Printing unit and method for replacing printing roller in printing unit

Abstract

The invention relates to a printing unit comprising a first printing roller (12) with a first shaft (14), a second printing roller (18) with a second shaft (20), a first mandrel (24) configured to hold each of the shafts (14, 20), a second mandrel (26) configured to hold each of the shafts (14, 20), and a carousel gripper (40), a carousel gripper (40) configured to move in translation in a printing position in an axial direction of the first and second printing rollers (12, 18) to pull the first shaft (14) out of the first mandrel (24) and pull the second shaft (20) out of the second mandrel (26); rotating about an axis parallel to the axes of the first and second printing rollers (12, 18) so as to change the position of the printing rollers (12, 18); and translatably moving in the axial direction of the first and second printing rollers (12, 18) to insert the first shaft (14) to the second mandrel (26) and the second shaft (20) to the first mandrel (24). The invention further relates to a method for changing printing rollers (12, 18) in a printing unit (10).

Description

Technical Field

[0001] The invention relates to a printing unit and also to a method for replacing a printing roller in a printing unit. Background Art

[0002] In many modern printing systems, particularly flexographic printing systems, a number of different rollers (eg, ink fountain rollers, anilox rollers, printing rollers, and impression cylinders) are used to apply ink to a substrate.

[0003] In order to create a new printing pattern or for maintenance reasons, it may be necessary to replace or exchange one or several rollers during or between printing processes.

[0004] Replacing or exchanging rollers, especially printing rollers, is often complex and time-consuming. To ensure optimal printing results, newly installed rollers must be precisely aligned. At the same time, to maximize the productivity of the printing system, replacement times need to be as low as possible.

[0005] For example, EP1767362A2 discloses a system for exchanging rollers in a printing press using a rotary lifting arm device. The printing roller is connected / disconnected to the printing press using bolts and / or pins, and thus may be time-consuming.

[0006] Therefore, there is a need for a means of enabling a simple, robust and time-saving replacement or exchange of rollers in a printing system. Summary of the Invention

[0007] The object of the present invention is solved by a printing unit comprising: a first printing roller with a first shaft, a second printing roller with a second shaft, a first mandrel configured to hold each shaft, and a second mandrel configured to hold each shaft. Each mandrel can hold one shaft at a time. The printing unit also includes a carousel clamp configured to

[0008] moving translationally in the printing position along the axis of the first and second printing rollers to extract the first shaft from the first mandrel and the second shaft from the second mandrel;

[0009] rotating about an axis parallel to the axes of the first and second printing rollers, thereby switching the positions of the printing rollers;

[0010] The first spindle is moved translationally in the direction of the axes of the first and second printing rollers to insert the first spindle to the second spindle and the second spindle to the first spindle.

[0011] As used herein, a "printing position" refers to a position within a printing system where the printing process occurs and / or a position close to where ink is applied to a substrate. In particular, the printing position may be a position between a set of rollers, such as the anilox roller and impression cylinder of a flexographic printing system.

[0012] One of the ideas of the present invention is to enable the user to set up a second printing roller, for example by mounting a printing kit on a second shaft, while the printing process is still running using the first printing roller.

[0013] The replacement or swapping of the first and second printing rollers is accomplished using a turntable gripper. This gripper grips the two rollers and switches their positions. The printing process only needs to be briefly stopped during this phase. In particular, the roller alignment is preserved during the changeover, reducing overall machine downtime and the occurrence of misalignment.

[0014] In an embodiment of the printing unit, the turntable clamp is further configured to move translationally from the printing position to the original position perpendicular to the axial direction of the first and second printing rollers, and to move translationally from the original position back to the printing position perpendicular to the axial direction of the first and second printing rollers.

[0015] In this context, "home position" means that there is enough space within the printing system to switch the positions of the two rollers by rotating them about a common axis.

[0016] For example, the carousel gripper may be moved into a home position before rotation and moved back into the printing position after rotation is complete, thereby ensuring that the carousel gripper and / or the printing roller do not collide with other machine parts during roller exchange.

[0017] The printing unit may also include an anilox roller and an impression cylinder.

[0018] In one variant, the first or second printing roller is located between the anilox roller and the impression cylinder. All three rollers are in contact with one another during printing. The anilox roller and the first and / or second printing roller are configured to move away from one another and away from the impression cylinder, thereby creating free space for the rotating carousel holder. In this variant, roller replacement is possible without requiring translational movement of the carousel holder.

[0019] Alternatively, the anilox roller, the impression cylinder and the first and / or second printing roller can be positioned in a triangle. The first and / or second printing roller is configured to move away from the anilox roller and the impression cylinder. In this variant, roller swapping can be achieved without moving the anilox roller and the impression cylinder.

[0020] In a preferred embodiment, the printing unit includes a first motor connected to the first spindle and configured to rotate the first spindle to control the printing process.

[0021] Plugging the first and second shafts into / out of the spindle allows only a single motor (the first motor) to be used to drive each printing roller. In other words, there is no need to use two motors (each motor is fixedly connected to one of the printing rollers) and / or there is no need to move the motors during printing roller changes.

[0022] In one embodiment, the printing unit further comprises a motorized linear guide coupled to the first spindle and configured to move the first spindle along the axis of the first printing roller. For example, the linear guide can move the first spindle and the coupled printing roller along the axis to couple or detach the printing roller to a counterholder. Furthermore, the motorized linear guide can be used to adjust the lateral position of the applied printing roller relative to other rollers of the printing system (e.g., an anilox roller and / or an impression cylinder).

[0023] It is also contemplated that the printing unit includes a source of pressurized gas connected to the second spindle, such that pressurized gas can pass through the second spindle and into the first or second shaft. Each shaft can have a cylindrical surface with an opening through which pressurized gas can escape. The escaping pressurized gas can reduce the contact surface and friction between the shaft and the corresponding kit, thereby facilitating kit exchange.

[0024] In another variant, the printing unit further includes a second motor connected to the carousel gripper and configured to rotate the carousel gripper from its home position. Specifically, the motor can rotate the carousel gripper 180°. This enables automated switching of the printing rollers and helps keep idle time of the printing system as short as possible.

[0025] The second motor can be further configured to rotate the carousel gripper in the printing position, causing it to simultaneously grip and / or release the first and second shafts. Specifically, the second motor can be moved together with the carousel gripper between a home position and a printing position. By using the same motor (the second motor) for different purposes (gripping / releasing and switching the printing roller) in both positions, the use of additional drive devices can be avoided. This reduces the complexity and cost of the overall setup.

[0026] In another preferred embodiment, the printing unit further comprises a pneumatic piston connected to a rotating shaft of the carousel clamper, wherein the pneumatic piston is configured to translate the carousel clamper along the axis direction of the first and second printing rollers.

[0027] The pneumatic piston can be used to engage and / or disengage the carousel gripper with the print roller with the spindle. In particular, the pneumatic piston can move the axle of the print roller toward or away from the spindle, allowing the spindle to quickly and accurately grasp and / or release the axle.

[0028] In another preferred embodiment, the printing unit includes a linear guide with a U-shaped frame and a plate configured to move within the U-shaped frame. The plate has a hole through which the rotary shaft of the carousel holder extends. This arrangement allows the carousel holder with the printing roller to be precisely moved between the printing and home positions. The U-shaped frame thus prevents any unintended movement perpendicular to the axis.

[0029] In particular, the wall of the hole in the plate can be configured to support the shaft of the carousel gripper.By offsetting the plate within the U-shaped frame, the carousel gripper and attached elements (such as the second motor and / or pneumatic piston) can be moved simultaneously.

[0030] In a technically simple and space-saving embodiment, the second motor is located between the pneumatic piston and the linear guide.

[0031] It is also conceivable that a portion of the pneumatic piston passes through the rotor of the second engine and / or forms a central part of the rotor.

[0032] In order to increase the robustness of the printing unit, the piston or parts of the piston and the shaft of the carousel gripper can also be formed from a single piece. This reduces the overall number of individual components and thus reduces the structural complexity.

[0033] The object of the present invention is achieved by a method for replacing a printing roller in a printing unit, the method comprising the following steps:

[0034] - rotating the carousel gripper in the printing position so that it simultaneously grips the first shaft of the first printing roller and the second shaft of the second printing roller;

[0035] - moving the carousel gripper in the printing position in translation along the axis of the printing roller in order to extract the first shaft from the first spindle and the second shaft from the second spindle;

[0036] - rotating the carousel holder about an axis parallel to the axis of the printing roller, thereby changing the position of the printing roller;

[0037] - moving the carousel gripper in translation along the axis of the printing roller in order to plug the first shaft to the second spindle and the second shaft to the first spindle.

[0038] The method may further comprise the following steps:

[0039] - moving the carousel gripper from the printing position to the home position in a translational manner perpendicular to the axial direction of the printing roller;

[0040] - moving the carousel gripper translationally perpendicular to the axial direction of the printing roller from the home position back into the printing position.

[0041] The advantages discussed for the printing unit also apply to the method for replacing the printing roller. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Further features and advantages will become apparent from the following description of the invention and the accompanying drawings, which show non-limiting exemplary embodiments of the invention, in which:

[0043] - Figure 1 Schematically shows a side view of an embodiment of a printing unit according to the invention;

[0044] - Figure 2 Shows a side view of a turntable gripper and a linear guide, which are Figure 1 part of a printing unit;

[0045] - Figure 3 Shown Figure 2 A front view of a linear guide;

[0046] - Figure 4 Shown as Figure 2 A front view of a turntable gripper;

[0047] - Figure 5 and 6 Shown Figure 1 a front view of a printing unit during a first step of a printing roller changing process;

[0048] - Figure 7 and 8 Shown Figure 1 a side view of a printing unit during a second step of a printing roller changing process;

[0049] - Figure 9 and 10 Shown Figure 1 side and front views of the printing unit during the third step of the printing roller changing process;

[0050] - Figure 11 Shown as Figure 1 a side view of the printing unit during the fourth step of the printing roller changing process;

[0051] - Figure 12 and 13 Shown Figure 1side and front views of the printing unit during the fifth step of the printing roller changing process;

[0052] - Figure 14 and 15 Shown Figure 1 a front view of the printing unit during a sixth step of a printing roller replacement process;

[0053] - Figure 16 Shown Figure 1 a front view of the printing unit during the seventh step of the printing roller replacement process;

[0054] - Figure 17 Shown Figure 1 a side view of the printing unit during the eighth step of the printing roller changing process;

[0055] - Figure 18 Shown Figure 1 a front view of the printing unit during a ninth step of the printing roller replacement process;

[0056] - Figure 19 Shown Figure 1 a front view of the printing unit shown during the tenth step of the printing roller changing process;

[0057] - Figure 20 Shown Figure 1 a front view of the printing unit during the eleventh step of the printing roller changing process;

[0058] - Figure 21 Shown Figure 1 A front view of the printing unit after completing the printing roller replacement process;

[0059] - Figure 22 shows a front view of a second embodiment of a printing unit according to the invention in a first state;

[0060] - Figure 23 Shown Figure 22 A front view of the printing unit in a second state;

[0061] - Figure 24 Shown Figure 22 A front view of the printing unit in a third state;

[0062] - Figure 25 Shown Figure 22 A front view of the printing unit in a fourth state after completing the printing roller replacement process;

[0063] - Figure 26 shows a front view of a third embodiment of a printing unit according to the invention in a first state;

[0064] - Figure 27 Shown Figure 26 A front view of the printing unit in a second state;

[0065] - Figure 28 Shown Figure 26 A front view of the printing unit in a third state; and

[0066] - Figure 29 Shown Figure 26 A front view of the printing unit in a fourth state after completing the printing roller replacement process. DETAILED DESCRIPTION

[0067] Figure 1 A side view of a first embodiment of a printing unit 10 according to the present invention is schematically shown. The printing unit 10 comprises a first printing roller 12 having a first shaft 14 and a first sleeve 16 circumferentially surrounding the first shaft 14. The printing unit 10 further comprises a second printing roller 18 having a second shaft 20 and a second sleeve 22 circumferentially surrounding the second shaft 20.

[0068] In an embodiment, the outer peripheral surfaces of the first and second sets 16, 22 are composed of a flexible rubber-like material forming a flexographic printing plate.

[0069] The printing unit 10 further comprises a first spindle 24 and a second spindle 26, each spindle 24, 26 being configured to hold the first and second shafts 14, 20. Figure 1 In the embodiment, the first spindle 24 holds the first shaft 14. The second spindle 26 holds the second shaft 20.

[0070] The printing unit 10 further comprises a source 28 of pressurized gas, in particular compressed air, which is connected to the second mandrel 26 so that the pressurized gas can pass through the second mandrel 26 and enter the connected shaft ( Figure 1 The second shaft 20 in the embodiment.

[0071] In an embodiment, the second mandrel 26 and the second shaft 20 include a common central passage 30 through which gas may flow from the source 28 into the second shaft 20 .

[0072] The second shaft 20 has a plurality of small openings 32 on its circumferential surface through which gas can escape. The escaping gas reduces the contact surface and thus reduces the friction between the second shaft 20 and the corresponding sleeve 22, thereby facilitating the exchange of the sleeves.

[0073] In the example described, the first printing roller 12 is located between the anilox roller and the impression cylinder. Figure 1The anilox roller and the impression roller are located in front of the first printing roller 12 in the Y direction. Since the anilox roller and the impression roller are not in the visual plane, they are Figure 1 Not displayed in .

[0074] The printing unit 10 further includes a first motor 34 connected to the first spindle 24 and configured to rotate the first spindle 24. Thus, the first motor 34 drives the printing roller ( Figure 1 In the embodiment described, the printing speed and the delivery amount of the printing unit 10 can be controlled by adjusting the rotation speed of the first motor 34.

[0075] The printing unit 10 further includes a motorized linear guide 36 connected to the first spindle 24 and configured to move along the axis direction of the first printing roller 12 ( Figure 1 The first spindle 24 is moved in the X direction.

[0076] In an embodiment, the motorized linear guide 36 may move the first spindle 24 and the attached first printing roller 12 such that the printing roller 12 is connected to or released from the counter holder 38 .

[0077] It is conceivable that the motorized linear guide 36 is driven by a register-controlled motor. Typically, register control is used to correctly align the color plates of the different printing units of a printing press. In other words, the motor needs to be independent of the printing roller replacement operation.

[0078] In an embodiment, a motorized linear guide 36 may be used to adjust the position of the first printing roller 12 in the X-direction so that precise alignment with the anilox roller and / or impression cylinder is achieved.

[0079] The printing unit 10 further includes a turntable gripper 40 having a rotating shaft 42 and a second motor 44 connected to the rotating shaft 42 .

[0080] Figure 2 The installation of the carousel gripper 40 is shown in a side view. The carousel gripper 40 and the second motor 44 are located on different sides of the machine frame 46. The rotating shaft 42 passes through an opening 48 in the machine frame 46 and connects the carousel gripper 40 to the second motor 44.

[0081] The printing unit 10 further comprises a pneumatic piston 50 connected to the rotation shaft 42 of the carousel gripper 40 .

[0082] The pneumatic piston 50 is configured to move the rotary disc clamper 40 in the axial direction of the printing rollers 12, 18 (along the axis of the printing rollers 12, 18). Figure 2 The X direction in the figure moves in a translational manner.

[0083] The printing unit 10 further comprises a linear guide 52 mounted on the machine frame 46. The second motor 44 is located between the pneumatic piston 50 and the linear guide 52 in a space-saving arrangement.

[0084] The linear guide 52 includes a U-shaped frame 54 and a plate 56 configured to move in the Z direction within the U-shaped frame 54. In this embodiment, the movement is controlled by a pneumatic cylinder 58 connected to the plate 56.

[0085] Figure 3 A front view of the linear guide 52 is shown. The plate 56 includes a hole 60. In an embodiment, the rotating shaft 42 of the carousel gripper 40 passes through the hole 60 and is connected to the rotor of the second motor 44.

[0086] Therefore, when the plate 56 moves in the Z direction, the rotating shaft 42 and the carousel gripper 40 and the second motor 44 also subsequently move in the same direction.

[0087] Figure 4 A front view of the carousel clamp 40 is shown. In an embodiment, the carousel clamp 40 is symmetrical about a center point 62. The carousel clamp 40 has two oppositely facing openings 64 that are configured to clamp and / or release the shafts 14, 20 of the printing rollers 12, 18 when rotated about the center point 62.

[0088] For the purpose of replacing the printing rollers 12, 18 in the printing unit 10, the carousel gripper 40 is configured to perform several different movements.

[0089] These movements will become apparent from the following description of a method of replacing printing rollers 12, 18 according to the invention. Figures 5 to 17 The printing unit 10 is shown schematically during different steps of the method.

[0090] Figure 5 and Figure 6 A front view of the printing unit 10 is shown during the first step of the method. The first printing roller 12 is positioned between the anilox roller 66 and the impression cylinder 68 in a printing position. The axes of the anilox roller 66, printing roller 12, and impression cylinder 68 are aligned horizontally. This allows the printing pressure to be set independently of the weight / diameter of the applied printing roller 12. In the first step, the anilox roller 66 and the printing unit 10 are moved away from the impression cylinder 68 (in the opposite direction to Y), thereby separating them from each other.

[0091] An operator (not shown) inserts the second printing roller 18 into the printing unit 10, for example, by mounting the second sleeve 22 on the second spindle 20. During the mounting process, pressurized air may be delivered from a source of pressurized air through a second spindle to the second spindle 20 ( Figure 5 and Figure 6 ), to allow the second set 22 to slide on the second shaft 20.

[0092] Figure 7 and Figure 8 A side view of the printing unit 10 is shown during the second step of the method. The first printing roller 12 is located between the first spindle 24 and the counter-holder 38. The first shaft 14 is held by the first spindle 24. In the second step, the motorized linear guide 36 moves the first spindle 24 and the connected first printing roller 12 in the direction opposite to X, so that the first shaft 14 is disengaged from the counter-holder 38.

[0093] Figure 9 and 10 The side view and the front view of the printing unit 10 during the third step of the method are shown. In this step, the second motor 44 rotates the rotary shaft 42 and thus the carousel clamp 40 in the YZ plane (about the X axis) so that the first shaft 14 and the second shaft 20 are clamped simultaneously towards the opposite openings 64.

[0094] Figure 11 A side view of the printing unit 10 is shown during the fourth step of the method. In this step, the pneumatic piston 50 pushes the rotary shaft 42 and thus the carousel gripper 40 in the X direction, so that the first and second shafts 14, 20 of the printing cylinders 12, 18 are pulled out of the spindles 24, 26. This displacement is large enough to completely disengage the spindles 24, 26, but small enough to prevent the first shaft 14 from reengaging in the counter holder 38.

[0095] Figure 12 and 13 The printing unit 10 is shown in side and front views during the fifth step of the method. In this step, the pneumatic cylinder 58 moves the plate 56 in the Z direction in the U-shaped frame 54 of the linear guide 52. Due to this movement, the carousel gripper 40 lifts the first and second printing rollers 12, 18 into a home position in which they are spaced a defined distance from the anilox roller 66 and the impression cylinder 68.

[0096] Figure 14 and 15 The figure shows a front view of the printing unit 10 during the sixth step of the method. In this step, a second motor (not shown) rotates the carousel gripper 40, which is located in the original position, by 180° about an axis (in this embodiment, the X axis) parallel to the axis of the printing rollers 12, 18, thereby switching the positions of the printing rollers 12, 18.

[0097] Figure 16A front view of the printing unit 10 is shown during a seventh step of the method, wherein the carousel gripper 40 and the connected printing rollers 12, 18 are moved in the reverse Z direction back to the printing position.

[0098] Figure 17 A side view of the printing unit 10 is shown during the eighth step of the method. In this step, the carousel gripper 40 is moved in the opposite direction X, so that the first shaft 14 of the first printing roller 12 is inserted into the second spindle 26, and the second shaft 20 of the second printing roller 18 is inserted into the first spindle 24.

[0099] Figure 18 A front view of the printing unit 10 is shown during a ninth step of the method, wherein the second motor rotates the rotary shaft and thereby rotates the carousel gripper 40 in the YZ plane (about the X axis) such that the first shaft 14 and the second shaft 20 are released toward opposite openings 64 .

[0100] Figure 19 A side view of the printing unit 10 is shown during the tenth step of the method, in which the motorized linear guide 36 moves the first spindle 24 and the attached second printing roller 18 in the X direction, thereby inserting the second shaft 20 into the counter holder 38 and fixing the second printing roller 18 in the printing position.

[0101] Figure 20 A front view of the printing unit 10 is shown during the eleventh step of the method.In this step, the anilox roller 66 and the printing unit 10 are moved towards the impression cylinder 68 (in the Y direction) so that they are connected to each other.

[0102] It is conceivable that the seventh step corresponds to the fifth step, the eighth step to the fourth step, the ninth step to the third step, the tenth step to the second step and the eleventh step to the first step, but with the directions of movement of the individual components reversed.

[0103] Figure 21 The front view of the printing unit 10 after the method is completed is shown. In this state, the second printing roller 18 can be used for printing. The operator can access the first printing roller 12 (and / or the set 16 of the first printing roller 12) for maintenance or replacement.

[0104] Of course, the embodiments described above are merely examples. In particular, the method according to the present invention may include more or fewer steps than those described above. Furthermore, it is conceivable that the method may be repeated frequently during or between printing runs to maintain and / or replace the printing rollers 12, 18.

[0105] Figures 22 to 25 A second embodiment of a printing unit 10 according to the invention is shown.

[0106] The second embodiment corresponds to the first embodiment in several basic features, so only the differences are discussed below. Identical components and components that have identical functions are given the same reference numerals.

[0107] Figure 22 The printing unit 10 is shown in a first state. The printing unit 10 includes an anilox roller 66, an impression cylinder 68, a first printing roller 12, a second printing roller 18, and a carousel clamp 40. In the first state, the first printing roller 12 is located between the anilox roller 66 and the impression cylinder 68 and is in direct contact with both. To interchange the first and second printing rollers 12, 18, the anilox roller 66 and the first printing roller 12 are configured to move away from each other and away from the impression cylinder 68.

[0108] Figure 23 The printing unit 10 is shown in a second state after the movement of the anilox roller 66 and the first printing roller 12. In this state, a free space 70 for rotating the carousel gripper 40 is formed between the anilox roller 66 and the impression cylinder 68. Due to the free space 70, the carousel gripper 40 can be rotated to exchange the first and second printing rollers 12, 18 without any prior translation.

[0109] Figure 24 The printing unit 10 is shown in a third state after rotation of the carousel gripper 40. In this state, the second printing roller 18 is located between the anilox roller 66 and the impression cylinder 68. The second printing roller 18 and the anilox roller 66 can be moved towards the impression cylinder 68.

[0110] Figure 25 The printing unit 10 is shown in a fourth state after the printing roller exchange has been completed. In this state, the second printing roller 18 is in direct contact with the anilox roller 66 and the impression cylinder 68. The first printing roller 12 can be accessed for maintenance.

[0111] Figures 26 to 29 A third embodiment of a printing unit 10 according to the invention is shown.

[0112] The third embodiment corresponds to the first and second embodiments in several essential features, so only the differences are discussed below. Identical components and components that have identical functions are given the same reference numerals.

[0113] Figure 26 The printing unit 10 is shown in a first state. The printing unit 10 includes an anilox roller 66, an impression cylinder 68, a first printing roller 12, a second printing roller 18, and a carousel clamp 40. In the first state, the anilox roller 66, the impression cylinder 68, and the first printing roller 12 are positioned in a triangle. In the first state, the first printing roller 12 directly contacts the anilox roller 66 and the impression cylinder 68.

[0114] The carousel clamp 40 and thereby the first and second printing rollers 12 , 18 can be moved away from the anilox roller 66 and the impression cylinder 68 (in the Z direction).

[0115] Figure 27 The printing unit 10 is shown in a second state after this movement. In this state, the carousel clamp 40 can be rotated to exchange the first and second printing rollers 12,18.

[0116] Figure 28 The printing unit 10 is shown in a third state after the rotation of the rotary carousel gripper. The carousel gripper 40 and thus the first and second printing rollers 12, 18 can be moved back towards the anilox roller 66 and the impression cylinder 68 (in the opposite Z direction).

[0117] Figure 29 The printing unit 10 is shown in a fourth position after the printing roller exchange is complete. In this position, the second printing roller 18 is in direct contact with the anilox roller 66 and the impression cylinder 68. Access to the first printing roller 12 is possible for maintenance. Unlike the first and second embodiments, the relative position of the anilox roller and the impression cylinder is maintained throughout the exchange process.

Claims

1. A printing unit comprising: A first printing roller (12) with a first shaft (14), a second printing roller (18) with a second shaft (20), a first mandrel (24) configured to hold one of the shafts (14, 20) at a time, a second mandrel (26) configured to hold one of the shafts (14, 20) at a time, and a turntable clamp (40) configured to Moving translationally in the printing position along the axis of the first and second printing rollers (12, 18) to extract the first shaft (14) from the first mandrel (24) and the second shaft (20) from the second mandrel (26); Rotating about an axis parallel to the axes of the first and second printing rollers (12, 18) to thereby convert the positions of the printing rollers (12, 18); The first and second printing rollers (12, 18) are moved in translation along the axis direction to insert the first shaft (14) into the second spindle (26) and insert the second shaft (20) into the first Mandrel (24).

2. The printing unit according to claim 1, wherein the rotary disc holder (40) is further configured as Translating perpendicularly to the axial direction of the first and second printing rollers (12, 18) from the printing position to a home position; The printing rollers (12, 18) are moved translationally perpendicular to the axis direction of the first and second printing rollers (12, 18) from the home position back to the printing position.

3. The printing unit according to claim 1 or 2, further comprising an anilox roller (66) and an impression cylinder (68).

4. The printing unit according to claim 3, wherein the first printing roller (12) or the second printing roller (18) is located between the anilox roller (66) and the impression cylinder (68), and wherein The anilox roller (66) and the first and / or second printing rollers (12, 18) are configured to move away from each other and away from the impression cylinder (68) thereby creating a free space (70) for rotating the carousel holder (40).

5. The printing unit according to claim 3, wherein the anilox roller (66), the impression cylinder (68) and the first and / or second printing roller (12, 18) are positioned so that their axes form a triangle, and wherein The first and / or second printing rollers (12, 18) are configured to move away from the anilox roller (66) and the impression cylinder (68).

6. The printing unit according to any of the preceding claims, further comprising a first motor (34) connected to the first spindle (24) and configured to rotate the first spindle (24) to control the printing process.

7. The printing unit according to any one of the preceding claims, further comprising a motorized linear guide (36), which is connected to the first spindle (24) and is configured to move the first spindle (24) along the axis of the first printing roller (12).

8. A printing unit according to any one of the preceding claims, further comprising a source (28) of pressurized gas, wherein the second spindle (26) and the second shaft (20) comprise a common central channel (30), and wherein the source (28) of pressurized gas is connected to the second spindle (26) such that pressurized gas can pass through the second spindle (26) via the channel (30) and into the first or second shaft (14, 20).

9. The printing unit according to any one of the preceding claims, further comprising a second motor (44) connected to the carousel gripper (40) and configured to rotate the carousel gripper (40).

10. A printing unit according to claim 9, wherein the second motor (44) is further configured to rotate the turntable clamp (40) in the printing position so that it clamps the first shaft (14) and the second shaft (20) at the same time or releases the first shaft (14) and the second shaft (20) at the same time.

11. The printing unit according to any one of the preceding claims, further comprising a pneumatic piston (50), which is connected to the rotating shaft (42) of the turntable clamp (40) and is configured to move the turntable clamp (40) translationally along the axis of the first and second printing rollers (12, 18).

12. The printing unit according to claim 11 further comprises a linear guide (52) having a U-shaped frame (54) and a plate (56) configured to move in the U-shaped frame (54), wherein the plate (56) comprises a hole (60), and wherein the rotating shaft (42) of the turntable clamp (40) passes through the hole (60).

13. Printing unit according to claims 9 and 11, wherein the second motor (44) is located between the pneumatic piston (50) and the linear guide (52).

14. A method for replacing a printing roller (12, 18) in a printing unit (10), comprising the following steps: - rotating the carousel clamp (40) in the printing position so that it simultaneously clamps the first shaft (14) of the first printing roller (12) and the second shaft (20) of the second printing roller (18); - moving the carousel gripper (40) in the printing position in translation along the axis of the printing rollers (12, 18) in order to extract the first shaft (14) from the first spindle (24) and the second shaft (20) from the second spindle (26); - rotating the turntable holder (40) about an axis parallel to the axis of the printing roller (12, 18), thereby switching the position of the printing roller (12, 18); - moving the carousel gripper (40) in translation along the axis of the printing rollers (12, 18) in order to plug the first shaft (14) to the second spindle (26) and the second shaft (20) to the first spindle (24).

15. The method according to claim 14, further comprising the steps of: - moving the carousel holder (40) translationally from the printing position to a home position perpendicular to the axial direction of the printing rollers (12, 18); - moving the carousel gripper (40) translationally from the home position back into the printing position perpendicular to the axial direction of the printing rollers (12, 18).

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