EP1815983A2 - Printing press - Google Patents

Abstract

The machine includes an engraved roller (3) adjoining a doctor type ink fountain (4) having a doctor blade (16). The rear wall (8) of the ink fountain is pivoted by a rotary joint (13) and made adjustable for leveling the ink. A flow profile that induces mechanical flow in the ink is formed in the rear wall.

Description

The present invention relates to a printing machine comprising an inking unit comprising a roller and a squeegee box associated with the roller, comprising an adjustable backplane for adjusting a color level of an ink stored in the squeegee box, according to the preamble of claim 1.

In US 6,705,223 B2 is such a printing machine described. In this prior art printing machine, the roller is an anilox roller and transfer of the ink from the squeegee box to the anilox roller, ie, the filling of the anilox roller with the ink, may not be sufficiently uniform. The cup filling may depend on the printing speed and be affected by troublesome turbulence of the ink stored in the squeegee box and air bubbles forming in the ink.

The invention is therefore an object of the invention to provide a type of printing machine corresponding to the type mentioned, in which a more uniform transfer of the ink from the Rakelfarbkasten is ensured on the roller.

This object is achieved by a printing machine with the features of claim 1. The printing press according to the invention, comprising an inking unit comprising a roller and a squeegee box associated with the roller, comprising an adjustable rear wall for adjusting a color level of an ink stored in the squeegee box, characterized in that the rear wall has a flow profile for fluidically influencing the printing ink ,

The airfoil may be attached to the rear wall in a multi-piece design and may be integrally formed on the rear wall. Under the printing ink is understood in the context of the present invention, a paint, which is understood by the inking unit and a coating unit.

An advantage of the airfoil is that it improves the uniformity of transfer of the ink from the squeegee box to the roller. The uniformity no longer depends so much on the printing speed. The uniformity affecting turbulence and air bubbles in the ink are reduced to a sufficient extent. If the roller as an anilox roller with a z. B. consists of wells existing grid structure, the filling of the grid structure with the ink, the so-called cup filling, is made uniform and improved by the fluidic action of the airfoil.

An additional advantage is the fact that the fluidic effect of the airfoil on the ink can be done without disturbing side effect on a doctor blade and a box bottom of Rakelfarbkästen. The as a result of the back pressure of the accumulating upstream of the airfoil ink from this exerted on the flow profile hydrodynamic forces are derived from the airfoil on the back wall. Due to the articulated, d. h., thrust or preferably pivotal connection of the rear wall with the bottom of the box, the hydrodynamic forces absorbed by the rear wall are not transmitted to the bottom of the box and the squeegee attached thereto.

Another additional advantage is the fact that the airfoil is very easily accessible when the rear wall is adjusted away from the roller and therefore can be easily cleaned when the ink is changed.

Advantageous developments of the printing press according to the invention are mentioned in the subclaims.

In a further development, the rear wall is optionally in a first position, in which or as a result of which the color level is above a doctor blade of a squeegee of Rakelfarbktenstens, and in a second position, in or as a result of which the color level below the squeegee blade of the squeegee box is lying, adjustable. The squeegee blade forms the highest point of the squeegee.

In a further development, the rear wall is pivotally mounted about a hinge in the first position and in the second position, which rotary joint is arranged above a box bottom of the doctor blade box.

In a further development, the flow profile and the circumferential surface of the roller together form a constriction, which lies above the doctor blade, when the rear wall is in the first position.

In a further development, the flow profile has an outer corner defining the constriction at an angle which is greater than 45 ° and less than 135 °. In particular, this angle can be greater than 60 ° and less than 120 °. Preferably, the angle of the outer corner is about 90 °, d. h., the outer corner is approximately at right angles.

According to a further development, the flow profile on an inner corner. The inner corner can have an angle that is at least 90 °. This angle can be about 135 °.

In a further development, at least one element is present for securing a contact existing between the rear wall and a foil. The film is inserted into the doctor blade box, so that the film covers at least the bottom of the box.

According to a further development, said element is a pad, which is arranged between the film and the box bottom of the doctor blade box. The pad can be a solid pad, z. B. a plastic cushion, be. Here, the pad can be foamed. The film and the pad can be made of a composite material in one piece. Instead, the film and the pad can also be made in two pieces, wherein the film is located in Rakelfarbkasten on the pad.

According to a further development, the film is designed as a disposable article which can be regularly disposed of during the cleaning of the doctor blade box. In a color change, the ink used for the previous print job is removed from the Rakelfarbkasten and then the film together with the on it removed color residues from the Rakelfarbkasten and thrown away. After inserting an unused, new film in the Rakelfarbkasten the ink required for the following print job is filled in the Rakelfarbkasten.

In a further development, the rear wall has a metallically hard sliding surface, with which the rear wall rests against the film for producing the contact.

In a further development, the film and the back wall together define an offset ink supply formed by the ink and stored in the squeegee box. The ink stored in the Rakelfarbkasten is therefore preferably highly viscous.

In a further development of the film facing surface of the box bottom is concave.

According to a further development, the inking unit is an anilox inking unit and the roller is an anilox roller.

Other constructive and functional advantageous developments of the invention will become apparent from the following description of a preferred embodiment and the accompanying drawings.

Figur 1a

einen Rakelfarbkasten, der eine verstellbare Rückwand mit einem Strömungsprofil aufweist, das in eine von einer Walze zurückgezogene Wartungsposition verstellt ist,

Figur 1b

die verstellbare Rückwand mit dem Strömungsprofil in einer Betriebsposition in der Nähe der Walze, und

Figur 2

den Rakelfarbkasten in einer dreidimensionalen Darstellung von hinten.

In this shows:

FIG. 1a

a squeegee box having an adjustable back wall with an airfoil that is adjusted to a maintenance position retracted by a roller,

FIG. 1b

the adjustable rear wall with the airfoil in an operating position in the vicinity of the roller, and

FIG. 2

the Rakelfarbkasten in a three-dimensional view from behind.

A printing machine 1 comprises an anilox inking unit 2 with an anilox roller 3 and a doctor blade box 4, which has an ink fountain 5 and a doctor blade 6. The doctor blade 6 is fastened to the ink fountain 5 by means of a clamping device 25 designed as a quick-action closure.

The ink fountain 5 comprises a rear wall 8, which is fastened by means of a rotary joint 13 to a side wall 26 of the ink fountain 5. A cup-shaped box bottom 7 of the ink fountain 5 has a surface 23 which is curved in a circular arc and whose center of curvature is the rotary joint 13. A highest lying point of the doctor blade 6 is formed by the doctor blade 16 which abuts the anilox roller 3 in the printing operation.

The interior of the ink fountain 5 is lined with a film 17, which consists of a plastic, for. As polyethene (PE) or polyethylene terephthalate (PET) exists. The film 17 may have an ink repellent, oleophobic and thus anti-adhesive surface. The ends of the film 17 are angled substantially U-shaped, wherein a hook-shaped part of the front end together with the doctor blade 6 forms a package which is clamped in the clamping device 25. The rear end of the film 17 also forms a hook 19 which is mounted for securing in a arranged on the ink fountain 5 projection 20.

The back wall 8, the film 17, the side wall 26 and an opposite side wall 26 of the ink fountain 5 together define an offset ink supply 14 stored in the doctor blade box 4. Of course, may be stored instead of the offset ink supply 14, a supply of other ink, which has a similar viscosity as the offset printing ink.

By taking place about the pivot 13 pivoting the rear wall 8 to the doctor blade 16 towards a formed by the offset ink supply 14 color level 15 is raised so far that this color level 15 is above the doctor blade 16. This lifting of the Color level 15 takes place after the doctor blade 6 has been set for the printing operation of the anilox roller 3 at a negative angle of attack. The first position in which the rear wall 8 is held during the printing operation is shown in FIG. 1b. In this first position, as it were, the capacity of the squeegee box 4 is reduced with respect to a second position of the rear wall 8 (see FIGURE 1a), so that the offset ink supply 14 would overflow the squeegee 6 and leak out of the squeegee box 4, if the latter were not the anilox roller 3 would be employed. To the doctor blade 4 of the anilox roller 3, z. B. for the purpose of a change of the offset ink supply 14, the color level 15 is lowered by one of the squeegee 6 wegwirkgendes pivoting the rear wall 8 so far that when located in the second position rear wall 8 of the color level 15 below Doctor blade 16 is located. After this lowering of the ink level 15, the offset ink supply 14 can no longer leak from the doctor blade 4, when the latter is turned off by the anilox roller 3.

The rear wall 8 has at its free end a sliding surface 12 which slides on pivoting of the rear wall 8 on the film 17. The sliding surface 12 is made of the same metal, for. As steel or preferably aluminum, from which the entire remaining rear wall is made. In order to ensure a permanent and elastic contact between the rear wall 8 and the film 17 and to avoid between the rear wall 8 and the film 17 passing ink, an elastic or resilient element is provided.

The element is a solid pad 22, which consists of a plastic foam, for. As polyethylene terephthalate foam (PET foam) or ethylene / propylene / diene rubber foam (EPDM foam), and which is arranged as a support for the film 17 between this and the concave surface 23 of the box bottom 7. The solid pad 22 and the film 17 may be successively inserted into the doctor blade box 4 or may instead be assembled in sandwich construction and be inserted in one piece in the Rakelfarbkasten 4.

The solid pad 22 is compressible to lie in both the first position and the second position and also in any one of these two positions Intermediate position of the rear wall 8, the film 17 presses against the rear wall 8. The pretensioning action exerted by the solid pad 22 can be seen in FIGS. 1a and 1b on the basis of the small reversible deformation of the film 17 and of the solids pad 22 in the region of the sliding surface 12. The sliding surface 12 presses a little into the solid pad 22, the latter and the overlying film 17 in the region of the sliding surface 12 form a small and reversible depression on relief.

FIGS. 1a and 1b show that the rear wall 8 has an airfoil 9 facing the anilox roller 3, which is arranged at the lower end of the rear wall 8 opposite the rotary joint 13. The airfoil 9 has an outer corner 11 which forms an edge perpendicular to the image plane of FIGS. 1a and 1b. This edge can be provided with a small rounding or bevel. An angle α of the outer corner 11 is approximately a right angle. In addition, the airfoil 9 has an inner corner 21 with an angle β which is blunt. The outer corner 11 is located between the pivot 13 and the inner corner 21. The inner corner 21 is located between the outer corner 11 and the sliding surface 12th

In the case of the rear side of the anilox roller 3 adjusted for printing operation (see FIG. 1b), the outer corner 11 is the region of the airfoil 9 closest to the anilox roller 3. The airfoil 9 and its outer corner 11 are not in contact with the anilox roller 3, However, they are very close to the latter. The outer corner 11 thus forms, together with the peripheral surface of the anilox roller 3, a constriction 10. In the region of the inner corner 21, the rear wall 8 forms an ink-side chamber, which lies below the outer corner 11. Above the outer corner 11 is a main ink chamber whose storage volume is greater than that of the ink-side chamber.

FIG. 2 shows that a positioning pin 27, which serves to align the doctor blade box 4 relative to the anilox roller 3, is attached to the one side wall 26. The positioning pin 27 has a substantially bone-shaped profile. On the other side wall 26, a downwardly projecting pivot pin 28 and a half-shell-shaped socket 29 are arranged. The pivot pin 28 engages in a hinge hole in a machine side frame or a component attached thereto. The Machine side frame and the attached component are not shown drawing for better clarity. The joint socket 29 is supported on a likewise not shown in the drawing and attached to the machine side frame pivot pin, so that the four components form a hinge 30 with a vertical geometric axis of rotation.

For maintenance purposes, the entire doctor box 4 is pivotable about the rotary joint 30, ie in the horizontal plane, and away from the anilox roller 4. The pivot pin 28 and the socket 29 allow a tool-free removal of the ink fountain 4 from the printing press 1. For the purpose of this removal of the Rakelfarbkasten 4 is raised so far up until the pivot pin 28 is pulled out of the joint bore. In other words, the rotary joint 30 makes it possible to unhook and detach the squeegee box 4 during its removal from the printing press 1 for servicing purposes and subsequent reinsertion of the squeegee box 4.

On the side opposite the rotary joint 30 of the doctor blade box 4, a coupling 24 is arranged, via which the rear wall 8 is drivingly connected to an actuator. The actuator is not shown in the drawing and may be a pneumatic cylinder or an electric motor comprising an upstream screw gear with a threaded spindle. The actuator is drivingly connected via a likewise not graphically illustrated lever with the rear wall 8, when arranged on the lever coupling half with the arranged on the rear wall 8 and diagrammatically illustrated coupling half of the clutch 24 is engaged. The coupling 24 consisting of the two coupling halves is a dog clutch and arranged coaxially with the rotary joint 13. At the mentioned lever in the case of the formation of the actuator as a working cylinder whose piston rod articulated and engages in the case of the formation of the actuator as an electric motor whose upstream screw gear. The actuator driven pivotal movement of the lever is transmitted via the coupling 24 to the rear wall 28 to adjust the latter either in the first position (see Figure 1b) and in the second position (see Figure 1a).

The flow profile 9 causes a back pressure of the ink in the region of the constriction 10 when the ink is conveyed by the rotation of the anilox roller 3 to the constriction. As a result of this dynamic pressure, the grid recesses (wells or grooves) of the anilox roller 3 are largely filled without air bubbles and very evenly.

As a result of said dynamic pressure, a force acts on the rear wall 8, which force pushes the rear wall 8 away from the anilox roller 3 and tends to pivot about the rotary joint 13 with respect to FIG. 1b in a clockwise direction. This force flows from the rear wall 8 via the coupling 24 and the aforementioned lever on the actuator, which receives said force. The force can not due to the movable connection (swivel joint 13) of the rear wall 8 with the side walls 26 is not absorbed by these, not transferred from these on the attached to the side walls 26 box bottom 7 and not from the box bottom 7 to the means of the clamping device 25 at the Box bottom 7 fixed squeegee 6 are transmitted so that resulting from the power flow deflections and deformation of the box bottom 7, the clamping device 25 and especially the squeegee 26 are reliably avoided and the latter over the entire printing width away evenly applied to the anilox roller 3.

LIST OF REFERENCE NUMBERS

1

press

2

Anilox inking unit

3

anilox roller

4

Squeegee ink fountain

5

paintbox

6

doctor

7

box bottom

8th

rear wall

9

flow profile

10

bottleneck

11

outside corner

12

sliding surface

13

swivel

14

Offset printing ink supply

15

color level

16

doctor blade

17

foil

18

./.

19

hook

20

head Start

21

inside corner

22

Solid cushion

23

area

24

clutch

25

clamper

26

Side wall

27

positioning

28

pivot pin

29

socket

30

swivel

α

angle

β

angle

Claims (15)

Printing machine (1) with an inking unit comprising a roller (3) and a squeegee box (4) associated with the roller (3), which has an adjustable rear wall (8) for setting a color level (15) in the squeegee box (4). includes stored ink (14),
characterized,
that the rear wall (8) has a flow profile (9) for fluidic influencing the printing ink (14). Printing machine according to claim 1,
characterized,
in that the rear wall (8) is optionally in a first position in which the color level (15) over a doctor blade (16) of a doctor blade (6) of the doctor blade box (4), and in a second position in which the color level (15) is under the doctor blade (16), is mounted adjustable. Printing machine according to claim 2,
characterized,
in that the rear wall (8) is pivotably mounted about a pivot joint (13) in the first position and the second position, which is arranged above a box bottom (7) of the doctor blade box (4). Printing machine according to claim 2 or 3,
characterized,
form that the flow profile (9) and the roller (3) has a constriction (10), which lies above the doctor blade (16) when the rear wall (8) is in the first position. Printing machine according to claim 4,
characterized,
in that the flow profile (9) has an outer corner (11) defining the constriction (10) with an angle (α) which is greater than 45 ° and less than 135 °. Printing machine according to claim 5,
characterized,
that the angle (α) of the outer corner (11) is approximately 90 °. Printing machine according to one of claims 1 to 6,
characterized,
that the flow profile (9) has an inside corner (21). Printing machine according to claim 7,
characterized,
that the inner corner (21) has an angle (β) which is at least 90 °. Printing machine according to one of claims 1 to 8,
characterized,
is that at least one element for securing a between the rear wall (8) and a film (7) existing contact file. Printing machine according to claim 9,
characterized,
in that the element is a pad (22) which is arranged between the film (17) and a box bottom (7) of the doctor blade box (4). Printing machine according to claim 10,
characterized,
in that the film (17) is a disposable article that can be regularly disposed of when cleaning the squeegee box (4). Printing machine according to one of claims 9 to 11,
characterized,
in that the rear wall (8) has a metallically hard sliding surface (12), with which the rear wall (8) bears against the film (17) for producing the contact. Printing machine according to one of claims 9 to 12,
characterized,
in that the film (17) and the rear wall (8) define an offset-ink supply (14) formed by the ink and stored in the squeegee box (4). Printing machine according to one of claims 10 to 13,
characterized,
that one of the film (17) facing surface (23) of the box bottom (7) is concavely curved. Printing machine according to one of claims 1 to 14,
characterized,
that the inking unit an anilox inking unit (2) and the roller is a raster roller (3).

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