EP2860036B1 - Printing press, printing machine and method for operating a printing press - Google Patents

Description

The invention relates to a printing machine with a printing device for printing on a peripheral surface of an object, with at least two printheads, each having at least one row of Farbdosierelementen, especially ink nozzles, each of which is designed for an individual predefinable release of color to the object. Furthermore, the invention relates to a method for operating a printing press with a printing device.

From the US 7,467,847 B2 a printing device for printing on the surface of a three-dimensional object is known, comprising an ink jet printing system with a plurality of circumferentially adjacent to each other at a fixed distance arranged individual print heads, which can be moved during the execution of the printing operation along an axis of rotation for the object to be printed to a helical Allowing printing of the article, wherein a pitch between adjacent nozzles of the individual print heads is greater than a resolution of the image to be applied to the printed image and wherein the desired resolution is achieved by the helical printing of the article.

The EP 2 471 665 A1 discloses a marking and / or scanning head having a plurality of receiving spaces, in which individual marking and / or sensor devices can be arranged for marking and / or scanning an object, wherein the receiving spaces are arranged in at least two subarrays, wherein at least one subarray is movable and / or rotatable relative to at least one other subarray, wherein the marking and / or scanning head further comprises a holding frame, which are arranged at least two sub-arrays on a common mounting frame, which is movable and / or rotatable relative to the holding frame, the sub-arrays are each about an axis of rotation, which passes through the center of the corresponding sub-array rotatable and the receiving spaces of each sub-array are arranged in a plurality of rows and columns to form a two-dimensional array of receiving spaces.

The US 2011/084995 A1 discloses an ink jet printing method comprising the steps of: performing a print job within a print area using two or more print units, the print units being determined to be active; Determining one of the printing units as the idle printing unit; Moving the idle printing unit from the printing area to a maintenance area; Moving a predetermined idle pressure unit from the maintenance area to the pressure area; Determining the previously named idle printing unit as active; and continuing execution of the print job using two or more print engines that are currently designated as active.

From the WO 2014/076704 A1 a printing machine for printing on cylindrical hollow bodies is known, in which an ink jet printing method is used and in which opposite to an ink jet print head, a cleaning arrangement is mounted, which is designed for a cleaning of the ink jet print head.

The CH 695 555 A5 discloses a printing machine for three-dimensional printing objects, comprising a printing device for applying at least one colorant to a printing object and with a drying device for drying the colorant, the printing device having one or more print heads and wherein the print heads and the drying device are arranged such that the drying of Color medium of a printed image can be done before its completion.

The object of the invention is to provide a printing machine and a method for operating a printing press with a printing device, with which a particularly efficient printing of a high-resolution object is made possible.

This object is achieved according to a first aspect of the invention for a printing device of the type mentioned with the features of claim 1. It is provided that the printing device of the printing press for carrying out the method according to one of claims 11 to 13 is formed.

In this case, it is assumed that the print head has a plurality of ink dosing elements arranged along an extension axis, wherein each of the ink dosing elements is designed for individual dispensing of color particles or drops of ink, in particular ink droplets. Preferably, the Farbdosierelemente are arranged at a constant pitch along the extension axis, so that each adjacent Farbdosierelemente have a constant distance from each other. The along the extension axis arranged Farbdosierelemente form a print line, wherein a print head can be equipped with one or alternatively with multiple print lines, wherein a plurality of print lines are preferably arranged parallel to each other and with the same distance. With the help of electrically controllable adjustment, in the it may be, for example, an electric linear linear drive, an electric spindle drive or a belt or cable drive, a relative movement of a first print head relative to a second print head is made possible. This relative movement can influence which position the ink metering elements of the first print head occupy along the extension axis relative to the ink metering elements of the second print head. For example, it may be provided that the Farbdosierelemente the first print head are offset with respect to the extension axis by an amount relative to the Farbdosierelementen the second print head, which corresponds to 50 percent of the pitch of the Farbdosierelemente. As a result, with appropriate control of the two print heads on the peripheral surface of the object to be printed, a printed image are generated whose resolution along the extension axis is twice as large as the pitch for the Farbdosierelemente the two printheads along the extension axis.

Furthermore, by changing the relative position of the first print head relative to the second print head, an adjustment of the position of the ink metering elements to print tracks can be achieved which have different slopes due to different requirements for the resolution of the print image to be generated and / or due to different diameters of the articles to be printed , When a helical print track is applied to the object, an adjustment of the pitch for the helical print track must be achieved, depending on the desired resolution for the print image to be generated and depending on the diameter of the article, which is achieved by adjusting the relative position of the print heads by relative movement the extension axis can be guaranteed to each other.

By means of the electrically controllable adjusting device, a change in the resolution of the printed image along the extension axis can also be provided during the execution of a printing operation, which is of interest, for example, if partial regions of the printed image are to be produced with higher resolution than other regions of the printed image. For carrying out the printing operation, it is provided that the object to be printed relative to the printing device performs a relative movement, which is aligned at least substantially, in particular exactly, transversely to the extension axis of the Farbdosierelemente. This relative movement of the object relative to the printing device may in particular be a pure translational movement, a pure rotational movement or an overlay of a translational movement and a rotational movement. Preferably, a helical printing of the article is provided, which is optionally by a, in particular synchronous, translational movement of the printing heads along the axis of extension in exclusive rotation of the article or by a superimposed rotational and translational movement of the article relative to the stationary printheads or by a combination of a superimposed rotary and translational movement of the article with a, in particular synchronous, translational movement of the print heads along the extension axis can be performed. It can be provided that the relative position of the print heads along the extension axis to each other depending on the achievable resolution and / or the diameter of the article before the implementation of the printing process is set and maintained during the execution of the printing operation.

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

It is expedient if the at least one further print head, in particular all other print heads, is connected to an electrically controllable setting device and arranged movably along the extension axis of the ink metering elements on the print head carrier. In this way, each of the print heads, in particular also during the execution of a printing operation for an object, can be adjusted with regard to its positioning along the extension axis of the ink metering elements. If the image to be printed on the peripheral surface of the object to be printed has, for example, a print area with low expansion and high image resolution along the extension axis and surrounding print areas with greater expansion and lower image resolution along the extension axis, then it can be provided that the print heads are used to generate the print area high resolution relative position to each other, which differs from a relative positioning of the printheads to produce the low-resolution printing areas.

In an advantageous embodiment of the invention is provided, characterized in that the print heads are aligned parallel to each other and transverse to the extension axis of the Farbdosierelemente immediately adjacent, in particular slidably adjacent to each other, are arranged. This makes it possible to achieve a compact arrangement of the print heads, which is advantageous, in particular, when printing on at least substantially rotationally symmetrical, in particular circular cylindrical objects such as aerosol can blanks, since otherwise, depending on the dimensioning of the objects to be printed, compliance with a distance specification between the print heads and the object difficult. Preferably, the juxtaposed Farbdosierelemente the adjacent printheads are each parallel aligned with each other and arranged transversely to the extension axis, in particular with respect to a circumferential direction of the object to be printed, at a fixed distance from each other. Optionally, it may also be provided to make a spacing of the print heads transversely to the extension axis adjustable by suitable adjustment means. Additionally or alternatively, it may be provided to arrange at least one print head rotatably mounted about a pivot axis, wherein the pivot axis is preferably aligned parallel to the extension axis, so that an incident direction for the color particles emitted by the print head, in particular ink drops, can be adjusted to the outer surface of the object. This is of particular interest when articles with very different diameters are to be printed with the same printing device.

In a further embodiment of the invention it is provided that the printheads by means of at least one adjustment between a first functional position in which the Farbdosierelemente adjacent printheads are arranged transversely to extension axis overlapping, and a second functional position in which an overlap of Farbdosierelementen adjacent printheads transversely to extension axis present, are adjustable. In this way, an advantageous adaptation of the resolution of the printing device with respect to the extension axis to the respective need can be made. In the first functional position is provided that the Farbdosierelemente adjacent, in particular all, printheads lie on mutually parallel lines, the parallel lines are aligned transversely to the extension axis and a distance of the parallel lines respectively corresponds to the pitch of the Farbdosierelemente. It is preferably provided that on each of the parallel lines two Farbdosierelemente adjacent printheads are arranged. At this Adjustment corresponds to the resolution to be achieved along the extension axis, at least in the event that each surface region of the object to be printed is passed over only once by the print heads, exactly the pitch of the ink metering elements and a maximum print length can be printed. In contrast, it is provided in the second functional position that there is an at least partial overlap of neighboring print heads with respect to the extension axis, whereby a higher resolution for the print image to be generated can be ensured in the overlap area, as is predetermined by the division of adjacent Farbdosierelemente with respect to the extension axis. At least part of the ink metering elements of the first print head lie on the same parallel lines as at least part of the ink metering elements of the second print head. Hereby, for example, in the overlapping area of the adjacent print heads, a higher print resolution along the extension axis can be achieved than and the areas without overlap. This is especially true in the event that each surface area of the object to be printed is only passed over once by the printheads.

Preferably, at least one print head comprises at least two rows of color metering elements aligned parallel to the extension axis, in particular as ink nozzles. Preferably, the at least two rows of Farbdosierelementen along the extension axis each have the same pitch for the Farbdosierelemente. Optionally, the Farbdosierelemente adjacent rows relative to the extension axis by a predetermined amount, in particular by a fraction of the respective pitch offset from each other. In particular, it can be provided that adjacent rows of Farbdosierelementen for dispensing different colors, especially cyan, magenta and yellow (yellow) provided are. In this way, the respective print head can generate the entire associated image section of the print image during a printing process, whereby depending on the printing method used, in particular when using the inkjet printer process, predictable mixing of the colors emitted by the different ink dosing elements occurs.

It is advantageous if the Farbdosierelemente along the extension axis are arranged in a predetermined pitch and that the adjustment is designed for positioning of the print head with a positioning accuracy, the smaller, preferably less than 50 percent, preferably less than 25 percent, more preferably less than 10 percent, in particular less than two percent, the pitch of the Farbdosierelemente along the extension axis. With such positioning accuracy for the adjustment means, the respective printhead can be arranged in a reproducible manner relative to adjacent printheads, for example, to allow for different resolutions and different printing speeds for the printing of the article during the execution of a printing operation. By way of example, it is provided that the setting device has a positioning accuracy of less than 5 micrometers and that a pitch of the ink metering elements is in a range of 0.25 millimeters.

It is expedient if at least two mutually relatively movably mounted groups of print heads are assigned to the print head carrier, wherein each group of print heads comprises at least one, in particular two, print heads. With the aid of the at least two groups of printheads, the peripheral surface of an article may optionally be subjected to a single rotation or possibly only a partial rotation high resolution in the circumferential direction and / or printed along the extension axis, for which purpose the two groups of print heads are arranged at least partially overlapping each other. Alternatively, it may be provided to print the peripheral surface of the object in the course of several revolutions, with no or only a slight overlap of the groups of printheads being provided for each other and the printheads of the adjacent groups of printing heads being adjusted to one another depending on the desired pitch of the printing track , It is preferred that the respective groups of printheads are each designed to dispense a single color.

It is advantageous if the printhead support is associated with a drying station arranged opposite the print heads, in order to allow drying of the applied ink following the application of paint. With the aid of the drying station, a curing process is carried out for the color particles or drops of color emitted by the ink dosing elements onto the surface of the object to be printed. In this case, a contactless energy coupling, for example by infrared light or ultraviolet light, is preferably provided on the object. Such a drying or curing process is particularly advantageous when the article is an at least substantially rotationally symmetric article which is rotated during the printing operation about an axis of rotation which is aligned at least substantially parallel to the extension axis of the print heads. In this case, the surface area of the object to be printed first passes the printing head (s) in order to pass the drying station in the course of its rotation, so that ideally within approximately a rotational movement of approximately 200 degrees about the axis of rotation the printing operation for the object is completed can be completed.

In a further development of the invention, it is provided that the drying station is coupled to a cleaning station for the print heads and is mounted so relatively movable on the Drucckopfträger that optionally a drying of the paint on the objects or cleaning of the print heads is made possible. The task of the cleaning station may optionally be to perform a print head cleaning in mechanical contact with the printheads or to pick up and bind color particles or drops of paint emitted as part of a cleaning process for the ink metering elements. Cleaning of the printhead (s) may be provided if appropriate printing errors are detected on printed articles by suitable sensor means or if a certain number of printing operations have been performed. Preferably, the cleaning station is designed such that the printhead to be cleaned is sealed at an edge region and then in the free jet emitted by the printhead in the direction of the cleaning station color particles, in particular ink drops, can be collected and removed.

According to the invention, the printing press comprises a machine frame, on which a workpiece rotary table is rotatably mounted, and a workpiece rotary table associated drive unit for a particular freely definable, rotational positioning of the workpiece turntable and with workpiece holders for receiving objects to be printed, wherein the workpiece holders in the radial direction of the workpiece rotary table protrude and are each mounted rotatably on the workpiece rotary table, and drive means for the workpiece holders and at least one, in particular in at least one spatial direction movable relative to the workpiece rotary table movably mounted, printing device. Preferably, a rotational axis of the workpiece rotary table is aligned in the vertical direction, so that the workpiece holders extend in at least substantially horizontal direction.

In this way, the at least one printing device can be arranged on the machine frame in such a way that a color output from the print heads onto the object takes place essentially in the vertical direction, in particular downwards. Through this use of gravity for carrying out the printing process, a favorable printing result is favored. The drive unit assigned to the workpiece rotary table is preferably designed such that it allows a freely selectable positioning of the workpiece holders. In this way, for example, to perform a cleaning operation for the print heads, an intermediate position can be approached, in which the workpiece receivers between two adjacent work stations, in particular printing units, are positioned. In such an intermediate position unwanted contamination of the objects to be printed are avoided during the execution of the cleaning process.

In a further development of the printing press is provided that the workpiece holders are designed as spindles for receiving sleeve-shaped objects and / or that each spindle is assigned its own drive means for initiating a freely definable rotational movement relative to the workpiece rotary table and / or that the workpiece holders with a heating device for heating the objects received thereon are formed. Preferably, the printing machine is provided for printing aerosol can blanks or tube blanks and therefore has rod-shaped workpiece receptacles, which are also referred to as spindles. It is advantageous if each spindle has its own drive device is assigned to optionally allow control of the rotational movement of the object to be printed in dependence on the requirements of the printed image and the relative positioning of the print heads to each other. In one embodiment, the printheads are inkjet printheads that are designed to eject ink drops onto the peripheral surface of the article during are carried out the implementation of the printing process, it is advantageous if already during or at least shortly after performing the printing operation, a heating of the article can be made to accelerate curing of the ink droplets.

The object of the invention is achieved according to a second aspect with a method according to claim 11. This method is used to operate a printing device comprising a plurality of mutually parallel and electrically relative to each other relatively movable printheads, wherein at least one of the printheads is associated with an adjusting device for initiating a relative movement relative to at least one further printhead and wherein at least one workpiece holder for a rotatable mounting of an of its peripheral surface to be printed on the article, comprising the steps of: placing an object on the workpiece holder, performing a relative movement between at least two printheads for influencing an axial resolution of a printed image to be applied to the peripheral surface, rotating the article by means of the workpiece holder about an axis of rotation parallel to one another is aligned with an extension axis of ink dosing elements of the print heads, so that the peripheral surface passes through the print heads, discharging v on color on the peripheral surface of the article by a predetermined control of the Farbdosierelemente. For carrying out the method, it can be provided that the at least two print heads can be set in the circumferential direction and in the direction of the extension axis along the extension axis in their relative position relative to one another as a function of achievable resolutions for the print image. Further, a diameter of the article to be printed may be included in determining and adjusting the relative positioning of the printheads to each other. The delivery rate for the Farbdosierelemente the printheads is also dependent on the achievable Resolution and the diameter of the object selected. Further, additional electrical adjustment means may be provided for a particularly synchronous, automatable movement of the printheads adapted to maintain a spacing of the printheads from the peripheral surface of the object constant. An advantageous distance between the print head and the peripheral surface is in a range of less than 5 mm, preferably less than 3 mm, in particular less than 2 mm. Furthermore, additional electrical adjustment means for a, in particular synchronous, pivoting movement of the print heads can be provided about a pivot axis, wherein the pivot axis is aligned at least substantially normal to the axis of rotation of the objects. With such a pivoting movement, an additional degree of freedom for influencing the resolution of the printed image to be generated by the print heads can be made available.

In one embodiment of the method it is provided that a synchronous movement of the print heads along the axis of rotation is carried out by means of the adjusting means during the rotation of the object and / or that by means of the adjusting means during the rotation of the object, a relative movement of the print heads is performed parallel to the extension axis to a Compensation of printing errors. By the synchronous movement, a helical track of pressure points on the peripheral surface of the article can be generated by the respective Farbdosierelemente, preferably a proportional, in particular constant relationship between the rotational movement of the article about its axis of rotation and the movement of the print heads along the extension axis is provided. Upon occurrence of typographical errors identified either in real time during the printing process or by subsequent inspection of a printed object, the printheads may be provided during the printing process or at least during a subsequent printing process Adjust printing process relative to each other to compensate for failures of individual Farbdosierelemente, in particular ink nozzles, at least to a large extent at the individual printheads.

According to the invention, it is provided that a rotational speed of the workpiece holder is detected and a dispensing rate for a color output by the color metering elements is adapted to the determined rotational speed.

Another, not claimed aspect of the invention relates to a printing machine with a machine frame on which a workpiece rotary table is rotatably mounted, with a workpiece rotary table associated drive unit for a predetermined rotary positioning of the workpiece turntable and with workpiece holders for receiving objects to be printed, the workpiece holders each rotatably mounted on the workpiece rotary table, and with drive means for the workpiece holders and with at least one printing device, in particular according to claims 1 to 9 and a cleaning station, which is at least temporarily opposite to the printing device. The drive unit for the workpiece turntable is, as in the other claimed embodiments of the printing press, adapted to allow a rotational stepping movement of the workpiece turntable comprising a sequence of rotation steps and stoppage phases. The rotational steps are dimensioned during a printing phase for the objects to be printed so that the recorded on the workpiece receptacles objects in successive steps of the workpiece turntable, which are always performed in particular with the same angular pitch, respectively opposite to each other to adjacent workstations are arranged to then in processed appropriately, in particular to be printed on printing devices. To allow cleaning of the printing devices may be provided be that the drive means for the workpiece turntable approach an intermediate position in which the recorded on the workpiece holders objects are not arranged opposite to the workstations. Preferably, a rotation step for such an intermediate position is half an angular separation of a usual during the execution of the printing operation rotation step. By virtue of the fact that the workpiece receivers and the objects received thereon are now not arranged opposite the workstations, in particular a relative movement of the cleaning station in the direction of the respective printing device can be undertaken. This relative movement serves, for example, to approach the cleaning station by means of a translatory movement parallel to an axis of rotation of the workpiece rotary table in such a way to the printing device that a sealing contact between the cleaning station and the printing heads of the printing device can be achieved. Thus, the respective print head can be cleaned by targeted delivery of color particles, in particular ink droplets, or, if appropriate, a solvent flows through them. It is provided that the color particles or the solvent are taken up and removed by the cleaning station. Additionally or alternatively it can be provided that the cleaning station is designed for dispensing solvent onto the print heads, in order to bring about a dissolution of ink particles adhering to the print heads, in particular ink droplets. After completion of the cleaning operation, the cleaning station is transferred to a position in which a collision-free further movement of the objects recorded on the workpiece receptacles can be performed by a rotary step movement until reaching the next workstation to then resume the usual processing sequence for the objects.

Figur 1

eine schematische Draufsicht auf eine Druckmaschine mit einem drehbeweglich gelagerten Werkstückrundtisch und mehreren Arbeitsstationen zur Bedruckung und Inspektion von zylindrischen Gegenständen,

Figur 1a

eine Ausschnittvergrößerung der Druckmaschine gemäß der Figur 1 in einer Zwischenstellung für den Werkstückrundtisch,

Figur 2

eine schematische Vorderansicht einer als Druckstation ausgebildeten Arbeitsstation der Druckmaschine,

Figur 3

eine schematische Ansicht von unten auf die Druckstation gemäß der Figur 2 in einer ersten Funktionsstellung,

Figur 4

eine schematische Darstellung einer Düsenanordnung der Druckstation gemäß der Figur 3,

Figur 5

eine schematische Ansicht von unten auf die Druckstation gemäß der Figur 2 in einer zweiten Funktionsstellung,

Figur 6

eine schematische Darstellung der Düsenanordnung der Druckstation gemäß der Figur 5,

Figur 7

eine schematische Ansicht von unten auf die Druckstation gemäß der Figur 2 in einer dritten Funktionsstellung,

Figur 8

eine schematische Darstellung der Düsenanordnung der Druckstation gemäß der Figur 7

Figur 9

eine schematische Darstellung einer Druckstation und einer gegenüberliegend angeordneten Funktionsbaugruppe, die eine Trocknungsstation und eine Reinigungsstation umfasst, in einer ersten Funktionsstellung,

Figur 10

die Funktionsbaugruppe in einer zweiten Funktionsstellung,

Figur 11

eine weitere Ausführungsform einer für Mehrfarbdruck ausgerüsteten Druckstation und

Figur 12

eine zweite Ausführungsform einer Funktionsbaugruppe.

An advantageous embodiment of the invention is shown in the drawing. Hereby shows:

FIG. 1

a schematic plan view of a printing machine with a rotatably mounted workpiece rotary table and several workstations for printing and inspection of cylindrical objects,

FIG. 1a

a detail enlargement of the printing machine according to the FIG. 1 in an intermediate position for the workpiece turntable,

FIG. 2

a schematic front view of a designed as a printing station workstation of the printing press,

FIG. 3

a schematic view from below of the printing station according to the FIG. 2 in a first functional position,

FIG. 4

a schematic representation of a nozzle assembly of the printing station according to the FIG. 3 .

FIG. 5

a schematic view from below of the printing station according to the FIG. 2 in a second functional position,

FIG. 6

a schematic representation of the nozzle assembly of the printing station according to the FIG. 5 .

FIG. 7

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

FIG. 8

a schematic representation of the nozzle assembly of the printing station according to the FIG. 7

FIG. 9

1 a schematic representation of a printing station and a function module arranged opposite one another, which comprises a drying station and a cleaning station, in a first functional position,

FIG. 10

the functional module in a second functional position,

FIG. 11

Another embodiment of a equipped for multi-color printing printing station and

FIG. 12

a second embodiment of a functional assembly.

One in the FIG. 1 illustrated printing machine 1 comprises a rotatably mounted about a rotation axis 2 on a machine frame not shown workpiece rotary table 3 and a plurality, each pairwise mounted on the workpiece rotary table workpiece holders 4. The workpiece holders 4 are individually rotatably mounted with rotational drive axes 5 not shown drive means and for receiving sleeve-shaped , in particular as aerosol can blanks or tube blanks formed, at least substantially cylindrical objects 6 are provided. Preferably, the workpiece holders 4 are formed as mandrels on which the hollow body, in particular as unilaterally closed hollow cylinder, formed, 6 objects can be plugged. In one of the workpiece holders 4 during a rotational movement of the workpiece rotary table 3 about the axis of rotation 2 swept annular region 7, extending in the radial direction extends around the workpiece rotary table 3, a plurality of work stations 8 to 18 are arranged, which are designed for processing and / or testing of the transported objects 6. Since it is in the view according to the FIG. 1 is a plan view and the workstations 9 to 17 are usually arranged in the vertical direction above the workpiece holders 4, the workstations are shown 9 to 17 only in dashed lines.

The work station 8 is a loading station, on which the cylindrical objects 6 are exemplarily in pairs on the workpiece holders 4 by a suitable transport device 19, which is coupled to a conveying system, not shown for the cylindrical objects 6, are pushed.

By way of example, a rotary position of the cylindrical objects 6 is determined at the work station 9 by a first optical scanning of the cylindrical objects 6, for example to ensure a correct rotational alignment of the cylindrical objects 6 for a printing operation taking place at the workstation 10. This is particularly important if the surface to be printed on the objects is provided with features that are to be in a predetermined manner with the applied print image in a predetermined manner. These features may be, for example, local embossing and / or embossing in and / or out of the surface of the article 6 and / or pre-printed areas, which in turn are to serve as a primer for the subsequent printing. It can preferably be provided to print on a partially reshaped or already completely reshaped article, which in particular embosses and / or embossments, so that an alignment of the printed image with respect to the deformed Areas is done and not, as has been known from practice, a deformation of the objects is carried out on the basis of a pre-applied printed image. Preferably, it is provided to print a reshaped aerosol can blank with indentations and / or characteristics locally or over its entire peripheral surface, wherein the aerosol can blank after printing in the printed areas with a protective coating, in particular a transparent varnish, can be coated and then ready for a filling ,

The workstation 10 includes an example in the Figures 2 . 3 . 5 , and 7 closer to printing station 21, at which the cylindrical objects 6 during rotation about respective axes of rotation 5 using printheads 22, 23, as shown in the Figures 3 . 5 and 7 are shown in more detail, are printed in a predetermined range.

The work station 14 is embodied as an inspection device by way of example and makes it possible to determine a print quality of the print image applied by the printing station 21 to the peripheral surface of the object 6.

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

At the workstation 18 takes place an unloading process in which the cylindrical objects 6 by means of a transport device 20 of the mandrel-like workpiece holders 4 are deducted and fed to a non-illustrated further transport system.

The workpiece turntable 4 leads to the stepwise processing of the cylindrical objects 6 at the respective workstations 8 to 18 a rotary step movement by the angle W, in which the paired workpiece holders 4 from one of the respective workstation 8 to 18 opposite position in one of the subsequent workstation 8 to 18 opposite position are transported, wherein the rotational step movement is carried out as a sequence of acceleration from standstill, a deceleration of the achieved target speed and a subsequent downtime. Preferably, a non-illustrated drive for the workpiece rotary table 3 is designed such that the acceleration and deceleration of the workpiece rotary table 3 are completely freely adjustable over a wide range and downtime and adapted to the requirements of processing the respective cylindrical objects 6 at the workstations 8 to 18 can be. As will be described in more detail below, the drive of the workpiece rotary table 3 can be controlled such that the workpiece holders 4 in an intermediate step, which can be used for cleaning or other maintenance of workstations 8 to 18, by a rotational step movement with the step size W / 2 between the workstations 8 to 18 come to rest, as shown schematically in the FIG. 1a is shown. This is important, for example, for carrying out a cleaning of the printing station 21.

The in the Figures 2 and 3 illustrated printing station 21 includes two mirror images of each other arranged pressure means 24, 25 for the sake of clarity in the FIG. 3 only one in two with the Print station 21 printable cylindrical objects 6 shown, in contrast, are in the FIG. 2 both arranged opposite to the printing station 21 and rotatably mounted cylindrical objects 6 shown.

Each printing device 24, 25 comprises by way of example in each case two printing heads 22, 23, each of which has a strip-like shape and on whose cylindrical object 6 facing end face 26, 27 an exemplary nozzle row 28, 29 is formed. Each of the rows of nozzles 28, 29 comprises several, preferably in the same pitch or spacing along an extension axis 30, exemplified as nozzles 31 formed Farbdosierelemente. Each of the nozzles 31 in the nozzle rows 28, 29, as shown in the FIGS. 4 . 6 and 8th are shown in section, is exemplarily individually controlled and formed in the illustrated embodiment for dispensing drops of ink.

By way of example, the two print heads 22, 23 are designed to deliver a first color, in particular the color cyan. In the illustrated embodiment, further printing stations 32, 33 for dispensing a second or third color, in particular the color magenta and the color yellow (yellow) are formed. Accordingly, a printed image, not shown in greater detail, can be produced by a combination of differently colored ink drops which are dispensed onto the object 6 at the respective printing stations 21, 32, 33. In one embodiment, not shown, more than three printing stations are provided in order to apply a larger number of colors, especially white as at least partially applied primer for the printing and / or a transparent topcoat for the carried out printing on the article 6.

At one in the FIG. 11 illustrated embodiment of a printing station, the respective printheads for dispensing a plurality of colors, in particular the colors cyan, magenta and yellow, formed so that a printing of an object can be done in a single printing operation.

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

For the following explanations, it is assumed that each nozzle 31 of each print head 22, 23 can be driven at a predetermined frequency and can deliver drops of ink onto the peripheral surface of the object 6 at the predetermined frequency. Depending on a rotational speed of the object 6 about the axis of rotation, the frequency determines the resolution in the circumferential direction. At a low rotational speed results in a high resolution in the circumferential direction, at high rotational speed results in a low resolution in the circumferential direction.

A resolution for the printed image in a spatial direction parallel to the axis of rotation 5 is determined based on a print head 22 or 23 exclusively by the pitch of the nozzles 31 along the extension axis 30 of the respective print head 22, 23, as long as during the execution of the printing process no translational displacement of the respective Printhead 22, 23 along the axis of rotation 5 takes place. In this case, an annular application of the ink drops takes place on the peripheral surface of the article 6. Is, however, during the rotational movement of the article 6 in the implementation the printing operation, an additional translational displacement of the respective print head 22, 23 provided longitudinal axis of rotation 5, the result is a helical application of the ink droplets on the peripheral surface of the article 6, wherein a slope of a helical path for the ink droplets generated thereby determines which distance adjacent helix have , As a result, a resolution of the printed image in the direction along the axis of rotation 5 is determined.

This can be used, in particular for the case that the object 6 passes through the respective print head 22, 23 several times, to a considerable increase in resolution along the extension axis 30.

For a fast and thus inexpensive printing usually only a simple passage of the article 6 is provided on the respective print head, so that a 360-degree printing of a peripheral surface of an article with a rotational movement of 360 degrees can be performed. If only a portion of the peripheral surface to be printed, the rotational movement of the article 6 may also be less than 360 degrees.

In order to be able to realize a high-resolution printed image when the entire circumferential surface of the object 6 is printed with a single revolution of the object 6 about its axis of rotation 5, the respective printing device 24, 25 is set in a suitable manner. For this purpose, the two printing heads 22, 23 of the respective printing device 24, 25 each associated with an electric drive 34, 35, which is electrically connected to a control device 36, respectively. In the drive 34, 35 is an example of an electric motor, the drive shaft, not shown, with a rotatable and stationary in the as a print head carrier Serving pressure device 24, 25 mounted threaded spindle 37, 38 is connected. In the threaded spindle 37, 38 engages a connected to the respective print head 22, 23, non-visible lock nut, which is designed to implement a rotational movement of the threaded spindle 37, 38 in a translational movement of the respective print head 22, 23. For guiding the respective print head 22, 23 in the printing device 24, 25 sliding guide surfaces 39, 40, 41, and 42 are provided, which enable a slide-movable and rotationally fixed mounting of the print heads 22, 23 on the printing device 24, 25. The control device 36 is designed for an independent control of the electrical drives 34, 35, so that the translational position of the print heads 22, 23 along the extension axis 30 can be adjusted freely.

For a printing operation with easy passage of the peripheral surface of the article 6 on the printheads 22, 23 and high resolution in the circumferential direction and in the direction of the extension axis 30, the print heads 22, 23 for generating a helical print track, as shown in the FIG. 2 is indicated by the parallel and equidistant lines on the object 6, positioned by means of adjusting means serving as drives 34, 35 to each other such that the in the FIG. 4 shown nozzles 31 of the adjacent print heads 22, 23 are each on the parallel and mutually equidistant lines. Such an adjustment and synchronized use of the printheads 22, 23 can achieve a doubling of the resolution for the print image over a use of only one printhead 22 or 23 in a helical printing operation. The spacing of the lines depends on the desired resolution, the number of revolutions of the object 6 during the printing process with respect to the printheads 22, 23 and the diameter of the object 6.

In an operating mode, not shown, for the printing devices 24, 25, the print heads 22, 23 can be arranged offset by half the pitch t to each other and remain stationary during the simple rotation of the article 6.

A further increase in the resolution can be achieved if the object 6 opposite to the two printheads 22, 23 performs several revolutions and the printheads 22, 23 during the rotational movement of the article 6 for performing the printing operation synchronously shifted along the extension axis 30, as a result a helical shape for a trace of pressure points, which are discharged from a nozzle 31 on the peripheral surface of the article 6, is achieved, in which the successively generated pressure traces of the individual nozzles are applied to the object 6 far less than a pitch t apart. Preferably, the synchronous displacement of the printheads 22, 23 during the printing operation is selected so that a slope of the track of printing dots during one revolution of the object corresponds to a value obtained by dividing the pitch t of the nozzles 31 of a printhead 22 or 23 along the axis of extent 30 corresponds to an integer value. In order to achieve a further doubling of the resolution in this case when using both print heads 22, 23 of the respective printing device 24, 25, the two print heads 22, 23 with the respective drives 34, 35 are exemplarily set such that they along the track of Pressure points are arranged offset to one another such that they lie on mutually parallel and equidistant lines and that this position of the print heads 22, 23 is also maintained during the execution of the printing operation.

Alternatively it can be provided that the two print heads 22, 23 during the execution of a printing operation not only be moved synchronously to the extension axis but also be moved relative to each other. For example, it may be provided to print the peripheral surface of the article 6 with different resolutions. In this case, for a variation of the resolution, both the relative position of the print heads 22, 23 along the extension axis 30 and a change in the rotational speed of the object 6 and / or a drive frequency for the control of the print heads 22, 23 may be provided. For example, an increase in resolution for the print image in the circumferential direction can be achieved by reducing the rotation speed for the object 6 while maintaining the drive frequency for driving the print heads 22, 23 and / or the drive frequency for driving the print heads 22, 23 is increased.

In a further, alternative approach, it may be provided that the printing device 24, 25 connected to the control device 36 is adjusted in response to the detection of printing errors in the generated print image by the inspection system in the workstation 14 for compensation of these printing errors at the next article to be printed , For this purpose, it may be provided that the two print heads 22, 23 are positioned relative to one another in such a way that a nozzle 31 of one of the print heads 22, 23 can be used to deliver a clogged nozzle 31 of the other print head 22, 23. For this purpose, the intact nozzle 31 does not necessarily have to be arranged on the same track of pressure points, in particular a helical path, like the defective nozzle 31, even a slight offset which is smaller than the pitch t may possibly be acceptable.

In the FIGS. 4 and 5 is shown as a printing of a high-resolution object 6 in the direction of the extension axis 30 is made, whose extent along the extension axis 30 is greater than a corresponding extent of the print heads 22, 23. The printing process begins by way of example with a positioning of the two print heads 22, 23 in a lower starting position according to FIG FIG. 3 in which the print heads 22, 23 are arranged in accordance with the slope of the intended spiral pressure taking into account the desired resolution. Starting from this positioning, the print heads 22, 23 are moved synchronously to one another during the execution of the printing process along the extension axis 30 and the object 6 is rotated about the rotation axis 5 until the entire peripheral surface of the object 6 has been moved past the print heads 22, 23 and with Color could be provided.

At the in FIG. 7 shown setting of the print heads 22, 23 to each other a helical printing of the peripheral surface of the article 6 is provided with a resolution along the extension axis 30, which is greater than the pitch t of the nozzles 31 to the printheads 22, 23. For this purpose, for example, a multiple rotation of the article 6 with respect to the print heads 22, 23 is provided, during which the print heads 22, 23 are moved synchronously with each other along the extension axis 30 to produce the desired helical shape for the print tracks. If the last nozzle 31 of the printhead 22 arranged as an example below would be arranged at the pitch t with respect to the first nozzle 31 of the printhead 23 arranged by way of example above, this would result in an offset of the print tracks of the adjacent print heads relative to the desired pitch for the helical printing of the object 6 22, 23 by the amount ds. To ensure that all of the nozzles 31 of the two print heads 22, 23 print tracks on parallel and spaced by the distance s from one another equidistantly arranged lines must be the two Printheads 22, 23 are shifted by a resolution-dependent and diameter-dependent amount relative to each other, so that the amount ds disappears. Thus, seamless printing of the peripheral surface of the article 6 can be realized.

In the FIGS. 9 and 10 By way of example, a functional module 43 is arranged opposite the respective printing device 24, 25. The functional module 43 comprises a cleaning station 44 and a drying station 45, which by way of example on a common, rotatable about a perpendicular to the plane of the FIGS. 9 and 10 aligned rotational axis 46 mounted pivot receptacle 47 are mounted. The cleaning station 44 is equipped with an absorbent material, not shown, which can receive a large amount of dye, in particular ink, discharged from the print heads 22, 23 during the execution of a cleaning cycle. During this cleaning cycle, preferably all ink dosing elements of the print heads 22, 23, which are designed as nozzles 31 for dispensing ink, are preferably activated and, as a result, optionally re-established. For carrying out the cleaning cycle, the workpiece rotary table 3 is controlled such that the respective workpiece holders 4 in the in the FIG. 1a illustrated intermediate position between two workstations 9 to 17 are arranged so that no interfering objects between the print heads 22, 23 and the respective cleaning station 44 are arranged.

For carrying out a printing, the pivot receptacle 47 is pivoted about the pivot axis 46, so that the cleaning station 44 is removed from the print head 22 or 23 and the drying station 45 reaches the print head 22 or 23 opposite position. Preferably it is at the drying station 44 to an array of light sources not shown, in particular light-emitting diodes. These light sources are designed to emit light of a predeterminable intensity and wavelength, these properties being adapted to the properties of the ink or ink to be hardened, which are dispensed from the respective print heads 22, 23 onto the object.

By way of example, it can be provided that a further workstation, in particular the workstation 15, is equipped with a further printing station 48, which is responsible for applying a closed or selective, in particular transparent, topcoat to the peripheral surface of the object 6, in particular to the printing stations 21 , 32 and 33 printed areas, are formed and which has the same structure as one of these printing stations 21, 32, 33.

The in the FIG. 11 illustrated printing station 50 is provided for a multi-color printing of the article 6 in a printing operation and has for this purpose three printheads 51, 52 and 53, each having three nozzle strips 54, 55 and 56. Each of the three nozzle strips 54, 55 and 56 is provided for the discharge of a color, in particular from the group cyan, magenta and yellow. Each of the print heads 51, 52, and 53 can be positioned in the same way along the extension axis 30 by means of an associated drive 57, 58, 59 and a respective associated threaded spindle 60, 61, 62, as for the printing stations 21, 32, 33 the case is.

By way of example, it is provided that the arrangement of printing heads 51, 52, and 53 of the printing station 50 by means of a drive 63, which comprises a transmission device, not shown, relative to the axis of rotation 5 of the workpiece holder 4 can be tilted. In this case, the tilting direction is selected such that a distance from the print heads 51, 52 and 53 relative to the object 6 remains at least substantially constant. By way of example, a drive 64 is provided with a gear device not shown in detail, which allows a displacement of the print heads in the radial direction to keep a controlled or regulated adjustment of a radial distance between the print heads 51, 52 and 53 and the object 6 at least largely constant. This is of interest if the article 6 does not have a circular cross-section or if articles 6 having different diameters are to be printed in successive printing processes. The drives 63 and 64 can be provided in the same way also at the printing stations 21, 32 and 33, if there is a controlled or controlled adaptation to different geometries of objects 6 is required.

Deviating from the functional assembly 43 according to the FIGS. 9 and 10 In the case of the functional module 65, the cleaning station 66 together with the drying station 67 is accommodated on a movably mounted carriage 68. The cleaning station 66 has a receptacle, not shown, which is provided at an upper, the printheads 22, 23 facing edge region with a circumferential elastic sealing means 69. The carriage 68 is designed for carrying out two mutually perpendicular translational movements 70, 71 and for this purpose with drive means, not shown, for example, electric or pneumatic drives equipped. The translational movement 70, which is preferably carried out transversely to the axis of rotation 2 of the workpiece turntable 3, serves to selectively clean the cleaning station 66 or the drying station 67 below and opposite to the printheads 22, 23 to be arranged. The translational movement 71, which is preferably carried out parallel to the rotation axis 2 of the workpiece turntable 3, serves to bring the cleaning station 66 into sealing contact with the print heads 22, 23. This allows the desired cleaning cycle to be carried out.

For the implementation of the cleaning cycle, the workpiece rotary table 3 is controlled such that the respective workpiece holders 4 in the in FIG. 1a represented intermediate position between two work stations 9 to 17 are arranged so that no interfering objects between the Druccköpfen 22, 23 and the respective cleaning station 66 are arranged.

For carrying out the printing, the cleaning station 66 is removed from the printheads by means of the translatory movements 70 and 71 such that the drying station 67 reaches a position opposite the printhead 22, 23 and activates ink applied by the printheads 22, 23 to the object 6 , hardened or dried.

In an embodiment of the printing press, not shown, it is provided that as an alternative or in addition to the movement of the print heads along the extension axis, a translational movement of the object to be printed, in particular provided parallel to its axis of rotation. In a further alternative embodiment, a rotation of the print heads around the stationary or translationally moving object is provided around.

Claims (13)

1. Printing machine having a machine frame on which a workpiece rotary table (3) is rotatably mounted, having a drive unit, assigned to the workpiece rotary table (3), for a rotational positioning of the workpiece rotary table (3), in particular a position which can be freely predetermined, and having workpiece holders (4) for receiving objects (6) to be printed on, wherein the workpiece holders (4) project in the radial direction from the workpiece rotary table (3) and are each mounted rotatably on the workpiece rotary table (3), as well as with drive means for the workpiece holders (4) and with at least one printing device (21, 32, 33; 50) mounted movably in at least one spatial direction relative to the workpiece rotary table (3), the printing device (21, 32, 33; 50) being designed for printing on a peripheral surface of the object (6) and comprises at least two printing heads (22, 23; 51, 52, 53) being provided for printing on the peripheral surface of the object (6) which each have at least one row arrangement of ink metering elements (31), in particular ink nozzles, which are each designed for an individually predeterminable delivery of ink onto the object (6), wherein at least one of the print heads (22, 23; 51, 52, 53) being movable along an axis of extension (30) of the ink metering elements (31) on a print head carrier (21, 32, 33; 50) and wherein an electrically controllable adjusting means (34, 35; 57, 58, 59) for setting a relative position relative to the at least one further print head (22, 23; 51, 52, 53) is assigned to the movably mounted print head (22, 23; 51, 52, 53), characterized in that the printing device is designed 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 further print head (22, 23; 51, 52, 53), in particular all further print heads (22, 23; 51, 52, 53), is connected to an electrically controllable adjusting means (34, 35; 57, 58, 59) and is arranged on the print head carrier (21, 32, 33; 50) movably along the axis of extension (30) of the ink metering elements (31).
3. Printing machine according to claim 1 or 2, characterized in that the print heads (22, 23; 51, 52, 53) are aligned parallel to one another and are arranged directly adjacent to, in particular slidably adjacent to one another, transversely to the extension axis (30) of the ink metering elements (31).
4. Printing machine according to one of the preceding claims, characterized in that the print heads (22, 23; 51, 52, 53) can be positioned by means of the at least one adjusting means (34, 35; 57, 58, 59) between a first functional position in which the ink metering elements (31) of adjacent print heads (22, 23; 51, 52, 53) are arranged without overlap transversely to the axis of extension (30), and a second functional position, in which an overlap of ink metering elements (31) of adjacent print heads (22, 23; 51, 52, 53) is present transversely to the axis of extension (30).
5. Printing machine according to one of the preceding claims, characterized in that at least one print head (22, 23; 51, 52, 53) comprises at least two rows of ink metering elements (31) which are aligned parallel to the extension axis (30), in particular in the form of ink nozzles.
6. Printing machine according to one of the preceding claims, characterized in that the ink metering elements (31) are arranged along the axis of extension (30) in a predeterminable pitch (t) and in that the adjusting means (34, 35; 57, 58, 59) for positioning the print head (22, 23; 51, 52, 53) is designed for a positioning accuracy which is smaller, preferably smaller than 50 percent, preferably smaller than 25 percent, particularly preferably smaller than 10 percent, in particular smaller than two percent, of the pitch (t) of the ink metering elements (31) along the extension axis (30).
7. Printing machine according to one of the preceding claims, characterized in that the print head carrier (21, 32, 33; 50) is associated with at least two groups of print heads (22, 23; 51, 52, 53) which are relatively movable relative to one another, each group of print heads (22, 23; 51, 52, 53) comprising at least one, in particular two, print heads (22, 23; 51, 52, 53).
8. Printing machine according to one of the preceding claims, characterized in that a drying station (45; 67) arranged opposite the print heads (22, 23; 51, 52, 53) is assigned to the print head carrier (21, 32, 33; 50) in order to enable drying of the applied ink following ink application.
9. Printing machine according to claim 8, characterized in that the drying station (45) is coupled to a cleaning station (44) for the print heads (22, 23; 51, 52, 53) and is mounted relatively movably on the print head carrier (21, 32, 33; 50) in such a way that optionally drying of the ink application on the objects (6) or cleaning of the print heads (22, 23; 51, 52, 53) is possible.
10. Printing machine according to claim 1, characterised in that the workpiece holders (4) are constructed as spindles for receiving sleeve-shaped objects (6) and/or in that each spindle is assigned its own drive device for initiating a freely predeterminable rotational movement relative to the workpiece rotary table (3) and/or in that the workpiece holders (4) are constructed with a heating device for heating the objects (6) received thereon.
11. Method for operating a printing device which comprises a plurality of print heads (22, 23; 51, 52, 53) aligned parallel to one another and electrically movable relative to one another, wherein at least one of the print heads is assigned an adjusting means (34, 35; 57, 58, 59) for initiating a relative movement relative to at least one further print head (22, 23; 51, 52, 53), and wherein at least one workpiece holder (4) is provided for rotationally movable mounting of an object (6) to be printed on its circumferential surface, comprising the steps: placing an object (6) on the workpiece holder (4), performing a relative movement between at least two print heads (22, 23; 51, 52, 53) for influencing an axial resolution of a print image to be applied to the peripheral surface of the object (6), rotating the object (6) by means of the workpiece holder (4) about an axis of rotation (5) which is parallel to an axis of extension (30) of ink metering elements (31) of the print heads (22, 23; 51, 52, 53) by means of the workpiece holder (4), so that the circumferential surface passes the print heads (22, 23; 51, 52, 53), discharging ink onto the circumferential surface of the article (6) by a predetermined driving of the ink metering elements (31), characterized in that a rotational speed of the workpiece holder (4) is detected and a discharge rate for ink discharge by the ink metering elements (31) is adapted to the determined rotational speed.
12. Method according to claim 11, characterized in that, by means of the adjusting means (34, 35; 57, 58, 59), synchronous movement of the print heads (22, 23; 51, 52, 53) along the rotation axis (5) is carried out during the rotation of the object and/or in that, by means of the adjusting means (34, 35; 57, 58, 59) during the rotation of the object (6) a relative movement of the print heads (22, 23; 51, 52, 53) parallel to the axis of extension (30) is carried out in order to compensate for printing errors.
13. Method according to one of claims 11 or 12, characterized in that an uneven area of the peripheral surface of the object (6) is used as a reference for a printing operation and that a, preferably exclusive, printing of the uneven area is carried out.

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