Die-cutting unit

Abstract

A die-cutting unit (10) for a digital and / or flexographic printing machine, comprising a rotary cutting cylinder (12) on which a cutting die (14) can be mounted, at least one counter-pressure cylinder (16,17), a mounting station (30), a dismounting station (32), a magazine (50) adapted for storing a plurality of cutting dies (14), and a displacement system (52) adapted for displacing the magazine (50). The magazine (50) is displaced by the displacement system (52) between a plurality of loading positions in which one of the plurality of cutting dies (14) can be transferred from the magazine (50) into the mounting station (30). Furthermore, the displacement system (52) displaces the magazine (50) between a plurality of unloading positions in which a cutting die (14) can be transferred from the unloading station into the magazine (50).

Description

[0001] Die-cutting unit

[0002] The invention relates to a die-cutting unit for a digital and / or flexographic printing machine.

[0003] Especially when printing labels or similar commodities on a self-adhesive material, printing machines often include a die-cutting unit. Most commonly, a cutting die is placed on a rotating cylinder and the material is fed through a gap between the cylinder and a counter-pressure cylinder such that the web containing the print is pressed against the cutting die.

[0004] However, the number of prints required for a job is usually small and since the size and shape of the printed product varies from job to job, the cutting die needs to be changed between each job. Currently, an operator is required to start the removal process of the cutting die from the rotary cutting cylinder and remove the cutting die to place it into a storage unit. Similarly, the operator needs to manually insert the new cutting die into the die-cutting unit.

[0005] DE 10 2021 131 718 B3 shows such system in which an operator uses a trolley for storing the dies and for transporting them form a dismounting station to an mounting station.

[0006] Therefore, it is an objective of the invention to provide a die-cutting unit, which is able to change the cutting die in an automated process.

[0007] The objective is solved by a die-cutting unit for a digital and / or flexographic printing machine, comprising a rotary cutting cylinder on which a cutting die can be mounted, at least one counter-pressure cylinder, a mounting station, a dismounting station, a magazine configured for storing a plurality of cutting dies, and a displacement system configured for displacing the magazine between a plurality of mounting positions in which one of the plurality of cutting dies can be transferred from the magazine into the mounting station, and further between a plurality of unloading positions in which a cutting die can be transferred from the dismounting station into the magazine so that the magazine can move into the loading or unloading position such that the cutting die can be transferred in a fully automated manner. In other words, the magazine used to store the cutting dies can be displaced by the displacement system such that one of the cutting die can be transferred from the magazine into the mounting station and such that a cutting die can be removed from the die-cutting unit via the dismounting station. Therefore, the basic idea of the present invention is that the magazine is displaceable such that a cutting die can be transferred directly from the magazine into the die-cutting unit and / or from the die-cutting unit directly back into the magazine. By having the magazine be movable between a loading and an unloading positions, the process of changing the cutting die becomes automated since an operator no longer has to select the correct cutting die and place it into the machine or alternatively remove the cutting die by hand and select the right storage position. Instead, the magazine moves into the loading or unloading position such that the cutting die can be transferred in a fully automated manner.

[0008] The cutting die can be loaded and unloaded in any sequence. This means that you have the flexibility to load any cutting die from the magazine without being constrained by the position of the previously used die in the die-cutter.

[0009] The printing machine generally comprises a printer located upstream of the die-cutting unit, such that the die-cutting unit cuts the already printed labels. Downstream of the die-cutting unit may be further processing steps.

[0010] In order to differentiate between the different cutting dies, each cutting die may have an identification marking, for example a QR-code. That way, the desired cutting die can easily be identified and transferred from and / or to the magazine.

[0011] Preferably, the magazine comprises a plurality of distinct storage spaces configured for receiving one cutting die each. A transfer system is provided for transferring a respective cutting die into the respective storage space and out of the respective storage space. Therefore, the process of loading and unloading a cutting die becomes fully automated since the transfer system of the magazine transfers the cutting die. In the long run, this reduces production costs since an operator for loading and unloading the cutting die is no longer required.

[0012] According to an embodiment, the transfer system comprises a belt drive associated with each storage space. Belt drives are easy and cheap to produce, such that the overall cost of the die-cutting unit is kept low. Belt drives also provide an easy mechanism to move the cutting die from its loading position into the die-cutting unit. Similarly, belt drives can easily transfer a cutting die back into the magazine from the dismounting station.

[0013] Further, the displacement system may comprise a first guide for guiding the magazine in a translational manner between the mounting station and the dismounting station, and a slider, which is configured for being displaced along the first guide. By using a guide and a slider, the movement of the magazine is exact and easily controlled such that the magazine can be moved safely from one position to another.

[0014] Preferably, the guide comprises a guide rail. Guide rails are generally readily available such that they provide a mechanism, which is cheap and simple.

[0015] Preferably, a displacement system is provided for displacing the slider along the guide rail. In particular, the transfer system may comprise a linear pneumatic cylinder which moves the slider and therefore the magazine from one side of the guide to the other side. The transfer system is programmable such that it can move the magazine a defined distance.

[0016] According to a preferred embodiment, the displacement system comprises a second guide. By having two guides, the magazine and the slider are movable in different directions, e.g. a vertical and a horizontal direction. The second guide here is provided between the slider and the magazine.

[0017] Preferably, a piston / cylinder drive is provided. The piston can move the magazine with respect to the slider a distinct distance such that a distinct storage space lines up with the mounting station of the die-cutting unit.

[0018] Alternatively, an electric motor comprising an encoder may be provided in order to displace the magazine a distinct distance with respect to the slider.

[0019] According to a preferred embodiment, the first guide and the storage spaces extend horizontally. By having the storage spaces extend horizontally, no measures for keeping the cutting die on their respective storage spaces need to be provided.

[0020] Since the cutting dies are usually made of steel, the storage spaces may comprise a magnetic component to keep the cutting die in place provided the storage spaces do not extend horizontally. Furthermore, the die-cutting unit may comprise a user interface, preferably a digital front end, configured to receive instructions about the required cutting die, the user interface being connected to a control unit configured for achieving a fully automated loading and unloading of the cutting dies. Therefore, the operator only needs to select the desired cutting die on the user interface and the diecutting unit will start the loading and unloading process of the respective cutting dies.

[0021] The digital front end is preferably located upstream of the printer. That way, an operator can provide an input of the overall printing job description via the digital front end connected to the control unit which then executes the printing job.

[0022] Preferably, instructions regarding the cutting die for the respective printing jobs are stored on the control unit such that the operator does not need to select a fitting cutting die every time a new printing job is started. Instead, the operator can store the information, including the required cutting die size, about the printing jobs to be performed that day and the control unit selects the respective cutting dies accordingly.

[0023] According to a preferred embodiment, the mounting station and the dismounting station are connected to the control unit. This allows the control unit not only to choose the necessary cutting die but also to automate the loading and unloading process, eliminating the need for manual intervention by an operator to change the cutting dies. Additionally, the control unit takes charge of regulating the slider's and magazine's movements.

[0024] According to a further embodiment, the dismounting station comprises a dismounting plate which has at least two teeth, wherein the distance between the at least two teeth is the same distance as the distance between corresponding grooves on the rotary cutting cylinder. Since the rotary cutting cylinder comprises grooves in which the teeth can engage, the cutting die currently placed on the rotary cutting cylinder can be removed easily and without causing any damage to the cutting die since the teeth do not need to be inserted between the peripheral surface of the rotary cutting cylinder and the cutting die. Further features and advantages of the invention will become apparent from the following description and from the accompanying drawings to which reference is made. In the schematic drawings,

[0025] Figure 1 shows a cutting unit according to the subject invention;

[0026] Figure 2 shows a magazine used in the die-cutting unit of Figure 1;

[0027] Figure 3 shows a mounting station of the die-cutting unit;

[0028] Figure 4 shows a dismounting station of the die-cutting unit;

[0029] Figure 5 shows an operating situation of the die-cutting unit; and

[0030] Figure 6 shows a close-up of a cutting mechanism used in the cutting unit of Figure 1.

[0031] Figure 1 shows a schematic drawing of a die-cutting unit 10 for a digital and / or flexographic printing machine. Preferably the die-cutting unit 10 is located downstream of a printing unit.

[0032] The die-cutting unit 10 comprises a rotary cutting cylinder 12 on which a cutting die 14 can be mounted. Since the cutting die 14 are usually made from steel, the rotary cutting cylinder 12 is preferably magnetic such that the cutting die 14 can be easily attached and removed from the rotary cutting cylinder 12. The cutting die 14 covers at least a part of the peripheral surface of the rotary cutting cylinder 12.

[0033] Since the size and shape of the cutting dies 14 vary depending on the print job, the cutting dies 14 may each have an identification marking, e.g. a QR-code, such that they can be easily differentiated.

[0034] Next to the rotary cutting cylinder 12 is at least one counter-pressure cylinder 16. In the embodiment shown in figure 1 and figure 6, the die-cutting unit 10 comprises two counter-pressure-cylinders 16, 17.

[0035] The counter-pressure cylinders 16,17 are positioned on either side and below the rotary cutting cylinder 12 and are pushed against the rotary cutting cylinder 12 by a clamping system 18. In particular, the clamping system 18 may consist of an eccentric actuator 20, preferably a pneumatic actuator. The eccentric actuator 20 adjusts the clamping force by changing the rotation angle of an eccentric mechanism 22.

[0036] The die-cutting unit 10 also comprises clamping rollers 24 designed to push a web 26 comprising the printed labels to be cut against the counter-pressure cylinders 16,17 which guide the web 26 between them and the rotary cutting cylinder 12.

[0037] Furthermore, the die-cutting unit 10 comprises a compensation roller 28, which is used to adjust the path length of the web 26 depending on the size of the cutting die 14.

[0038] Additionally, the die-cutting unit 10 also comprises a mounting station 30 and a dismounting station 32. The mounting station 30 and the dismounting station 32 are preferably located on opposite sides of the rotary cutting cylinder 12 and can be moved towards and away from the rotary cutting cylinder 12 via their respective pneumatic actuators 34.

[0039] The mounting station 30 consists of a mounting plate 36 onto which a mounting ramp 38 is attached, e.g. with screws. At the edge of the mounting plate 36 in front of the mounting ramp 38 a guide rail 40 is positioned. The guide rail 40 ensures that the cutting die 14 is positioned correctly and can easily be attached to the rotary cutting cylinder 12.

[0040] The dismounting station 32 located on the opposite side of the rotary cutting cylinder 12 comprises a dismounting plate 42 and a dismounting ramp 44. At the edge of the dismounting plate 42 facing the rotary cutting cylinder 12 multiple teeth 46 are positioned.

[0041] The teeth 46 are positioned such that they can engage in corresponding grooves 48 in the rotary cutting cylinder 12. This way, the teeth 46 can easily slide below a cutting die 14 placed on the rotary cutting cylinder 12 in order to peel the cutting die 14 off.

[0042] Additionally, the die-cutting unit 10 also comprises a magazine 50 and a displacement system 52. The magazine 50 is adapted for storing a plurality of cutting die 14. The magazine 50 comprises multiple storage spaces 54. The magazine 50 shown in Figure 2 has five distinct storage spaces 54, which consist of a belt drive each. In particular, each belt drive has a conveyor belt driven by a motor with an encoder.

[0043] The displacement system 52 comprises a first guide 56 as well as a second guide 58. The first guide 56 is preferably provided by guide rails, which extend horizontally and parallel to the storage spaces 54. The second guide 58 is positioned perpendicular to the first guide 56 such that it allows for a vertical displacement of the magazine 50.

[0044] The magazine 50 is attached to the first guide 56 via a slider 60, wherein the slider 60 can be displaced along the first guide 56 and hence provides a horizontal movement of the magazine 50 and the second guide 58. Preferably, the slider 60 can be displaced along the first guide 56 via a linear pneumatic cylinder. However, the displacement system 52 may be provided by any number of drives that provide a displacement of the slider 60 along the first guide 56.

[0045] The second guide 58 positioned between the slider 60 and the magazine 50 comprises a piston / cylinder drive 64, which is responsible for displacing the magazine 50 along the vertical second guide 58.

[0046] In order to provide a completely automated printing and cutting process, the die-cutting unit 10 also comprises a user interface 66. Since the die-cutting unit 10 is part of a digital and / or flexographic printing machine, the user interface 66 may be combined with a user interface for the printing unit in order to provide a user interface 66 for the entire digital and / or flexographic printing machine. In that case, the user interface 66 is preferably located upstream of the printing unit. Furthermore, the user interface 66 is preferably provided by a digital front end.

[0047] The user interface 66 is connected to a control unit 68, which executes the instructions provided via the user interface 66. At the beginning of a day an operator will input the printing jobs to be done that day and enter the required specifications via the user interface 66. Additionally, the operator will place the required cutting dies 14 into the magazine 50.

[0048] After starting the printing process, the printing jobs will be executed completely automated. The control unit 68 positions the magazine 50 on the side of the die-cutting unit 10 where the mounting station 30 is located. When the control unit 68 has determined the required cutting die 14 based on the identification marking on the cutting die 14, or based on its predetermined position in the magazine 50, the control unit 68 starts the vertical displacement along the second guide 58 by activating the piston drive 64.

[0049] The piston drive 64 is aligned with the mounting station 30 and the control unit 68 turns on the belt drive of the storage space 54 containing the required cutting die 14. Then, the cutting die 14 is attached to the rotary cutting cylinder 12 via the mounting station 30.

[0050] In particular, the cutting die 14 is fed through the guide rail 40 on the mounting plate 36 such that it is aligned properly. Then it is pushed from the mounting plate 36 onto the rotary cutting cylinder 12 via the mounting ramp 38.

[0051] Once the cutting die 14 is correctly placed on the rotary cutting cylinder 12, the web 26 starts to traverse the die-cutting unit 10.

[0052] The counter-pressure cylinders 16,17 rotate at a constant speed corresponding to the line speed of the whole printing machine. The rotary cutting cylinder may rotate using a variable speed to ensure a continuous cutting of the web 26 despite the variable size of the cutting die 14 and the fixed size of the cutting cylinder 12.. Furthermore, the compensation roller 28 adjusts the path length according to the cutting die 14 currently positioned on the rotary cutting cylinder 12. This allows cutting the sheet in two passes: in a first pass by contact of the cutting die 14 with the first counter roller 16, and in a second pass by contact with the second counter roller 17. When the cutting die 14 passes the second counter cylinder 17, the speed of the rotary cutting cylinder 12 may be adapted (accelerated and decelerated, or vice-versa) so that the cutting against the first counter cylinder 16 starts at the correct location to ensure a continuous cutting of the web 26. That means that the compensation roller 28 is moved before each cutting job in order to optimize the path length of the web 26 and optimize the cutting result.

[0053] Once a cutting job is finished, the dismounting station 32 is moved towards the rotary cutting cylinder 12 via its pneumatic actuators 34. In particular, the dismounting station 32 is moved towards the rotary cutting cylinder 12 until its teeth 46 engage with the corresponding grooves on the rotary cutting cylinder 12.

[0054] Once the rotary cutting cylinder 12 has rotated enough that the cutting die 14 slides over the teeth 46 of the dismounting station 32, the cutting die 14 is peeled off the rotary cutting cylinder 12 and slides over the dismounting ramp 44.

[0055] The cutting die 14 is transferred from the dismounting station 32 onto its storage space 54 on the magazine 50, which now is positioned on the side opposite to the mounting station 30.

[0056] That means, the magazine 50, the second guide 58 and the slider 60 have been moved along the first guide 56 to the opposite side of the rotary cutting cylinder 12 while the piston drive 64 has moved the magazine 50 in the vertical direction such that the correct storage space 54 aligns with the dismounting ramp 44 of the dismounting station 32.

[0057] Then the process is repeated with the cutting die 14 required for the next print job.

Claims

Claims1. A die-cutting unit (10) for a digital and / or flexographic printing machine, comprising a rotary cutting cylinder (12) on which a cutting die (14) can be mounted, at least one counter-pressure cylinder (16,17), a mounting station (30), a dismounting station (32), a magazine (50) configured for storing a plurality of cutting dies (14), and a displacement system (52) configured for displacing the magazine (50) between a plurality of loading positions in which one of the plurality of cutting dies (14) can be transferred from the magazine (50) into the mounting station (30), and further between a plurality of unloading positions in which a cutting die (14) can be transferred from the dismounting station into the magazine (50) so that the magazine can move into the loading or unloading position such that the cutting die can be transferred in a fully automated manner.

2. The die-cutting unit (10) according to claim 1, wherein the magazine (50) comprises a plurality of distinct storage spaces (54) configured for receiving one cutting die (14) each, a transfer system (62) being provided for transferring a respective cutting die (14) into the respective storage space (54) and out of the respective storage space (54).

3. The die-cutting unit (10) according to claim 2, wherein the transfer system (62) comprises a belt drive associated with each storage space (54).

4. The die-cutting unit (10) according to any of the preceding claims, wherein the displacement system (52) comprises a first guide (56) for guiding the magazine (50) in a translational manner between the mounting station and the dismounting station, and a slider (60) which is configured for being displaced along the first guide (56).

5. The die-cutting unit (10) according to claim 4, wherein the first guide comprises a guide rail.

6. The die-cutting unit (10) according to claim 5 wherein a displacement system (52) is provided for displacing the slider (60) along the guide rail.

7. The die-cutting unit (10) according to any one of claims 4 to 6, wherein the displacement system (52) comprises a second guide (58).

8. The die-cutting unit (10) according to claim 7, wherein a piston / cylinder drive (64) is provided.

9. The die-cutting unit (10) according to claim 8 wherein the first guide (56) and the storage spaces (54) extend horizontally.

10. The die-cutting unit (10) according to any of the preceding claims, wherein the die-cutting unit (10) comprises a user interface (66), preferably a digital front end, configured to receive instructions about the required cutting die (14), and wherein the user interface (66) is connected to a control unit (68) configured for achieving a fully automated loading and unloading of the cutting dies (14).

11. The die-cutting unit (10) according to claim 10, wherein the mounting station and the dismounting station are connected to the control unit (68).

12. The die-cutting unit (10) according to any of the preceding claims, wherein the dismounting station (32) comprises a dismounting plate (42) which has at least two teeth (46), wherein the distance between the at least two teeth (46) is the same as the distance between corresponding grooves (48) on the rotary cutting cylinder.

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