Ink distributor for circulating ink supply to multiple printheads

Abstract

An ink distributor according to the invention for circulating liquid ink to a plurality of printheads, comprising an ink chamber (14) providing the ink (13), which includes a plurality of outlet openings (15) and a plurality of inlet openings (16) for the circulating ink (13), and a plurality of switchable valves (20) for closing the outlet openings (15) and inlet openings (16), is characterized in that the valves (20) each comprise a valve flap (23) arranged within the ink chamber (14) and are each switchable without contact. The invention advantageously enables the ink valves to be switched in a simple and at the same time reliable manner. The invention is preferably used in industrial inkjet printing presses.

Description

invention The invention relates to an ink distributor for circulating the supply of liquid ink to a plurality of printheads, having the features of the preamble of claim 1. field of technology The invention lies in the technical field of the graphic arts industry, and therein particularly in the area of ​​industrial, i.e., highly productive and high-quality inkjet printing on flat substrates, i.e., the image-based application (jetting) of the finest droplets of liquid ink onto sheet-, web-, film-, or label-shaped printing materials, preferably made of paper, cardboard, corrugated board, plastic, metal, or composite materials, with a plurality of printheads. Specifically, the invention relates to the subfield of storing and distributing the liquid ink, in particular the circulating supply of liquid ink to printheads, i.e., with an ink feed and return. State of the art Ink distributors for the circulating supply of liquid ink to a plurality of printheads are already known in industrially operated inkjet printing machines, namely such ink distributors with an ink-providing ink chamber which includes a plurality of outlet openings and a plurality of inlet openings for the circulating ink, and with a plurality of switchable valves for closing the outlet openings and inlet openings. German patent DE102013006106A1 discloses a low-maintenance shut-off valve for ink with a solid-state joint, a pressure piece that traces the contour of an outlet, and a permanent magnet. The magnet serves only as an aid in closing the valve. The valve is preferably opened by a bellows. Manufacturers of graphic products—such as printing companies with prepress, printing, and finishing departments—constantly demand increased production speed and reliability. In inkjet printing, in particular, disruptions in the ink supply, such as leaks, can lead to costly production downtime. Furthermore, the components of such an ink supply system should be inexpensive to purchase and operate, yet function reliably over the long term. Technical task It is therefore an object of the present invention to provide an improvement over the prior art which in particular makes it possible to switch ink valves in a simple and at the same time safe manner. Inventive solution to the problem This problem is solved according to the invention by an ink distributor according to claim 1. Advantageous and therefore preferred embodiments of the invention are evident from the dependent claims as well as from the description and the drawings. An ink distributor according to the invention for circulating and supplying a plurality of printheads with liquid ink, comprising an ink chamber providing the ink, which includes a plurality of outlet openings and a plurality of inlet openings for the circulating ink, and comprising a plurality of switchable valves for closing the outlet openings and inlet openings, is characterized in that the valves each comprise a valve flap arranged within the ink chamber and each can be switched without contact. Advantageous forms and effects of the invention The invention advantageously enables the simple and safe switching of ink valves. The invention is preferably used in industrial inkjet printing presses, e.g., when printing with water-based inks. Within the ink chamber, each ink-supplied printhead preferably has one supply valve and one return valve. Part of the valve closing mechanism is located entirely within the ink chamber and thus in the ink. The other part of the valve closing mechanism, however, is located entirely outside the ink chamber. The outer part acts on the inner part without contact. This clever arrangement effectively prevents disruptive leakage. Further developments of the invention Preferred embodiments of the invention (hereinafter referred to as embodiments) are described below. These can also be combined with one another, unless technically precluded. A further development can be characterized by the fact that the valves for contactless switching each include a first magnet, or that the valves for contactless switching each form a first magnet. It can be provided that the first magnets are arranged within the ink chamber. It can be provided that the first magnets are arranged or formed on the valve flaps. It can be provided that the first magnets are designed as permanent magnets. A further development can be characterized by the fact that the valves for contactless switching each include a second magnet. The second magnets may be arranged outside the ink chamber. The second magnets may be arranged to be movable for switching. Pairs of second magnets may be arranged to be movable together. The second magnets may be arranged to be rotatable. Pairs of second magnets may be arranged to be rotatable together. Pairs of second magnets may be arranged on a common shaft. An actuator may be provided to rotate the shafts. Each shaft may have its own actuator. The second magnets may be designed as permanent magnets.The second magnets may be designed as electromagnets. The second magnets may be designed to exchange their north and south poles during each switching operation. The permanent magnets may be designed to rotate 180° during each switching operation. The electromagnets may be designed to reverse their polarity during each switching operation. The valves may be designed as solenoid valves. A further development can be characterized by the fact that each valve includes a joint. The joints may be designed as solid joints, or alternatively as rotary or sliding joints. A further development can be characterized by the fact that the valves are arranged on an inner surface of the ink chamber. The inner surface may be the bottom of the ink chamber. Each valve may include a seal. The seals may be arranged on the valve flaps. The seals may seal the respective outlet or inlet opening to be closed on the inner surface of the ink chamber. The valves may be designed as poppet valves. Further training can be characterized by the fact that the valves are designed as shut-off valves. A further training device may be characterized by the fact that the ink chamber is enclosed. It may be designed so that the ink chamber includes side walls and a lid. A further development can be characterized by the fact that the printheads each comprise a nozzle area with a multitude of nozzles for ejecting ink droplets. The printheads may be connected to the outlet and inlet openings via pairs of ink lines. These ink lines may be designed as tubes. A further development can be characterized by having a plurality n of outlet openings, a plurality n of inlet openings and a plurality 2n of switchable valves, where n≥2. 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 combination with one another – further advantageous developments of the invention. Exemplary embodiments of the invention and figures Figures 1, 2, 3, 4, 5 to 6 show a preferred embodiment of the invention and its further developments. Corresponding features are designated with the same reference numerals in the figures. Reference numerals that are repeated in the figures have been omitted for clarity. Figure 1 shows a sectional view of a preferred embodiment of an ink distributor according to the invention. Figure 2 shows the preferred embodiment of Figure 1 with a modified position of the valves. Figure 3 shows a perspective view of a preferred embodiment of an ink distributor according to the invention. Figure 4 shows a side view of a preferred embodiment of an ink distributor according to the invention. Figure 5 shows a sectional view of a preferred embodiment of an ink distributor according to the invention.Figure 6 shows a sectional view of a preferred embodiment of an ink distributor according to the invention. Figure 1 shows a section of an ink distributor 12 (a so-called manifold) according to the invention for the circulating distribution of ink to several printheads 2 of an industrial inkjet printing press 1 for printing on substrate 3, in which liquid ink 13 is stored in an ink chamber 14. The ink chamber 14 has a preferably horizontal inner surface 14a, in particular a bottom 14e, and at least one side wall 14b. The ink chamber 14 can also be closed with a cover 14c. The ink chamber 14 has a longitudinal direction 14d. Several outlet openings 15 are present on the inner surface 14a and in the base 14e, two of which are shown as examples. Ink lines 15a for the supply, i.e., the delivery of ink to the printheads, are connected to each of these outlet openings 15. Additionally, several inlet openings 16 are present, each connected to ink lines 16a for the return flow to the circulating ink. The inlet openings 16 are located behind the outlet openings in Figures 1 and 2 and are therefore not visible. Each individual ink orifice, i.e., both the outlet orifices 15 and the inlet orifices 16 for the ink 13, is equipped with a switchable valve 20. The valves 20 can be switched without physical contact. Two valves 20 together can form a valve pair 26: one for the supply and one for the return of the ink to the same printhead. The valves 20 of each pair 26 are arranged one behind the other in Figures 1 and 2, and therefore only the front one is visible. The valves 20 are designed as switchable valves 20 and, in particular, as shut-off valves, and each comprises valve flaps 2. The valve flaps 23 are arranged on the inner surface 14a, preferably screwed on. The valve flaps 23 can assume at least two (end) positions: In Fig. 1, the valves 20 and the valve flaps 23 are shown in a first position 20a and in an open position; in Fig. 2, they are shown in a second position 20b and in a closed position. Each valve 20 comprises a body 21, e.g., made of plastic, which is preferably attached to the inner surface 14a by means of a fastening element 22, e.g., a screw. Each valve 20 further comprises a movable valve flap 23, which is pivotable, in particular, with respect to the inner surface 14a. The pivotability can be effected, as shown, by a joint 24, in particular a rigid joint, and further, in particular, by a flexible joint. A seal 25 is preferably arranged on each valve flap 23, in particular inserted into a hole in the valve flap 23. In Fig. 1, the seal 25 does not rest against the inner surface 14a, and the opening 15 or 16 is accordingly open (valve open), while in Fig. 2, the seal 25 rests against the inner surface 14a, and the opening 15 or 16 is accordingly tightly closed (valve closed). The following is provided for opening and closing the individual valves 20 or, alternatively, the pairs of valves 26. A first magnet 30, preferably a permanent magnet, is arranged on the valve flap 23, the valve 20 preferably comprising the following sequence of elements: fastening element 22, hinge 24, seal 25, and first magnet 30. Alternatively, the valve flap 23 itself can be magnetic. The first magnet 30 has a fixed polarity, with, for example, the north pole 33 pointing upwards and the south pole 34 pointing downwards. A rotatable second magnet 31, preferably also a permanent magnet, is arranged in the base 14e (below the inner surface 14a), in particular in a cylindrical bore. Two second magnets 31, i.e., a pair 32, can be assigned to the two first magnets 30 of a valve pair 26. In Fig. 1 and Fig.In Figure 2, the first magnets 30 and the second magnets 31 are shown one behind the other, so only the front magnet is visible in each case. The second magnets 31 are rotatable, preferably by 180° increments in one direction and / or by 180° in one direction and back again, thus reversing their respective polarities: In Figure 1, the north pole 33 points upwards and the south pole 34 downwards (polarity in the "valve open" state; first magnet 30 and second magnet 31 repel each other; magnetic opening force acts), while in Figure 2, the north pole 33 points downwards and the south pole 34 points upwards (polarity in the "valve closed" state; first magnet 30 and second magnet 31 attract each other; magnetic closing force acts). The rotation of the second magnets 31 can be achieved as follows: an actuator 40 can be present, which rotates each magnet 31, either directly or, for example, via a shaft. If the second magnets 31 form pairs 32, it can be provided that one actuator 40 rotates each pair 32 together and thus simultaneously (in this case, the forward and return feeds for a respective printhead open and close simultaneously). The actuator can be mechanically operated, and the control for opening and closing can be carried out via a digital computer if the circulating ink supply for a specific printhead, for a group of printheads, or for all printheads is to be activated or deactivated. The rotation of the second magnets 31 can alternatively be effected manually, e.g. via operable levers. In this case as well, the force transmission to the valve flap 23 is magnetic and therefore contactless. According to another alternative, the second magnets 31 are designed as electromagnets and can be switched accordingly. Fig. 3 shows an ink distributor according to the invention and the valves 20 already described with reference to Figs. 1 and 2, where in this illustration the two valves 20 of each valve pair 26 are also visible. For the sake of clarity, details of the ink chamber 14 have been omitted. With reference to Fig. 3 and the further Figs. 4, 5 to 6, the actuation of the valves 20 using the actuator 40 and using a switching device 41 for the actuator 40 is described below. The second magnets 31 described above are preferably arranged as a pair 32 in or on a shaft 50 of the actuator 40, which is preferably rotatably mounted in a bore in the base 14e. A switching wheel 51 of the actuator 40 is arranged on the shaft 50, preferably designed as a star wheel and having several radial projections 52 (drivers or drive wings; e.g., four). Furthermore, the shaft 50 has one or more detents 53 formed on the shaft body, which interact with a detent spring 54 or with a pair of detent springs 54, such that the shaft 50 engages after each rotation by preferably 90° or 180°. The rotation of the shaft 50 causes the second magnets 31 to rotate or to reverse their polarity, thereby opening or closing the switchable valves 20 without contact. Figures 4, 5 to 6 show a screw drive 60. This comprises a drive spindle 61, preferably a threaded spindle. The drive spindle 61 has a spindle axis 62. The screw drive 60 further comprises a spindle housing 63, which is preferably tiltable about a pivot axis 64 and is returned to its original position by a return spring 65. The switching device 41 comprises, in addition to the shift wheel 51(s) and the screw drive 60, several shift heads 70. Each shift head 70 has at least one shift cam 71 which, during its movement, interacts with the radial projections 52 of the shift wheel 51(s). Each shift head 70 shown here has, by way of example, a first shift cam 71a and a second shift cam 71b. The shift heads 70 can be moved back and forth together in an axial direction 72 by means of the screw drive 60. Figure 5 shows that the switching head 70 can assume a first (tilting) position 73, in which the switching head 70 is in a passive position. This means that the switching head 70, or rather its switching cam 71, does not come into contact with the radial projections 52 when moved in the axial direction 72. Figure 6, on the other hand, shows that the switching head 70 can also assume a second (tilting) position 74, in which the switching head 70 is in an active position. This means that the switching head 70, or rather its switching cam 71, comes into contact with the radial projections 52 when moved in the axial direction 72, thereby rotating the respective switching wheel 51, preferably by 90° or 180°. In this way, using a first drive 80 (preferably a rotary drive of the threaded spindle 61 for the linear movement 66 of the switching head 70) and a second drive 81 (preferably a pneumatic drive or-cylinder for the tilting movement 67 of the switching head 70) and, using a controlling computer 90, a valve 20 or a pair of valves 26 can be selectively opened or closed. The number of switching heads 70 determines how many switching wheels 51 can be actuated simultaneously. In the example shown, each switching head 70 has two switching cams 71, with each individual switching cam 71 rotating a switching wheel 51 by 90°, or with two switching cams 71 of a switching head 70 rotating a switching wheel 51 by twice 90°, and thus 180°. It may be provided that there are as many switching heads 70 as switching wheels 51. In this case, all valves 20 or valve pairs 26 can be opened or closed simultaneously. It may also be provided that there is only one switching head 70. In this case, all valves 20 or valve pairs 26 can be opened or closed sequentially with this switching head 70. Individual valves 20 or valve pairs 26 can also be selectively opened or closed with the single switching head 70. It may also be provided that there is more than one switching head 70 but fewer switching heads 70 than switching wheels 51. Reference symbol list 1 Industrial inkjet printing machine 2 Printheads 3 Substrate, sheet or web 12 Ink distributor (so-called manifold) 13 Ink 14 Ink chamber 14a Inner surface of the ink chamber 14b Side wall 14c Cover 14e Bottom 14d Longitudinal direction of the ink chamber 15 Outlet opening(s) 15a Supply ink line, in particular hose line 16 Inlet opening 16a Return ink line, in particular hose line 20 Switchable valve, in particular shut-off valve 20a First position, open position 20b Second position, closed position 21 Body 22 Fastening element 23 Valve flap (pivoting) 24 Joint, in particular solid-state joint 25 Seal 26 Valve pair 30 First magnet 31 Second magnet, in particular rotatable 32 Pair of second magnets 33 North pole 34 South pole 40 Actuator 41 Switching device 50 Shaft 51 Rotary wheelin particular star wheel 52 radial projections (drive wings) 53 detent(s) 54 detent spring or detent spring pair 60 helical gear 61 drive spindle (threaded spindle) 62 spindle axis 63 spindle housing (tiltable) 64 swivel axis 65 return spring 66 linear movement 67 tilting movement 70 switching head (linearly movable) 71 switching cam 71a first switching cam 71b second switching cam 72 axial direction 73 first position of the switching head, passive position 74 second position of the switching head, active position 80 first drive, rotary drive (for linear movement of the switching head) 81 second drive, pneumatic cylinder (for tilting movement of the switching head) 90 computer, QUOTES INCLUDED IN THE DESCRIPTION This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature DE 102013006106A1

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Claims

Ink distributor for circulating supply of liquid ink to a plurality of printheads, comprising an ink chamber (14) providing the ink (13), which includes a plurality of outlet openings (15) and a plurality of inlet openings (16) for the circulating ink (13), and a plurality of switchable valves (20) for closing the outlet openings (15) and inlet openings (16), characterized in that the valves (20) each comprise a valve flap (23) arranged within the ink chamber (14) and each are switchable without contact. Ink distributor according to claim 1, characterized in that the valves (20) for contactless switching each comprise a first magnet (30) or that the valves (20) for contactless switching each form a first magnet (30). Ink distributor according to claim 2, characterized in that the first magnets (30) are arranged inside the ink chamber (14). Ink distributor according to claim 3, characterized in that the first magnets (30) are arranged or formed on the valve flaps (23). Ink distributor according to one of the preceding claims, characterized in that the valves (20) for contactless switching each comprise a second magnet (31). Ink distributor according to claim 5, characterized in that the second magnets (31) are arranged outside the ink chamber (14). Ink distributor according to claim 6, characterized in that the second magnets (31) are arranged to be movable for switching. Ink distributor according to claim 7, characterized in that the second magnets (31) are rotatably arranged. Ink distributor according to claim 8, characterized in that the second magnets (31) exchange their respective north pole (33) and south pole (34) during each switching operation. Ink distributor according to one of the preceding claims, characterized in that each valve (20) comprises a joint (24). Ink distributor according to claim 10, characterized in that the joints (24) are designed as solid body joints (24). Ink distributor according to one of the preceding claims, characterized in that the valves (20) are arranged on an inner surface (14a) of the ink chamber (14). Ink distributor according to one of the preceding claims, characterized in that each valve (20) comprises a seal (25) and that the seals (25) are arranged on the valve flaps (23). Ink distributor according to one of the preceding claims, characterized in that a plurality n of outlet openings (15), a plurality n of inlet openings (16) and a plurality 2n of switchable valves (20) are provided, wherein n≥2.

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