EP2698256B2 - Printing device, print head for same and method for extraction of printing ink - Google Patents

Description

The present invention relates to a printing device having the features of independent claim 1. The invention also relates to a method for sucking off sprayed and/or spattered printing ink in the area of a print head, having the features of independent method claim 8.

Printing devices for printing on items such as containers or bottles are known, inter alia, as so-called direct printing devices, which normally include at least one electronically or digitally controllable print head with which the items, containers or bottles can be printed. For this purpose, the at least one print head is in a defined position relative to a print area on an article or container outer surface, at least during a printing process, so that the defined print area can be exposed to the printing liquid, ink or ink. Such a direct printing process can replace labelling, since the print area forms a feature that, like a conventional label, refers to the content and/or can form a sales-promoting motif. For example, electrostatic print heads such as inkjet or similar print heads can be used for such direct printing methods, which have a large number of individual nozzles, which are normally arranged in the form of a matrix and can be controlled individually, so that any motifs can be produced. Since the print area is usually significantly larger than the coverage area of the nozzle matrix of the print head, either the print head or the print area must be moved relative to one another to create the motif through the printing process, or both. If multi-colored motifs are to be generated, the printing device can be formed by a plurality of print heads, each with different colors, which are normally in a fixed spatial relationship to one another, but can optionally also be assigned to the print areas of a number of containers, as is the case, for example, in EP 2 152 519 A1 is revealed.

In most direct printing processes that work with inkjet printing technology, undesirable print fog effects occur, which can lead to a loss of quality in the printed image and to contamination problems in downstream handling stations in a machine environment. Such a print mist is caused by droplets breaking off when the printing liquid is ejected from the nozzles and/or when the jets of liquid hit the printing area of the article or container and is distributed in the surrounding air as a fine aerosol in an uncontrolled manner. In the case of increased printing distances, the individual drops can also be strongly decelerated by air friction effects, in which case a considerable proportion of the drop impulses can be lost. This can also lead to floating states. The spray of finely distributed ink or printing ink particles can undesirably be deposited on elements of the respective printing device and/or on parts of the machine environment, where it causes dirt that can only be removed again with a great deal of cleaning effort. A discharge of the precipitation from printing ink particles to other machine parts and their accumulation can lead to significant pollution problems and malfunctions. Especially with high machine outputs and the associated high transport speeds, additional turbulence can arise, which can increase the formation of pressure mist and/or contribute to an imprecise printed image.

In addition, such ink or printing ink particles that have deposited outside the actual printing area may not be able to be detected by a curing station that works with UV light and will therefore not cure. These particles can be wiped off and can thus also get into the beverage that is filled into the container, which can lead to impaired taste or even to health hazards, depending on the printing ink used.

the EP 2 250 026 A1 proposes a printing device for printing bottles and containers with several printing positions to reduce the pollution problem and to improve the print quality, each of which has a container carrier in the form of a bottle or container plate and a stamp for fixing the bottle or the container on the plate. Each printing position or each plate is assigned a sleeve-like housing that completely encloses and accommodates the container or bottle when closed. The housing or protective sleeve also accommodates print heads with which the bottle or container is printed, possibly with several different colors. Fixing devices for curing the printing ink are also located within the lockable housing. A suction device is used to suck off sprayed printing ink, which is sucked off by means of a plurality of suction pipes on an upper side of the housing and is guided to a common suction device via collecting pipes or lines. In order to enable the sprayed printing ink to be sucked off, each protective sleeve is designed in such a way that a slit-shaped opening remains at the lower edge of the closed protective sleeve for a supply air flow into the inner space of the protective sleeve. After the printing and curing of the ink, the housing or protective sleeve is opened again and the printed bottle or container is removed or transferred to another transport star.

The one in the EP 2 250 026 A1 proposed suction device requires a considerable construction effort for the mechanically closable and openable protective sleeves for each printing position, since all individual protective sleeves must be precisely controlled without disturbing or influencing the container flow. The suction upwards requires a sufficient volume flow of the suction device, but cannot prevent that part of the printing ink is entrained upwards before it hits the printing area of the container and, under unfavorable circumstances, condenses in the upper area of the container, where the deposited particles may not be reached by the curing device and/or may lead to a reduction in the perceived quality and/or the print image quality of the entire container.

The patent documents U.S. 2012/0133705 A1 and DE 10 2009 013 477 A1 disclose a printing device having the features of the preamble of claim 1. The document DE 10 2006 053 821 A1 shows a printing device with ink mist extraction. DE 10 2010 036 839 A1 shows a method for renewing the ink in nozzles of an ink print head in an ink printing device, with a suction flow of such strength being passed between the ink print head and a printing material that only the ink droplets of smaller volume are deflected in such a way that they do not reach the printing material. EP 2 361 774 B1 shows an ink jet printer in which a print head is arranged between suction openings of a suction device for sucking ink. The documents JP 2010 058441 A and JP 2000 255083 A each disclose an ink jet print head and an ink jet printer, which are designed for printing on paper and suction devices, which are arranged in the direction of movement before and after the print head.

A primary aim of the invention is to provide a printing device for printing articles such as containers or bottles, with at least one print head, which avoids the disadvantages mentioned. The printing apparatus should be mechanically simple in construction and capable of removing and/or avoiding as much spray as possible from ejected ink without exposing larger article or container exterior surfaces to the spray.

This object of the invention is achieved with the subject matter of the independent claims. Features of advantageous developments of the invention result from the dependent claims. In order to achieve the stated objective, the invention proposes a printing device with at least one print head which, at least during a printing process, is in a defined position relative to a printing area on an article or container outer surface and is prepared to apply liquid printing ink to the article, the container or to apply to the bottle, optionally in one-color or multi-color printing, which then hardens and dries and can thus replace a subsequently applied label. According to the present invention, the print head or the printing device is coupled to a suction device for sucking off sprayed and/or spattered printing ink, which is spatially and functionally assigned to the at least one print head. The term spatial allocation means that the suction device is not only arranged in the vicinity of the print head and its outlet openings, so that print mist is extracted from the vicinity of the print head and/or the printing area, but that largely all of the print head and Particles, satellites, droplets, etc. detached from the printing ink to be applied to the container, which are capable of depositing and condensing as disruptive printing mist away from the actual printing area, are sucked off in the immediate vicinity of the outlet openings of the print head for the ejected liquid printing ink, preferably immediately after their formation and not only after a pressure mist has formed in the vicinity of the printing device. The term functional assignment means that the suction device does not suck the detached particles and droplets out of a larger spatial environment, a chamber or the like, but rather immediately after they have formed at the outlet openings of the print head, so that they are already sucked off. before they settle on the container or the machine environment and can lead to disruptive paint mist there.

In principle, the printing device according to the invention is suitable for printing all types of bottles which have a definable printing area on their outer surfaces and can be reached by a print head.

The formation of droplets, which is unavoidable in ink-jet printing due to drop breaks and/or due to air friction effects, which occur due to hovering, which occurs particularly with larger printing distances, can be largely removed with the suction device according to the invention, so that high print quality and minimal machine contamination can be guaranteed. In this context, it should be mentioned that droplet break-offs and the mentioned suspension states (e.g. decelerated droplets, suspended particles and aerosols) cannot generally be completely avoided in ink-jet printing technology. However, the optimization measures according to the invention make a significant contribution to keeping these disadvantageous effects as low as possible. The extraction does not take place in closed housings or on rotating elements, as is the case with known printing stations, but directly on the fixed or movable print heads. It is not extracted in a closed housing or housing, but in an open space, whereby the extraction can take place before, after, above and/or below the print head. The advantage here is the lack of effort that would be required with moving and/or circulating suction in the form of rotary distributors and the generation of negative pressure on the rotating or moving parts. The complex opening and closing mechanism associated with a housing can also be omitted. In addition, the suction is located directly where the pressure mist is generated. Contamination of components as well as housing elements etc. is reduced to a minimum with the present invention.

In the printing device according to the invention, the suction device is thus arranged in the immediate vicinity of outlet openings in the print head for the printing ink. Thus, the suction device can optionally be combined with the print head in a structural unit and/or integrated into it. However, it is also possible to combine the suction device with the print head in such a way that it is guided and attached to the outside of the housing, so that the suction openings are in the immediate vicinity of the outlet openings of the print head for the printing ink come.

The suction device can have, for example, one, two, three or more suction openings and/or suction slots, which can either be integrated in the print head or in its housing or can be arranged on the outside of the print head. For example, an integrated arrangement may be configured in such a way that a plurality of suction slots are arranged on both sides of nozzle openings of the print head, so that the suction slots are located in front of and behind the nozzle openings in the direction of movement when the article or container for forming the printed image is stationary stationary print head is moved in an oscillating manner in the horizontal direction. However, such print heads can also be used to print shaped containers and/or non-rotatable or only partially rotatable containers by means of a pure relative movement or a coupled movement—partially rotating and translational movement. In principle, the print head can either be fixed or movable. The suction according to the invention can of course also be implemented with a movable print head. In such a variant, the suction device would have to be stationary in relation to the print head and would have to move with it. So when we speak of an oscillating movement, this is in no way to be understood as limiting to a specific direction of movement, but means a back and forth movement in all conceivable and meaningful spatial directions.

In the same way, the suction slots can be arranged above and below the nozzle openings, so that the suction slots are located above and below the nozzle openings in the direction of movement when the article or container is oscillating in the vertical direction and/or in combined directions to generate the printed image with the print head stationary directions is moved. Ring-shaped or ring-segment-shaped suction openings are also conceivable, which are arranged in a ring around the central nozzle openings. In addition, numerous other design variants for the suction openings are also conceivable, such as suction nozzles, suction lines, suction slots or the like attached to the outside of the housing of the print head, which can optionally be designed to be removable or dismountable.

The floating droplets created by the printing process - the so-called satellite droplets - are sucked off adjacent to the nozzles of the print head. For a trouble-free and contact-free rotation or movement of the container to be printed in front of the print head, a space is required from which the print mist is to be extracted during the printing process. The deflection of the ink droplets emitted by the print nozzles at high speed should be as small as possible in order not to impair the print quality. It is advantageous for this to have suction around the print head or suction in front of and behind the print head in the direction of movement of the object to be printed. Due to the relative movement of the body to be printed and the superimposition of the suction flows, a container-specific flow profile is created between the container and the print head. By extracting the respective volume flows of the slot extractions, this flow profile can be achieved for optimal extraction of the print mist with minimal impact on the ink-jet print.

It is advantageous that the suction device can be subjected to variable and/or controllable or adjustable suction pressure, with the suction pressure being adjustable and/or adjustable differently, for example for two or more suction openings or slots, as described in claim 1. In this way, the print mist extraction can be adjusted to different operating conditions such as, for example, to different distances between the print head and the print area to be printed on the article or container. Different suction pressures at two or more suction openings of the print head can also be useful if, for example, a specific direction is to be imposed on the suction flow or if this is to be variable depending on the respective processing and/or printing speeds.

An intake slot width of an intake slot or an intake opening can be, for example, between 0.1 mm and 10 mm, preferably between 0.2 and 7 mm, particularly preferably 0.2 to 5 mm. These dimensions have proven to be advantageous in practice, with the larger cross-sections and slit widths making sense when the distance between the print head and the print area on the article or container is relatively large, which is particularly important in the case of an uneven print area or relief-like characteristics on the Container jacket surface is necessary, since in this case a relatively large volume flow is required for effective suction. In the case of such container surfaces, the pressure distance can be, for example, up to 7 mm or more. However, if the cross-sections of the suction openings are too small, a large suction volume flow would lead to a very high air velocity of the suction flow, which could possibly have a negative effect on the print quality, since in this case parts of the printing ink are also sucked off or the printing ink emerging from the nozzles at high speed is deflected could become. If the distance between the print head and the print area is very small, for example 1 mm or less, the suction volume flow can be smaller, which means that smaller slot widths and cross sections of the suction openings are also sensible.

The flow velocities along the suction slot can be influenced and varied by adapting the geometry of the intake channels and their side wall design, and thus adapting them to the typical place where the ink mist is generated. So it may depend on the container design and the resulting different pressure differences, it makes sense to increase the flow velocities in areas with large pressure differences. An increase in the flow rate can be achieved, for example, by narrowing the cross section. It is also conceivable to achieve different flow speeds by adjusting the suction power.

The necessary negative pressure or suction volume flow can be generated either centrally via distributed lines or locally for the individual print heads or their suction devices.

Each of the suction openings can also be equipped with devices for holding back liquid that has been sucked in, such as a so-called ink trap, e.g. in the form of a trough, a sponge or the like, so that the print heads can be pivoted (e.g. when changing format or product), without any liquid printing ink that is contained and/or deposited or condensed escaping from the suction opening. A trough or channel can be arranged in a lower area of the suction opening, so that in the area of the suction opening condensed or precipitated hydraulic fluid is held there and can be drawn off before it emerges from the suction opening in an undesired manner, before it has been entrained by the suction flow.

Since the print head together with the suction device should also be variably operable in an inclined position or can be tilted for maintenance purposes or when changing products, appropriate measures must be taken to prevent the ink droplets sucked in from running out. This can be implemented, for example, by the ink traps mentioned, by a bypass with a suction device, by absorbent sponges or similar devices.

Furthermore, the printing device can be assigned or subordinated to a fixing device for curing the printing ink on the printing area of the article, the container or the bottle, which covers a fixing area that is larger than the printing area and extends beyond this printing area on several, preferably all sides. In this context, each print head can optionally be assigned its own hardening or fixing device, which can ensure partial hardening after each color applied. After the complete printing of a container has been applied, it can be subjected to UV curing, for example.

The invention further relates to a print head for applying liquid printing ink to a print area, which is in particular part of a printing device according to one of the embodiment variants described above and has an integrated suction device.

Finally, the invention comprises a method for sucking up sprayed and/or spattered ink in the immediate vicinity of ink outlet openings of a print head which is prepared for applying liquid ink to a printed area of an article, container or bottle or the like and which is at least during a printing process in a defined position relative to the printing area on an article or container outer surface. In the method, a large number of detached satellites and/or suspended droplets of the liquid ink can be sucked off in the vicinity of the printing area, in particular in the immediate vicinity of the outlet openings of the print head and/or in the immediate vicinity of the printing area of the article or container. In addition, a variable volume flow can be present at at least one suction opening, which can be between 0 and approximately 20 m ³ /h. Different and/or variable volume flows can also be present at several suction openings, each of which can be between 0 and approx. 20 m ³ /h.

In addition to the variants and aspects of the invention mentioned above, further options are conceivable, such as error detection, which is coupled to the suction device in such a way that the suction device is regulated or controlled depending on optical measurement parameters that are obtained in the error detection e.g. to set stronger suction in the case of stronger print mist formation or weaker suction in the case of too much deflected printing ink and an associated deterioration in print quality. Another option is an additional housing or guide elements for the respective pressure stations in order to be able to direct the exhaust air flows more precisely and to completely rule out the formation of pressure mist outside the pressure areas. In addition, different variants of multi-color printing are conceivable, for example a rotatable ring with print heads arranged thereon, which can be moved relative to the container positions in order, for example, to be able to apply different printing colors one after the other.

• Fig. 1 zeigt in zwei schematischen Ansichten einen Kunststoffbehälter, der mittels einer Druckvorrichtung im Direktdruckverfahren an seiner Außenmantelfläche bedruckt wird.
• Fig. 2 zeigt eine schematische Perspektivansicht einer Ausführungsvariante eines erfindungsgemäßen Druckkopfes.
• Fig. 3 zeigt in einer schematischen Draufsicht die Strömungsverhältnisse beim Bedrucken eines Behälters.
• Fig. 4 zeigt einen schematischen Längsschnitt durch einen Ansaugkanal eines Druckkopfes.
• Fig. 5 zeigt einen Detailschnitt eines Teils des Ansaugkanals des Druckkopfes.
• Fig. 6 zeigt eine schematische Darstellung eines Förderabschnittes mit einem Druckbereich zur direkten Bedruckung von Behältern.
• Fig. 7 zeigt eine Ausführungsvariante eines ringförmigen Druckbereichs, der einem Förderstern der Anlage zugeordnet ist.

In the following, exemplary embodiments are intended to explain the invention and its advantages in more detail with reference to the attached figures. The proportions of the individual elements to one another in the figures do not always correspond to the real proportions, since some forms are shown in simplified form and other forms are shown enlarged in relation to other elements for better illustration.

• 1 shows two schematic views of a plastic container which is printed on its outer lateral surface by means of a printing device using the direct printing method.
• 2 shows a schematic perspective view of a variant embodiment of a print head according to the invention.
• 3 shows the flow conditions when printing a container in a schematic plan view.
• 4 shows a schematic longitudinal section through an intake channel of a print head.
• figure 5 shows a detail section of part of the suction duct of the printhead.
• 6 shows a schematic representation of a conveyor section with a printing area for the direct printing of containers.
• 7 shows a variant embodiment of an annular pressure area, which is associated with a star conveyor of the plant.

Identical reference symbols are used for elements of the invention that are the same or have the same effect. Furthermore, for the sake of clarity, only reference symbols are shown in the individual figures that are necessary for the description of the respective figure. The illustrated embodiments only represent examples of how the device according to the invention or the method according to the invention can be designed and do not represent any final limitation.

The two schematic views of the 1 show a plastic container 10 which is printed on its outer lateral surface 14 by means of a printing device 12 according to the invention using the direct printing method. The plastic container 10 can in particular be a PET container, as is used in large numbers in the beverage industry. After printing, the container 10 can be filled with a liquid, such as a drink, in a downstream filling station and then sealed gas-tight at its top opening. The printing device 12 comprises at least one print head 16, which is in a defined position relative to a printing area 18 on the container lateral surface 14 at least during a printing process and is prepared to apply liquid printing ink 20 to the container 10 or the bottle. After the container 10 has been printed, the printing ink 20 applied in the printing area 18 can be cured, for example by means of UV curing, by means of heating or by other suitable measures. This hardening (not shown) can optionally take place immediately after the printing of each individual container 10 in a subsequent processing step or in a downstream treatment station.

The impingement of the printing area 18 with printing ink 20 can optionally take place in single-color or multi-color printing, with multi-color printing normally requiring a plurality of print heads 16 which successively apply different printing inks 20 in each case. This type of direct printing can replace a label that is applied later. Optionally, however, the printing can also be applied to a previously applied blank label.

The print head 16 of the printing device 12 is coupled to a suction device 22 for sucking off sprayed and/or spattered printing ink 20, which is indicated by the broken arrows in the side view of FIG Fig. 1a and in the top view of the Fig. 1b is indicated, which in each case indicate a suction air flow 24 that suck the splattered and/or sprayed printing ink 20 out of a space between the print head 16 and the printing area 18 . According to the present invention, the suction device 22 is associated with the print head 16 both spatially and functionally. The spatial assignment - meaning, for example, an integration of the suction device 22 in the housing 26 of the print head 16 - means that the suction device 22 is not only arranged in the immediate vicinity of the print head 16 and its outlet openings for the printing ink 20, so that Print mist is extracted from the environment of the print head 16 and/or the printing area, but that largely all particles, satellites, droplets, etc. that have escaped from the print head 16 and are detached from the printing ink 20 to be applied to the container 10 and that are able to deposit and knock down as disruptive pressure mist away from the actual printing area 18, be sucked off in the immediate vicinity of the outlet openings of the print head 16. This suction thus takes place immediately after the formation of detached droplets and not only after the formation of a pressure mist in the vicinity of the printing device 12, which is expressed by the concept of functional association. The detached particles and droplets are sucked off immediately after they have formed at the outlet openings of the print head 16 before they are deposited on the container 10 or on parts of the machine environment and can lead to disruptive ink mist and contamination problems there.

As the schematic perspective view of an embodiment of the print head according to the invention 16 of 2 shows, the suction device 22 is arranged in the immediate vicinity of outlet openings 28 in the print head 16 for the printing ink 20. Like it the 2 indicates that the suction device 22 is combined in a structural unit with the print head 16 and integrated into its housing 26 . As can be seen there, the suction device 22 comprises a plurality of suction slits 30, the suction slits 30 being optionally arranged on both sides of the nozzle openings 28 of the print head 16 to which the printing ink 20 is applied, so that the suction slits 30 are located in front of and behind the nozzle openings 28 in the direction of movement. when the container 10 is moved in an oscillating manner in the horizontal direction to generate the print image with the print head 16 stationary (cf. double arrow of Fig. 1b ). In this context, the term oscillating movement is not to be understood as limiting, but essentially means that an oscillating component of movement is present. Optionally can non-round and/or non-rotatable shaped containers that are moved when the print head is stationary or in relation to which the print head is moved can also be printed with a direct printing process. Relative movements between the surface to be printed and the printhead 16 are normally required without these relative movements having to be specified in more detail.

In the same way, the suction slots 30 can be arranged above and below the nozzle openings 28, so that the suction slots 30 are located above and below the nozzle openings 28 in the direction of movement when the container 10 moves oscillatingly in the vertical direction to generate the print image with the print head 16 stationary is (cf. double arrow of Fig. 1a ). The supply of the print head 16 with printing ink 20 is also indicated by an arrow, as is the suction air flow 24 of the suction device 22.

The schematic top view of the 3 illustrates the flow conditions that can arise when printing a container 10 by means of a direct printing device 12. The relative movement of the container 10 to be printed and the superimposition of the suction flows 24 create a container-specific flow profile 34 in a space 32 between container 10 and print head 16. The pressure mist 38 in the space 32 is to be sucked off by means of the volume flows 36 of suction air guided through the suction slots 30 . The deflection of the ink droplets 40 should remain as small as possible in order not to adversely affect the print quality. Suction with suction slots 30 arranged around the outlet openings 28 of the print head 16 has therefore proven to be advantageous, optionally an arrangement of the suction slots 30 in front of and behind the print head 16 in its direction of movement (corresponding to Fig. 1b ). An optional adjustment of the volume flows 36 can also achieve optimal suction of the pressure mist 38 with minimal influencing of the ink-jet print or the ink droplets 40 ejected in this context in the area of the flow profile 34 . If necessary, the occurring flow profiles and thus the required extraction performance can be determined using model calculations and simulations for certain bottle types or for certain container shapes.

A variable adaptation and/or a controllable or adjustable suction pressure can also be useful, it being possible for the suction pressure to be adjustable and/or adjustable differently, for example for two or more suction openings or slots 30 . In this way, the print mist extraction can be adjusted to different operating conditions such as, for example, to different distances between the print head 16 and the print area 18 to be printed on the container 10 . Different suction pressures at two or more suction openings 30 of the print head 16 can also be useful if, for example, a specific direction is to be imposed on the suction flow 36 in order to influence the flow profile 34 .

the 4 shows a schematic longitudinal section through an embodiment variant of a suction channel 42 of the print head 16. By adapting the design of the geometry and the course of the side walls 44 of the suction device 22, the flow speeds 46 of the volume flows 36 along the suction slot 30 can be varied and adapted to the place where the pressure mist 38 is generated will. Depending on the container design and the resulting different pressure differences (variable intermediate spaces 32), it can make sense to increase the flow velocities 46 in areas with large pressure differences. An increase in the flow speed 46 can be achieved, for example, by narrowing the cross section. Furthermore, the flow rate 46 can be adjusted by different or variable suction capacities.

The suction slot width of the suction slots 30 can be, for example, between 0.1 mm and 10 mm, preferably between 0.2 and 7 mm, particularly preferably between 0.2 and 5 mm. These dimensions have proven to be advantageous in practice, with the larger cross-sections and slot widths being useful when the distance 32 between the print head 16 and the print area 18 on the container 10 is relatively large, which is particularly the case with an uneven print area 18 or relief Characteristics on the container jacket surface 14 is necessary, since in this case a relatively large volume flow 36 is required for effective suction. With such container surfaces 14, the pressure distance 32 can be, for example, up to 7 mm or more. However, if the cross-sections of the suction openings 30 are too small, a large suction volume flow would lead to a very high air speed of the suction flow, which could possibly have a negative effect on the print quality, since in this case parts of the printing ink are also sucked out or the printing ink exiting the nozzles at high speed could be distracted. With very small distances between the print head and the print area of, for example, 1 mm or less, the suction volume flow can turn out to be smaller, which means that smaller slot widths and cross sections of the suction openings also make sense. The volume flows 36 of the suction can be between 0 and 20 m ³ /h, for example.

Since the print head 16, together with the parts of the suction device 22 arranged on it, can also be installed in an inclined position (angle of attack a; cf. 4 ) can be operated, appropriate measures must be taken to prevent the ink droplets sucked in from escaping. Thus, each of the suction openings or slits 30 can preferably be equipped with suitable devices for retaining liquid that has been sucked in, such as a so-called ink trap 48 (cf. figure 5 ) Be equipped, for example. In the form of a trough 50, a sponge 52 (cf. 4 ) o. A trough 50 or channel can be arranged in a lower area of the suction opening 30, so that in the area of the suction opening 30 condensed or precipitated hydraulic fluid is retained there and can be drawn off via a bypass line 54, for example, and fed to the suction flow 36 (cf. 4 ).

The schematic top view of the 6 shows a conveyor section of a container treatment and/or filling system 56 with a printing area 58 for the direct printing of containers 10, which are moved on a transport star wheel 60 and brought to the printing area 58. A rotating infeed starwheel 62 conveys the containers 10 to the transport starwheel 60 of the system 56, while a rotating outfeed starwheel 64 transports the containers to another station, for example to a bottling plant, where the containers 10 are filled with liquid. the 6 also indicates an optional fuser 66 for curing the ink on the print area 18 of each container 10. FIG. Like the print area 58 formed by one or more print heads 16, the fixing device 66 can also be arranged on the outer circumference of the transport star wheel 60, but is necessarily arranged downstream of the print area 58. It may be useful to use fixing device 66 to cover a fixing area on container lateral surface 14 that is larger than print area 18 and extends beyond this print area 18 on several sides, preferably all, so that all of the deposits deposited on container 10 can be reliably relied upon, but in all Hardly visible droplets are usually fixed and cannot be smudged in later treatment steps.

The schematic view of 7 shows another variant of a container treatment and/or filling system 56, in which the printing area 58 is arranged within the transport star wheel 60 and can be adjusted concentrically to it in order to be able to apply different printing inks to several containers 10 at the same time, as is done in a similar way, e.g. in the EP 2 152 519 B1 is revealed. The printing area 58 designed as a ring can have a number of printing stations, each with a number of print heads for different colors, which can be assigned to the respective containers 10 by rotating the ring. Since the ring can be rotated in both directions depending on the progress of the printing, several adjacent containers can be sprayed at the same time, each with different inks if necessary. The suction device 22 according to the invention is also assigned to each of the print heads here, it being possible for a central suction line for the ring of the printing area 58 to be useful.

Furthermore, it would also be conceivable for only a single ink to be applied to the containers on a carousel, with each container receptacle on the circumference of the carousel being assigned at least one print head 16 with the suction device according to the invention. Two print heads 16 can preferably also be arranged vertically if, for example, a shoulder area of bottles is also to be printed and an upper print head is oriented at a different angle for this purpose, so that it is essentially perpendicular to the shoulder surface of the bottle. The internal rotating ring can also be dispensed with here, as other colors are applied in other carousels. For this purpose, the carousels can be arranged one after the other in a modular manner.

The invention has been described with reference to a preferred embodiment. However, it will be apparent to a person skilled in the art that modifications or variations can be made to the invention without departing from the scope of the following claims. The extracted ink droplets can be disposed of via appropriate traps. the ink droplets can also be converted from the liquid to the solid aggregate state via a form of hardening adapted to the ink and can be filtered or separated accordingly. In addition, it is conceivable for the collected inks to be reused or recycled.

Reference List

10

Container, article, bottle, plastic container

12

printing device

14

Outer jacket surface, tank jacket surface

16

printhead

18

print area

20

ink

22

suction device

24

exhaust airflow

26

Housing

28

exit port

30

Intake slots, intake openings

32

gap, printing distance

34

flow profile

36

flow rate

38

pressure mist

40

ink droplets

42

intake duct

44

side walls

46

flow rate

48

ink trap

50

trough

52

sponge

54

bypass line

56

Plant, container treatment and/or filling plant

58

print area

60

transport star

62

inlet star

64

outlet star

66

fixing device

a

angle of the print head

Claims (11)

1. A printing device (12) for printing on bottles, comprising at least one print head (16), which, at least during a printing operation, is located in a defined relative position to a printing area (18) on an outer surface (14) of the bottle (10) and which is coupled to a suction device (22) for sucking off sprayed and/or splashed printing ink, wherein the suction device (22) is spatially and functionally associated with the at least one print head (16), characterized in that,

   in the printing device (12), the suction pressure for two or more suction openings or slots (30) can be adjusted and/or regulated differently in each case, and

   the suction device (22) can be subjected to variable and/or controllable or adjustable suction pressure.
2. The printing device as recited in claim 1, wherein the suction device (22) is positioned in the immediate vicinity of outlet openings (28) in the print head (16) for the printing ink.
3. The printing device as recited in claim 1 or 2, wherein the suction device (22) is combined with and/or integrated in the print head (16) to form a structural unit.
4. The printing device as recited in one of the claims 1 to 3, wherein the suction device (22) has one, two, three or more suction openings and/or suction slots (30).
5. The printing device as recited in one of the preceding claims, wherein a suction slot width of a suction slot (30) and/or a suction opening is between 0.1 mm and 10 mm, preferably between 0.2 and 7 mm, particularly preferably 0.2 to 5 mm.
6. The printing device as recited in one of the preceding claims, wherein each of the suction openings (42) or ducts is provided with means for retaining in-coming liquid (48).
7. The printing device as recited in one of the preceding claims, which printing device is assigned a fixing device (66) for curing the printing ink on the printing area (18) of the article, the container (10) or the bottle, which fixing device (66) covers a fixing area, which is larger than the printing area (18) and extends beyond this printing area (18) on several, preferably all, sides.
8. A method for sucking off, by a suction device (22) of a printing device, sprayed and/or splashed printing ink in the immediate vicinity of outlet openings (28) for printing ink of a print head (16) which is provided for applying liquid printing ink to a printing area (18) of a bottle and which, at least during a printing operation, is in a defined relative position to the printing area (18) on an outer surface (14) of the bottle (10), characterized in that a variable and/or controllable or adjustable volume flow (36) is applied to at least one suction opening (30) and, in the printing device (12), the suction pressure for two or more suction openings or slots (30) is adjusted and/or regulated differently in each case.
9. The method as recited in claim 8, wherein a plurality of detached satellites and/or floating droplets of the liquid printing ink are sucked off in the vicinity of the printing area (18), in particular in the immediate vicinity of the outlet openings (28) of the print head (16) and/or in the immediate vicinity of the printing area (18) of the article or container (10).
10. The method as recited in claim 8 or 9, wherein the variable volume flow (36) present at at least one suction opening (30) is between 0 and approximately 20 m³/h.
11. The method as recited in one of the claims 8 to 10, wherein in each case different and/or variable volume flows (36) are present at several suction openings (30), each of which being between 0 and approximately 20 m³/h.

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