Printing machine with several inkjet printheads arranged together in one printing unit

Description

[0001] The invention relates to a printing machine with several inkjet print heads arranged together in a printing unit according to claim 1.

[0002] DE 10 2014 208 896 A1 and DE 10 2018 207 245 A1 each disclose a printing machine, wherein the respective printing machine has at least one transport path provided for transporting substrate and a plurality of inkjet print heads controlled by a control unit.

[0003] WO2015 / 079680 A1 discloses a printing machine in which a reaction liquid is applied to the printing substrate in an inkjet process in the transport direction before printing, wherein different reaction liquids are applied depending on whether a paper-based printing substrate or a film-based printing substrate is being printed.

[0004] JP2021-194895A discloses a method for producing a printed product using an inkjet printer designed as a flatbed printer, wherein the printing substrate is a textile and consists of a fabric, wherein a plurality of inkjet print heads are provided which apply different types of inks, wherein the mass ratio of the inks to be applied from different inkjet print heads to the printing substrate in question can be variably adjusted depending on the printing substrate to be printed.

[0005] US 2012 / 300086 A1 discloses an image recording device comprising: a housing; an upper supply tray mounted at an upper mounting position in the housing and configured to support a sheet; a lower supply tray mounted at a lower mounting position in the housing and configured to support a sheet, the lower mounting position being lower than the upper mounting position; a first printing engine configured to record an image on the sheet conveyed by the upper supply tray; a second printing engine configured to record an image on the sheet conveyed by the lower supply tray; a lower output tray configured to support the sheet on which the image is recorded by the first printing engine;an upper output tray configured to support the sheet on which the image is recorded by the second printing engine, the upper output tray being located at a higher position than the lower output tray; and a first display configured to display at least one of: a first correspondence between the lower output tray and the upper supply tray; or a second correspondence between the upper output tray and the lower supply tray.

[0006] In industrial digital printing, the ink applied to a substrate in a printing press with an inkjet print head to create a print image must be matched in terms of its chemical and / or physical, e.g., rheological properties to the material and / or the properties of the surface of the substrate to be printed in order to achieve an optimal print result. This means that in each printing process, an ink with properties adapted to the respective substrate must be used, and consequently, a variety of different chemically and / or physically different inks must be used.

[0007] For example, a substrate to be printed on in a printing press with an inkjet print head can be paper made from at least one fibrous material or a printing material made from a plastic or a metal, wherein the substrate can be sheet-shaped, i.e. as a printing sheet, or in the form of a material web, e.g. as a film. Fibres used for paper production can be, for example, cellulose or wood pulp or waste paper. A substrate made of paper can be, for example, graphic paper, i.e. normal paper, or decorative paper or wallpaper or packaging paper, e.g. cardboard, or hygiene paper or special paper such as filter paper or banknote paper. The surface of the substrate in question to be printed on can differ in its nature in that it is uncoated or, for example, has been coated before being transported to the printing unit in question.is coated with a primer or that the surface of the substrate in question is coated or uncoated. A coated paper has a surface refined with a coating color, wherein the coating color consists in particular of pigments, binders and additives and wherein a substrate treated with such a coating color generally forms a closed and smooth surface. A substrate to be printed on in a printing machine with an inkjet print head can also be made of wood or glass or as a hybrid printing material with a surface to be printed, e.g. made of wood or a metallic material. The surface to be printed on the substrate in question can therefore be absorbent or non-absorbent and can have good or less good adhesion to the ink applied with an inkjet print head.In any case, to achieve acceptable printing results, the ink to be printed must be matched to the substrate type and its surface condition.

[0008] In practice, there are therefore a multitude of different substrate types, which differ from one another, particularly in terms of their material and / or at least in the nature of the surface to be printed on at the time of printing. If a printing press with multiple inkjet print heads is to be converted from a first printing process for printing on a first substrate type to another printing process for printing on a second substrate type, this entails considerable effort in converting this printing press, as at least one ink change is usually required, which involves a thorough cleaning of the ink-carrying machine elements, such as hoses, valves, and the inkjet print heads themselves.In addition to the fact that this cleaning process incurs costs for cleaning agents and their disposal, as well as resulting in flushing losses of the used ink, it also represents an increased risk of wear for the inkjet printheads in question due to the ink mixing, deposits, and drying of the ink in the printheads, which cannot be completely eliminated. Furthermore, such an ink change requires several hours of time and usually also requires reconfiguring the inkjet system or calibrating the printing system in question. As a result, the printing press being converted remains in an unproductive operating state for a long period of time.An equally uneconomical alternative would be to dedicate a specific printing press only to the printing process of a single, specific substrate type in order to avoid retooling, or to arrange several selectively usable printing units in the printing press, with only one of these multiple printing units then being assigned to printing on a specific substrate type, which, however, leads to increased space requirements and high investment costs for the printing press in question. In the following, a printing unit is understood to be a structural machine unit which has several inkjet print heads on a single transport device for the substrate to be printed, closely spaced, i.e. without the use of further transport means for the substrate to be printed, in a common frame or housing.

[0009] The invention is based on the object of creating a printing machine with several inkjet print heads arranged together in a printing unit, which can be used flexibly in industrial digital printing for various substrates.

[0010] The object is achieved according to the invention by the features of claim 1. The dependent claims relate to advantageous developments and / or embodiments of the solution found.

[0011] The advantages that can be achieved with the invention are, in particular, that the aforementioned otherwise existing disadvantages are avoided and that the printing machine can be used very flexibly for printing on substrates of different substrate types without complex conversion.

[0012] Embodiments of the invention are illustrated in the drawings and are described in more detail below.

[0013] They show: Fig. 1 shows a first arrangement variant of inkjet print heads in a printing unit of a printing machine; Fig. 2 shows a second arrangement variant of inkjet print heads in a printing unit of a printing machine; Fig. 3 shows a control unit controlling the inkjet print heads with a distribution device for the data stream containing a control signal from the control unit.

[0014] Without being limited thereto, the invention is explained below by way of example using a printing press designed as a rotary printing press, wherein this printing press prints a substrate designed, for example, as a material web, i.e. a printing material, using a plurality of inkjet print heads arranged together in a single printing unit. In the case of a printing press printing a material web, this is preferably designed as a web-fed printing press, in particular as a web-fed rotary printing press. In an alternative embodiment of the invention, it is provided that sheet-shaped substrates are printed, so that the printing press is then designed as a sheet-fed printing press, preferably as a sheet-fed rotary printing press.

[0015] In the Fig. 1 and 2is shown schematically, in a simplified manner and only in a section, a printing unit 01 of the printing press according to the invention, for example for multi-color printing, wherein inks are printed in the printing unit 01 shown, wherein one ink is a fluid colored with at least one colorant and colors the printing material when applied to the latter. These inks are, for example, the process colors commonly used in industry, cyan, magenta, yellow and black, but they can also be a different color, e.g. as a customer-specific special color. Each of these inks, which for example has one of the process colors, is printed by one of the several inkjet print heads 06; 07; 08; 09 arranged together in this printing unit 01, i.e. is applied to a substrate 02 that is moved relative to the relevant inkjet print heads 06; 07; 08; 09.Since the inks can also be designed as a different coloring fluid as an alternative to the aforementioned process colors cyan, magenta, yellow and black, it should be generally accepted that at least one first ink and at least one second ink different from this first ink are printed by the printing unit 01.

[0016] As mentioned, the Fig. 1 and 2by way of example and in a highly simplified manner, a printing press designed as a web-fed rotary printing press, wherein the printing unit 01 of this printing press, which has a plurality of inkjet print heads 06; 07; 08; 09, has a transport cylinder 03 rotating in the direction indicated by the respective rotational direction arrow for transporting the substrate 02 designed as a material web. The plurality of inkjet print heads 06; 07; 08; 09 are arranged in the periphery of this transport cylinder 03 with their respective ink-applying effective direction at a small distance of, for example, less than 3 mm from the surface of the substrate 02 to be printed, preferably radially to this transport cylinder 03.The inkjet print heads 06; 07; 08; 09 of the illustrated printing unit 01 are thus each arranged such that they are used to print, or at least can print, on the substrate 02, which is moved relative to them by a transport device embodied in this example as a transport cylinder 03. In the printing unit 01, the position of each of the inkjet print heads 06; 07; 08; 09 arranged in the periphery of the transport cylinder 03, relative to its respective arrangement, defines a printing point with reference to a specific position a; b; c; d fixed in the printing press in the transport path of the respective substrate 02.

[0017] The Fig. 1 and 2show two different arrangements of inkjet print heads 06; 07; 08; 09; 11; 12; 13; 14 with reference to each of the specific positions a; b; c; d fixed in the printing machine in the transport path of the respective substrate 02. In the respective illustrated printing unit 01, it is provided that at each of its printing points at least two inkjet print heads 06; 07; 08; 09; 11; 12; 13; 14 are arranged together or jointly with reference to each of the specific positions a; b; c; d fixed in the printing machine in the transport path of the respective substrate 02.

[0018] According to the Fig. 1 In the first arrangement variant shown, two inkjet print heads 06; 07 are arranged at position a for printing a substrate 02 of a first substrate type and two inkjet print heads 08; 09 are arranged at position b for printing a substrate 02 of the same first substrate type. In this first arrangement variant, two inkjet print heads 11; 12 are arranged at position c for printing a substrate 02 of a second substrate type and two inkjet print heads 13; 14 are arranged at position d for printing a substrate 02 of the same second substrate type. In this first arrangement variant, the inkjet print heads 06; 07; 08; 09; 11; 12; 13; 14, which are arranged jointly at all fixed positions a; b; c; d in the transport path of the respective substrate 02, are each designed such that they each print inks of different colors from one another, in particular different process colors. In the Fig. 1 In the example shown, at position a, for example, the process colors cyan and magenta and at position b, for example, the process colors black and yellow are each applied to a substrate 02 of a first substrate type, whereas at position c, for example, the process colors cyan and magenta and at position d, for example, the process colors black and yellow are each applied to a substrate 02 of a second substrate type.

[0019] In the alternative second arrangement variant according to the Fig. 2 it is also provided that in this printing unit 01 at least two inkjet print heads 06; 07; 08; 09; 11; 12; 13; 14 are arranged at each of its printing positions, wherein of the inkjet print heads 06; 07; 08; 09; 11; 12; 13; 14 arranged jointly with respect to each of the specific positions a; b; c; d fixed in the printing machine in the transport path of the respective substrate 02, a first of the respective inkjet print heads 06; 07; 08; 09; 11; 12; 13; 14 is used for printing a substrate 02 of a first substrate type and a second of these respective inkjet print heads 06; 07; 08; 09; 11; 12; 13; 14 for printing a substrate 02 of a second substrate type are controlled by a control unit 04.The difference to the first arrangement variant is that the inkjet print heads 06; 07; 08; 09; 11; 12; 13; 14, which are each arranged together at a specific one of the fixed positions a; b; c; d in the transport path of the respective substrate 02, each apply inks of the same color, in particular the same process color, to the respective substrate 02 and thus different colors, in particular process colors, are printed or at least can be printed at the successive fixed positions a; b; c; d in the transport path of the respective substrate 02.

[0020] All inkjet printheads 06; 07; 08; 09 of the Fig. 1 and 2The printing unit 01 shown is controlled by a preferably digital, in particular programmed, control unit 04.According to the invention, it is now provided that the control unit 04 is designed such that, in the case of a substrate 02 of a first substrate type which is moved past one of the respective stationary positions a; b; c; d in the transport path of the respective substrate 02, it controls a first of these inkjet print heads 06; 07; 08; 09 arranged at the respective printing point, and that, in the case of a substrate 02 of a second substrate type which is moved past one of the respective stationary positions a; b; c; d in the transport path of the respective substrate 02, it controls a second of these inkjet print heads 11; 12; 13; 14 arranged at the respective printing point, wherein the first substrate type and the second substrate type are designed differently from one another with regard to their material and / or the nature of a surface to be printed.

[0021] As an alternative to the Fig. 1 and 2In contrast to the transport cylinder 03 shown in each case, the transport device can also be designed as at least one transport belt, on which the substrate 02 to be transported is arranged, in particular lying flat. If the transport device is designed as at least one transport belt, the inkjet print heads 06; 07; 08; 09; 11; 12; 13; 14 of the respective printing unit 01 are arranged stationary one after the other in a row in the transport direction of the respective substrate 02 along its transport path, wherein these inkjet print heads 06; 07; 08; 09; 11; 12; 13; 14 are arranged with their respective ink-applying effective direction at a small distance of, for example, less than 3 mm from the surface of the substrate 02 to be printed, preferably orthogonal to the respective transport belt.

[0022] Regardless of the respective concrete design of the transport device, in both the first and the second arrangement variant of the inkjet print heads 06; 07; 08; 09; 11; 12; 13; 14 these inkjet print heads 06; 07; 08; 09; 11; 12; 13; 14 preferably extend over the entire width of the respective substrate 02 to be printed, wherein this width is directed transversely to the transport direction of the respective substrate 02. The inkjet print heads 06; 07; 08; 09; 11; 12; 13; 14 are therefore each designed, for example, as a print bar with a nozzle array directed towards the respective substrate 02 to be printed, wherein this nozzle array has a multiplicity of nozzles, each of which is arranged in a row and which dispenses ink, and which extend, for example, transversely to the transport direction of the respective substrate 02. B. extends across its entire width. These nozzles dispense the ink according to their activation by a control signal from control unit 04.The inkjet print heads 06; 07; 08; 09; 11; 12; 13; 14 each preferably operate using an inkjet printing process.

[0023] In the Fig. 3 the control unit 04 controlling the relevant inkjet print heads 06; 07; 08; 09; 11; 12; 13; 14 is shown by way of example in connection with a distribution device 16, wherein this distribution device 16 is designed to conduct the respective control signal coming from the control unit 04 either to the inkjet print heads 06; 07; 08; 09 printing the substrate 02 of the first substrate type or to the inkjet print heads 11; 12; 13; 14 printing the substrate 02 of the second substrate type. The distribution device 16 is in this case switched either automatically, e.g. after sensory detection of the respective substrate type, from one printing process for printing a first substrate type to another printing process for printing a second substrate type and / or at a control station belonging to the relevant printing press, e.g. B. can be switched manually from one substrate type to another by an operator of this printing machine using an operating device.it is switched in such a way that in the . Fig. 3 on the distribution device 16 is indicated by an input arrow. The direction of the respective data stream containing a control signal of the control unit 04 is shown in the Fig. 3 indicated by directional arrows. List of reference symbols

[0024] 01Printing unit 02Substrate 03Transport cylinder 04Control unit 05- 06Inkjet print head 07Inkjet print head 08Inkjet print head 09Inkjet print head 10- 11Inkjet print head 12Inkjet print head 13Inkjet print head 14Inkjet print head 15- 16Distribution device aPosition bPosition cPosition dPosition

Claims

1. Printing machine comprising a plurality of inkjet print heads (06; 07; 08; 09; 11; 12; 13; 14) arranged together in a printing unit (01), the inkjet print heads (06; 07; 08; 09; 11; 12; 13; 14) being controlled by a control unit (04) and arranged in such a way that, using the inkjet print heads, at least one substrate (02) that is moved relative to the inkjet print heads by way of a transport device can be printed with an ink discharged by the inkjet print heads; in the printing unit (01), at least two of the inkjet print heads (06; 07; 08; 09; 11; 12; 13; 14) being jointly arranged, in relation to a certain stationary position (a; b; c; d) in the printing machine in a transport path of a relevant substrate (02), at a printing nip assigned to one of the positions (a; b; c; d) in the transport path of the relevant substrate (02); the control unit (04) being configured so as to activate a first of the inkjet print heads (06; 07; 08; 09) arranged at the relevant printing nip when a substrate (02) of a first substrate type moves past the relevant stationary position (a; b; c; d) in the transport path of the relevant substrate (02), and so as to activate a second of the inkjet print heads (11; 12; 13; 14) arranged at the relevant printing nip when a substrate (02) of a second substrate type moves past the relevant stationary position (a; b; c; d) in the transport path of the relevant substrate (02); and the first substrate type and the second substrate type being configured to differ from one another in terms of a material thereof and / or a nature of a surface to be printed, characterized in that the inkjet print heads (06; 07; 08; 09; 11; 12; 13; 14) arranged in the relevant printing unit (01) are each configured so as to print an ink that comprises at least one colorant, both for the first substrate type and for the second substrate type.

2. Printing machine according to claim 1, characterized in that the transport device is configured as a transport cylinder (03), on the outer cylindrical surface of which the substrate (02) to be transported is arranged resting flat thereon.

3. Printing machine according to claim 1, characterized in that the transport device is configured as a conveyor belt, on which the substrate (02) to be transported is arranged resting flat thereon.

4. Printing machine according to claim 1 or 2 or 3, characterized in that, in conjunction with the control unit (04) controlling the relevant inkjet print heads (06; 07; 08; 09; 11; 12; 13; 14), a distribution device (16) is provided, this distribution device (16) being configured so as to conduct a control signal coming from the control unit (04) either to the inkjet print heads (06; 07; 08; 09) printing the substrate (02) of the first substrate type or to the inkjet print heads (11; 12; 13; 14) printing the substrate (02) of the second substrate type.

5. Printing machine according to claim 4, characterized in that the distribution device (16) is switched, or at least can be switched, automatically, after the particular substrate type has been detected by way of sensors, from a printing process for printing a first substrate type to another printing process for printing a second substrate type.

6. Printing machine according to claim 4, characterized in that the distribution device (16) is switched, or at least can be switched, at a control console, which forms part of the relevant printing machine, at an operating device by an operator of this printing machine, from printing the one substrate type to the other substrate type.

7. Printing machine according to claim 1 or 2 or 3 or 4 or 5 or 6, characterized in that the inkjet print heads (06; 07; 08; 09; 11; 12; 13; 14) arranged jointly in each case at all stationary positions (a; b; c; d) in the transport path of the relevant substrate (02) are each configured so as to apply inks having differing process colors to the particular substrate (02).

8. Printing machine according to claim 1 or 2 or 3 or 4 or 5 or 6, characterized in that, of the inkjet print heads (06; 07; 08; 09; 11; 12; 13; 14) that are each arranged jointly in relation to each of the certain stationary positions (a; b; c; d) in the printing machine in the transport path of the relevant substrate (02), in each case a first of the relevant inkjet print heads (06; 07; 08; 09; 11; 12; 13; 14) is controlled by the control unit (04) to print a substrate (02) of a first substrate type, and a second of these relevant inkjet print heads (06; 07; 08; 09; 11; 12; 13; 14) is controlled to print a substrate (02) of a second substrate type, so that the inkjet print heads (06; 07; 08; 09; 11; 12; 13; 14) arranged jointly in each case at a certain stationary position (a; b; c; d) in the transport path of the relevant substrate (02) are in each case configured so as to apply the same process color to the particular substrate (02).

9. Printing machine according to claim 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8, characterized in that the inkjet print heads (06; 07; 08; 09; 11; 12; 13; 14) are arranged so as to extend across the entire width of the relevant substrate (02) to be printed, this width being oriented transversely to the transport direction of the relevant substrate (02).

10. Printing machine according to claim 2 or 4 or 5 or 6 or 7 or 8 or 9, characterized in that the plurality of inkjet print heads (06; 07; 08; 09) are arranged in the periphery of the transport cylinder (03), with the respective direction of action thereof applying ink, at a small distance of less than 3 mm with respect to the surface of the substrate (02) to be printed, radially with respect to this transport cylinder (03).

11. Printing machine according to claim 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10, characterized in that the inkjet print heads (06; 07; 08; 09; 11; 12; 13; 14) arranged in the relevant printing unit (01) are configured so as to print in each case the process colors cyan, magenta, yellow and black, both for the first substrate type and for the second substrate type.

12. Printing machine according to claim 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10, characterized in that the inkjet print heads (06; 07; 08; 09; 11; 12; 13; 14) arranged in the relevant printing unit (01) are configured so as to print in each case a customized special color, both for the first substrate type and for the second substrate type.

13. Printing machine according to claim 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10 or 11 or 12, characterized in that this printing machine is configured as a sheet-fed printing machine printing a substrate (02) configured as a print sheet.

14. Printing machine according to claim 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10 or 11 or 12, characterized in that this printing machine is configured as a web-fed printing machine printing a substrate (02) configured as a material web.

15. Printing machine according to claim 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10 or 11 or 12 or 13 or 14, characterized in that this printing machine is configured so as to print a substrate (02) made of a paper produced from at least one fibrous material, or in that this printing machine is configured so as to print a substrate (02) made of a plastic material, or in that this printing machine is configured so as to print a substrate (02) made of metal, or in that this printing machine is configured so as to print a substrate (02) made of wood.