EP2832546B1 - Printing machine with print head control - Google Patents

Description

The invention relates to a printing machine with movable print heads for printing on containers such as bottles.

State of the art

From the prior art, alignment of the container is, for example, at a marking relative to the print head DE 10 2009 020 702 B4 known. In this case, the container is aligned with respect to the printhead before printing in accordance with certain markings which are printed or attached to the container for more precise printing.

Furthermore shows the DE 102009033810 A1 a printing press in which a print head module can be aligned in all three spatial directions and at two angles with respect to the surface of a container to be printed by the print module.

Also the DE 102009041527 A1 shows a corresponding device. Here, too, the pressure module can be aligned with respect to a container clamped in a clamping device in order to be adapted to the surface contour of the container.

The EP 1435296 A1 also shows a printing press in which a printing unit can be aligned by means of a travel system in such a way that the ink jet strikes the surface of the container to be printed essentially perpendicularly.

task

Starting from the prior art, it is an object of the present invention to provide a printing press which increases the printing accuracy when printing on containers.

solution

This object is achieved by the printing press according to claim 1. Appropriate embodiments of the invention are covered in the subclaims.

The printing press according to the invention comprises at least one conveyor and a printing unit with a print head module with at least one print head, a travel system for adjusting the position of the print head module, a measuring system for determining the position of the print head module and a control unit for controlling the travel system, wherein the Travel system includes a radial module for adjusting the position of the print module in the radial direction, a height module for adjusting the height of the print head module. This printing machine allows a very precise adjustment of the print head module by means of the radial module and the height module provided.

Furthermore, a tilt module for setting the tilt of the print head module can be provided. The printhead module can thus be aligned depending on the surface shape of the container to be printed.

According to the invention, the traversing system further comprises an alignment module for the vertical alignment of rows of nozzles of the printhead module in relation to the direction of transport of the containers to be printed. If the rows of nozzles are in relation to the transport direction of the

container to be printed is slightly tilted, this tilt can be corrected so that a uniform resolution of the printed image can be achieved.

In a further embodiment, the radial module, the height module and the tilt module can be set independently of one another. This enables a misalignment of the printhead module to be corrected very precisely.

Furthermore, the radial module, the height module and the tilting module each comprise a motor, preferably a motor-spindle-nut drive. The provision of individual motors for the individual modules also allows separate control here.

In one embodiment, the printing press is characterized in that the printing unit comprises means for centering the printing unit on the printing press. If an exchange or a short removal of the printing unit from the printing machine should be provided, it can always be returned to the appropriate position, thus reducing the assembly effort.

In a further embodiment, the measuring system can measure the position of the print head module with an accuracy of <0.5 mm, preferably <0.1 mm, particularly preferably <0.01 mm. This enables the printhead module to be positioned with very high accuracy, which enables printing of corresponding containers with likewise very high accuracy.

In a further embodiment, the printing unit is provided interchangeably.

Furthermore, the control unit can adjust the position of the print head module with an accuracy of 0.5 mm, preferably 0.1 mm, particularly preferably 0.01 mm. The positions or necessary changes in position obtained from the data of the measuring system can thus be carried out with corresponding accuracy.

The printing unit can also be assigned an ink tank connected to it via a line. As a result, the entire printing unit can be provided in a modular manner. This means that few or no additional elements have to be provided for the printing unit in the printing press itself and that an exchange is particularly easy.

In a further embodiment, the control unit can adjust the position of the printhead module as a function of the data that can be transmitted from the measuring system to the control unit. Due to the precise measurement of the position of the printhead module by the Measurement system, this can result in a very precise position adjustment of the printhead module.

In a further embodiment, the radial module, the height module and the tilt module comprise clamps which can fix the radial module, the height module and the tilt module in one position.

In one embodiment, the printing press is characterized in that piezo elements assigned to a print head module are provided which are suitable for aligning the print head module relative to the container to be printed. By using piezo elements, very precise positioning can be achieved, on the one hand, and positioning in real time, that is, specific positioning for each container to be printed, on the other hand.

Furthermore, a protective position and / or a cleaning position and / or a maintenance position can be provided, into which the print head module can be moved. In this way, an unused printhead module can be protected from external influences or serviced or cleaned.

Furthermore, the printing press can comprise a cleaning unit which is suitable for cleaning the print head module when it is in the cleaning position. A preferably automatic and therefore time-saving cleaning of a printhead module to be cleaned can take place, which can shorten the times until it is used again.

Brief description of the figures

Fig. 1

shows a view of a printing press according to the invention.

Fig. 2

shows a detailed schematic representation of a printing unit of the printing press according to the invention.

Fig. 3

shows a possible change process of a printing unit.

Detailed description

Fig. 1 shows a printing machine 100 according to the invention in a schematic view. This printing machine 100 comprises at least one conveyor 101, with the aid of which the containers, such as for example bottles 110, can be transported. This conveyor 101 can be any type of conveyor commonly used in the container and packaging industry. In particular, it can be a linear conveyor or, as shown here, a conveyor star. This is fed, for example, by a further conveyor 180 to the containers 110 which are to be printed on by the printing press 100. The printing takes place while one of the containers 110 is on the conveyor 101 with the aid of printing units 120, which comprise at least one printhead module 102. Depending on the intended printing, for example single-color or patterned or multi-colored, a large number of printing units 120 can be provided in the printing press 100. Likewise, each of these printing units 120 can comprise one or more print head modules 102, the print head modules 102 of a printing unit 120 being able to print the container 110 to be printed either with the same color or with different colors. Furthermore, the individual printhead modules 102 of a printing unit 120 can also print on the container 110 at different locations. If the printing is completed after all printing units 120 have been run through, the printed container 110 can be removed from the printing press 100, for example, by a further conveyor 190. This transport can take place cyclically as well as continuously.

Fig. 2 shows a printing unit 120 with printhead modules 102. In relation to a container 110, which is on a like in Fig. 1 shown conveyor can be. The printhead modules are usually positioned as close as possible to the wall of the container in order to ensure correct printing. A printing unit 120 can either comprise only one printing head module 102 or also a plurality of printing head modules 102. These can then, as in Fig. 2 indicated to be arranged one below the other. However, it is also possible to arrange the printhead modules 102 next to one another. Each printhead module 102 includes at least one printhead, not shown here. This usually has one or more rows of nozzles, which can apply printer ink with special properties to the container 110, for example with the aid of a drop-on-demand printing method. Other printing processes can also be used here. For this purpose, these nozzle rows have a plurality of nozzles which can apply the ink to the container wall of the container 110 with very high accuracy. Typical accuracies range from a few hundredths of a millimeter to a few tenths of a millimeter, depending on the intended use. Coarser accuracies are also possible. However, in order to achieve a high printing accuracy with the aid of the print heads or the print head of the print head module 102, a correspondingly precise alignment of the print head and thus of the print head module 102 with respect to the container 110 is necessary.

For this purpose, a correspondingly precise position measurement of the printhead module 102 or the printhead is necessary, on the one hand, and, on the other hand, a correspondingly precise control of the printhead module 102 to adjust its position. For this purpose, the printing unit 120 comprises a measuring system 204. This measuring system 204 can be designed in a variety of ways. For example, it can use optical sensors to determine its position and thus the position of the printhead module 102 relative to the container 110 or the conveyor. Magnetic or capacitive measuring principles can also be used. It can also be provided that the measuring system determines its position on the basis of its own position on rails or similar devices provided for this purpose, and compares it with reference data stored in a system memory, which is not shown here, an embodiment of the measuring system 204 using magnetic or capacitive Measuring devices over optical is advantageous. This is particularly advantageous if the containers 110 are fed to the printing press with very high accuracy. Deviations in the positioning of the printheads of the printhead module 102 in relation to the container 110 then arise due to incorrect positions of the printhead or printhead or printhead module 102. It is provided that a corresponding control unit, which is not shown here, contains the data from the measuring system 204 can process in a suitable manner and the control of a travel system which is provided in the printing unit 120 positions the print head module 102 accordingly.

For this purpose, the traversing system can have three modules, a radial module 205, a height module 206 and a tilting module 207. The radial module is designed such that it can set a distance of the print head module 102 from the container 110. There is one like in Fig. 2a shown horizontally arranged rail provided. A corresponding motor, for example a motor-spindle-nut drive, can set the distance of the printhead module 102 from the container wall 110 in accordance with the instructions of the control unit.

In order to achieve a complete and correct printing of the container 110, the height module 206 can bring about a height adjustment of a print head module 102. For this purpose, it is preferably also equipped with a motor-spindle-nut drive and allows the print head module 102 or a corresponding extension 262 to be moved along a vertical axis.

The tilting module 207 is constructed similarly and advantageously also includes a motor-spindle-nut drive. However, it acts on the printhead module 102 in such a way that it can be tilted with respect to the outer wall of the container 110. Is in Fig. 2b to recognize. Here is a printhead module 102 on a side bevel of a container 110 along. The tilting of the printhead module 102 is achieved by the tilt module 207. For this purpose, it is provided that the tilting module 207 comprises a tilting rod 271 or other connection, which is arranged offset to a pivot point 272 on the printhead module 102. Moving this tilting rod 271 correspondingly rotates the push-button module 102 about the pivot point 272. Other designs are also conceivable here.

Since inaccuracies in the positioning of the printhead module 102 in relation to the container 110 can occur, in particular due to an unintentional change in the position of the printhead module 102 due to the continued running of the motor-spindle-nut drives, which may be constantly supplied with current, or more generally the motors of the individual modules preferred that these modules have clamps 251, 252 and 253 on the corresponding moving parts. These clamps enable the printhead module 102 to be fixed in the position specified by the control unit. This is not only advantageous if one of the print head modules 102 has carried out the setting according to the data specified by the control unit and a further movement of this module is not necessary, but in particular if, for example, the height module 206 is to carry out a height adjustment of the print head module 102, the tilting module 207, however, should not cause additional tilting.

Preferably, there is no movement of the printhead module 102 during the printing process. Corresponding movements of the print head module 102 by means of at least one of the modules 205, 206, 207 are therefore preferably carried out before the printing process to adjust the position of each print head module. However, since the printhead module 102 can also move at very high speeds in order to ensure a higher throughput in the printing press, high accelerations occur which can lead to unintentional tilting and / or displacements of the printhead module 102. The provision of corresponding clamps 251, 252 and 253 can therefore support fixing of the printhead module 102 with regard to either a change in position by the radial module 205, a change in position by the height module 206 or a change in position by the tilting module 207. For this purpose, the jams can be mechanically designed in the form of brake shoes or clamping shoes, but can also be provided electromagnetically.

Furthermore, each printing unit 120 advantageously has at least one ink tank 225 assigned to it, in which the ink that is to be applied to the containers 110 is held. In addition, each printing unit 120 advantageously has at least one a means for centering and / or clamping / fastening (for example a clamping / or centering system such as a zero point clamping element) 211 of the printing unit 120. Since it can be advantageous if the entire printing unit 120 can be exchanged with the ink tank 225, this can also be corresponding means for centering and / or clamping / fastening 211 for attachment to other stationary machine parts 230 of the printing press. The means for centering the printing unit 120 can be designed such that they can be attached to the ink tank 225. However, the printing unit can also be centered directly on further machine parts 230 of the printing press. Thus, even after replacement of a corresponding printing unit 120, it is ensured that it can be reintroduced into a predetermined position with very high accuracy.

Although not shown here, the row of nozzles or rows of nozzles of a print head of a print head module 102 can be tilted with respect to the transport direction of the containers 110 to be printed. This is a tilt that cannot be compensated for by the tilt module 207. The tilt module 207 acts accordingly Fig. 2b tilting of the print head module 102 such that the print head module 102 runs as parallel as possible to the surface of the container 110 to be printed. The rows of nozzles can, however, be tilted perpendicular to it, that is to say in the transport direction of the container to be printed. This malposition cannot be compensated for by the tilting module. In order to compensate for this tilting, an alignment module is additionally provided which ensures a vertical alignment of the rows of nozzles of the printhead module 102 with respect to the direction of transport of the containers 110 to be printed. All in all, this makes it possible to adjust the print head module and, in particular, the nozzle rows with respect to each degree of freedom of movement.

Although the radial module 205, the height module 206 and the tilt module 207 have been described here as being suitable for changing the position of the print head module 102, corresponding assemblies can also be provided in order to enable the position of an individual print head to be changed separately. It is particularly advantageous if the measuring system 204 can measure the position of the print head module 102 and / or the print head with an accuracy of less than 0.5 mm, preferably less than 0.1 mm, particularly preferably less than 0.01 mm Corresponding data can be passed on to the control unit, which in turn can adjust the position of the print head and / or the print head module 102 with a corresponding accuracy.

The in the 2a and 2b shown embodiment with the help of the radial module, the height module and the tilt module is basically suitable for positioning the print head module to reach. However, in order to be able to carry out an even finer adjustment of the print head position, it can be provided that each individual print head module 102 according to FIG Fig. 2c additionally connected to the printing unit 120 via a holder 280. In the 2a and 2b The described attachment of the modules, ie the radial module 205, the height module 206 and the tilting module 207, can then be carried out on this holder 280. The printhead module 102 is then preferably attached to this holder via piezo elements 281, 282 (as in FIG Fig. 2d shown) and 283 attached (as in Fig. 2c shown). These piezo elements can be used to position the print head module 102 in the X direction and Y direction shown Fig. 2c and Z direction according to Fig. 2d with respect to the container 110 to be printed, which in this example defines the Y axis, can be carried out with very high accuracy. On the one hand, this allows the printhead module 102 to be positioned very precisely, even without loosening the clamps 251, 252 and 253, which is particularly advantageous in the case of necessary changes in position that are clearly below one millimeter. Furthermore, the use of the piezo elements 281, 282 and 283 allows, due to the quick response of the piezo elements, a fine adjustment of the positioning of the print head modules 102 even during the operation of the device.

This fine adjustment can advantageously be carried out even for each container to be printed and can be achieved, for example, using sensors that determine the position of the container very precisely or register and evaluate the print image that was generated with the aid of the previous print head module. For example, it can be provided that each print head module, for example with the aid of UV ink, attaches markings to a container, which can be registered and evaluated by a correspondingly provided sensor, so that the control unit, depending on the position of the print image, relative to the sensor Fine adjustment of the next printhead module using the piezo elements. Such sensors are preferably between two printhead modules 102, as shown, for example, in FIG Fig. 1 are attached, so that a fine adjustment of a printhead module can take place depending on the information of the position marking, which was applied by the previous printhead module to the container to be printed.

In connection with the configuration of the fine adjustment, it should be mentioned here that when using linear machines for positioning or fine adjustment with the aid of a piezo element in the Z direction, as in FIG Fig. 2c can be dispensed with, provided that the containers to be printed are transported within the linear conveyor with sufficiently precise positioning by the linear conveyor in relation to the Z direction.

Fig. 3 shows a possible embodiment of the replacement or removal of a printing unit 120. In order to make this possible, it can be provided that in addition to the centerings 211 which are shown in FIG Fig. 2 an axis of rotation 350 is provided which enables the printing unit 120 'to be unscrewed from its starting position (shown here in dashed lines) into a transport position which is indicated by the printing unit 120. The printing unit 120 to be exchanged can then be removed by separation from the axis of rotation 350. A quick and flexible expansion of a printing unit 120 is thus possible. To install a new printing unit 120, the same procedure is carried out in the reverse order. The printing unit 120 is brought into the position shown and connected to the axis of rotation 350. It is then guided through the axis of rotation 350, rotated to the centering means 211 and thus connected to the printing press at a specific position. In addition, the transport position enables appropriate access and the possible exchange / removal / maintenance of certain individual parts of the printing unit 120.

In addition to the alignment of the printhead modules 102 by means of the radial module 205, the height module 206 and the tilting module 207, further movements can also be provided, for example for the maintenance of the printhead module 102 or for protecting the rows of nozzles or for cleaning. For example, modules 205, 206, 207 can be used to move printhead module 102 to a protective position when not in use. For this purpose, the printhead module can be tilted, for example, by 90 ° and moved away from the containers in the radial direction, so that it can no longer be used for printing on containers and to avoid damage to the nozzle rows due to accidental contact with containers and the nozzle rows and especially to protect the ink from drying out or from foreign particles such as dust. For this purpose, it is particularly advantageous if the protective position is provided in an area shielded from light. It is also advantageous if the rows of nozzles point towards the ground so that any ink drops can drip off and thus do not impair the rows of nozzles. In an appropriate position or another position, the (automatic) cleaning of the printhead module 102 and in particular the rows of nozzles can also take place. It can advantageously be provided here that a cleaning unit starts the automatic cleaning of the rows of nozzles and / or the print head module 102 as soon as the print head module 102 is in the corresponding position. This offers a considerable advantage over removing the printhead module for cleaning purposes, since neither cleaning outside of the printing machine (100) is necessary, nor is it necessary to readjust the position of the printhead module 102 after reinstallation. The printhead module can also be serviced in such a position. If maintenance is automatic the maintenance position can be identical to the protective position. If it is done manually, it can be advantageous if the maintenance position is provided at a location on the machine that is easy to reach for an operator.

Claims (14)

1. Printing machine (100) for printing onto containers(110), such as bottles, comprising at least one conveyor (101) and at least one printing unit (120) with a print head module (102), with at least one print head, a movement system for adjusting the position of said print head module (102), a measuring system (204) for determining the position of said print head module (102) and a control unit for controlling said movement system, where said movement system comprises a radial module (205) for adjusting the position of said print head module (102) in the radial direction, a height module (206) for adjusting the height of said print head module (102) in the vertical direction, characterized in that said movement system further comprises an alignment module for vertical alignment of nozzle rows of said print head module (102) relative to the direction of transport of said containers (110) to be printed.
2. Printing machine (100) according to claim 1, characterized in that it further comprises a tilting module (207) for adjusting the tilting of said print head module (102).
3. Printing machine (100) according to claim 2, characterized in that said radial module (205), said height module (206) and said tilting module (207) are adjustable independently of each other.
4. Printing machine (100) according to one of the claims 2 to 3, characterized in that said radial module (205), said height module (206) and said tilting module (207) each comprise a motor (109), preferably a motor-spindle-nut drive.
5. Printing machine (100) according to one of the claims 1 through 4, characterized in that said printing unit (120) comprises a device for centering (211) said printing unit (120) at said printing machine (100).
6. Printing machine (100) according to one of the claims 1 through 5, characterized in that said measuring system (204) can measure the position of said print head module (102) with an accuracy of less than 0.5 mm, preferably of less than 0.1 mm, particularly preferably of less than 0.01 mm.
7. Printing machine (100) according to one of the claims 1 through 6, characterized in that said print head modules (102) are provided exchangeably.
8. Printing machine (100) according to one of the claims 1 through 7, characterized in that said control unit can adjust the position of said print head module (102) with an accuracy of 0.5 mm, preferably of 0.1 mm, particularly preferably of 0.01 mm.
9. Printing machine (100) according to one of the claims 1 through 8, characterized in that said printing unit (120) is associated via a line to an ink tank (225) connected to it.
10. Printing machine (100) according to one of the claims 1 through 9, characterized in that said control unit can adjust the position of said print head module (102) in dependency of the data that can be transmitted from said measuring system (204) to said control unit.
11. Printing machine (100) according to one of the claims 2 through 10, characterized in that said radial module (205), said height module (206), and said tilting module (207) comprise clamps which can fix said radial module (205), said height module (206) and said tilting module (207) in a position.
12. Printing machine (100) according to one of the claims 1 through 11, characterized in that piezo-electric elements (281, 282, 283) are provided associated to a print head module (102) and are adapted to align said print head module (102) relative to said container (102) to be printed.
13. Printing machine (100) according to one of the claims 1 through 13, characterized in that a protective position and/or a cleaning position and/or a servicing position are provided into which said print head module (102) can be moved.
14. Printing machine (100) according to claim 13, characterized in that a cleaning unit is provided which is adapted to clean said print head module (102) when it is located in said cleaning position.

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