ES2768283T3 - Printing equipment, printing machine and procedure for the operation of a printing equipment - Google Patents

Abstract

Printing machine with a machine frame on which a round workpiece table (3) is rotatably mounted, with a drive unit associated with the round workpiece table (3) for rotary positioning of the round workpiece table (3), which in particular can be freely predetermined, as well as with workpiece housings (4) for housing the objects (6) to be printed, with the piece housings protruding from work (4) in the radial direction from the round workpiece table (3) and each being rotatably mounted on the round workpiece table (3), as well as with drive means for the workpiece housings workpiece (4) and with at least one printing equipment (21, 32, 33; 50) movably mounted in particular in at least one spatial direction in relation to the round workpiece table (3), being configured the printing equipment (21, 32 , 33; 50) to print on a perimeter surface of the object (6), and comprising at least two print heads (22, 23; 51, 52, 53) to print a perimeter surface of the object (6), each having at least one arrangement in a row of ink dosing elements (31), in particular ink nozzles, each of which are configured for an individually presettable discharge of ink on the object (6), at least one of the print heads (22, 23; 51, 52, 53) movably along an extension axis (30) of the ink dosing elements (31) in a print head holder (21, 32, 33; 50) and an electrically controllable adjusting device (34, 35; 57, 58, 59) being associated with the print head (22, 23; 51, 52, 53) movably mounted for adjusting a relative position with respect to the at least one other print head (22, 23; 51, 52, 53), characterized in that the printing equipment The ion is configured to carry out the method according to one of claims 11 to 13.

Description

DESCRIPTION

Printing equipment, printing machine and method for operating printing equipment The invention relates to a printing machine with printing equipment for printing on a perimeter surface of an object, with at least two printing heads having in each case at least one row arrangement of ink metering elements, in particular ink nozzles, which are in each case configured for an individually presettable discharge of ink into the object. Furthermore, the invention relates to a method for operating a printing machine with printing equipment.

From US 7, 467, 847 B2, a printing equipment for printing on the surface of a three-dimensional object is known which comprises an ink jet printing system with several individual print heads arranged contiguously at a fixed distance from each other in the circumferential direction, which can be moved along an axis of rotation for the object to be printed during the printing operation, to allow helical printing of the object, being a division between adjacent nozzles of The individual print heads are greater than the resolution of the print image to be applied to the object, and the desired resolution is achieved by helical printing of the object.

EP 2471 665 A1 discloses a marking and / or scanning head with a plurality of housing spaces in which individual marking and / or scanning equipment can be arranged to mark and / or scan an object, the housing spaces being arranged in at least two submodules, at least one submodule being movable and / or rotatable relative to at least one other submodule, the marking and / or scanning head further presenting a holding frame, the at least two submodules being arranged in a frame of common assembly that is mobile and / or rotatable in relation to the support frame, the submodules being able to rotate in each case about an axis of rotation that passes through the center of the corresponding submodule, and the accommodation spaces of each submodule being arranged in a plurality of rows and columns, such that a two-dimensional set of accommodation spaces is formed.

US 2011/084995 A1 discloses an inkjet printing method comprising the following steps: performing a print job within a print area using two or more print units, the print units being designated as active; determining one of the printing units as a no-load printing unit; moving the print unit without load from the print area to a maintenance area; movement of a previously determined no-load printing unit from the maintenance area to the printing area; determination of the aforementioned no-load printing unit as active; and continuing to perform the print job using two or more print units currently determined to be active.

From WO 2014/076704 A1 a printing machine is known for printing on cylindrical hollow bodies in which an ink jet printing method is used and in which a cleaning arrangement is mounted in front of a print head. inkjet printer that is configured to clean the inkjet print head.

Document CH 695555 A5 discloses a printing machine for three-dimensional printing objects, with a printing equipment for applying at least one ink to a printing object and with a drying equipment for drying the ink, the printing equipment presenting one or more print heads and the print heads and drying equipment being arranged such that drying of the ink from a print image can take place before completion.

The object of the invention is to provide a printing machine as well as a method for operating a printing machine with printing equipment with which particularly efficient high-resolution printing on an object is possible.

This object is achieved according to a first aspect of the invention for a printing equipment of the type mentioned at the beginning with the characteristics of claim 1. In this sense, it is provided that the printing equipment of the printing machine is configured to carrying out the method according to one of claims 11 to 13.

In this regard, it is assumed that the print head has several ink metering elements arranged along an extension axis, each of the ink metering elements being configured for an individual discharge of ink particles or drops of ink, in particular drops of ink. Preferably, the ink metering elements are arranged with a constant division along the extension axis, such that the adjacent ink metering elements in each case have a constant distance from each other. The ink metering elements arranged along the extension axis form a print line, a print head may be equipped with one or alternatively several print lines, several print lines being arranged preferably in parallel and at the same distance each other in each case. With the help of electrically controllable adjusting equipment, which can be, for example, a direct linear electric drive, an electric spindle drive, or a belt or cable drive, relative movement of a first print head relative to with a second print head. This relative movement can influence the position of the ink metering elements of the first print head along the extension axis relative to the ink metering elements of the second print head. For example, provision can be made for the ink metering elements of the first print head to be offset relative to the axis of extension relative to the ink metering elements of the second print head by an amount corresponding to 50 percent of the division of the ink dosing elements. If the two print heads are properly controlled, a print image is thus generated on the perimeter surface of the object to be printed whose resolution along the axis of extension is twice the division for the ink from the two print heads along the extension axis.

Furthermore, by changing the relative position of the first print head with respect to the second print head, an adaptation of the position of the ink dosing elements for printing to print tracks having different gradients can be obtained due to different printing requirements. resolution of the print image to be generated and / or due to the different diameters of the objects to be printed. When applying a helical print track to the object, the gradient for the helical print track must be adapted based on the desired resolution for the print image to be generated and depending on the diameter of the object, which can be ensured by adjusting the relative position of the print heads by relative movement to one another along the extension axis.

By means of the electrically controlled adjusting equipment, a change in the resolution of the printed image along the extension axis can also be provided in addition or alternatively, also during the performance of a printing operation, which is of interest, for example, if partial areas of the printed image should be generated at a higher resolution than other areas of the printed image. For carrying out the printing operation, provision is made for the object to be printed to move relative to the printing equipment which is aligned at least essentially, in particular exactly, transversely to the axis of extension of the printing elements. ink dosage. This relative movement of the object with respect to the printing equipment can be, in particular, a pure translation movement, a pure rotation movement or an overlap of a translation movement and a rotation movement. Helical printing of the object is preferably provided, which can optionally be performed by a translational movement, in particular synchronous movement, of the print heads along the extension axis with exclusive rotation of the object or by a rotational and translational movement superimposed on the object with respect to the stationary print heads or by a combination of a rotational and translational movement superimposed on the object with a translational movement, in particular synchronous, of the print heads along the axis of extension. In this regard, provision can be made for the relative position of the print heads along the extension axis to be adjusted as a function of the resolution to be achieved and / or the diameter of the object before the printing operation is carried out and is held during the printing operation.

Advantageous refinements of the invention are the subject of the dependent claims.

It is useful if the at least one other print head, in particular all other print heads, are connected to electrically controlled adjusting equipment and are arranged movably along the axis of extension of the ink metering elements in the print head support. In this way, each of the print heads, in particular also during the performance of a print operation for an object, can be adjusted with respect to their positioning along the axis of extension of the ink dosing elements. If, for example, the print image to be generated presents on the perimeter surface of the object to be printed a print area with a small extension and high image resolution along the extension axis and surrounding print areas with a greater extension and lower image resolution along the axis of extension, the print heads for generating the high resolution print area can be envisioned to adopt a relative positioning relative to each other that differs from a relative positioning of the printing heads to generate the low resolution print areas.

In an advantageous further development of the invention, provision is made for the print heads to be aligned parallel to one another and to be arranged directly adjacent, in particular contiguously and in sliding motion, transversely to the axis of extension of the ink dosing elements. This makes it possible to obtain a compact arrangement of the recording heads, which is advantageous, in particular, when printing on objects with rotationally symmetry, at least essentially, in particular on circular cylindrical objects such as, for example, the blank parts of aerosols, otherwise, depending on the sizing of the objects to be printed, it would be difficult to maintain a preset distance between the print heads and the object. Preferably, the ink metering elements located in a row of the adjacent print heads are in each case aligned parallel to each other and arranged at a fixed distance from each other transversely to the axis of extension, in particular with respect to a circumferential direction of the object that must be printed. If necessary, provision can also be made for adjusting a distance between the print heads transversely to the extension axis by means of suitable adjusting agents.

In addition or alternatively, provision can be made for at least one print head rotatably mounted about a pivot axis, the pivot axis preferably being aligned parallel to the extension axis, such that the impact direction for the ink particles , in particular ink drops, discharged by the print head can be adjusted to the outer surface of the object. This is of special interest when objects with very different diameters must be printed with the same printing equipment.

In another design of the invention it is provided that the print heads can be adjusted by means of the at least one adjusting device between a first functional position, in which the ink metering elements of adjacent print heads are arranged without overlapping transversely to the axis of extension, and a second functional position, in which an overlap of ink dosing elements of printing heads adjacent transverse to the axis of extension occurs. This allows an advantageous adaptation of the resolution of the printing equipment with respect to the extension axis to the corresponding need. In the first functional position, it is provided that the ink dosing elements of adjacent printing heads, in particular of all of them, are on parallel lines, the parallel lines being aligned transversely to the axis of extension and corresponding a distance between the parallel lines in each case to the division of the ink dosing elements. In this regard, it is preferably provided that no ink metering elements of adjacent print heads are arranged on any of the parallel lines. With this setting, the resolution to be achieved along the extension axis corresponds exactly to the division of the ink dosing elements and can be printed at a maximum print length, at least in the case that each surface area of the object to be printed is only swept once by the print heads. On the other hand, in the second functional position it is provided that there is at least a partial overlap between adjacent print heads with respect to the extension axis, by means of which a higher resolution can be guaranteed for the printing image that comes from it. given by the division of the adjacent ink metering elements with respect to the axis of extension. In this regard, at least a part of the ink metering elements of the first print head are located on the same parallel lines as at least a part of the ink metering elements of the second print head. This allows, for example, a higher print resolution along the axis of extension in the overlap area of adjacent printheads than in areas without overlap. This is particularly true if each surface area of the object to be printed is only swept once by the print heads.

At least one print head preferably comprises at least two rows of ink metering elements aligned parallel to the extension axis, configured in particular in the form of ink nozzles. Preferably, the at least two rows of ink metering elements along the extension axis have the same division for the ink metering elements. If necessary, the ink metering elements of adjacent rows are arranged offset from each other by a predetermined amount, in particular by a fraction of the corresponding division, relative to the axis of extension. In particular, provision may be made for adjacent rows of ink metering elements to be provided for discharge of different colors, in particular cyan, magenta and yellow . As a result, the respective print head can generate the entire associated image section of the print image during a printing operation, producing a predictable mix of colors that are discharged by the different ink dosing elements depending on the procedure of Printing applied, particularly when using the ink jet printing procedure.

It is advantageous that the ink metering elements are arranged in a predetermined division along the extension axis and that the adjusting equipment is configured to position the print head with a positioning accuracy that is lower, preferably 50 percent lower, preferably lower 25 percent, particularly preferably lower 10 percent, in particular lower two percent, of the division of the ink metering elements along the extension axis. With such positioning precision for the adjusting equipment, the respective print head can be reproducibly arranged relative to the adjacent print heads, for example, to allow different resolutions and different print speeds for printing the object during performing a printing operation. By way of example, provision is made for the setting equipment to have a positioning accuracy of less than 5 microns and for a division of the ink metering elements to be in the range of 0.25 millimeters.

It is useful if at least two groups of print heads mounted so that they are relatively mobile relative to each other are associated with the print head support, each group of print heads comprising at least one, in particular two print heads. With the help of at least two groups of print heads, the perimeter surface of an object can optionally be printed within the framework of a single rotation or, optionally, only a partial rotation with high resolution in the circumferential direction and / or along the extension axis, the two groups of printing heads being arranged at least partially overlapping each other. Alternatively, it may be provided to print on the perimeter surface of the object within the framework of several rotations, providing for this purpose no overlap, or only a small one, of the groups of print heads with each other and adjusting the print heads of the Adjacent groups of print heads depending on the desired inclination of the print track. Preferably, it is assumed that the respective groups of print heads are configured in each case for the download of a single color.

It is advantageous that a drying station arranged opposite the print heads is associated with the print head support to allow, after the application of the ink, the drying of the applied ink. With the help of the drying station, a curing process is carried out for the ink particles or ink drops discharged by the ink dosing elements onto the surface of the object to be printed. Such a drying or curing operation is particularly advantageous if the object is an object with at least essentially rotational symmetry that rotates during the printing operation about an axis of rotation that is aligned at least essentially parallel to the axis of extension of print heads. In this case, the surface area to be printed on the object first passes through the print heads and then passes through the drying station while still rotating, so that, ideally, the printing operation of the object can be fully completed in approximately 200 degrees of rotation about the axis of rotation.

In a further development of the invention, provision is made for the drying station to be coupled to a cleaning station for the print heads and to be mounted on the print head holder relatively movably, so that it is optionally possible to dry the applying ink to objects or cleaning the print heads. The task of the cleaning station may optionally be to perform cleaning of the print heads in mechanical contact with the print heads or to collect and bind the ink particles or ink drops discharged during in the framework of a cleaning operation of the ink dosing elements. Cleaning of the print head or heads can be envisaged if corresponding printing errors are detected on the printed objects by suitable sensors or if a number of printing operations have been carried out. The cleaning station is preferably configured such that the print head to be cleaned is sealed in an edge area, and then that the ink particles, in particular the ink droplets, are discharged from the print head. Impression in the direction of the cleaning station in the free jet can be collected and evacuated.

In accordance with the invention, the printing machine comprises a machine frame on which a workpiece round table is movably rotatably mounted, as well as a drive unit associated with the workpiece round table, in particular , for a rotational, in particular freely determinable, positioning of the round workpiece table, as well as workpiece housings for the accommodation of objects to be printed, the workpiece housings protruding in the radial direction of the workpiece round table and in each case being movably rotatably mounted on the workpiece round table, as well as drive means for the workpiece housings and at least one pressure equipment movably mounted with relative to the workpiece round table, particularly in at least one spatial direction. An axis of rotation of the round workpiece table is preferably aligned in the vertical direction such that the workpiece housings extend at least in an essentially horizontal direction.

In this way, the at least one printing equipment can be arranged on the frame of the machine in such a way that the ink is discharged from the print heads onto the object essentially in the vertical direction, in particular downwards. This use of gravity to carry out the printing operation favors an advantageous printing result. The drive unit associated with the round workpiece table is preferably configured such that it allows freely selectable positioning of the workpiece housings. This allows, for example, to adopt an intermediate position to carry out a cleaning operation of the print heads, in which the workpiece housings are positioned between two adjacent work stations, in particular printing units. In such an intermediate position, unwanted contamination of the objects to be printed during the cleaning operation is avoided.

In a further development of the printing machine, provision is made for the workpiece housings to be configured as spindles for housing bush-shaped objects and / or for each spindle to be associated with its own drive equipment to initiate a movement of freely predetermined rotation relative to the workpiece round table and / or that the workpiece housings are configured with heating equipment to heat the objects housed therein. The printing machine is preferably intended for printing raw aerosol cans or tubular blanks and therefore has bar-shaped workpiece housings, which are also referred to as spindles. It is advantageous that each spindle is assigned its own drive equipment to allow, if necessary, a regulation of the rotational movement of the object to be printed depending on the requirements of the print image and the relative positioning of the print heads to each other. If the print heads are configured as ink jet print heads that are configured to discharge ink droplets onto the perimeter surface of the object during the performance of the printing operation, it is advantageous that the object can be heated during the print operation. printing, or at least shortly thereafter, to speed up the curing of the ink drops.

The object of the invention is solved according to a second aspect with a method according to claim 11. This method is used for the operation of a printing equipment comprising several print heads aligned parallel to each other and relatively electrically mobile relative to each other, being associated with at least one of the print heads an adjustment equipment to initiate a relative movement with with respect to at least one other print head and at least one workpiece housing being provided to accommodate a rotary moving object to be printed on its perimeter surface, with the steps: location of an object in the part housing work, performing a relative movement between at least two print heads to influence the axial resolution of a print image to be applied on the perimeter surface, rotation of the object by housing the workpiece around an axis of rotation that is aligned parallel to an axis of extension of the ink dosing elements of the print heads such that the perimeter surface passes through the print heads, discharging ink onto the perimeter surface of the object by means of a default control of ink dispensing elements. For carrying out the process, provision can be made that the relative positions of at least two print heads along the extension axis relative to each other can be adjusted as a function of the resolutions to be achieved for the print image in the circumferential direction and in the direction of the extension axis. In addition, a diameter of the object to be printed can be included in determining and adjusting the relative positioning of the print heads relative to each other. The discharge rate of the ink metering elements from the print heads is also selected depending on the resolution to be achieved and the diameter of the object. In addition, additional electrical adjusting agents may be provided for automated, in particular synchronous, movement of the print heads, which are configured to maintain a constant distance between the print heads and the perimeter surface of the object. An advantageous distance between the print head and the perimeter surface is in a range of less than 5mm, preferably less than 3mm, in particular less than 2mm. Furthermore, additional electrical adjusting agents may be provided for pivoting, in particular synchronous, movement of the print heads about a pivoting axis, the pivoting axis being aligned at least essentially normal to the axis of rotation of the objects. With such a pivoting motion, an additional degree of freedom can be adjusted to influence the resolution of the print image to be generated by the print heads.

In a process design, provision is made for synchronous movement of the print heads along the axis of rotation by means of adjusting equipment during object rotation and / or for relative movement of the heads of printing parallel to the axis of extension by means of the adjustment equipment during the rotation of the object to carry out compensation for printing errors. By means of synchronous movement, a helical track of printing points can be generated on the perimeter surface of the object by means of the respective ink dosing elements, preferably providing a proportional, in particular constant, relationship between the rotation movement of the object around its axis of rotation and the movement of the print heads along the axis of extension. If printing errors occur which are identified in real time during the execution of the printing operation or by subsequent inspection of a printed object, provision may be made to adjust the print heads to one another during the printing operation or at least during a subsequent printing operation to compensate at least as much as possible for failures of individual ink metering elements, in particular ink nozzles, in the individual print heads.

In accordance with the invention, provision is made for a rotational speed of the workpiece housing to be detected and a discharge rate for an ink discharge by means of the dosing elements to be adapted to the detected rotational speed.

Another aspect of the invention not claimed relates to a printing machine with a machine frame in which a round workpiece table is movably rotatably housed, with a drive unit associated with the round workpiece table. for a preset rotary positioning of the round workpiece table, as well as workpiece housings for accommodating objects to be printed, the workpiece housings being in each case rotatably movable on the table round workpiece, as well as with drive means for the workpiece housings and with at least one printing equipment, in particular according to one of claims 1 to 9, and with a cleaning station which is arranged at least temporarily located opposite the printing equipment. The drive unit for the round workpiece table is configured, as in the other claimed embodiments of the printing machine, to allow rotary stage movement of the round workpiece table comprising a sequence of rotation stages and stop phases. In this regard, the stages of rotation during a printing phase of the objects to be printed are dimensioned such that the objects housed in the workpiece housings are arranged in consecutive stages of rotation of the workpiece round table , which in particular are always carried out with the same angular division, in each case opposite to the workstations arranged adjacent to each other, in order to be properly processed, in particular to be printed on printing equipment . To allow cleaning of the printing equipment, provision can be made for the drive means for the round workpiece table to advance to an intermediate position where the objects housed in the workpiece housings are not arranged opposite to the work stations. Preferably, a rotation stage for such an intermediate position is half the angular division of a usual rotation stage during the performance of the printing operation. As the workpiece housings and the objects housed therein are not arranged in front of the workstations, in particular a relative movement of the cleaning station can be carried out in the direction of the corresponding printing equipment. This relative movement serves, for example, to bring the cleaning station closer to the printing equipment by means of a translational movement parallel to a rotational axis of the workpiece round table so that a sealing contact can be achieved between the cleaning station and the print heads of the printing equipment. In this way, the corresponding print head can be cleaned by specifically discharging ink particles, in particular ink drops, or, if necessary, being run through with a solvent. In this regard, it is foreseen that the ink particles or the solvent are collected and evacuated by the cleaning station. In addition or alternatively, provision can be made for the cleaning station to be configured for the discharge of solvent onto the print heads to effect the dissolution of the ink particles, in particular the ink droplets, which adhere to the print heads. After the cleaning operation is complete, the cleaning station is transferred to a position where additional movement without collision of the objects housed in the workpiece housings can be carried out by a movement of rotating stages until reaching the next workstation, in order to resume the usual processing sequence for objects.

An advantageous embodiment of the invention is shown in the drawing. In this sense, it shows:

Figure 1 a schematic top view of a printing machine with a rotary movable housed workpiece round table and various work stations for printing and inspecting cylindrical objects;

Figure 1a a fragment enlargement of the printing machine according to figure 1 in an intermediate position for the workpiece round table,

Figure 2 a schematic front view of a printing machine workstation configured as a printing station,

Figure 3 a schematic bottom view of the printing station according to figure 2 in a first functional position,

Figure 4 a schematic representation of a nozzle arrangement of the printing station according to figure 3,

Figure 5 a schematic view from below of the printing station according to figure 2 in a second functional position,

Figure 6 a schematic representation of the nozzle arrangement of the printing station according to figure 5,

FIG. 7 a schematic bottom view of the printing station according to FIG. 2 in a third functional position,

Figure 8 a schematic representation of the nozzle arrangement of the printing station according to figure 7

Figure 9 a schematic representation of a printing station and an oppositely arranged functional assembly, comprising a drying station and a cleaning station, in a first functional position,

Figure 10, the functional assembly in a second functional position,

FIG. 11 another embodiment of a printing station equipped for multi-color printing, and FIG. 12 a second embodiment of a functional assembly.

A printing machine 1 depicted in FIG. 1 comprises a round workpiece table 3 rotatably mounted about a axis of rotation 2 on a machine frame not shown in more detail, and various workpiece housings of work 4 mounted in each case in pairs on the round table of the workpiece as an example. The workpiece housings 4 are individually rotatably mounted about axes of rotation 5 by means of actuating means not shown, and are intended to accommodate bush-shaped objects 6, configured in particular as raw aerosol cans or at least essentially cylindrical tubular blanks. The workpiece housings 4 are preferably configured as mandrels into which the objects 6 configured as hollow bodies can be fitted, in particular as hollow cylinders closed on one side. In an annular zone 7 which is swept by the workpiece housings 4 during a rotational movement of the round workpiece table 3 about the axis of rotation 2 and which extends in the radial direction around the table round work piece 3, several work stations 8 to 18 are arranged which are configured to machine and / or inspect the transported objects 6. Since the view shown in accordance with figure 1 is a plan view and given While workstations 9 to 17 are generally arranged vertically above workpiece housings 4, workstations 9 to 17 are shown with dashed lines only.

The work station 8 is a loading station in which the cylindrical objects 6 are pushed by way of example in pairs on the workpiece housings 4 by means of a suitable transport equipment 19, which is coupled with a system of transport for cylindrical objects 6 and not shown in detail.

For example, the rotary position of the cylindrical objects 6 is determined at the workstation 9 by a first optical scan of the cylindrical objects 6, for example, to ensure correct rotational alignment of the cylindrical objects 6 for a printing operation that it is carried out at the workstation 10. This is particularly important if the surface of the objects to be printed is provided with characteristics that must adapt to the print image to be applied in a predetermined manner. These characteristics They can be, for example, local embossing on the surface of the object 6 and / or preprinted areas that in turn serve as a primer for subsequent printing. Preferably, it may be provided to print on a partially or fully shaped object, in particular with prints and / or reliefs, in such a way that an alignment of the printed image with respect to the deformed areas is carried out and not, as hitherto known by the practice, that a deformation of the objects is carried out on the basis of a previously applied printed image. Preferably, provision is made to print a crude aerosol can shaped with impressions and / or reliefs locally or on its entire perimeter surface, the raw aerosol can being able to be coated with a protective lacquer, in particular a transparent lacquer, in the areas printed afterwards. of the impression and thus be ready to be filled.

The work station 10 comprises, for example, a printing station 21 shown in more detail in Figures 2, 3, 5 and 7, in which the cylindrical objects 6 are printed in a predetermined area during a rotational movement around to the respective axes of rotation 5 using the print heads 22, 23, as shown in Figures 3, 5 and 7.

The workstation 14 has been configured, for example, as inspection equipment and allows to determine the print quality of the print image applied by the print station 21 to the perimeter surface of the object 6.

The other workstations 11 to 13 and 15 to 17 are used for the subsequent processing of the cylindrical objects 6, for example, for applying a protective lacquer on the print or for mounting components on the objects 6.

At the work station 18 a unloading operation takes place during which the cylindrical objects 6 are extracted from the chuck-shaped workpiece housings 4 with the help of a transport equipment 20 and fed to another transport system which not represented in detail.

For staged processing of the cylindrical objects 6 at the corresponding work stations 8 to 18, the workpiece round table 4 performs a rotary stage movement at angle W at the corresponding work stations 8 to 18, in the that the workpiece housings 4, arranged in pairs in each case, are transported from a position opposite to the corresponding work station 8 to 18 to a position opposite to the respective following work station 8 to 18, the movement of rotating stage as a sequence of acceleration from the stop position, braking from the target speed reached and a subsequent stop time. Preferably, a drive not shown in detail for the workpiece round table 3 is configured such that the acceleration and braking of the workpiece round table 3 can be freely adjusted over wide ranges and the stopping time , completely freely, and can be adapted to the requirements of the processing of the respective cylindrical objects 6 in the work stations 8 to 18. As described in more detail below, the drive of the workpiece round table 3 can controlled in such a way that the workpiece housings 4 come to rest at an intermediate stage, which can be used for cleaning or other maintenance of the workstations 8 to 18, with a rotary movement of the width of W / 2 partition between workstations 8 to 18, as shown schematically in Figure 1a. This is important, for example, for cleaning the printing station 21.

The printing station 21 shown in Figures 2 and 3 comprises, for example, two printing equipment 24, 25 arranged with specular symmetry relative to each other. For reasons of clarity, Figure 3 shows only one of the two cylindrical objects 6 that can be printed with the printing station 21, while Figure 2 shows the two cylindrical objects 6 arranged opposite to the printing station 21 and mounted in such a way rotary.

Each printing equipment 24, 25 comprises, for example, in each case two printing heads 22, 23, each of which has a strip shape and on whose front surface 26, 27 oriented to the cylindrical object 6, is configured to by way of example a row of nozzles 28, 29. Each of the rows of nozzles 28, 29 comprises several ink metering elements preferably arranged with the same division or spacing along an extension axis 30 and configured so as to eg as nozzles 31. Each of the nozzles 31 of the nozzle rows 28, 29, as shown in Figures 4, 6 and 8 in a fragmentary manner, can be individually controlled by way of example and configured to discharge droplets of ink in the embodiment shown.

For example, the two print heads 22 and 23 are configured to discharge a first color, in particular the cyan color. In the shown embodiment, other printing stations 32, 33 are configured for downloading a second or third color, in particular magenta or yellow. Accordingly, a printed image that is not shown in detail can be produced by combining differently colored ink drops that are discharged onto the object 6 at the respective printing stations 21, 32 and 33. In an embodiment not shown, they are provided more than three printing stations to be able to apply a greater number of colors, in particular also white, as a primer that must be applied at least partially for printing, and / or a clearcoat lacquer for printing already made on the object 6.

In one embodiment of a printing station shown in FIG. 11, the respective printing heads are configured to discharge various colors, in particular cyan, magenta, and yellow, such that an object can be printed on a single print operation.

At the printing stations 21, 32, 33, a resolution of a printed image, that is, a minimum distance between the adjacent ink drop center points, can be influenced in different spatial directions in different ways.

For the following explanations, it is assumed that each nozzle 31 of each print head 22, 23 can be controlled with a predetermined frequency and that the ink drops can be discharged onto the perimeter surface of the object 6 with the predetermined frequency. The frequency determines the resolution in the circumferential direction as a function of the speed of rotation of the object 6 about the axis of rotation. A low speed of rotation results in a high resolution in the circumferential direction, a high speed of rotation results in a low resolution in the circumferential direction.

The resolution of the print image in a spatial direction parallel to the axis of rotation 5 is determined relative to a print head 22 or 23 exclusively by dividing the nozzles 31 along the extension axis 30 of the respective print head 22, 23, as long as there is no translational displacement of the respective print head 22, 23 along the axis of rotation 5 during the performance of the printing operation. In this case, an annular application of the ink drops takes place on the perimeter surface of the object 6. If, on the contrary, during the rotational movement of the object 6, during the printing operation, it is foreseen a further translational displacement of the respective print head 22, 23 along the axis of rotation 5, a helical application of the ink drops occurs on the perimeter surface of the object 6, determining a gradient of a helical track that occurs for ink drops the distance between adjacent propellers. This determines the resolution of the print image in the direction along the axis of rotation 5.

This can be used, in particular in the event that the object 6 passes several times through the corresponding print head 22, 23, to considerably increase the resolution along the extension axis 30.

For fast and therefore economical printing, normally only a simple passage of the object 6 is provided by the corresponding printing head, in such a way that a 360-degree impression of a perimeter surface of an object can be made with a 360 degree rotation movement. If you only want to print a part of the perimeter surface, the rotational movement of object 6 can also be less than 360 degrees.

In order to achieve a high-resolution printing image with a printing of the entire perimeter surface of the object 6 with a single rotation of the object 6 about its axis of rotation 5, the corresponding printing equipment 24, 25 is suitably adjusted. To the two printing heads 22, 23 of the respective printing equipment 24, 25 there is associated in each case an electric drive 34, 35, which is electrically connected in each case with a control unit 36. The drive 34, 35 is by way of example an electric motor whose drive shaft, not shown in this case, is connected with a threaded spindle 37, 38 rotatably and stationary mounted with the printing equipment 24, 25 which serves as the print head support. A non-visible lock nut attached to the corresponding print head 22, 23 penetrates the threaded spindle 37, 38 and is configured to convert a rotational movement of the threaded spindle 37, 38 into a translational movement of the corresponding print head 22, 23 The sliding guide surfaces 39, 40, 41 and 42 are provided to guide the corresponding print head 22, 23 in the printing equipment 24, 25, allowing the printing heads 22, 23 to be mounted in the printing equipment 24, 25 sliding and rotation resistant. Control unit 36 is configured for independent control of electrical drives 34, 35 such that the translational position of print heads 22, 23 can be freely adjusted along extension axis 30.

For a printing operation with a simple pass of the perimeter surface of the object 6 through the printing heads 22, 23 and of high resolution in the circumferential direction, as well as in the direction of the extension axis 30, the printing heads are positioned 22, 23 to generate a helical print track, as indicated in figure 2 in object 6 by means of parallel and equidistant lines, by means of drives 34, 35 serving with adjusting agents, such that the nozzles 31 of the adjacent print heads 22, 23 are in each case on the lines parallel and equidistant from each other. Thanks to such adjustment and the synchronized use of the print heads 22, 23, the resolution of the print image can be doubled with a helically running printing operation compared to the use of a single print head 22 or 23. The spacing of the lines depends on the desired resolution, the number of revolutions of the object 6 during the printing operation with respect to the print heads 22, 23 and the diameter of the object 6.

In an unrepresented mode of operation of the printing equipment 24, 25, the printing heads 22, 23 can be arranged offset from each other in half division t and remain immobile during the simple rotation of object 6.

A further increase in resolution can be achieved if the object 6 performs several revolutions with respect to the two print heads 22, 23 and the print heads 22, 23 move synchronously with each other along the extension axis 30 during rotational movement of the object 6 to carry out the printing operation, since in this way a spiral shape is obtained for a track of printing points that are discharged from a nozzle 31 on the perimeter surface of the object 6, in the that the successively generated print tracks of the individual nozzles are applied to the object 6 at a distance from each other essentially less than a division t. Preferably the synchronous displacement of the print heads 22, 23 during the printing operation is selected such that a gradient of the print dot track during one revolution of the object corresponds to a value that corresponds to an integer value per formation of quotient of the division t of the nozzles 31 of a print head 22 or 23 along the extension axis 30. To achieve, in this case, another doubling of the resolution using the two print heads 22, 23 of the respective printing equipment 24, 25, the two printing heads 22, 23 are adjusted with the respective drives 34, 35 by way of example such that they are arranged offset from each other along the track of the printing points of such that they are located on lines parallel and equidistant from each other and that this position of the print heads 22, 23 is also maintained during the operation of the operation d and printing.

Alternatively, provision can be made for the two print heads 22, 23 to move not only synchronously with respect to the extension axis during a print operation, but also to move relative to each other. For example, provision may be made to print the perimeter surface of object 6 at different resolutions. In this regard, for a variation of the resolution, it is possible to provide both the relative position of the printing heads 22, 23 along the extension axis 30, and a change in the speed of rotation of the object 6 and / or of a control frequency for control of the print heads 22, 23. For example, an increase in resolution of the print image in the circumferential direction can be achieved by maintaining the control frequency for control of the print heads 22 , 23, but reducing the rotation speed of the object 6 and / or increasing the control frequency for the control of the printing heads 22, 23 ,.

In another alternative procedure, provision may be made for the printing equipment 24, 25 connected to the control equipment 36 to be configured to compensate for printing errors on the next object to be printed in response to detection by the system Inspection at workstation 14 for printing errors in the generated print image. To this end, provision can be made for the two print heads 22, 23 to be positioned relative to one another in such a way that, with a nozzle 31 of one of the print heads 22, 23, an ink discharge can be carried out to a clogged nozzle 31 of the other print head 22, 23. For this, the intact nozzle 31 need not necessarily be arranged on the same print dot track, in particular a helical track, as the faulty nozzle 31, even a slight displacement less than division t may be acceptable.

Figures 4 and 5 show how to print on an object 6 with high resolution in the direction of the extension axis 30, whose extension along the extension axis 30 is greater than a corresponding extension of the print heads 22, 23. The printing operation begins by way of example with the positioning of the two printing heads 22, 23 in a lower starting position according to figure 3 in which the printing heads 22, 23 are arranged according to the gradient of the planned helical impression taking into account the desired resolution. From this positioning, the print heads 22, 23 move synchronously with each other during the printing operation along the extension axis 30 and the object 6 rotates around the axis of rotation 5 until the entire surface The perimeter of the object 6 has passed through the print heads 22, 23 and has been provided with ink.

In the adjustment of the print heads 22, 23 to each other shown in Figure 7, a helical print of the perimeter surface of the object 6 is provided with a resolution along the extension axis 30 that is greater than the division t of the nozzles 31 in the print heads 22, 23. For this, for example, multiple rotation of the object 6 in relation to the print heads 22, 23 is provided, during which the print heads 22, 23 move synchronously each other along extension axis 30 to generate the desired helical shape for the print tracks. If the last nozzle 31 of the print head 22, arranged by way of example at the bottom, were arranged with the division t with respect to the first nozzle 31 of the print head 23, arranged by way of example at the top, a displacement of the print tracks of the adjacent print heads 22, 23 would take place in the magnitude ds in relation to the desired gradient for the helical print of the object 6. To ensure that all the print tracks of the nozzles 31 of the two print heads 22, 23 lie on parallel lines arranged equidistant from each other at a distance s, the two print heads 22, 23 must move relative to each other by a magnitude dependent on resolution and diameter, such that the magnitude ds disappear. In this way a seamless impression of the perimeter surface of object 6 can be made.

Figures 9 and 10 show an example of a functional assembly 43 arranged opposite to the corresponding printing equipment 24, 25. Functional assembly 43 comprises a cleaning station 44 and a drying station 45, which are mounted by way of example. in a common pivot housing 47 rotatably mounted about a rotation axis 46 aligned perpendicularly to the plane of representation of Figures 9 and 10. Cleaning station 44 is equipped with an absorbent material which is not shown in detail and which it can absorb a large amount of colorant, in particular ink, which is dispensed by the print heads 22, 23 during the performance of a cleaning cycle. During this cleaning cycle, all of the ink metering elements of the print heads 22, 23, which are configured as exemplary nozzles for ink discharge, are preferably controlled and therefore moved again. if required. To carry out the cleaning cycle, the round workpiece table 3 is controlled in such a way that the respective workpiece housings 4 are arranged in the intermediate position shown in figure 1a between two workstations 9 to 17 , so that annoying objects are not arranged between the print heads 22, 23 and the respective cleaning station 44.

For printing, pivot housing 47 pivots about pivot axis 46 so that cleaning station 44 moves away from print head 22 or 23 and drying station 45 reaches a position opposite to print head 22 or 23. Preferably, drying station 44 is an arrangement of light sources not shown in detail, in particular light emitting diodes. These light sources are configured to emit light with a predetermined intensity and wavelength, these properties being adapted to the properties of the color or ink to be cured and which is discharged onto the object by the respective print heads 22, 23.

By way of example, provision can be made for another work station, in particular work station 15, to be equipped with another printing station 48 configured for the application of a closed or selective finish coat, in particular transparent, on the perimeter surface of the object 6, in particular in the areas printed with the help of the printing stations 21, 32 and 33, and having the same structure as one of these printing stations 21, 32 and 33.

The printing station 50 shown in FIG. 11 is provided for the multi-color printing of the object 6 in a printing operation and for this purpose presents by way of example three printing heads 51, 52 and 53, each of which has three bars of nozzles 54, 55 and 56. Each of the three nozzle bars 54, 55 and 56 is intended for the discharge of an ink, in particular from the cyan, magenta and yellow group. Each of the print heads 51, 52 and 53 can be positioned along the extension axis 30 by means of an associated drive 57, 58, 59 and a corresponding threaded spindle 60, 61, 62 associated in each case in the same way than in the case of printing stations 21, 32, 33.

By way of example, provision is made for the print head arrangement 51, 52 and 53 of the printing station 50 to be tiltable with respect to the axis of rotation 5 of the workpiece housing 4 by means of a drive 63 comprising a transmission equipment not represented in detail. In this regard, the tilt direction is selected such that the distance between the print heads 51, 52 and 53 and the object 6 is kept constant at least to a large extent. For example, a drive 64 is provided with transmission equipment not shown in detail which allows a displacement of the print heads in the radial direction to maintain at least to a large extent a controlled or regulated adaptation of a radial distance between the print heads 51, 52 and 53 and object 6. This is interesting if the object 6 does not have a circular cross section or if the objects 6 must be printed with different diameters during successive printing operations. Drives 63 and 64 can also be provided in the same way for printing stations 21, 32 and 33, provided that a controlled or regulated adaptation to different object geometries 6 is required therein.

Unlike functional assembly 43, as shown in Figures 9 and 10, in functional assembly 65 cleaning station 66 is housed together with drying station 67 on a carriage 68 movably mounted. Cleaning station 66 has a receiving container, not shown in detail, which is provided with a perimeter elastic sealing kit 69 in an area of the upper edge facing print heads 22 and 23. Carriage 68 is configured to carry out two translational movements 70, 71 perpendicular to each other and is equipped for this with drive means, for example, electric or pneumatic drives, which are not shown in detail. The translational movement 70, which is preferably carried out transversely to the axis of rotation 2 of the round workpiece table 3, serves to optionally arrange the cleaning station 66 or the drying station 67 below and in front of the heads 22, 23. The translational movement 71, which is preferably carried out parallel to the axis of rotation 2 of the workpiece round table 3, serves for the cleaning station 66 to make hermetic contact with the print heads 22 and 23. In this way, the desired cleaning cycle can be carried out.

To carry out the cleaning cycle, the round workpiece table 3 is controlled in such a way that the respective workpiece housings 4 are arranged in the intermediate position shown in figure 1a between two workstations 9 to 17 in such a way that no disturbing object is arranged between the print heads 22, 23 and the corresponding cleaning station 66.

To carry out the printing, the cleaning station 66 is moved away from the print heads by the translation movements 70 and 71 in such a way that the drying station 67 reaches a position opposite to the print head 22, 23 and the ink applied to the object 6 by the print heads 22, 23 can be activated, cured or dried.

In a non-illustrated embodiment of the printing machine, provision is made for a translational movement of the object to be printed, in particular parallel to its axis of rotation, to occur alternatively or in addition to the movement of the printing heads along the axis of extension. In another alternative embodiment, a rotation of the print heads is provided around the object at rest or only moved in translation.

Claims (13)

1. Printing machine with a machine frame on which a workpiece round table (3) is rotatably movably mounted, with a drive unit associated with the workpiece round table (3) for positioning rotary of the round table of workpiece (3), which in particular can be freely predetermined, as well as with workpiece housings (4) for accommodating the objects (6) to be printed, the housings protruding workpiece (4) radially from the workpiece round table (3) and each being movably rotatably mounted on the workpiece round table (3), as well as drive means for the housings of workpiece (4) and with at least one printing equipment (21, 32, 33; 50) movably mounted in particular in at least one spatial direction relative to the round table of workpiece (3), the printing equipment (21, 32, 33; 50) to print on a perimeter surface of the object (6), and comprising at least two printing heads (22, 23; 51, 52, 53) to print a perimeter surface of the object (6), each of which have at least one row arrangement of ink metering elements (31), in particular ink nozzles, each configured for an individually predeterminable discharge of ink into the object (6), at least one of the print heads (22, 23; 51, 52, 53) movably along an extension axis (30) of the ink metering elements (31) on a print head holder (21, 32, 33; 50) and with an electrically controllable adjustment equipment (34, 35; 57, 58, 59) associated with the print head (22, 23; 51, 52, 53) movably mounted to adjust a relative position with respect to the at least one other print head (22, 23; 51, 52, 53), characterized in that the printing equipment The configuration is configured to carry out the method according to one of claims 11 to 13. 2. Printing machine according to claim 1, characterized in that the at least one other printing head (22, 23; 51, 52, 53), in particular all other printing heads (22, 23; 51, 52, 53 ), is attached to electrically controlled adjusting equipment (34, 35; 57, 58, 59) and is movably arranged along the extension axis (30) of the ink dosing elements (31) in the print head support (21, 32, 33; 50). Printing machine according to claims 1 or 2, characterized in that the printing heads (22, 23; 51, 52, 53) are aligned parallel to each other and are arranged directly adjacent, in particular contiguous and movably sliding, and transversely to the extension axis (30) of the ink dosing elements (31). Printing machine according to one of the preceding claims, characterized in that the printing heads (22, 23; 51, 52, 53) can be adjusted by means of the at least one adjusting device (34, 35; 57, 58 , 59) between a first functional position, in which the adjoining printhead ink metering elements (31) (22, 23; 51, 52, 53) are arranged without overlapping transversely to the extension axis (30), and a second functional position where an overlap of the ink metering elements (31) of adjacent print heads (22, 23; 51, 52, 53) occurs transversely to the extension axis (30). Printing machine according to one of the preceding claims, characterized in that the at least one printing head (22, 23; 51, 52, 53) comprises at least two rows of ink dosing elements (31), in particular configured like ink nozzles, aligned parallel to the extension axis (30). Printing machine according to one of the preceding claims, characterized in that the ink dosing elements (31) are arranged along the extension axis (30) in a division (t) that can be predetermined and in that the Adjusting equipment (34, 35; 57, 58, 59) is configured to position the print head (22, 23; 51, 52, 53) with a positioning accuracy that is less, preferably less than 50 percent, preferably less than 25 percent, particularly preferably less than 10 percent, in particular less than two percent, of the division (t) of the ink metering elements (31) along the extension axis (30) . Printing machine according to one of the preceding claims, characterized in that the printing head support (21, 32, 33, 50) has associated with at least two groups of printing heads (22, 23; 51, 52, 53 ) mounted relatively movably with respect to each other, each group of print heads (22, 23; 51, 52, 53) comprising at least one, in particular two print heads (22, 23; 51, 52, 53). Printing machine according to one of the preceding claims, characterized in that the printing head support (21, 32, 33; 50) has an associated drying station (45; 67) arranged opposite to the printing heads (22 , 23; 51, 52, 53) to allow drying of the applied ink after application of the ink. 9. Printing machine according to claim 8, characterized in that the drying station (45) is coupled with a cleaning station (44) for the printing heads (22, 23; 51, 52, 53) and is mounted in relatively mobile in the print head holder (21, 32, 33; 50) such that it is optionally possible to dry the ink application on the objects (6) or to clean the print heads (22, 23; 51, 52, 53). 10. Printing machine according to claim 1, characterized in that the workpiece housings (4) they are configured as spindles for housing bush-shaped objects (6) and / or because each spindle is associated with its own drive equipment to initiate a rotational movement that can be freely predetermined in relation to the round part table (3) and / or because the workpiece (4) housings are configured with heating equipment to heat the objects (6) housed in it. 11. Procedure for the operation of a printing equipment comprising several printing heads (22, 23; 51, 52, 53) aligned parallel to each other and electrically mobile with each other, having at least one of the printing heads associated with a team adjusting (34, 35; 57, 58, 59) for the introduction of a relative movement with respect to another recording head (22, 23; 51, 52, 53), and at least one workpiece housing being provided (4) for a rotatable movable placement of an object (6) to be printed on its perimeter surface, with the steps of: placing an object (4) in the workpiece housing (4), performing a relative movement between at least two print heads (22, 23; 51, 52, 53) to influence an axial resolution of a print image to be applied to the perimeter surface of the object (6), rotation of the object (6) by of the workpiece housing (6) about an axis of rotation (5 ) which is aligned parallel to an extension axis (30) of ink metering elements (31) of the print heads (22, 23; 51, 52, 53) in such a way that the perimeter surface passes through the print heads (22, 23; 51, 52, 53), discharge ink on the perimeter surface of the object (6) by means of a predetermined control of the elements metering unit (31), characterized in that a rotation speed of the workpiece housing (4) is detected and a discharge rate is adapted, for an ink discharge rate through the ink metering elements (31), at the determined speed of rotation. 12. Method according to claim 11, characterized in that, by means of the adjustment equipment (34, 35; 57, 58, 59), a synchronous movement of the print heads (22, 23; 51, 52, 53) is carried out along the axis of rotation (5) during the rotation of the object and / or because, by means of the adjustment equipment (34, 35; 57, 58, 59), a relative movement of the print heads (22) is carried out , 23; 51, 52, 53) parallel to the extension axis (30) during the rotation of the object (6) to carry out a printing failure compensation. Method according to one of claims 11 or 12, characterized in that an irregular area of the perimeter surface of the object (6) is used as a reference for a printing process and in that a printing preferably exclusive to the area is carried out irregular.