EP4335647A1 - Direct printing press - Google Patents

Abstract

The invention relates to a method for printing containers (10, 110), wherein the containers (10, 110) rotate in a transport carousel (4) and each container (10, 110) on the transport carousel (4) has a rotating printing station (5). is assigned and the containers (10, 110) only in a partial area (H_D) of the printable container height (H_max) from the respective printing station (5) with a single print head (5b) can then be printed with a maximum of two ink supplies (13a, 13b). The invention further relates to a direct printing machine (1) for carrying out the method mentioned.

Description

The present invention relates to a method for printing containers and a direct printing machine.

In bottling plants for beverages, but also in the pharmaceutical industry, containers, e.g. plastic containers, in particular bottles made of polyethylene terephthalate (PET) as well as glass or pulp, are equipped with labels for identification or printed using paint/inks.

For printing, direct printing machines are used, for example, in which the containers are placed on the turntable of a container carousel, on which they are then rotated and printed as they circulate. There are systems in which the printing devices are arranged in a stationary manner outside the transport carousel, and those in which the printing stations rotate with the transport carousel.

Direct printing machines prefer to equip the containers to be processed with graphic elements, text and coding such as 2-D codes.

If the printing device is located outside the transport carousel, a printing device is not required for each turntable, but the rotational speed of the rotating carousel is limited by the external printing process. This type of printing leads to slow process speeds, especially for more complex container markings.

If the printing devices are attached to rotate within the transport carousel, only the rotation speed of the turntable, but not that of the carousel, needs to be adjusted to the printing process. In addition, all turntables that carry a container can be printed at the same time. In this way, the nominal output of the direct printing machine can be increased compared to printing using an externally arranged printing device.

So that different labels can be printed on a wide variety of containers, the individual printing devices of the direct printing machines typically have several print heads with different colors, which print the containers essentially in multiple colors over the entire area/height that can be printed on the container. The associated printing times are therefore longer and the associated printing ink consumption is high.

Proceeding from this, the present invention is based on the object of specifying alternatives and of proposing a method and a device which make it possible to increase the nominal output and thus the throughput of direct printing machines and/or at the same time to reduce the process and machine costs.

According to the invention, this object is achieved with a method having the features of claim 1 and a device having the features of claim 8. Appropriate embodiments of the invention are covered in the subclaims.

According to the invention, it is therefore proposed to limit the printing to a maximum of two colors, which are applied to the containers with a single color print head, and also only to a partial area of the overall possible printable height of a container. On the one hand, this "less" reduces the effort required to implement the rotating printing stations, and at the same time the entire printing process is shortened because only a maximum of two colors, preferably only one, are printed for the final printing. In addition, this saves printing ink, so that the method and device according to the invention can still save resources while simultaneously increasing performance and are therefore also advantageous from an environmental point of view. The theoretical maximum printable area of typical containers, such as bottles, extends from the bottom to the area of the shoulder where the bottle merges with the neck. With typical bottle heights of 15 to 35 cm, the typically printable area is only 3 to 4/5 of this. According to the invention, only a partial area of this area, for example only 3 to 14 cm, is printed. This could, for example, be used to specifically print the usual brand lettering of a soft drink bottle, which is incorporated into the bottle as a relief.

Preferably, the portion that is printed can be adjusted by changing the height and/or the angle of inclination of the print head. This means the printing process can be adapted to the different container shapes.

In particular, an adjustment of the print head in the direction of the container thickness, i.e. in the direction of the axis of the turntable, is also provided in order to be able to adjust the print head to containers of different diameters.

Preferably, a portion of the printable container height is printed, which makes up a maximum of half, in particular only a third, of the printable container height. Additionally, because there is only one printhead in each print station, the overall machine is lighter than traditional machines equipped with multiple printheads per station, allowing for energy-efficient operation.

Before printing, the container is preferably aligned, which brings the container into a preferred rotational position. Particular preference is given to using optical sensors or cameras to detect features such as embossing, debossing reliefs and support elements, which are subsequently aligned in such a way that these structures can be specifically, completely or partially printed.

Partially printed can mean that a glass lettering is only printed with a contrasting color on its outer contour or that only the peaks of a mountain panorama are provided with contrasting white. In an advantageous embodiment of the invention, an optical detection unit can be used to determine whether the pressure to be applied is already on individual containers to be processed, for example a baked coating. At these treatment stations, further printing can be specifically suppressed or, if partial areas are missing, missing parts or fragments can be specifically reprinted.

Preferably, the ink supply for printing on the containers comes from at least one tank that rotates with the transport carousel. This means that there is no need for a rotary feedthrough in the ink supply system, since the at least one ink tank rotates with the carousel and can therefore be connected to the print head using simple lines.

Preferably, a labeling unit for labeling the containers is also arranged on the periphery of the transport carousel. The containers can also be labeled, especially as an alternative to printing. This allows the variability of the machine to be increased with regard to the different marking processes.

The labeling unit can in particular also be operated simultaneously with the direct printing machine. For example, a price label can be labeled and a graphic element printed at the same time.

In addition, a pretreatment unit for pretreating the containers can also be arranged on the periphery of the transport carousel. The pretreatment can increase the print quality and promote a smooth direct printing process.

In a further embodiment of the invention, each printing station is assigned a rotating post-treatment unit, which post-treats the containers, in particular using light, in particular UV light emitted by pinning lamps. The post-treatment fixes the ink applied to the container during direct printing and makes the marking more durable. Because each printing station is assigned a post-treatment unit, the throughput speed is increased again, as the containers can be post-treated immediately after printing until they leave the transport carousel. With external, non-rotating after-treatment units, the after-treatment would be limited to a specific process area, which results from the containers being moved past the stationary after-treatment unit.

Preferably, a cleaning device is also arranged on the periphery of the transport device, which cleans the printing stations and/or the turntable, in particular after the printed and post-treated container has been removed from the transport carousel and before a container is taken back into the transport carousel. This ensures that direct printing runs smoothly even with long maintenance intervals, as the printing stations and turntables are less likely to be contaminated by ink or other substances.

Preferably, there is also an optical final inspection in the machine, which subsequently removes containers that are subsequently assessed as defective from the container stream using a rejection unit. The final inspection preferably includes a closed-loop function, by means of which the applied pressure is assessed qualitatively and can provide correction data or raw data on alignment and pressure control. The correction data or raw data can contain information about the rotation position, size, coordinates and coverage of the print.

The advantages of the features according to the invention described at the beginning also apply to claim 8 and the features of the direct printing machine correspondingly claimed in the dependent device claims.

• Figur 1 zeigt eine schematische Draufsicht auf eine erfindungsgemäße Direktdruckmaschine
• Figur 2 ist eine schematische Seitenansicht auf eine erfindungsgemäße Druckstation beim Bedrucken eines zylindrischen Behälters;
• Figur 3 ist eine schematische Seitenansicht auf eine erfindungsgemäße Druckstation beim Bedrucken eines konischen Behälters.

The invention is explained in more detail below with reference to the figures.

• Figure 1 shows a schematic top view of a direct printing machine according to the invention
• Figure 2 is a schematic side view of a printing station according to the invention when printing a cylindrical container;
• Figure 3 is a schematic side view of a printing station according to the invention when printing a conical container.

Figure 1 shows a direct printing machine 1, which has a transport carousel 4 with a plurality of printing stations 5 formed thereon, at which containers 10 standing on turntables, not shown, can be printed during the rotation of the transport carousel.

The containers are handed over to the individual printing stations of the transport carousel 4 by a conveyor belt 2 via an inlet star 3, and leave the carousel fully printed - that is, no further printing takes place afterwards - via an outfeed star 6. They can then be used directly or via another transport route, for example be transported further to a filler.

At each printing station 5 there is a single print head 5b and optionally a pinning lamp 5a for printing a partial area H _D of the container with only one color, for example black or white, and subsequent post-treatment. In the sub-area H _D , printing on the container 10 is possible around the entire circumference or even just part of the circumference. The print head itself can, as in Figs. 2 and 3 indicated, possibly have two ink supply connections so that you can choose between two printing colors. The ink supply connections 13a and 13b are supplied by at least one ink tank 15, which is positioned in particular on the transport carousel 4 so that it rotates. This makes it possible to print the containers with a maximum of two different colors. In particular, only one ink supply with one color can be provided. When printing with only one color, it is preferable to choose a color that contrasts with the container color or, in the case of transparent containers10, the liquid color. This means that the legibility of the marking can be guaranteed even with just one color.

In addition, the print area of each print head is also different Figs. 2 and 3 results in adjustable height and distance from the axis of rotation A of each turntable as well as the angle of inclination towards the container.

After a container has been handed over, it can be aligned for the subsequent pressure in a first area I, in particular with the help of sensors (not shown). In the second area II, a pretreatment can then take place with the help of a pretreatment unit 7.

The actual printing process takes place via the adjoining third area III, which in this exemplary embodiment extends over 240°. The printed container can then be finally cured in the subsequent fourth area IV with the aid of an after-treatment unit 20, in particular a UV light-emitting, preferably LED or mercury vapor lamp, which can be provided in addition to or as an alternative to the individual rotating pinning lamps 5a.

Finally, the marking, which was carried out by pressure, can be checked in the fifth area V, in particular with the help of sensors (not shown).

In particular between the two rotating stars 3 and 6, the unoccupied printing station 5 and the turntable (not shown) can now be cleaned of ink residue and other dirt using the cleaning unit 9.

Since the individual printing stations 5 are relatively simple and therefore take up little space, there is enough space to arrange one or even more labeling units 8 on the periphery of the carousel in such a way that the machine can also be used for labeling either or in addition to printing. The labeling unit is preferably an unit with which wrap-around labels can be applied.

Furthermore, a cleaning unit 9 for cleaning the printing stations 5 can also be arranged on the periphery of the transport carousel 4.

With reference to Fig. 2 The invention will be further explained below using an example in which a substantially cylindrical bottle is printed.

In Fig. 2 a commercially available bottle to be provided with a label stands on the turntable 12 in a printing station 5. The bottle, for example, has a total height _H between 15 and 35cm. The maximum printable area H _max , which in conventional bottles extends from the bottom to the beginning of the tapered shoulder area/bottle neck, is therefore less than the total height and is only about 3/5 to 4/5 of it.

According to the invention, with the single print head 5b of the printing station 5, only a partial area H _D is printed, which preferably extends over less than half, in particular less than only a third, of the H _max . In the exemplary embodiment shown, this is the area of a brand lettering, for example, incorporated into the bottle in relief, as is common in soft drink bottles, for example.

For this purpose, the height of the print area of the print head can be adjusted to this range, either by shifting the height of the entire print head or by using only part of the print nozzles of a print head that extends over a greater height. Preferably, the print heads are height-adjustable by means of a motor drive; particularly preferably, all print heads are height-adjusted by means of a common drive.

The distance R to the axis of rotation A of the turntable is also adjustable.

In Fig.3 There is a container 110 for printing at a printing station 5, the shape of which differs from that in Fig. 2 differs in that the maximum printable area H _max tapers conically from the bottom of the container to the neck. So that such containers can also be printed, the inclination angle α of the print head 5a according to the invention of the printing station 5 can also be adjusted accordingly. The print heads are preferably adjustable in inclination angle by means of a motor drive.

Claims (15)

Method for printing containers (10, 110), wherein the containers (10, 110) rotate in a transport carousel (4) and each container (10, 110) on the transport carousel (4) is assigned a rotating printing station (5),
characterized in that
the containers (10, 110) are finally printed only in a partial area (H _D ) of the printable container height (H _max ) by the respective printing station (5) with a single print head (5b) with a maximum of two ink supplies (13a, 13b). Method according to claim 1, wherein the partial area (H _D ) is adjustable by changing the height and/or the inclination angle ( α ) of the print head. Method according to claim 1 or 2, wherein the printed partial area (H _D ) makes up a maximum of one third of the printable container height (H _max ). Method according to one of claims 1 to 3, wherein the maximum two ink supplies (13a, 13b) for printing on the containers (10, 110) are supplied with ink from at least one tank (15) rotating with the transport carousel (4). Method according to one of the preceding claims, wherein the containers (10, 110) are labeled with a labeling unit (8) arranged on the periphery of the transport carousel (4). Method according to one of the preceding claims, wherein the containers (10, 110) are pretreated with a pretreatment device (7) arranged on the periphery of the transport carousel (4). Method according to one of the preceding claims, wherein each printing station (5) is assigned a rotating after-treatment unit (5a), and the containers (10, 110) are after-treated by the after-treatment unit (5a), in particular using light. Direct printing machine (1) for printing containers (10, 110), comprising a transport carousel (4) for transporting containers (10, 110) standing on turntables, each with a rotating printing station (5) per container (10, 110)
characterized in that
each printing station (5) has a single print head (5b) with a maximum of two ink supplies (13a, 13b) and the printing stations (5) are designed so that they only print a partial area (H _D ) of the printable container height (H _max ). Machine (1) according to claim 8, wherein the printing stations (5) are designed such that the position of the print heads (5b) in the direction of the container height and the angle of inclination ( α ) of the print heads can be changed. Machine (1) according to claim 8 or 9, wherein the printing stations (5) are designed so that they print on the containers (10, 110) at most in a partial area (H _D ) of a third of the printable container height (H _max ). Machine (1) according to one of claims 8 to 10, wherein the maximum two ink supplies (13a, 13b) of the printing stations (5) are supplied with ink from at least one tank (15) rotating with the transport carousel (4). Machine (1) according to one of claims 8 to 11, wherein a cleaning device (9) for cleaning the print heads (5) is arranged on the periphery of the transport carousel (4). Machine (1) according to one of the preceding claims 8 to 12, wherein a labeling unit (8) for labeling the containers (10, 110) is arranged on the periphery of the transport carousel (4). Machine (1) according to one of the preceding claims 8 to 13, wherein a pretreatment device (7) for pretreating the containers (10, 110) is arranged on the periphery of the transport carousel (4). Machine (1) according to one of claims 8 to 14, wherein each printing station (5) is assigned a rotating after-treatment unit (5a) for after-treating the containers (10, 110), in particular with light.

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