Device for cleaning a row of print heads of a printing machine and cleaning method

Abstract

A device according to the invention for cleaning a row of print heads of an (ink-jet) printing press, comprising a cleaning head (21) which can be moved along the row (2) during cleaning - preferably manually - and which comprises a cleaning adapter (23) supplied with cleaning fluid (51), is characterized in that the device is designed as a two-part device (10, 20, 30) which can be temporarily positioned in the printing press (1) for cleaning and which comprises - as a first part - a cleaning part (20) with the cleaning head (21) and a cleaning guide (25) for the cleaning head (21), and - as a second part - a positioning part (30) with a positioning guide (33) for the cleaning part (20). The invention advantageously makes it possible to clean print heads or their nozzle surfaces and nozzle openings safely and without damage, in particular by hand and, for example, by service personnel in mobile applications.The invention is preferably used in inkjet printing machines in industrial environments.

Description

invention

[0001] The invention relates to a device for cleaning a series of print heads of a printing machine having the features of the preamble of claim 1 and to a cleaning method having the features of claim 10. field of technology

[0002] The invention lies in the technical field of the graphic arts industry, and therein in particular in the field of industrial, i.e., highly productive and high-quality inkjet printing on flat substrates, i.e., the image-wise application of extremely fine drops of liquid ink to sheet, web, film, or label-shaped printing materials, preferably made of paper, cardboard, paperboard, plastic, metal, or composite material. In particular, the invention lies in the subfield of cleaning print heads and the sensitive nozzle surfaces. State of the art

[0003] Print heads for inkjet printing have nozzle surfaces in which the fine nozzles for ejecting ink droplets are located. The nozzle surfaces and nozzles are very sensitive and must be protected, especially from persistent contamination with ink or paper dust. Therefore, in industrial environments, print heads are subjected to recurring cleaning processes. It also happens that nozzles or their nozzle openings are already clogged, and cleaning is only possible by service personnel. For this purpose, it is already known to clean the print heads with a cleaning fluid, which also uses ultrasound.

[0004] DE102020105736A1 discloses a mobile and compact cleaning device that is locked and applied at a suitable location in an inkjet printing machine. The device comprises an ultrasonic source and a guide. Such a cleaning device can be moved manually along a row of print heads. However, this poses the risk of damaging the sensitive print heads, especially their nozzle surfaces. Direct contact with the nozzle surfaces with a cleaning device must be prevented.

[0005] US2008 / 0316251A1 discloses another cleaning device which comprises a reservoir for cleaning fluid and a pump. Technical task

[0006] It is therefore an object of the present invention to provide an improvement over the prior art which, in particular, makes it possible to clean print heads or their nozzle surfaces and nozzle openings safely and without damage. Inventive solution to the problem

[0007] This object is achieved according to the invention by a device according to claim 1 and a method according to claim 10.

[0008] Advantageous and therefore preferred developments of the invention emerge from the subclaims as well as from the description and the drawings.

[0009] A device according to the invention for cleaning a row of print heads of a printing press, with a cleaning head which is movable along the row during cleaning and which comprises a cleaning adapter supplied with cleaning fluid, is characterized in that the device is designed as a two-part device which can be temporarily positioned in the printing press for cleaning and which comprises a cleaning part with the cleaning head and a cleaning guide for the cleaning head as well as a positioning part with a positioning guide for the cleaning part.

[0010] A method according to the invention for cleaning a series of print heads of a printing machine, using a device according to the invention, is characterized in that the following steps are carried out: - temporary insertion of the positioning part into the printing machine; - temporarily attaching the positioning part to the printing machine; - temporarily inserting the cleaning part into the positioning part; - Cleaning the print heads by moving the cleaning head; - Removing the cleaning part from the positioning part; - Loosening the fastening of the positioning part from the printing machine; and - Removing the positioning part from the printing machine. Advantageous embodiments and effects of the invention

[0011] The invention advantageously enables print heads, their nozzle surfaces, and nozzle openings to be cleaned safely and without damage. The invention is preferably used in inkjet printing machines in industrial environments.

[0012] The invention offers the advantage over the prior art that (mobile) manual cleaning is possible, but it ensures that the cleaning device is correctly positioned at the cleaning location, preventing damage to the print heads and their sensitive nozzle surfaces and nozzle openings. This allows service personnel to perform necessary cleaning procedures on inkjet printing machines, particularly on clogged nozzle openings, or to reactivate failed print heads. This avoids the premature replacement of contaminated / clogged print heads. Expensive print heads can then be used for longer, and costs can be reduced.The mobile cleaning device is preferably used when the printing press has a built-in cleaning unit, but this does not allow for ultrasonic cleaning. It may happen that the existing cleaning unit cannot remove existing contaminants and blockages without ultrasound. In such cases, the machine manufacturer's technical service department can be called, who will bring the inventive cleaning device to the site as a mobile device.

[0013] According to the invention, a two-part cleaning device is used. The first part of this cleaning device can be attached to the printing press, and the second part can be arranged inside the first part, brought into the correct position for cleaning, and moved back and forth during cleaning. Thus, positioning and cleaning are two separate processes and can each be carried out with great precision.

[0014] The two parts of the device according to the invention are preferably separate parts, meaning they can be easily separated and joined together. They can be inserted into the printing press separately and one after the other before and for cleaning. During cleaning, the two parts can be joined together. After cleaning, the parts can be separated again. After cleaning, they can be removed from the printing press separately and one after the other.

[0015] The term “two-part” does not mean that the device comprises only two parts, but that it comprises at least the two parts mentioned (cleaning part and positioning part), preferably as the main parts that characterize the device.

[0016] The positioning part of the device according to the invention is preferably designed symmetrically such that it can be inserted and secured in the printing press in a first and a second orientation. The cleaning part can then be inserted into the positioning part and pushed to the "right" in one case, and pushed to the "left" in the other case (only the "right" case is shown as an example in the figures). The two different orientations can be used to clean print heads for CMYK or other colored inks in one case, and print heads for white, for example, in the other case. Further developments of the invention

[0017] Preferred developments of the invention as a device and as a method (hereinafter referred to as "developments") are described below. These can also be combined with one another where not technically mutually exclusive. Further developments of the device according to the invention

[0018] A further development can be characterized in that the cleaning head comprises an ultrasonic source. This source has an electrical connection. A supplementary or alternative development can be characterized in that the cleaning head comprises a cloth cleaning device, e.g., with a cleaning fleece. The cloth is or will preferably be saturated with a liquid cleaner.

[0019] A further development can be characterized in that the positioning part comprises a first section in which the cleaning part is moved essentially parallel to the row of print heads. The cleaning part is preferably pushed into the positioning part from the operating side (BS) of the printing press and towards the drive side (BS) of the printing press. The cleaning part can slide, be pushed or pulled. A further development can be characterized in that the positioning part comprises a second section in which the cleaning part is moved essentially perpendicular to the row of print heads. The second section can comprise one positioning guide. The second section can comprise two positioning guides. The cleaning part can also slide, be pushed or pulled. The two sections can be connected to one another. The two sections can have a common base.A further development can be characterized by the fact that the cleaning part moves from the first section to the second section. The two sections can merge seamlessly into one another.

[0020] A further development can be characterized in that the positioning part is designed as a sheet metal part. A further development can be characterized in that the sheet metal part has a sheet metal base. A further development can be characterized in that the respective positioning guide is designed as at least one sheet metal wall. The two sheet metal walls lie opposite each other. A third, intermediate sheet metal wall can be designed as a stop for the cleaning part when the cleaning part is moved from the first section to the second section. The sheet metal walls can be produced by one or more folds. Plastic could also be used instead of (metal) sheet metal.

[0021] A further development can be characterized in that the cleaning guide is designed as at least one rail which guides the cleaning head. A further development can be characterized in that the cleaning guide is designed with two rails. The two rails are preferably parallel to one another. The two rails are preferably designed as sliding rods with a round cross-section. Bearing openings for the rails are preferably provided on the body of the cleaning head. The movement of the cleaning head during cleaning and along the rails preferably takes place from AS to BS or from BS to AS. A further development can be characterized in that the two rails are connected to one another at their ends via strips. A further development can be characterized in that two strips are provided; one at each end. A further development can be characterized in that the strips are designed as sliding strips.A further development can be characterized by the fact that the strips are designed to be guided by the positioning guide. The slide strips preferably slide in the positioning guides and on the base of the positioning part.

[0022] A further development can be characterized in that the positioning part comprises at least one fastening element, which serves to temporarily fasten the positioning part to the printing press. A further development can be characterized in that two fastening elements are provided. A further development can be characterized in that the fastening elements are designed as knurled screws; preferably one on the AS and one on the BS.

[0023] A further development can be characterized in that the cleaning head comprises a body. The body can be made of plastic. The body can be formed in one piece. A further development can be characterized in that the cleaning adapter is movable relative to the body into an active position for cleaning and into a passive position (parking position; not for cleaning). A further development can be characterized in that a spherical guide is formed between the body and the cleaning adapter, which allows the cleaning adapter to be tilted in any direction relative to the body and thus compensates for tolerances and, in the active position, can be aligned parallel to the surface to be cleaned. For this purpose, the body can have a cylindrical opening and the cleaning adapter can have a counterpart fitting into the opening with a spherical or spherical segment-shaped outer contour.The cleaning adapter preferably has spherical freedom of movement. A further development can be characterized in that at least one spring, in particular a compression spring, is arranged between the cleaning adapter and the body, which presses the cleaning adapter into the active position. The cleaning adapter can be provided with a protective cap, which is removed manually before cleaning. The cleaning process takes place in the active position. In the passive position, the cleaning part can be moved into and out of the cleaning position. In the active position, the cleaning adapter can be raised (relative to the body); in the passive position, it can be lowered.

[0024] A further development can be characterized in that the device comprises a storage container for the cleaning fluid. A further development can be characterized in that the storage container is designed as a bag-in-box. A further development can be characterized in that the device comprises a pump module with at least one pump for the cleaning fluid. A further development can be characterized in that the storage container for cleaning can be temporarily connected to the pump module via a first supply line and a first return line. A further development can be characterized in that the cleaning head for cleaning can be temporarily connected to the pump module via a second supply line and a second return line. The respective lines can preferably be designed as hoses. Further developments of the method according to the invention

[0025] A further development can be characterized in that the print heads are moved into a cleaning position. In the cleaning position, the print heads are preferably further away from the conveyor line than in a printing position. The device according to the invention for cleaning can be arranged in the free space created as a result. A further development can be characterized in that the positioning part is temporarily fastened to the printing press. A further development can be characterized in that the positioning part is temporarily arranged and fastened to a conveyor line for printing material of the printing press; in particular by arranging it on the roller journals of (printing material) transport rollers and preferably with spring clips; alternatively, for example, on the side walls. The temporary fastening is preferably carried out by means of two knurled screws.

[0026] A further development can be characterized in that the cleaning head is moved manually, in particular by pushing and pulling. A further development can be characterized in that a rod for manual movement is arranged on the cleaning head. The rod is preferably arranged parallel to the alignment of the row of print heads. The cleaning movement preferably takes place parallel (and back and forth) to the alignment of the row of print heads.

[0027] A further development can be characterized in that the cleaning adapter is moved into the active position for cleaning. A further development can be characterized in that the cleaning adapter is raised relative to the body of the cleaning head in the active position. In the active position, the cleaning adapter, in particular only its lateral sliding surfaces, touches the print heads or their nozzle surfaces to be cleaned or preferably only areas next to the (sensitive) nozzle surfaces; but under no circumstances the area with the nozzle openings. A further development can be characterized in that the cleaning adapter is moved into the passive position before and after cleaning. A further development can be characterized in that the cleaning adapter is lowered relative to the body of the cleaning head in the passive position. In the passive position, the cleaning adapter does not touch the print heads or is arranged or parked away from them.A further development can be characterized in that the lowering and raising take place by means of a thrust wedge; preferably two thrust wedges are provided. A further development can be characterized in that a bracket is actuated for moving into the passive position and / or for moving into the active position. A further development can be characterized in that the bracket moves the thrust wedge or a counterpart to the thrust wedge. A further development can be characterized in that the bracket is pushed or pulled by hand. It can preferably be provided that a back and forth movement of the bracket parallel to the alignment of the row of print heads causes an up and down movement of the cleaning adapter perpendicular to the nozzle surfaces of the print heads. The bracket can be designed as a rod.

[0028] The features and combinations of features disclosed in the above sections Technical Field, Invention and Further Developments as well as in the following section Exemplary Embodiments represent - in any desired combination with one another - further advantageous developments of the invention. Embodiments of the invention and figures

[0029] The Fig. Figures 1 to 3 show preferred embodiments of the invention and its further developments. Corresponding features are provided with the same reference numerals in the figures. Recurring reference numerals have been partially omitted for clarity. Fig. 1 shows a perspective view of a preferred embodiment of a device according to the invention during assembly or positioning. Fig. 2 also shows a perspective view of a preferred embodiment of the device according to the invention during cleaning. Fig. 3 shows a perspective view of a cleaning head of the device according to the invention.

[0030] Fig. 1 shows a section of a printing press 1 for industrial inkjet printing with several print heads 2 arranged in a row. The print heads all print the same color onto a substrate conveyed underneath, for example paper, cardboard or film, and preferably in the form of a web. Additional rows of print heads (not shown) are provided for other colors, for example CMYK. Row 2, also called the print bar, is arranged in a cleaning position 3 in the illustration or is adjusted to this position (upwards, see stopping movement 80). In cleaning position 3, there is a distance 3a between the undersides of the print heads 2 or their nozzle surfaces to be cleaned and the top side of the conveyor line 4 for the printing substrate. The section of the printing press 1 shown also shows its side walls 5.

[0031] In Fig. 1 also shows three spatial directions (X, Y, and Z): the X direction 90 is the direction in which the substrate is conveyed (longitudinal direction of the substrate); the Y direction 91 is a transverse direction to this (transverse direction of the substrate); the Z direction 92 is a direction vertical to the X and Y directions. Since the conveying path for the substrate can be slightly curved, the X direction can also be curved accordingly.

[0032] In Fig. Figure 1 shows a (mobile cleaning) device 10, which has the two-part construction according to the invention and is inserted into the printing press 1 or into the free space formed by the gap 3a (by service personnel, manually). The device 10 comprises the cleaning part 20 (as the first part of the device) and the positioning part 30 (as the second part of the device).

[0033] The cleaning part 20 comprises a movable cleaning head 21 with a body 22, which can be moved in particular along a cleaning guide 25. The cleaning part 20 is mounted and movable on two rails 26, which are connected to each other via two (sliding) strips 27. The movement is carried out manually by means of a rod 46 in and against the Y-direction (see cleaning movement 84 in Fig. 2). For the correct cleaning positioning of the cleaning part 20 in the printing press, a positioning part 30 is provided according to the invention.

[0034] The positioning part 30, which is essentially designed as a sheet metal with lateral folds, is inserted in the Y direction into the printing machine or the free space (see insertion movement 81; by service personnel, by hand) and can be placed on the conveyor line 4 or the side walls 5 (see setting movement 81a) and temporarily (i.e., can be removed again) fastened to the conveyor line 4 or to the side walls 5 by means of the fastening elements 31.

[0035] The cleaning part 20 is then pushed in the Y direction into the positioning part 30 (see insertion movement 82) and positioned in the first section 34 on the floor 32 (in an intermediate position).

[0036] In Fig. 2 shows that the cleaning part 20 is then pushed in the positioning part 30 or its positioning guides 33 (i.e., along the walls 33a) up to a stop 33b into the second section 35 against the X direction (see insertion movement 83). The cleaning part 20 slides with the two strips 27 on the floor 32. In this (final) position, i.e., in the second section 35 of the positioning part 30, the cleaning part 20 can carry out the cleaning of the print heads 2.

[0037] The cleaning device 10 further comprises a storage container 50 for cleaning liquid 51 with a connection 50a. In addition, the cleaning device 10 comprises a pump module 52 with at least one pump 53 for the cleaning liquid 51. The pump module 52 has a first supply line 54 and a first return line 55, wherein the first supply line 54 is connected to the connection 50a of the storage container 50 and the first return line 55 is connected to a waste container 60 or its connection 60a. The pump module 52 further has a second supply line 56 and a second return line 57, via which the pump module 52 is connected to the cleaning head 21 or its body 22.Clean cleaning fluid 51 flows from the reservoir 50 via the first supply line 54 and the second supply line 56 through the pump module 52 to the cleaning head. Used and therefore contaminated cleaning fluid flows back to the waste container 60 via the pump module 52 via the first return line 55 and the second return line 57. The pump 53 pumps both the clean and contaminated cleaning fluid back. The pump module is preferably a separate unit and can be positioned independently of the cleaning part 20 and the positioning part 30, as can the reservoir 50 and waste container 60.

[0038] In Fig.3 shows details of the cleaning head 21. This comprises a body 22 with a circumferential and upwardly open channel 22a for collecting used and therefore contaminated cleaning fluid 51. The cleaning head 21 also comprises a cleaning adapter 23, which has a raised active position 40 and a lowered passive position 41. The cleaning adapter 23 is adjustable between these two positions. The adjustment is carried out manually by the service personnel. For this purpose, a bracket 45 is moved in and against the Y direction. The up and down movement of the cleaning adapter is carried out by the interaction of two thrust wedges 43 on the cleaning adapter 23 and two counterparts 44 each on the bracket 45. At least one spring 42 is attached below the cleaning adapter 23, which presses the cleaning adapter 23 upwards into the active position 40. The movement of the bracket 45 causes the cleaning adapter 23 to be lowered against the spring force.

[0039] The cleaning fluid 51 supplied to the cleaning head 21 via a supply connection 58 exits the cleaning adapter 23 at the cleaning head 21. The cleaning adapter 23 has two sliding surfaces 23a, which are positioned against the nozzle surface to be cleaned, but not against the sensitive nozzle openings, of each print head 2 to be cleaned. The sliding surfaces 23a are preferably made of Teflon. Furthermore, the cleaning adapter 23 has an overflow 23b, from which the cleaning fluid 51 exits and collects in the body 22. From there, the cleaning fluid flows into the channel 22a and is conveyed back via a return connection 59 into the waste container 60.

[0040] The cleaning head 21 further comprises an ultrasonic source 24 with an electrical connection 24a, which applies ultrasonic vibrations to the cleaning fluid under the nozzle surfaces and thereby effectively supports the cleaning.

[0041] The mobile cleaning device 10 can be installed and operated, for example, by service personnel. Due to their manageable dimensions, the cleaning part 10 and the positioning part 20 are preferably designed to be housed in a case and transported to the site of use. List of reference symbols 1 printing press 2 printheads, row of printheads 3 cleaning positions 3a distance 4 conveyor line 5 side wall(s) 10 (Cleaning) device 20 Cleaning part, first part of the device 21 Cleaning head 22 Corpus 22a Canal 23 cleaning adapters 23a Sliding surfaces 23b Overflow 24 Ultrasound source 24a connection 25 Cleaning guide 26 rails 27 strips 30 Positioning part, second part of the device 31 Fasteners, fastening 32 floor 33 Positioning guide 33a Wall / Walls 33b stop 34 first section 35 second section 40 Active position 41 Passive position 42 spring 43 thrust wedge 44 counterpart 45 brackets 46 rod 50 storage containers 50a connection 51 Cleaning fluid 52 Pump module 53 Pump 54 first supply line 55 first return line 56 second supply line 57 second return line 58 supply connection 59 Return line connection 60 waste bins 60a connection 80 (Print head) stop movement 81 (Positioning part) insertion movement 81a (Positioning part) settling movement 82 (Cleaning step) insertion movement parallel to the print head row 83 (Cleaning step) insertion movement across the print head row 84 Cleaning movement 90 X-direction 91 Y-direction 92 Z-direction 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] DE 102020105736A1

[0004] US 2008 / 0316251A1

[0005]

Claims

[1] Device for cleaning a row of print heads of a printing machine, with a cleaning head (21) which is movable along the row (2) during cleaning and which comprises a cleaning adapter (23) supplied with cleaning fluid (51), characterized by that the device is designed as a two-part device (10, 20, 30) which can be temporarily positioned in the printing press (1) for cleaning and which comprises a cleaning part (20) with the cleaning head (21) and a cleaning guide (25) for the cleaning head (21) as well as a positioning part (30) with a positioning guide (33) for the cleaning part (20). [2] Device according to claim 1, characterized by that the positioning part (30) comprises a first section (34) in which the cleaning part (20) is moved substantially parallel to the row of print heads (2). [3] Device according to claim 2, characterized bythat the positioning part (30) comprises a second section (35) in which the cleaning part (20) is moved substantially perpendicular to the row of print heads (2). [4] Device according to claim 3, characterized by that the cleaning part (20) moves from the first section (34) into the second section (35)). [5] Device according to one of the preceding claims, characterized by that the positioning part (30) is designed as a sheet metal part. [6] Device according to claim 5, characterized by that the positioning guide (33) is designed as at least one sheet metal wall (33a). [7] Device according to one of the preceding claims, characterized by that the positioning part (30) comprises at least one fastening element (31) which serves for the temporary fastening of the positioning part (30) to the printing machine (1). [8] Device according to one of the preceding claims, characterized bythat the cleaning head (21) comprises a body (22). [9] Device according to claim 8, characterized by that the cleaning adapter (23) is movable relative to the body (22) into an active position (40) for cleaning and into a passive position (41). [10] A method for cleaning a series of print heads of a printing machine, using a device (10) according to any one of the preceding claims, characterized by that the following steps are carried out: - temporarily inserting the positioning part (30) into the printing machine (1); - temporarily attaching the positioning part (30) to the printing machine (1); - temporarily inserting the cleaning part (20) into the positioning part (30); - cleaning the print heads (2), whereby the cleaning head (21) is moved; - removing the cleaning part (20) from the positioning part (30); - releasing the fastening (31) of the positioning part (30) from the printing machine (1); and - Removing the positioning part (30) from the printing machine (1). [11] Method according to claim 10, characterized by that the positioning part (30) is temporarily attached to the printing machine (1). [12] Method according to one of the preceding claims 10 or 11, characterized by that the cleaning adapter (23) is moved into the active position (40) for cleaning. [13] Method according to claim 12, characterized by that the cleaning adapter (23) is raised in the active position (40) relative to the body (22) of the cleaning head (21). [14] Method according to one of the preceding claims 10 to 13, characterized by that the cleaning adapter (23) is moved to the passive position (41) before and after cleaning. [15] Method according to claim 14, characterized bythat the cleaning adapter (23) is lowered in the passive position (41) relative to the body (22) of the cleaning head (21).

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