PRINTING DEVICE AND METHOD FOR PRINTING CONTAINERS

Abstract

An apparatus for printing on containers includes a transport arm and a lift that cooperate to form a first container-transport device that moves a container at a container-loading position into a printing position. The transport arm is arranged on the lift and pivotable about a pivot axis thereof. The lift is axially displaceable and displaces the transport arm axially in relation to the pivot axis. At the printing position, a print head prints on the container.

Claims

1-17. (canceled)

18. An apparatus for printing on a container, said apparatus comprising a first print head, a lift, and a transport arm, wherein said transport arm and said lift cooperate to form a first container-transport device that moves said container from a container-loading position to a printing position, wherein said transport arm is arranged on said lift, wherein said transport arm is pivotable about a pivot axis, wherein said lift is axially displaceable, wherein said lift displaces said transport arm axially in relation to said, pivot axis, and wherein said first print head prints on said container once said container has been brought to said printing position.

19. The apparatus of claim 18, wherein said transport arm comprises a holding-and-centering unit for holding and centering said container.

20. The apparatus of claim 18, wherein said, container comprises a mouth, and wherein said apparatus further comprises a holding-and-centering unit configured to suspend said container from a region of said mouth.

21. The apparatus of claim 18, wherein said first container-transport device comprises a drive for rotating said container about a vertical container-axis thereof.

22. The apparatus of claim 18, wherein said transport arm projects away from said lift, laterally at a fixed angle.

23. The apparatus of claim 22, wherein said lift comprises a rod.

24. The apparatus of claim 22, wherein said lilt is aligned vertically.

25. The apparatus of claim 22, wherein said lift is displaceable along a longitudinal axis thereof.

26. The apparatus of claim 22, further comprising a pivot drive, said pivot drive being configured to pivot said transport arm about one of a longitudinal axis of said lift and an axis parallel to said longitudinal axis.

27. The apparatus of claim 22, wherein said holding-and-centering unit is on a free end of said transport arm, and wherein said free end faces away from said lift.

28. The apparatus of claim 18, further comprising a plurality of print heads and a holding device, wherein said first print head is one of said plurality of print heads, wherein said plurality of print heads comprises a second print head, wherein said holding device accommodates said plurality of print heads, wherein movement of said holding device causes said first print head to move away from said printing position and causes said second print head to move toward said printing position.

29. The apparatus of claim 28, wherein said holding device is configured to be linearly displaceable.

30. The apparatus of claim 28, wherein said holding device can be moved to cause different print heads to be at said printing position at different times.

31. The apparatus of claim 28, further comprising a drying device provided on said holding device, said drying device configured to one of dry and set a printing ink deposited by a print head from said plurality of print heads.

32. The apparatus of claim 18, said apparatus being configured for polychrome printing in which said container remains fixed at said printing position while a sequence of different printing heads, each of which prints one color, is brought to said printing position to print on said container, said printing heads being brought in sequence one after the other.

33. The apparatus of claim 18, further comprising a second container-transport device, wherein said first and second container-transport devices operate in chronologically alternate cycles such that, alter said first container-transport device has brought a first container from said container-loading position to said printing position said second container-transport device brings a second container from said container-loading position to said printing position.

34. The apparatus of claim 33, wherein said first and second container-transport devices are controlled such that said first container is held at said printing position by said first container-transport device while said second container is picked up at said container-loading position by said second container-transport device.

35. The apparatus of claim 33, wherein said first and second container-transport devices are controlled such that said first container is held at said printing position by said first container-transport device while said second container is set down at a container-unloading position by said second container-transport device.

36. A method comprising using a transport arm to move a container situated at a loading position into a printing position, and, using a print-head, printing on said container while said container is at said printing position, wherein using said transport arm comprises pivoting said transport arm about a pivot axis and axially displacing said transport arm along said pivot axis.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0029] The invention is explained in detail below through the

[0030] use of embodiment examples with reference to the figures. In the figures:

[0031] FIG. 1 shows a perspective view of a printing device, and

[0032] FIG. 2 shows a side view of the printing device from FIG. 1.

DETAILED DESCRIPTION

[0033] FIGS. 1 and 2 show a printing device 1 for printing

[0034] on a container 2. The printing device 1 comprises a print station 8 that uses a digital direct-printing method to print upon a container wall of a container 2. The printing device 1 is typically used for printing on small batches of containers or for producing sample containers. In some embodiments, the print station 8 is a single-print station.

[0035] In the illustrated embodiment, the printing device 1 is arranged on a frame that includes a container-transport device 4. The container-transport device 4 picks up a container 2 at a container-loading position LP and conveys that container 2 to a printing position DP.

[0036] The printing position DP has at least one print station 8 that has at least one print head 3 for printing on an outside of the container's wall. In the depicted embodiment, the print station 8 has a plurality of print heads 3, In a typical embodiment, the print heads 3 are digital print-heads that can carry out ink-jet printing.

[0037] The container-transport device 4 also has a transport arm 4.1 and a lifting element 4.2. The lifting element 4.2 can be configured entirely, or at least in some sections, as a rod. In some embodiments, the lifting element 4.2 extends vertically or substantially vertically. In other embodiments, the lifting element 4.2 projects up away from a mounting surface 9 of the printing device 1.

[0038] The lifting element 4.2 is displaceable along a longitudinal axis thereof. It is therefore possible for a drive to change the distance between a free end of the lifting element 4.2, which faces away from the mounting surface 9, and the mounting surface 9. Examples of suitable drives include hydraulic drives, pneumatic drives, drives that rely on cam control, and electromagnetic linear drives.

[0039] The transport arm 4.1, which projects away at an angle from the lifting element 4.2, is provided on the free end of the lifting element 4.2 projecting away from the mounting surface 9. In particular, a rigid angle-coupling can exist between the lifting element 4.2 and the transport arm 4.1. In some embodiments, the transport arm 4.1 projects laterally away from the lifting element 4.2 at a fixed angle. Among these are embodiments in which the transport arm 4.1 projects away from the lifting element 4.2 at a right angle.

[0040] A pivot drive pivots the transport arm 4.1 about a pivot axis, and in particular, about a vertical pivot axis. In some embodiments, the pivot axis is the longitudinal axis of the lifting element 4.2. In other embodiments, the pivot axis is parallel to the longitudinal axis of the lifting element 4.2. With the transport arm 4.1 being aligned horizontally, or substantially horizontally, it becomes possible to pivot the transport arm 4.1 so that it moves along a horizontal or substantially horizontal plane.

[0041] A holding-and-centering unit 5 at a free end of the transport arm 4.1 faces away from the lifting element 4.2. The holding-and-centering unit 5 picks up and holds a container 2 that is to be printed upon. It does so by suspending the container 2 from a region of its mouth and suspending.

[0042] In some embodiments, the holding-and-centering unit 5 includes a contact piece that is brought into contact with the edge of the container's opening. Although a variety of configurations are possible, in typical embodiments, the contact piece is either a centering piece or a centering cone.

[0043] The holding-and-centering unit 5 also has a clamping piece that at least partially encompasses a container's neck ring. To pick up and hold a container, the holding-and-centering unit 5 moves the clamping piece relative to the contact piece so that the clamping piece presses the container 2 up against the contact piece by an edge near the container's opening.

[0044] The holding-and-centering unit 5 is coupled to a drive that rotates a container 2 that has been picked up by the holding-and-centering unit 5. In some embodiments, the drive is a servo motor that rotates the contact piece and the clamping piece. This rotates a container 2 that has been picked up at the holding-and-centering unit 5 about a vertical or substantially vertical axis of rotation that is preferably parallel to the longitudinal axis of the lifting element 4.2.

[0045] The container-transport device 4 executes a lifting and pivoting movement to move the container 2 from the container-loading position LP into the printing position DP. At the container-loading position LP, a container-conveying device feeds containers. Examples of a container conveying device include a linear conveyor and a transport star wheel. Alternatively, it is possible to manually feed containers into the container-loading position LP.

[0046] The printing process for printing on a container begins with picking up the container 2 at the loading position LP. This is carried out by lowering the holding-and-centering unit 5 down onto the container's mouth and then by having the holding-and-centering unit 5 grip the container 2 in the region of its mouth as previously described (arrow I). The holding-and-centering unit 5 is lowered down onto the container mouth by displacing the lifting element 4.2 along the latter's longitudinal axis.

[0047] Next, the lifting element 4.2 is displaced in the opposite direction so that the holding-and-centering unit 5 lifts the container it has just gripped (arrow II).

[0048] The transport arm 4.1 is then pivoted about the lifting element's longitudinal axis. This moves the container from the loading position LP and into the printing position DP (arrow III).

[0049] At this printing position 2, a print head 3 prints on the container 2 as the container 2 rotates about its vertical container-axis (arrow IV). In the case of a rotationally-symmetric container 2, the container 2 preferably remains at a fixed spatial position during this printing process. In such a case, the container-transport device 4 refrains from pivoting about the vertical axis of the lifting element 4.2.

[0050] In the case of a rotationally asymmetric container 2, as the container 2 rotates, the transport arm 4.1 pivots about the longitudinal axis of the lifting element 4.2 or about an axis parallel to that axis. As a result, the distance between the container's wall and the print head 3 can remain at a desired distance.

[0051] A measurement-and-control system controls the pivoting of the transport arm 4.1 in an attempt to maintain the distance between the print head 3 and the container wall. The measurement-and-control system comprises a sensor that measures the distance between the container wall and the print head 3. Based on this measurement, the drive pivots the transport arm 4.1 such that the distance between the container wall and the print head 3 remains constant or approximately constant as the print head 3 prints upon the container 2.

[0052] Certain embodiments print multiple colors on the container. Such embodiments include a holding device 6 that holds plural print heads 3 at the print station 8. The print heads 3 are aligned parallel with one another. As a result, ink coming from ail print heads 3 arrives at the container from the same direction.

[0053] When printing directly on a container 2, it is important that an active print head, i.e. a print head that is currently in the process of printing upon the container 2, adopt a position relative to the container 2 in which that the print head comes to rest at a short distance away from the container wall. A suitable distance is between one millimeter and three millimeters. This position is referred to herein as the print head's “printing location.”

[0054] During the printing process, it is often the case that several print heads 3 at the print station 8 will be used to print upon the container 2 as the container 2 sits in the printing position DP. These print heads 3 take turns printing. Because the print heads 3 print sequentially upon the container 2, it is necessary to move a print head 3 out of the printing location after it is done printing and to move another print head 3 into that printing location to take its place. This movement is referred to below as a “print-head change.”

[0055] To carry out a print-head change, the holding device 6 moves, either by linear translation or by pivoting. Since the holding device 3 carries the print heads 3, the print heads 3 also move.

[0056] In the illustrated embodiment, a linear table 12 supports the holding device 6. This linear table 12 moves along a straight line, thus moving the holding device 6 along the straight line. A suitable linear table 12 is a high-resolution linear table having a reproducible repeat accuracy in the range of a hundredth of a millimeter. This resolution promotes accurate placement of differently colored printed images that are to be arranged above one another, thus promoting high print-quality.

[0057] The holding device 6 can carry function elements other than print heads 3. In some embodiments, the holding device 6 carries a drying device 7 for drying or setting the printing color or printing ink. A suitable drying device 7 includes a UV lamp.

[0058] A supply space 10 accommodates storage tanks 11 beneath the print station 8, These storage tanks 11 store operating media, such as ink. Flexible supply lines bring this operating media from the storage tanks 11 up to the print heads 3 or other function elements. These flexible supply lines lead to the rear side of the holding device 6, which faces away from the printing position DP.

[0059] During the printing operation, a holding-and-centering unit 5 holds a container 2 to be printed upon at the printing position DP. A print head 3 is then positioned at the printing location. Then, as the print head 4 prints, the container 2 is moved relative to its print head, for example by being rotated about its vertical container-axis.

[0060] Once the print head 3 is done printing, a print-head change takes place. This includes moving the initially active print head 3 from the printing location and moving another print head 3 in its place.

[0061] With the new print head in place, further movement of the container 2 relative to the new print head 3 takes place. As the container moves, the print head 3 prints another image in another printing color. This procedure repeats until all the required print heads 3 have had their turn at printing, This results in successive application of printed images in different printing colors to create a complete printed image having many colors. In some embodiments, pinning occurs during an interval between moving one print head 3 out of the way and moving the new print head 3 in its place. A suitable drying device 7 between successive print heads 3 carries out pinning.

[0062] Once all printed images have been applied, a curing step takes place. A suitable drying device 7 for carrying out this curing step is disposed at one end of the holding device 6. Once all the printed images have been applied to the container 2, the drying device 7 carries out the final hardening of the complete printed image.

[0063] On completion of printing, a pivoting movement of the transport arm 4.1 moves the container 2 into an unloading position (arrow V). The lifting element 4.2 than lowers the container 2 and sets it down on the unloading position. Once the container 2 is safely at the unloading position, the holding-and-centering unit 5 releases it.

[0064] In some embodiments, the unloading position is the same as loading position LP. In other embodiments, the loading position LP and the unloading position are at different places. The container 2, now having been printed upon, is then conveyed away, either manually or by a suitable conveyor.

[0065] Some embodiments have at least two container-transport devices 4. These container-transport devices 4 take turns feeding containers 2 from the container-loading position LP to the printing position DP or back to the unloading position. This means that while one container-transport device 4 holds a container 2 during printing, the other container-transport device 4 can be busy doing something else, such as conveying a container that has just been printed upon to the unloading position or picking up a new container at the loading position LP.

[0066] The container-transport devices 4 are positioned to avoid collisions between each other as well as between the holding-and-centering units 5 and any containers 2 being carried. In some embodiments, the relative movement can be brought about by a vertical offset of the transport; arms 4.1, or alternatively by a radial relative movement of the holding-and-centering units 5 provided on the transport arms 4.1. Other measures for the collision-free relative movement of the container-transport devices 4 are also conceivable.

[0067] The invention has been described hereinbefore by reference to embodiments. Variations or modifications are possible without departing from the inventive concept underlying the invention, as defined in the appended claims.