking roller.

At the pivot lever 18 engages one end of a piston-cylinder unit 28, which is preferably operated with compressed air as a pressure medium. The second end of the piston-cylinder unit 28 is mounted rotatably in the side plate 11 by means of bearings 31. It is advantageous to use a piston-cylinder unit which can be acted upon by the pressure medium for both directions of movement, so that always the shortest positioning times are achieved. The piston-cylinder unit 28 is mounted so that the cylinder 29 engages the pivot lever 18 and the piston 30 engages the side plate. This avoids that if accidentally ink hits the piston-cylinder unit, the piston and the seals of the piston-cylinder unit are affected.

In the FIG. 2 is the piston-cylinder unit 28 connected so that it holds the pivot lever 18 and thus the ink fountain 14 in its operating position. In this operating position, the printing operation, but also the cleaning operation can take place.

In the FIG. 3 is the same printing unit D4 as in the FIG. 2 shown, but with swung-ink pan 14, which is thus in its emptying position. For this purpose, the piston-cylinder unit 28 is switched accordingly. In the FIG. 3 It can now be seen that the roller 19 were moved by the pivoting movement to the other ends of the recesses 16, 17. The pivoting movement takes place to such an extent that the ink can flow over the edge 32, which separates the trench 33 from the drainage channel 34, into the drainage channel 34 and finally into the outlet nozzle 35. This emptying position is also adjusted when the ink tray 14 is to be emptied of a cleaning fluid.

The FIGS. 4 and 5 show a further embodiment of a printing unit according to the invention, which relative to the printing unit of the FIGS. 2 and 3 has some differences. The components, however, are the same, have not been largely provided with reference numerals for the most part. In addition, the inking roller 24 and the related components have not been redrawn. Nevertheless, these components with the embodiment according to the FIGS. 4 and 5 combined.

Essential elements are now the bolts 40 and 41. While the bolt 40 is disposed directly on the side plate 11, the bolt 41 is in communication with the lever arm 42, which is rotatable about the pivot pin 43, which is also hinged to the side plate , The lever arm 42, the may have an approximately triangular configuration as shown in the figures, is reciprocated by the piston-cylinder unit 28 between the end points. In FIG. 4 is the lever arm in its upper position, which represents the operating, so the printing position. In the FIG. 5 on the other hand, the lever arm 42 is in its lower position, in which the paint is poured out.

On the ink tray 14 are now in addition to the end wall 44 and the support elements 45 and 46 directly or indirectly, d. H. over other, unspecified components arranged. The support element 45 rests on the bolt 40, the support element 46 on the bolt 41. Particular mention should be made of the shape of the support element 46, which includes a notch 47, which ensures that the support member 46 does not move relative to the bolt 41, as long as the lever arm 42 remains in its upper position. It should also be mentioned that the end wall 44 is formed in such a way that the pin 48 of the cylinder T4 can pierce it, which is ensured by a U-shaped recess 49. Due to this recess, the end wall 44 can be moved together with the ink tray in the vertical direction, but not in the horizontal direction. A movement of the ink tray 14 in the horizontal direction comes about only by a pivoting movement, which will be described below. Due to the forces applied by this recess 49, the ink fountain 14 is always pivoted about the axis of rotation of the cylinder T4 or its pin 48, so that a collision between the cylinder T4 and ink tray is avoided. The pin 48 and the recess 49 and the end wall need not be in direct contact with each other, but other components may be interposed. The focus is therefore on the operative connection between the end wall 44 and pin 48 to be addressed.

As already described, the piston-cylinder unit 28, which pivots the lever arm 42, is actuated to swivel the ink tray 14. As a result, the curved edge 50 of the support element 46 now slides along the bolt 41, which, moreover, exactly like the bolt 40, can be configured as a slider or a roller. This comes a combined Abschwenk- and lowering movement, which is determined by the pin 48 and the bolt 40, that is fixed, is. By this movement additionally slides the support member 45 a small piece along the bolt 40, which explains the intended elongated extension of the support member 45, as shown in the FIGS. 4 and 5 can be seen. The movement of the ink tray 14 is now so far that the color over the edge 32 can get away into the paint channel 34. LIST OF REFERENCE NUMBERS 1 Gravure printing machine 2 unwinding 3 deflecting 4 web 5 preferred unit 6 pulling roller 7 pressure roller 8th winding device 9 10 machine frame 11 side plate 12 gear 13 rack 14 paint tray 15 printing ink 16 recess 17 recess 18 pivoting lever 19 role 20 supporting member 21 semicircular course 22 camp 23 lever arm 24 inking 25 Direction of rotation of the inking roller 24 26 housing 27 inlet connection 28 Piston-cylinder unit 29 cylinder 30 piston 31 camp 32 edge 33 dig 34 gutter 35 drain connection 36 D1 to D4 printing unit P1 to P4 impression roller T1 to T4 Gravure cylinders x Transport direction of the material web. 4 y Displacement direction of the impression roller P1 to P4 y ' Displacement direction of the side plate 11

Claims (13)

1. Printing unit of a gravure printing machine (1),

   - having a gravure printing cylinder (T1 - T4) by way of which printing ink (15) is transferable according to a format onto a printed material (4) ;

   - having an ink pan (14) which is disposed below the gravure printing cylinder (T1 - T4) and in which printing ink (15), into which the gravure printing cylinder (T1 - T4) is immersible, is providable;

   - wherein the ink pan (14) comprises an outflow trough (34);

   - wherein the ink pan (14) is pivotable at least to the extent that the printing ink (15) is transferable into the outflow trough (34);
   characterized in that
   the ink pan (14) comprises an end wall (44) which has a U-shaped clearance (49), wherein the journal (48) of the gravure printing cylinder (T1 - T4) penetrates the clearance (49), such that the end wall (44) and the ink pan (14) are vertically displaceable in relation to the gravure printing cylinder (T1 - T4) and are pivotable about the rotation axis of the gravure printing cylinder (T1 - T4).
2. Printing unit according to Claim 1,
   characterized in that
   the ink pan (14) is attached on holding arms which are fastened on a ring, wherein the ring is rotatable about journals (48) which support the gravure printing cylinder (T1 - T4).
3. Printing unit according to one of the preceding claims,
   characterized in that
   side plates (11) on which the ink pan (14), or pivot levers (18) which support the ink pan (14), are supported are provided, wherein the ink pan (14) and/or the pivot levers (18) are moveable in relation to the side plates (11).
4. Printing unit according to the preceding claim,
   characterized in that
   the side plates (11) comprise sliding elements or roller elements (19), and the ink pan (14) or the pivot levers (18) comprise clearances (16, 17) in which the sliding elements or roller elements (19) are guidable.
5. Printing unit according to Claim 3,
   characterized in that
   the ink pan (14) or the pivot levers (18) comprise sliding elements or roller elements (19), and the side plates (11) comprise clearances (16, 17) in which the sliding elements or roller elements (19) may slide or roll.
6. Printing unit according to one of the two preceding claims,
   characterized in that
   the clearances (16, 17) are of circular-arc shape and run in a concentrical manner to the rotation axis of the gravure printing cylinder (T1 - T4).
7. Printing unit according to one of the preceding claims,
   characterized in that
   a force-providing element (28) engages on the ink pan (14) or on the pivot levers (18).
8. Printing unit according to Claim 7,
   characterized in that
   the force-providing element is a compressed-air cylinder (28).
9. Printing unit according to one of the six preceding claims,
   characterized in that
   the side plates (11) are displaceable in relation to a machine frame (10).
10. Printing unit according to the preceding claim,
    characterized in that
    at least one lever arm (23) which mounts an inking roller (24) is articulated in the side plates (11), by way of which lever arm (23) the inking roller (24) is placeable against the gravure printing cylinder (T1 - T4).
11. Printing unit according to the preceding claim,
    characterized in that
    the inking roller (24) is partially surrounded by a housing (26) in which a fluid supply connector (27) is incorporated.
12. Printing unit according to one of the two preceding claims,
    characterized in that
    the ink pan (14) comprises end walls (44) in which clearances are incorporated, such that the inking roller (24) can engage through the end walls (44).
13. Method for cleaning ink-conducting parts of a printing unit of a gravure printing machine (1), wherein printing ink (15) or a cleaning fluid is provided or collected in an ink pan (14) and a gravure printing cylinder (T1 - T4) is immersible into the printing ink (15) or into the cleaning fluid, wherein the ink pan (14) is pivoted to the extent that the printing ink (15) or the cleaning fluid is transferred into the outflow trough (34) which is encompassed by the ink pan (14),
    characterized in that
    the ink pan (14) comprises an end wall (44) which has a U-shaped clearance (49), wherein the journal (48) of the gravure printing cylinder (T1 - T4) penetrates the clearance (49), such that the end wall (44) and the ink pan (14) are vertically displaced in relation to the gravure printing cylinder (T1 - T4) and are pivoted about the rotation axis of the gravure printing cylinder (T1 - T4).

Images