Ink unit in a printing press for printing on hollow bodies

Abstract

The invention relates to an inking unit in a printing press for printing hollow bodies, comprising an ink application roller mounted on a plate cylinder, an anilox roller mounted on the ink application roller, and an ink distribution system extending in the axial direction of the anilox roller, wherein printing ink is supplied to the ink distribution system from at least one ink reservoir, wherein the ink distribution system is configured to distribute the printing ink supplied from the respective ink reservoir to ink zones arranged in a row in the axial direction of the anilox roller, wherein the ink distribution system comprises several ink metering pumps arranged side by side in the axial direction of the anilox roller, each of which delivers printing ink, wherein each of the ink metering pumps is configured to feed a quantity of the printing ink supplied to the ink distribution system into at least one of the ink zones.wherein the quantity of printing ink to be fed into a specific color zone by each of the ink metering pumps is determined by a control unit controlling the respective ink metering pump, wherein the control unit is configured to selectively control the ink metering pumps, wherein different printing inks from different ink reservoirs are supplied to the ink distribution system for the execution of a specific printing process, and wherein the ink distribution system is configured to feed these different printing inks into different color zones.

Description

[0001] The invention relates to an inking unit in a printing machine for printing hollow bodies according to the preamble of claim 1.

[0002] As is known, for example, from WO 2012 / 148576 A1, in the packaging industry, several printing units are usually used in a printing press to decorate hollow bodies, each of which has a cylindrical outer surface. Each of these printing units transfers a printing ink to a printing blanket used jointly by these printing units. The outer surface of the respective hollow body is then decorated with a multi-colored print motif, for example, by a relative movement between the outer surface of the respective hollow body and the previously inked, in particular multi-colored, printing blanket, in particular by rolling the outer surface of the respective hollow body on this printing blanket.

[0003] Such a printing machine for printing, i.e. for decorating hollow bodies, each having a preferably cylindrical outer surface, is used, for example, in conjunction with a production plant, which generally has several workstations, for the manufacture and further processing of such hollow bodies. Since the printing or decoration of the hollow bodies is carried out using a printing process, these hollow bodies can generally also be referred to as printed products. In such a production plant, the hollow bodies to be printed are manufactured in mass production, for example at a rate of several hundred or even several thousand pieces per minute, for example at a rate of between 1,500 and 2,500 pieces per minute, particularly preferably at a rate of between 1,800 and 2,200 pieces per minute. Such hollow bodies are made, for example, from metal, in particular from steel or aluminum, or from a plastic. Such hollow bodies made of metal are, for example,used as beverage cans or as aerosol cans. Such hollow plastic bodies are produced, for example, in the form of thermoplastic moldings and used, for example, as cups for packaging, for example, liquid or pasty foodstuffs, in particular dairy products or beverages. The respective hollow body can also be a round tube body made either of plastic or aluminum, whereby a tube is understood to be an elongated, solid, but malleable container which is intended to be filled with a particularly paste-like substance. Aluminum tubes are produced, for example, using a reverse extrusion process. Plastic tubes are produced, for example, by extrusion as seamless tubes. Another type of hollow body to be printed in an aforementioned printing machine can be preferably cylindrical containers or vessels made of glass, e.g. bottles or flacons.

[0004] The aforementioned WO 2012 / 148576 A1 describes a printing press, also referred to as a decorator, for decorating cans. An arrangement of multiple printing units, each with an inking unit, is provided for the multi-color decoration of a plurality of cans. Each inking unit belonging to one of the printing units has an ink fountain for supplying printing ink, with each ink fountain having an ink fountain roller, also referred to as an ink duct roller, for receiving the printing ink from the respective ink fountain. Each inking unit has an ink separator, each of which receives printing ink from the respective ink fountain roller. A roller train following the respective ink separator in the respective inking unit contains a plurality of iridescent ink distributor rollers and a plurality of ink transfer rollers, each of which interacts with at least one of the ink distributor rollers.For each inking unit there is a plate cylinder with at least one printing plate, whereby only a single inking roller interacts with the respective plate cylinder to apply the printing ink.

[0005] When printing or decorating hollow bodies, especially cans, each having a preferably cylindrical outer surface, the trend in recent times has been increasingly towards small-scale production, which in can printing means the production of a series of fewer than 100,000 cans, preferably even only 50,000 cans or an even smaller number of cans. Customers expect and demand an increasingly individual design of the print image, which is to be applied, in particular, to the outer surface of the hollow body in question. This requires several changes of printing inks on the printing press, i.e., by the decorator per work shift. Sometimes, this customer request results in the printing inks having to be changed practically every hour at a production speed of between 1,500 and 2,500 units (cans) per minute, preferably between 1,800 and 2,200 units (cans) per minute on the printing press, because the printing inks usuallyare designed as order-specific special colors and thus differ from one another in color, for example, depending on the production. A decorator is just one of several workstations in the production facility for manufacturing such hollow bodies. Typically, such a production facility has a large number of functionally interlinked workstations, i.e., workstations coordinated with one another in the production process. It is undesirable for the entire production facility, with all its workstations, to come to a standstill in order to carry out a changeover to a decorator due to a production change.Rather, intermediate storage is provided at various points in the production plant, in which the other workstations can temporarily store the workpieces they have processed and are required for the production of decorated hollow bodies, until the entire production plant is ready for continuous production again after the conversion of an individual workstation such as a decorator. Therefore, the time available for converting the decorator is practically only until an intermediate storage facility upstream of this decorator is filled by the continued production of upstream workstations. This period is, for example, a maximum of 15 to 20 minutes. In order to be able to implement rapid production changes in a generic production plant, short setup times are therefore also essential at a decorator.This applies in particular to a printing unit and / or inking unit arranged in a decorator, whereby it should be noted that such a decorator has, for example, eight to ten printing units and / or inking units, so that a corresponding number of printing inks may also have to be changed when production changes. The realization of a rapid changeover is made even more difficult by the fact that highly viscous printing inks are used, particularly when decorating hollow bodies such as cans, i.e. in particular when printing their respective outer surfaces, so that an inking unit and / or printing unit using these inks is difficult, i.e. requires increased effort, to clean. This is because these printing inks are not easy to remove from ink-carrying components due to their viscosity and high pigmentation, i.e. their low flowability and adhesive properties.Moreover, the printing inks most frequently used in a decorator, particularly the job-specific special inks, are more expensive than other printing inks, i.e. standard printing inks or printing inks for other printing processes such as offset printing or gravure printing, so that these highly viscous, particularly job-specific printing inks must be used sparingly for economic reasons.

[0006] The printing of the outer surface of a hollow body, in particular with a multi-coloured print motif, i.e. at least one print image, is preferably carried out using a letterpress printing process, in which printing ink is first applied to a printing blanket and only from there to the outer surface of a hollow body. To carry out this special letterpress printing process, a printing cliché is arranged on the outer surface of a plate cylinder, which is why this cylinder is sometimes also referred to as a cliché cylinder. The printing cliché ready for use in the printing process is a printing plate with a printing relief, whereby this printing relief forms the print image intended for the printing process of the indirect letterpress printing process, in contrast to the classic, i.e.direct letterpress printing process without mirroring, whereby in trouble-free printing operation only the printing relief is involved in the transfer of the printing ink fed to the plate cylinder from the inking unit to at least one printing blanket interacting with this plate cylinder. The printing plate or printing cliché to be mounted on a plate cylinder has a plate-shaped, preferably flexible support of finite length, e.g. made of sheet steel, with a particularly flexible printing body being arranged on this support. At least the ends of the support opposite each other in the circumferential direction of the plate cylinder can, for example, be pre-bent or angled to match the curvature of the outer surface of the plate cylinder in order to enable easier mounting of the printing plate, i.e. here in particular of the printing cliché, on the plate cylinder. The support of the printing plate or printing cliché has a thickness in the range of, for example, 0.2 mm to 0.3 mm.The printing plate, including its carrier, has a total thickness in the range of, for example, 0.7 mm to 1.0 mm, preferably approximately 0.8 mm. The printing body is made of, for example, a plastic. To produce the printing plate suitable for the printing process, the printing body is exposed, for example, with a negative film reproducing the printed image. The printing areas are hardened, for example, using a laser, and unexposed areas are subsequently removed from the printing body, for example, by washing out.

[0007] A printing press, also referred to as a decorator, for printing or decorating hollow bodies, each having a preferably cylindrical outer surface, preferably has several, e.g. eight or ten or even more printing units - also called printing stations -, wherein at least one of these printing units, in the preferred embodiment all of these printing units, each have a rotatable plate cylinder and an inking unit. The printing units or printing stations and optionally also the plate cylinders in this printing press are each mounted in a frame and can be used in the same printing process to create a multi-colored print motif on the same hollow body, corresponding to the number of printing units or plate cylinders involved. On the outer surface of each plate cylinder, there is usuallyIn each case, only a single printing cliché is arranged, the carrier of the printing cliché enclosing the circumference of the plate cylinder in question completely or at least largely, in particular by more than 80%. A length of the printing body of the printing cliché directed in the circumferential direction of the plate cylinder in question is preferably shorter than the circumferential length of the plate cylinder in question. The printing plate or the printing cliché is arranged or at least can be arranged by means of its carrier, in particular magnetically, on the outer surface of each plate cylinder, ie the printing plate or the printing cliché is held there preferably magnetically, ie by means of a magnetic holding force.

[0008] In a preferred embodiment, each plate cylinder has a diameter in the range between 100 mm and 150 mm, in particular between 120 mm and 130 mm, with an axial length of the respective plate cylinder being, for example, between 200 mm and 250 mm, in particular between 200 mm and 220 mm. The printing plate to be arranged on the outer surface of the respective plate cylinder has a width in the axial direction of the respective plate cylinder in the range of 150 mm to 200 mm, preferably approximately 175 mm.

[0009] Each of the plate cylinders used in the printing process transfers a specific printing ink to a printing blanket with its printing plate or printing cliché. The printing inks used are usually premixed, particularly job-specific special inks which, for example, are specially matched to the material of the hollow body to be printed in terms of their respective printability, depending on whether the surface being printed is made of aluminum, tinplate or plastic. These job-specific special inks also usually differ in their respective color tone. In a preferred embodiment of a printing press for printing or decorating hollow bodies, each having a cylindrical outer surface, a device is provided for transferring printing ink from the printing plate or printing cliché to the outer surface of the hollow body in question.This printing ink transfer device is preferably designed as a segmented wheel rotating around a horizontal axis, in particular, wherein on the periphery of this segmented wheel, i.e. along its circumference, preferably several, e.g. eight, ten, twelve or even more printing blankets are arranged or at least can be arranged one behind the other. The arrangement of the printing blankets on the circumference of the segmented wheel is achieved, for example, in that the printing blankets are attached to the circumference of the segmented wheel, for example by a material connection, preferably by gluing. The preferably several plate cylinders are each radially positioned or at least can be positioned against the printing blankets arranged on the circumference of the respective segmented wheel. In a particularly preferred embodiment of a printing press for printing or decorating hollow bodies each having a cylindrical outer surface, i.e.a decorator - a larger number of printing blankets are arranged one behind the other along the circumference of the segment wheel than there are plate cylinders radially positioned or at least adjustable to the segment wheel.

[0010] The preferably carousel-shaped ink transfer device, in particular the segmented wheel, has a diameter of, for example, 1,400 mm to 1,600 mm, preferably approximately 1,520 mm to 1,525 mm, and, with, for example, eight associated plate cylinders, has, for example, twelve printing blankets arranged one behind the other around its circumference. The surface of each printing cliché is preferably designed with a harder surface than the respective surface of the printing blankets. The surface of the printing blankets is preferably flat, i.e., has no profiling. In an operating state in which the plate cylinders involved in the printing process are each radially positioned against the printing blankets of the rotationally driven segmented wheel, the respective printing plates of these plate cylinders or their respective printing clichés roll on the printing blankets moved by the segmented wheel, the printing clichés each imprinting their printing relief into the respective printing blanket.The intensity of the impression can be adjusted, for example, before or at the start of a printing process, for example by means of remote control, by adjusting the contact pressure exerted by the respective plate cylinder on the respective printing blanket of the segment wheel, or is adjusted in such a way.

[0011] The printing process for printing, in particular on the respective outer surface of hollow bodies held, for example, on a mandrel wheel and fed to the segment wheel by means of the mandrel wheel, begins with all the printing inks required for the print image to be printed on the respective outer surface of the hollow body being applied, for example, from the respective printing cliché of the plate cylinders positioned, for example, against the segment wheel, to said hollow body by one of the printing blankets arranged on the circumference of the segment wheel. The printing blanket, thus inked with all the required printing inks, then transfers these printing inks simultaneously to the outer surface of the hollow body to be printed during a single rotation of the hollow body to be printed, held on the mandrel wheel, around its longitudinal axis.During the transfer of the printing inks from the printing blanket to the outer surface of the hollow body, the hollow body to be printed, held e.g. by the mandrel wheel, rotates at a circumferential speed equal to the relevant printing blanket arranged e.g. on the circumference of the segmented wheel. The respective circumferential speeds of the hollow body and printing blanket or segmented wheel are therefore synchronized with one another, whereby the hollow body to be printed, held e.g. on the mandrel wheel, is accelerated accordingly, in particular by a drive means, e.g. from its standstill, in particular until the circumferential speed of e.g. the segmented wheel is reached. In the preferred embodiment, the segmented wheel carrying the relevant printing blanket specifies the circumferential speed to be set e.g. on the mandrel wheel. The circumferential speed of the plate cylinder carrying the printing plate or printing cliché is also preferably dependent on the circumferential speed, e.g.of the segment wheel. In the preferred embodiment, the mandrel wheel and the segment wheel are each driven individually by their own drive and their respective rotational behavior is controlled or regulated by a control unit.

[0012] As already mentioned, hollow objects such as cans are printed with highly viscous printing inks. This means that the printing inks used in a decorator have a dynamic viscosity in a range between 2 Pa*s and 40 Pa*s at 20°C and are therefore quite viscous and thick and significantly less flowable than printing inks used in other printing processes such as offset printing. A preferred range for the dynamic viscosity of the printing inks used in a decorator is between 6 Pa*s and 10 Pa*s at 20°C. Printing inks with a lower dynamic viscosity are less fluid, but tend to splash onto the hollow objects in question during the printing process during their application and create a spray mist. This spray mist contaminates at least the inking unit of the decorator and its surroundings, i.e. the immediate vicinity of the inking unit in question, in an intolerable manner.This contamination also impairs subsequent production by the decorator, for example, by causing ink to be carried over from a previous printing process. Such highly viscous printing ink is heavier than water and has a density in the range of 1.1 kg / dm³, for example. 3 and 1.2 kg / dm 3 and is applied in the form of a wet layer in hollow bodies made of aluminum, for example, with up to 1.2 g / m 2 and for hollow bodies made of steel, for example, with up to 1.8 g / m 2 applied to their respective lateral surfaces.

[0013] Printing inks are generally very complex mixtures of substances. It has been observed that highly viscous printing inks in an inking unit tend to clump due to polymerization, i.e., a progressive curing process, due to their high proportion of color pigments and / or their high proportion of long-chain polymers. To keep these inks flowing despite their tendency to polymerize, attempts have been made in practice to keep such inks constantly agitated by stirring. Stirring can be done manually by an operator working on the decorator or mechanically by an agitator located in, or at least operatively connected to, the inking unit.Although stirring improves the flowability of the printing ink in question, the resistance of the stirred ink to the shear stress exerted by the stirring leads to frictional heat, so that the printing ink in question can heat up locally to a temperature of up to 80°C, particularly in a printing process lasting several hours. However, such a high temperature in turn promotes and accelerates the polymerization of the printing ink in question in an undesirable way. Such a high temperature not only changes the rheological properties of the printing ink in question, but can also lead to the printing ink in question changing its color and no longer accurately reproducing the color originally intended in the printing process. This is completely unacceptable because in a printing process, printing inks must, without exception, be printable in the correct color location and with as much stability as possible throughout the entire printing process.For example, a white printing ink can turn gray after heating and thus become unusable because no customer would accept this color change for the printed product they commissioned. Blocked printing inks and / or those whose color has changed due to unwanted heating are therefore no longer usable and certainly not reusable in a subsequent printing process. Given the usually comparatively high procurement costs of these highly viscous printing inks, this has a very negative impact on the cost-effectiveness of the printing process carried out by a decorator and can even prevent their use altogether.

[0014] For example, DE 10 2019 123 631 A1 discloses an inking unit of a printing press, particularly designed as a decorator, comprising at least one container for providing printing ink, an anilox roller, a doctor blade chamber, and an ink pump with a pump housing. A motor that rotatably drives the ink pump is arranged outside the pump housing. The pump housing is designed as a replaceable unit in the inking unit that can be replaced independently of the motor. This replaceable unit is detachable from the inking unit and the motor of the ink pump and can therefore preferably be replaced without tools. The printing ink to be pumped by the ink pump has a dynamic viscosity at 25°C, preferably in the range from 5 Pa*s to 75 Pa*s.

[0015] DE 10 2019 123 634 A1 discloses an ink agitator for circulating printing ink in an ink tray arranged in an inking unit of a printing press, comprising an agitator element, wherein the agitator element is moved or at least movable bidirectionally along the longitudinal extent of the ink tray by a drive, wherein a frequency of the working cycles carried out by the agitator element is set as a function of the viscosity of the printing ink arranged in the ink tray and / or wherein the frequency of the working cycles carried out by the agitator element is set differently for different printing inks.

[0016] DE 298 20 075 U1 discloses an inking unit with an ink tray. The ink tray is equipped with a screw conveyor and an ink pump. This ink pump preferably has its own drive, for example, an electric motor, but it can also be connected via coupling means to the drive of the printing press or the inking unit, provided the latter has its own drive. Within the ink tray, the printing ink is transported by a screw conveyor, which in turn is driven by a drive. The screw conveyor transports the printing ink toward the ink pump.

[0017] US 5,280,750 A also discloses an inking unit with an ink tray, wherein the ink tray is equipped with a conveyor screw and has an ink pump.

[0018] DE 691 17 645 T3 discloses an inking unit with an ink reservoir, wherein a screw conveyor is arranged in the ink reservoir.

[0019] DE 196 24 440 A1 discloses an inking unit with an anilox roller and a doctor blade device.

[0020] DE 110 081 T1 discloses an inking unit for a rotary printing press with printing rollers, printing cylinders and inking rollers, wherein provided are a) a feed roller, b) an ink feed rail mounted adjacent to the feed roller, which is movable between an operating position in which ink can be applied to the feed roller, and a rest position in which this is not the case, wherein the ink feed rail is provided with resilient means projecting therefrom, which smooth the surface of the ink applied to the surface of the feed roller without influencing the metering, and c) an ink metering pump which is connected to an ink source and to the ink feed rail and delivers metered quantities of ink to the ink feed rail for subsequent uniform application to the feed roller.

[0021] The invention is based on the object of creating an inking unit in a printing press for printing hollow bodies. This inking unit should be capable of printing a highly viscous printing ink with a dynamic viscosity, particularly in a range between 2 Pa*s and 40 Pa*s. This printing ink is kept permanently flowable by a suitable design of this inking unit, and the rheological properties of this printing ink remain at least virtually unchanged during the printing process. A color shade of the printing ink in question also remains stable during an ongoing printing process.

[0022] The object is achieved according to the invention by the features of claim 1. The dependent claims relate to advantageous embodiments and / or further developments of the solution found.

[0023] The advantages achievable with the invention consist in particular in the fact that the inking unit is designed in such a way that printing ink is kept permanently flowable within it, and the rheological properties of this printing ink remain at least virtually unchanged during the printing process, and a color shade of the printing ink in question also remains stable during the printing process. This means that any residual printing ink can be reused in a subsequent printing process. Ideally, no residue remains at all, since all the ink quantities introduced into the inking unit are also printed. Keeping the printing ink flowable in the inking unit also facilitates cleaning of this inking unit, which is necessary, for example, during a production change. The proposed inking unit is designed in such a way that exposure to shear forces on the printing ink is minimized, and unavoidable shear forces do not act on the printing ink for an extended period.

[0024] The proposed inking unit is also designed to allow for very fine, zonal ink dosing. The ink dosing pumps used for this purpose are controlled, or at least controllable, as needed and selectively as required, depending on the print image to be created. The amount of printing ink supplied by the ink dosing pumps to the respective ink zones is largely consumed, i.e., absorbed by the anilox roller and not recycled.

[0025] Further advantages will become apparent from the following description.

[0026] An embodiment of the invention is shown in the drawing and is described in more detail below.

[0027] They show: Fig. 1 a printing machine for printing or decorating hollow bodies each having a shell surface; Fig. 2 a color unit of the Fig. 1 printing machine shown; Fig. 3 a part of a paint distribution system of the Fig. 2 shown inking unit; Fig. 4 a micro annular gear pump.

[0028] Fig. 1 shows a simplified schematic representation of a printing machine for printing or decorating hollow bodies 01, e.g. two-part cans, each having a preferably cylindrical outer surface, wherein these hollow bodies 01 are sequentially fed by a conveyor device to a transport device designed as a mandrel wheel 02 and are held there individually on a holder on this transport device. The conveying direction is in the Fig. 1 by a directional arrow. A printing ink transferring device designed as a rotating or at least rotatable segmented wheel 03 cooperates with the mandrel wheel 02, wherein several printing blankets 07 are arranged one behind the other along the circumference of this segmented wheel 03. The respective rotation directions of the mandrel wheel 02 and the segmented wheel 03 are shown in the Fig. 1, each indicated by an arrow indicating the direction of rotation. Associated with the segmented wheel 03, along its circumferential line, are several plate cylinders 04 that are radially positioned or at least positionable against this segmented wheel 03. A printing plate, in particular a printing cliché, is arranged on the respective circumferential surface of each plate cylinder 04, said printing cliché being designed in particular for carrying out a letterpress printing process. A specific printing ink is supplied to each of the plate cylinders 04 by means of an inking unit 06 for inking its printing plate or printing cliché.

[0029] An inking unit 06 involved in the printing process receives the printing ink to be printed by means of a line system 34 carrying the printing ink from an ink reservoir 33, wherein this ink reservoir 33 can be realized, for example, by an ink container provided on the printing press, in particular a commercially available ink container, or by a central ink supply tank provided in the printing shop, i.e. assigned to the printing press, for example, or by an ink tray arranged in the printing press and manually filled with printing ink, for example. Each of the inking units 06 arranged on the circumference of the segment wheel 03 and each connected or at least connectable to one of the plate cylinders 04 prints, for example, a different printing ink, wherein these printing inks differ from one another, in particular in their respective color tone.The printing ink used in a high-pressure printing process is highly viscous, which means that the respective printing ink has a dynamic viscosity at 20°C, particularly in a range between 2 Pa*s and 40 Pa*s, sometimes even up to 60 Pa*s. This highly viscous and thus viscous printing ink is fed to the respective inking unit 06 from the respective ink reservoir 33 via the line system 34 with a pre-pressure in a range between 2 bar and 10 bar, preferably between 6 bar and 8 bar. The line system 34 carrying the printing ink is formed, for example, by a rigid pipe and / or a flexible hose connection.

[0030] Each of the inking units 06 is - as shown in a longitudinal section of the Fig. 2 shown in a simplified manner - preferably each designed as a short inking unit, which means that in its roller train transporting the printing ink to the plate cylinder 04 it only consists of an anilox roller 08 receiving the printing ink and a single ink forme roller 09. The anilox roller 08, with depressions on its outer surface, e.g. in the form of cells, receives the printing ink supplied to the relevant inking unit 06 from the ink reservoir 33 and passes this printing ink on to the ink forme roller 09 which interacts directly with this anilox roller 08, wherein the ink forme roller 09 is positioned against the plate cylinder 04 to be inked during an ongoing printing process. In the preferred embodiment, the plate cylinder 04 and the ink forme roller 09 are of the same size in terms of their respective diameters D.The plate cylinder 04, the inking roller 09, and the anilox roller 08 each have their own electric drive, i.e., a motor M, for their respective rotational movement, each controlled or regulated by a particularly digital control unit 28. This control unit 28 can be arranged, for example, in a control station belonging to the printing press.

[0031] To even out the ink absorption, an iridescent ink transfer roller 11 and, for example, a rider roller 12, which also irides, are advantageously mounted on the anilox roller 08. The ink transfer roller 11 preferably has a rubberized outer surface. An iridescent ink transfer roller 13 is also preferably mounted on the ink forme roller 09, likewise to even out the ink application. The respective stroke frequency of the iridescent rollers 11; 12; 13 is preferably set or at least adjustable on the control unit 28, which advantageously controls various functions of the inking unit 06, up to a maximum stroke frequency of, for example, 2 Hz. The axial stroke executed by the oscillating movement of the aforementioned rollers 11; 12; 13 extends, for example, over a range between 10 mm and 50 mm. The direction of rotation of the Fig. 2 only partially shown segment wheel 03 and the respective direction of rotation of the plate cylinder 04, the anilox roller 08, the ink application roller 09, the ink transfer rollers 11; 13 and the rider roller 12 are shown in the Fig. 2 are each indicated by an arrow indicating the direction of rotation.

[0032] In the periphery of the anilox roller 08, a washing device 14 with a washing doctor blade is advantageously additionally arranged, wherein the washing doctor blade can be adjusted to the anilox roller 08 in question, for example during a production change associated with a color change. The anilox roller 08 also has, for example, a tempering device 31 whose outer surface is provided with a specific temperature, wherein this tempering device 31 is formed in the interior of the anilox roller 08 and extends in the axial direction thereof, wherein these channels 23 have a tempering liquid flowing through them. This tempering liquid is, for example, water, preferably with a temperature in a range between 15°C and 25°C, in particular between 17°C and 22°C, wherein the tempering device 31 is designed such that it adjusts the temperature of the water starting from, for example,on the control unit 28 in the range between 15°C and 25°C with a tolerance of ±1°C. By controlling the temperature of the outer surface of the anilox roller 08, the viscosity of the printing ink to be transported by this anilox roller 08 is influenced with the aim of keeping this printing ink flowable on the one hand, but on the other hand also avoiding both sticking of the inking unit 06 and spraying of the printing ink as far as possible.

[0033] Fig. 2 shows a cross-section of a holder 16 extending in the axial direction of the anilox roller 08, e.g., in the form of a cross member, to which a doctor blade 17 is attached, which is positioned or at least adjustable against the outer surface of the anilox roller 08, in particular with a slight mechanical preload. The doctor blade 17 is arranged tangentially to the outer surface of the anilox roller 08 and is designed to apply printing ink to the outer surface of the anilox roller 08 in at least one of the inking zones. The doctor blade 17 is positioned with an adjustable, in particular slight, contact pressure against the outer surface of the anilox roller 08 and is arranged, e.g., between the holder 16 and a cover plate 18 attached to the side of the holder 16 facing the anilox roller 08.On the side of the holder 16 facing away from the anilox roller 08, at least one ink metering pump 21 is arranged, the ink-conveying conveyor device of which is rotationally driven by an electric motor 19. The respective motor 19, preferably designed as a stepper motor, allows the ink-conveying conveyor device of the respective ink metering pump 21 to rotate in a speed range starting from its standstill up to a speed of, for example, 200 rpm, whereby this speed is preferably variably adjustable and then also set on the control unit 28. A preferred speed range is between 70 rpm and 100 rpm. To convey a very small amount of printing ink, stop-and-go operation of the ink-conveying conveyor device of the respective ink metering pump 21 is also possible, whereby the operating sequences can be flexibly defined in this operating mode.The control unit 28 is designed such that it sets an individual, time-dependent speed curve for the respective conveying device of the respective ink metering pump 21, depending on a specific production selected or set on the control unit 28. This means that the speed of the conveying device conveying the printing ink of the respective ink metering pump 21 is adjusted over time as needed, specifically according to the amount of printing ink to be made available to the doctor blade 17 by the respective ink metering pump 21. The amount of printing ink to be made available to the doctor blade 17 is determined, in particular densitometrically, before executing a specific printing process, e.g., from a print template. The data thus determined is transmitted to the control unit 28, where it is converted into a specific amount of printing ink.This prevents over-inking of the hollow bodies 01 to be printed. The control unit 28 is also designed such that it can change the respective, i.e., previously set, speeds of all ink metering pumps 21 of the respective inking unit 06 together and in equal steps. Therefore, the control unit 28 can, on the one hand, individually adjust the respective speed profile of all ink metering pumps 21 of a specific inking unit 06, thus corresponding to the printing ink demand in the individual ink zones, and, on the other hand, adjust the speed behavior of all ink metering pumps 21 together in the same way.

[0034] The quantity of printing ink to be fed into the respective ink zone by the ink metering pumps 21 is preferably guided orthogonally against the doctor blade 17. The conveying device of the respective ink metering pump 21 has an inlet 22, arranged e.g. at the upper end of the holder 16, for printing ink supplied from an ink reservoir 33 to the inking unit 06, wherein this inlet 22 is connected or at least connectable to the line system 34 carrying the printing ink. A barrier filter is preferably arranged in the line system 34 carrying the printing ink and / or in the inlet 22, which prevents solid particles with a size of more than 10 µm transported in or with the printing ink from entering the conveying device of the respective ink metering pump 21. This can prevent malfunctions in an ink distribution system that meters printing ink very finely. The holder 16 with the doctor blade 17 and usuallythe cover plate 18 and the at least one ink metering pump 21 flanged to the holder 16 and driven by the motor 19 form, with reference to the respective inking unit 06, the respective ink distribution system arranged or at least arrangeable on the respective anilox roller 08.

[0035] Fig. 3 shows a perspective view of part of the Fig. 2, comprising a doctor blade 17, which is held by a holder 16 on the side facing the anilox roller 08 and extends longitudinally to the anilox roller 08 over at least one ink zone, preferably over several, e.g. over three ink zones, and an ink distribution bar 24 preferably arranged at the upper end of the holder 16, wherein on the rear side, ie on the side of the holder 16 facing away from the anilox roller 08, at least one ink metering pump 21, preferably several, e.g. three ink metering pumps 21 are arranged next to one another, each with its motor 19. In a preferred embodiment, a single ink zone extends longitudinally to the anilox roller 08, e.g. over a width in a range between 20 mm and 60 mm, preferably 40 mm or 50 mm. In an advantageous embodiment of the inking unit 06, several, e.g.Three to six ink zones are arranged next to one another along the anilox roller 08, wherein these ink zones are preferably each of the same width. In the case of several ink zones arranged next to one another along the anilox roller 08, these can, however, also be of different widths if required. Furthermore, it can be provided that several holders 16 are arranged next to one another along the anilox roller 08. On the front side of the respective holder 16, i.e. on its side facing the anilox roller 08, a cover plate 18 is generally arranged (. Fig. 2), which in the Fig. 3 is not shown for a better understanding of the ink distribution system. The printing ink supplied from the ink reservoir 33 by means of the inlet 22 of the ink distribution bar 24 is guided in channels and / or grooves inside this ink distribution bar 24 and is initially fed to the respective conveying device of at least one of the ink metering pumps 21. The conveying device of the respective ink metering pump 21 is controlled by the control unit 28 such that a precisely defined amount of printing ink is fed into a specific ink zone. The ink distribution system is accordingly designed such that it feeds the printing ink supplied to it from the respective ink reservoir 33 in an amount determined by the control unit 28 into at least one ink zone or distributes it over a plurality of ink zones arranged in a row in the axial direction of the anilox roller 08.It can also be provided that different printing inks are supplied to the ink distribution system from different ink reservoirs 33 for executing a specific printing process, wherein the ink distribution system is designed to feed these different printing inks into different ink zones. An advantage of this type of ink distribution system is that only the ink zones required for the respective printing process are actually supplied with printing ink, thus supplying the inking unit 06 with the exact amount of printing ink and in the required dosage.

[0036] Fig. 3 shows, by way of example, a plurality of ink outlet openings 26 formed in connection with the ink distribution bar 24, from each of which an amount of printing ink measured by the conveying device of one of the respective ink metering pumps 21 emerges, wherein this printing ink is supplied to at least one specific ink zone via a shaped piece 27 which is preferably wedge-shaped in or on the holder 16, wherein the shaped piece 27 in question widens from the respective ink outlet opening 26 to the doctor blade 17 parallel to the axial direction of the anilox roller 08.

[0037] The at least one ink metering pump 21 is preferably designed as a micro gear pump. A minimum volume flow delivered by its conveying device is, for example, 0.004 l / h. A maximum volume flow delivered by its conveying device is, for example, 2.5 l / h. The ink metering pump 21 in question is preferably designed such that, even in continuous operation for, for example, 20 hours per working day, at a pre-pressure at the ink distribution bar 24 in a range of, for example, 2 bar to 10 bar, it delivers a quantity of printing ink in the range between its minimum volume flow and its maximum volume flow, wherein this printing ink has a dynamic viscosity in a range between 2 Pa*s and 40 Pa*s at 20°C.At the ink distribution bar 24, which is connected to the relevant ink reservoir 33 and extends longitudinally to the anilox roller 08, preferably over several ink zones, a certain pre-pressure of the printing ink guided in the line system 34 must be present in order to ensure precise metering of the printing ink distributed by the respective ink metering pumps 21 to the respective ink zones. Advantageously, a pressure sensor 29 is arranged at the inlet 22 or in the ink distribution bar 24 in order to detect the pre-pressure of the printing ink guided in the line system 34 present there. A flow direction of the printing ink guided in the line system 34 is shown in FIG. Fig. 2 indicated by directional arrows. The pressure sensor 29, which detects the pre-pressure, reports its measurement data to the control unit 28. The control unit 28 then controls, depending on the measurement data of this pressure sensor 29, the amount of printing ink to be withdrawn from the respective ink reservoir 33 and supplied to the ink distribution system. The amount of printing ink to be withdrawn from the respective ink reservoir 33 is supplied to the ink distribution system, for example, by at least one pump 32 controlled by the control unit 28 and conveying printing ink in the line system 34.

[0038] Fig. 4 shows, in a sectional view, an example of the structure of a micro annular gear pump. A micro annular gear pump is a rotary displacement pump and has an inlet opening 36 on its suction side for the printing ink to be metered and pumped by it, and an outlet opening 39 on its pressure side. An internally toothed outer rotor 37 and an externally toothed inner rotor 38 are located in a preferably cylindrical housing. The outer rotor 37 and the inner rotor 38 are mounted eccentrically to one another and each have cycloidal teeth, with their two tooth sets meshing. During the rotation of the aforementioned rotors 37; 38, their two tooth sets form a system of several sealed pumping chambers at all times. The inner rotor 38 has one tooth fewer than the outer rotor 37. With a tooth number ratio of e.g. six teeth on the inner rotor 38 to e.g. B. seven teeth on the outer rotor 37 - as in the Fig. 4 as an example - this results in a chamber number of six. A shaft of the micro annular gear pump is torsionally rigidly connected to the inner rotor 38 and is driven by the electric motor 19 belonging to the respective micro annular gear pump, wherein this motor 19, preferably designed as a stepper motor, is precisely controlled by the control unit 28. The outer rotor 37 is rotatably mounted on its circumference and is also driven by the inner rotor 38. By rotating the rotors 37; 38 around their offset axes - in the Fig. 4 - indicated by crosses - the pumping chambers enlarge on the suction side, while simultaneously decreasing on the pressure side. A uniform and low-pulsation flow is created between the kidney-shaped inlet opening 36 and outlet opening 39, which each connect several pumping chambers simultaneously. The pumping direction of the micro annular gear pump is reversible, with a preferred direction of rotation. Fig. 4, the direction of rotation chosen here as an example is indicated by a direction of rotation arrow. List of reference symbols 01 Hollow body 02 Mandrel wheel 03 Segment wheel 04 Plate cylinder 05 - 06 Inking unit 07 Printing blanket 08 Anilox roller 09 Ink application roller 10 - 11 Ink transfer roller 12 rider roller 13 Ink transfer roller 14 Washing facility 15 - 16 holders 17 doctor blades 18 Cover plate 19 Engine 20 - 21 Paint dosing pump 22 Inlet 23 Channel 24 color distribution bar 25 - 26 Paint outlet opening 27 fitting 28 Control unit 29 Pressure sensor 30 - 31 Tempering device 32 Pump 33 color reservoir 34 Pipeline system 35 - 36 Inlet opening 37 Outer rotor 38 inner rotor 39 Outlet opening D Diameter M engine QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] WO 2012 / 148576 A1 [0002, 0004] DE 10 2019 123 631 A1

[0014] DE 10 2019 123 634 A1

[0015] DE 298 20 075 U1

[0016] US 5,280,750 A

[0017] DE 691 17 645 T3

[0018] DE 196 24 440 A1

[0019] DE 110 081 T1

[0020]

Claims

[1] An inking unit (06) in a printing press for printing hollow bodies (01), comprising an ink form roller (09) mounted on a plate cylinder (04) and an anilox roller (08) mounted on the ink form roller (09), and comprising an ink distribution system extending in the axial direction of the anilox roller (08), wherein printing ink is supplied to the ink distribution system from at least one ink reservoir (33), wherein the ink distribution system is designed to distribute the printing ink supplied from the respective ink reservoir (33) to ink zones arranged next to one another in the axial direction of the anilox roller (08), wherein the ink distribution system comprises a plurality of ink metering pumps (21) arranged side by side in the axial direction of the anilox roller (08), each of the ink metering pumps (21) being designed to feed a quantity of the printing ink supplied to the ink distribution system into at least one of the ink zones,wherein the quantity of printing ink to be fed into a specific ink zone by each of the ink metering pumps (21) is determined by a control unit (28) controlling the relevant ink metering pump (21), wherein the control unit (28) is designed to selectively control the ink metering pumps (21), wherein different printing inks from different ink reservoirs (33) are supplied to the ink distribution system for carrying out a specific printing process, wherein the ink distribution system is designed to feed these different printing inks into mutually different ink zones. [2] Inking unit (06) according to claim 1, characterized by that the ink dosing pumps (21) are designed to deliver printing ink with a dynamic viscosity at 20°C in the range between 2 Pa*s and 60 Pa*s. [3] Inking unit (06) according to claim 1 or 2, characterized bythat the respective printing ink is supplied to the ink dosing pumps (21) from the respective ink reservoir (33) with a pre-pressure in the range between 6 bar and 10 bar. [4] Inking unit (06) according to claim 1 or 2 or 3, characterized by in that the ink distribution system is designed to cooperate with a doctor blade (17) extending in the axial direction of the anilox roller (08), wherein the doctor blade (17) is designed to apply printing ink to a circumferential surface of the anilox roller (08) in at least one of the inking zones, wherein the doctor blade (17) is arranged tangentially to the circumferential surface of the anilox roller (08) and is applied to the circumferential surface of the anilox roller (08) with an adjustable contact pressure, wherein the quantity of printing ink to be fed into the respective inking zone by the respective ink metering pump (21) is guided in each case orthogonally against the doctor blade (17). [5] Inking unit (06) according to claim 1 or 2 or 3 or 4, characterized by that the ink application roller (21) and the anilox roller (08) are each individually motor-driven. [6] Inking unit (06) according to claim 1 or 2 or 3 or 4 or 5, characterized by that a speed of the ink application roller (21) and / or a speed of the anilox roller (08) is set by the control unit (28) in each case as a function of a speed of the plate cylinder (04). [7] Inking unit (06) according to claim 1 or 2 or 3 or 4 or 5 or 6, characterized by that each paint metering pump (21) is designed as a micro gear pump, wherein a minimum volume flow conveyed by a conveying device of the respective micro gear pump is 0.004 l / h and a maximum volume flow conveyed by it is 2.5 l / h. [8] Inking unit (06) according to claim 1 or 2 or 3 or 4 or 5 or 6 or 7, characterized bythat the control unit (28) is designed such that it determines the amount of printing ink required in each ink zone from data which have been made available to it before execution of a printing process selected or set thereon. [9] Inking unit (06) according to claim 7 or 8, characterized by that the control unit (28) is designed such that it adjusts the conveying device of the respective ink metering pump (21) such that the quantity of printing ink determined by the control unit (28) for a particular ink zone is fed into the respective ink zone by the respective conveying device. [10] Inking unit (06) according to claim 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9, characterized bythat the control unit (28) is designed such that it can change the amount of printing ink to be fed into the relevant ink zones both individually for each ink zone and for all ink zones together and in equal steps.

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