INKING UNIT OF A ROTARY PRINTING PRESS

Description

[0001] The invention relates to an inking unit of a rotary printing press, a rotary printing press and a method for transporting printing ink into recesses of an ink transfer roller in an inking unit of a rotary printing press.

[0002] An inking unit of a rotary printing press is designed to apply a printing ink to a printing substrate in accordance with the motif. An entire print image is often composed of multiple printing inks, so multiple inking units must be used—i.e., one for each printing ink. The invention relates to an inking unit comprising an ink transfer roller with depressions. The ink transfer roller absorbs printing ink into these depressions and then transports it to the printing substrate or to another ink transfer roller, where the printing ink is then released. After the printing ink has been released, the depressions are emptied. In other words, they are then filled with air.

[0003] The required printing ink is stored in an ink reservoir into which the ink transfer roller extends. Of course, the ink reservoir must contain enough ink to submerge the ink transfer roller. If the ink in the reservoir falls below a certain volume, it must be refilled.

[0004] In the printing industry, there is a continuing trend toward ever-faster printing presses. However, this leads to difficulties, as the dwell time of a surface element of the ink transfer roller in the printing ink is becoming increasingly shorter. This also reduces the time in which the air-filled recesses can be refilled with printing ink. The associated infiltration of air into the printing ink also makes it difficult to refill the recesses of the ink transfer roller. Ultimately, the print motif is not completely printed.

[0005] US Pat. No. 5,636,566 A shows a gravure inking unit with an ink tray and a gravure cylinder. The object of the invention described therein is to prevent ink residues from drying in the recesses of the gravure cylinder. For this purpose, an auxiliary device with a flexible guide skirt is provided downstream of the printing nip in the direction of travel, with printing ink being directed between the gravure cylinder and the guide skirt.

[0006] The document CN 209 580 789 U discloses a printing unit in which the printing cylinder is supplied with printing ink by means of an absorbent sponge.

[0007] With the printing units described in the above-mentioned publications, it is not guaranteed that the printing ink will reliably reach the recesses of the ink transfer roller even at higher printing speeds.

[0008] The object of the present invention is to provide an inking unit and a method with which the recesses of the ink transfer roller can be filled even at high speeds.

[0009] According to the invention, this object is achieved by an inking unit according to claim 1.

[0010] In an inking unit according to the invention, an ink transfer roller, which comprises depressions for transporting printing ink, projects into an ink reservoir. This ink reservoir contains printing ink with which the ink transfer roller comes into contact, so that the depressions of the ink transfer roller can be filled with printing ink. At least one flexible and / or elastic element also contributes to the solution of the stated object. The ink transfer roller and / or the ink reservoir can be subjected to a force. By applying a force, the ink transfer roller is brought into contact with the flexible and / or elastic element. The flexible and / or elastic element is deformed and thereby provides a restoring force. The ink transfer roller and the flexible and / or elastic element now have a common contact surface.The flexible and / or elastic element is connected to the bottom of the ink reservoir and, viewed in the circumferential direction of the ink transfer roller, is arranged immovably relative to the ink reservoir. The ink transfer roller thus moves past the flexible and / or elastic element, thus ensuring sliding contact between the two. Even if the element is immovable viewed in the circumferential direction of the ink transfer roller, the element can be deflected due to its flexibility or elasticity due to the force generated by the rotation of the ink transfer roller. Even if the term "immovable" is used in this disclosure, such deflection is to be understood as falling within this scope.

[0011] According to the invention, the ink transfer roller and / or the ink reservoir are moved by a force-providing device and / or by means of a position adjustment device. Consequently, the components are brought closer together in a force- and / or position-controlled manner. A position adjustment device also causes the ink transfer roller to contact the flexible and / or elastic element with a force.

[0012] Due to the force and the areal expansion of the contact, the elastic element is able to push air out of the recesses of the ink transfer roller and push new printing ink into the recesses.

[0013] In the circumferential direction of the ink transfer roller, the length of the contact surface is at least 5 mm, but preferably at least 1 cm. This dimension ensures reliable filling of the recesses.

[0014] In known prior art solutions, doctor blades are arranged within ink reservoirs, but these blades are positioned along a line against the ink transfer roller, ensuring only brief contact. In the prior art, the contact time is often insufficient to reliably fill the recesses of an ink transfer roller.

[0015] An ink transfer roller according to the invention can be an anilox roller, with which printing ink can be transferred to another cylinder. The ink reservoir can be a doctor blade chamber sealed from the environment by doctor blades. However, an ink transfer roller according to the invention can also be, in particular, a forme cylinder of a gravure inking unit.

[0016] In comparison to the prior art, the solution according to the invention also leads to low wear on the flexible and / or elastic element and also on the ink transfer roller, since the contact force is distributed over a large area and is not linear.

[0017] A flexible element is one whose shape can be reversibly changed, for example, it can be bent. This results in restoring forces that tend to return the element to its original shape. An elastic element is one whose volume can be changed. Such an element can, for example, be compressed by an ink transfer roller. This also results in restoring forces that tend to return the element to its original volume. Both a flexible element and an elastic element therefore obey Hooke's law. However, an elastic element can also be stretchable.

[0018] However, a flexible and / or elastic element can also include solid components. For example, it can be connected to metal parts, such as glued, to facilitate attachment to the paint reservoir. Such metal parts can be screwed or held in place by magnets for this purpose. Solid components can therefore be considered part of the flexible and / or elastic element.

[0019] In one embodiment of the invention, the flexible and / or elastic element comprises a body, in particular a body made of an elastomeric material. As already described, such a material is slightly compressed by the ink transfer roller, creating restoring forces within the material. These restoring forces partially press the material locally into the recesses of the ink transfer roller, forcing the air trapped in these recesses out. After the respective area of ​​the ink transfer roller has moved out of the area of ​​action of the body, the recesses, often referred to as cells, can be completely refilled with printing ink.

[0020] Furthermore, an elastomeric material from which such a body can be made can be rubber or a foamed plastic. The latter material in particular can be varied in its properties over a wide range and adapted to requirements through appropriate material selection and / or suitable manufacturing parameters, thus allowing the described advantages to be achieved in a simple and cost-effective manner.

[0021] In an advantageous embodiment, the flexible and / or elastic element comprises a body which at least partially surrounds a rigid base body. For example, a metal or plastic rail is conceivable as the base body, which can be connected in particular to the bottom of the paint reservoir. Such a rail can be attached to or on the paint reservoir and removed again in a few simple steps, for example by means of a screw connection. The flexible and / or elastic body can then be attached to this rail. For example, a rubber band can be vulcanized around the rigid body. A body can also be glued to the base body or connected with a detachable connection. The connection between the body and the base body can then be released outside the paint reservoir, in particular to replace a worn body.This can be done outside the printing press so that it can remain in operation, thus avoiding costly downtime.

[0022] In a further advantageous embodiment of the invention, the flexible and / or elastic element comprises at least one plate, which contacts the ink transfer roller with a surface area and is connected directly or indirectly to the ink reservoir with its edge areas. A plate is understood to be an element whose thickness is small compared to its surface area. The thickness can be a few millimeters, for example less than 20 mm, while the length and / or width can be several centimeters or even decimeters, for example more than 10 centimeters each. These dimensions ensure the flexibility of a plate. Flexibility is also ensured if the plate is connected directly or indirectly to the ink reservoir only by its edges, in particular by two opposite edge areas.This means that the majority of the plate is not subjected to constraining forces, thus maintaining the plate's flexibility. Due to the movement of the ink transfer roller and / or the ink reservoir, the ink transfer roller now presses against the plate, exerting a restoring force on the plate in the direction of the ink transfer roller. This, in turn, forces air out of the ink transfer roller's recesses, allowing printing ink to flow into the recesses without difficulty.

[0023] The flexible and / or elastic element can in principle, in particular independently of all described embodiments, be resiliently mounted relative to the ink reservoir, so that the flexibility and / or elasticity is further increased, which is advantageous with regard to the function according to the invention.

[0024] It is advantageous if the flexible and / or elastic element comprises at least one plate that is at least partially made of a plastic. Plastic is generally a cost-effective material, so potential wear is not costly. Furthermore, an ink transfer roller is usually made of a hard material (e.g., ceramic or metal), so a unit in contact with this roller should be made of a softer material to minimize wear on the roller. This requirement is met by a plastic.

[0025] In a further advantageous embodiment of the invention, the flexible and / or elastic element can be subjected to a restoring force generated by prestressing the element. Due to this restoring force, the element is held by at least two abutments, wherein the abutments are directly or indirectly connected to the ink reservoir. This eliminates the need to attach the flexible and / or elastic element to the ink reservoir using separate connecting elements. By avoiding such connecting elements, the flexible and / or elastic element can be replaced particularly quickly. It is particularly advantageous if, in this embodiment of the invention, a plate is provided as the flexible and / or elastic element. This plate can be prestressed, for example, by manual bending, which generates a restoring force.This allows the plate to be transformed into an arched shape and positioned between the abutments. When the plate is released, it bends back until at least some of its surface, such as the edges, rests against the abutments, so that the plate is pressed against the abutments by the restoring forces.

[0026] It is particularly advantageous if the abutments comprise hook-shaped holders. The opening sides of these holders preferably face each other. This measure reduces the risk of the flexible and / or elastic element, in particular a plate, being forced out of the space between the abutments by the force of the ink transfer roller.

[0027] In a further embodiment of the invention, a displacement device is provided with which the flexible and / or elastic element can be displaced, in particular oscillated, in the axial direction of the ink transfer roller. This displaceability can prevent uneven wear of the flexible and / or elastic element, because the displaceability distributes otherwise localized or linear wear over a larger area. This also increases the service life of the flexible and / or elastic element in the ink reservoir. The replacement frequency can thus be reduced.

[0028] The invention described above is particularly advantageous in combination with a rotary printing press, in particular a gravure printing press. A gravure printing press is generally a multi-column printing press in which each printing stand comprises an inking unit. A material web is guided from printing stand to printing stand and, in each printing stand, is guided over a counter-pressure roller, often referred to as an impression roller. The impression roller presses the material web against the ink transfer roller. The ink transfer roller is designed directly as a motif roller, with the motif being represented by the motif-specific depressions.

[0029] A further aspect of the invention relates to a method for transporting printing ink into depressions of an ink transfer roller in an inking unit of a rotary printing press. According to the invention, printing ink is provided by an ink reservoir, wherein the ink transfer roller projects at least partially into the ink reservoir to receive printing ink, wherein at least one flexible and / or elastic element is connected to the ink reservoir and held immovably in the circumferential direction of the ink transfer roller, wherein the ink transfer roller and / or the ink reservoir is subjected to a force, wherein the flexible and / or elastic element is deformed and wherein a contact surface exists between the ink transfer roller and the flexible and / or elastic element.

[0030] With this method, the same advantages can be achieved as have already been described in connection with an inking unit according to the invention.

[0031] Further advantages, features, and details of the invention will become apparent from the following description, in which various exemplary embodiments are explained in detail with reference to the figures. The features mentioned in the claims and in the description may be essential to the invention individually or in any combination of mentioned features. Within the scope of the entire disclosure, features and details described in connection with the method according to the invention naturally also apply in connection with the inking unit according to the invention, and vice versa, so that with regard to the disclosure, reference is always made to the individual aspects of the invention. The individual figures show: Fig. 1Schematic view of a multi-color gravure printing machine Fig. 2Section through an inking unit according to the invention Fig. 3How Figure 2 , but with lowered ink transfer roller Fig. 4View IV-IV from Figure 2

[0032] The Figure 1 shows a schematic view of a multi-color gravure printing press 1 as an example of a rotary printing press according to the invention, wherein the gravure printing press 1 is designed in the so-called column design. This gravure printing press 1 shown as an example is depicted with four inking units D1 to D4. However, a gravure printing press is not limited to this number of inking units. Printing presses with a column design are even modularly expandable, so that a user of such a printing press can use as many printing stands as desired. One printing color is printed in each individual inking unit.

[0033] Starting from an unwinding device 2, the material web 4 is fed to the printing press. Via guide rollers 3, preferably according to the invention, the material web 4 reaches the inking unit D1. There, the material web 4 is guided over an impression roller P1. This impression roller P1 can be adjusted in height in the direction of the double arrow y and can thus be positioned against the gravure cylinder T1. In this case, the material web 4 runs through the nip between the impression roller P1 and the ink transfer roller designed as a gravure cylinder T1. The material web 4 is printed with the print motif of a printing ink. The material web 4 reaches the inking unit D2 via further guide rollers 3. On the way to the inking unit D2, the material web 4 passes through several drying devices (not shown) so that the printing ink printed in the inking unit D1 can dry sufficiently. Guide rollers 3 according to the invention can also be installed in the drying device.

[0034] After printing in the inking unit D2, the material web 4 passes over further guide rollers 3 into the inking unit D3, where a third color can be printed. The last inking unit D4 shown is not shown printing, i.e. the impression roller P4 has been moved upwards so that the material web does not touch the gravure cylinder T4. In this inking unit D4, for example, all ink-carrying parts can be cleaned. After leaving the inking unit D4, the material web 4 passes over further guide rollers 3 to a feed device 5, which comprises a pull roller 6 and a pressure roller 7. Finally, the material web 4 reaches a winding device 8, where it is wound up into a roll.

[0035] The Figure 2shows a section through an inking unit according to the invention. The ink transfer roller 100, for example, a gravure cylinder, is immersed in the printing ink 101, which is provided in an ink reservoir configured as an ink tray 102. For this purpose, the ink transfer roller 100 and / or the ink tray 102 are displaceable in or against the direction y. During printing, the ink transfer roller can rotate, for example, in the direction R.

[0036] Two abutments are arranged on the base 103 of the paint tray 102 and are attached directly or indirectly to the paint tray. In the present embodiment, the abutments are designed as hooks 104 and 105. As shown, the hooks could represent open triangles whose open sides face each other. A plate 106 is arranged between these abutments, wherein the plate is an embodiment of an elastic and / or flexible element. This plate 106 has a greater extent along its visible cross-sectional line than the distance between the furthest apart points of the abutments. In the present case, these furthest apart points are the outer tips of the two hooks 104 and 105. In order to be able to place the plate between the two hooks, it is designed to be flexible and is elastically curved, forming an arc 107 pointing in the y-direction.This creates restoring forces that tend to return the plate 106 to its original shape. These restoring forces cause surface areas of the plate 106 to rest against the abutments, while the arch 107 remains intact.

[0037] The Figure 3 now shows the same situation as the Figure 2However, the ink transfer roller has now been displaced in the direction of arrow A, so that its outer surface presses in the arc 107 of the plate 106, forming a contact surface between the plate 106 and the respective circumferential section of the ink transfer roller 100 in the circumferential section indicated by the double arrow U. In doing so, the arc 107 is "pressed in" and, in a sense, forms a counter-arc. The formation of this contact surface has the effect of forcing the air entrained by the recesses of the ink transfer roller out of these recesses. After the respective recess has left the effective area of ​​the flexible and / or elastic element, the recess can now fill with fresh printing ink.

[0038] The Figure 4 represents view IV-IV from the Figure 2This is therefore a top view of the ink tray 102. This ink tray 102 extends in the direction z and thus parallel to the rotation axis 108 (see Figure 2 ) of the ink transfer roller 100, the latter, however, being in the Figure 4not shown. At its ends, the ink tray has two end walls 109, 110. The hooks 104, 105 are also rail-like and extend in the direction z. Each hook can be one-piece or multi-piece. It is advantageous if both hooks are connected at both ends by means of an end plate 111, 112. These end plates 111, 112 can then be fastened to the end walls 109, 110, for example by means of screw connections. Such a fastening option on the end walls is advantageous because they are easily accessible even when the ink tray 102 is located in an inking unit. Due to the end connection of both hooks to the end plates, the latter can now be removed from the ink tray as a unit together with the plate 106 or inserted into it. In this way, the plate 106 can be easily replaced manually or with the aid of tools outside the ink tray 102. List of reference symbols 1 Multi-color gravure printing machine 2 Unwinding device 3 Guide rollers 4 Material web 5 preferential facility 6 Pull roller 7 pressure roller 8 Changing facility D1-D4 Color works P1-P4 impression roller T1-T4 Gravure cylinder 100 Ink transfer roller 101 Printing ink 102 paint tray 103 Floor 104 Hook 105 Hook 106 plate 107 bow 108 axis of rotation 109 Front end wall 110 Front end wall 111 front plate 112 front plate y Shift direction R Direction of rotation A Arrow U double arrow

Claims

1. Inking unit (D1-D4) of a rotary printing press (1) having an ink transfer roller (100), which comprises recesses, in which printing ink (101) can be transported, having an ink reservoir (102) for providing printing ink (101), wherein the ink transfer roller (100) protrudes at least partially into the ink reservoir (102), in order to collect printing ink (101), having at least one flexible and / or elastic element (106), which is connected to the base of the ink reservoir (102) and is stationary in the circumferential direction of the ink transfer roller (100) wherein the ink transfer roller (100) and / or the ink reservoir (102) can also be moved by means of a position adjuster, wherein the components can be brought closer together in a force and / or position-controlled manner, wherein the flexible and / or elastic element (106) can be deformed, wherein there is a contact surface between the ink transfer roller (100) and the flexible and / or elastic element (106).

2. Inking unit (D1-D4) according to claim 1 characterized in that the flexible and / or elastic element comprises a body, in particular a body made from an elastomeric material.

3. Inking unit (D1-D4) according to any one of the preceding claims characterized in that the flexible and / or elastic element comprises a body, which consists at least partially of rubber or a foamed plastic.

4. Inking unit (D1-D4) according to any one of the preceding claims characterized in that the flexible and / or elastic element comprises a body, which at least partially surrounds a solid base body.

5. Inking unit (D1-D4) according to any one of the preceding claims characterized in that the flexible and / or elastic element comprises at least one plate, which is in contact with a surface region of the ink transfer roller and is directly or indirectly connected to the ink reservoir at two of its edge regions.

6. Inking unit (D1-D4) according to any one of the preceding claims characterized in that the flexible and / or elastic element comprises at least one plate, which consists at least partially of a plastic.

7. Inking unit (D1-D4) according to any one of the preceding claims characterized in that a restoring force generated by a prestressing of the flexible and / or elastic element can be applied to the flexible and / or elastic element, wherein the element can be held on at least two abutments by means of the restoring force, wherein the abutments are directly or indirectly connected to the ink reservoir.

8. Inking unit (D1-D4) according to the preceding claim characterized in that the abutments comprise hook-like holders.

9. Inking unit (D1-D4) according to any one of the preceding claims characterized in that a displacement device is provided, with which the flexible and / or elastic element can be displaced in the axial direction of the ink transfer roller, in particular displaced in an oscillating manner.

10. Rotary printing press (1), in particular gravure printing press (1), having an inking unit (D1-D4) according to any one of claims 1 to 9.

11. Method for transporting printing ink (101) in recesses of an ink transfer roller (100) into an inking unit (D1-D4) of a rotary printing press (1) wherein printing ink (101) is provided with an ink reservoir (102), wherein the ink transfer roller (100) protrudes at least partially into the ink reservoir (102), in order to collect printing ink (101), wherein at least one flexible and / or elastic element (106) is connected to the base of the ink reservoir (102) and is held stationary in the circumferential direction of the ink transfer roller (100) wherein the ink transfer roller (100) and / or the ink reservoir (102) is / are also moved by means of a position adjuster, wherein the components are brought closer together in a force and / or position-controlled manner, wherein the flexible and / or elastic element (106) is deformed, wherein there is a contact surface between the ink transfer roller (100) and the flexible and / or elastic element (106).