Printing device for printing individually on web- or sheet-like substrates

Abstract

A printing device based on the inkjet principle for printing individually on a web-like or sheet-like substrate has a number of positionable identical printing units (2, 2.1, 2.2), each having two print heads (23, 24) and producing separate print areas without errors or producing a common continuous print area using one or several adjacent printing units.

Description

[Technical field]

[0001] The invention relates to a printing device for individually printing web- or sheet-like printing substrates according to the preamble of claim 1 . [Background technology]

[0002] Printing devices are known, particularly from the field of paper processing and the production of boxes and containers made from cardboard or corrugated board, which are suitable for printing defined areas of a substrate web or substrate sheet individually, where the substrate is guided in a horizontal plane along a print head which is fixed in position with respect to the printing process, where the print head often operates according to the inkjet principle.

[0003] In many cases, it is not necessary to print over the entire surface of the substrate. Printing in strip-like areas is often sufficient. For cost reasons, WO2016174643 proposes using a print head whose printing width is significantly smaller than the width of the substrate. In this case, the printing width of the print head sets the maximum width of the printable strip.

[0004] In order to be able to change the position of the printable area depending on the product, a print head positioning device has been proposed, for which the print head is accommodated in the machine frame by means of a laterally arranged linear guide, along which the print head can be freely positioned laterally with respect to the feed direction of the printing substrate.

[0005] For this purpose, the printhead is accommodated in a carriage which, in addition to the elements for feeding and controlling the printhead, also comprises a feed drive, the gear of which engages in a rack which runs parallel to the linear guide and is fixed to the frame.

[0006] The maximum printable width of one printing process is given by the print head. The cost of the print head increases more than proportionally with the print width of the print head. Therefore, it is attempted to use a print head with the smallest possible print width. The possibilities of constructing the print image are accordingly limited by this, especially when several print images are laterally separated from each other. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] International Publication No. 2016174643 Summary of the Invention [Problem to be solved by the invention]

[0008] SUMMARY OF THE DISCLOSURE It is therefore an object of the present invention to provide a printing device, in particular for printing on materials such as cardboard or corrugated board, which makes it possible to avoid the aforementioned disadvantages in a technically easy manner and using economical measures. [Means for solving the problem]

[0009] The problem posed is solved according to the invention in a printing device as defined in the opening paragraph by the features set out in claim 1. Advantageous developments of the invention are characterized by the features set out in the dependent claims.

[0010] According to the invention, the printing device has a plurality of printing units arranged next to each other in the material flow direction, each of which can be individually positioned transversely to the material flow direction by a feed device along a linear guide.

[0011] The use of multiple printing units with small printing widths significantly expands the possibilities for constructing the print image at little cost, since the printing units can be freely positioned relative to one another transversely to the material flow direction. The position of the printable strips on the substrate can be selected within a wide range.

[0012] Additionally, multiple printheads of the same type provide redundancy, making the printing device more versatile.

[0013] Each printing unit is formed from a frame that houses a primary reservoir used as a main storage, a secondary reservoir used as a buffer, and a pump for the supply of printing material, for which the frame may be configured as a housing.

[0014] The frames of the printing units each accommodate at least two print heads, which are oriented in the same printing direction and point towards the same printing plane, which corresponds to the plane determined by the substrate. The use of identical print heads with a relatively small printing width allows for a simple adaptation to different customer requirements by adapting the number of identical printing units.

[0015] Advantageously, the print heads of the printing units are arranged laterally offset from one another. In this way, the print heads can print tracks of greater width together. In an advantageous embodiment, the printing areas of the print heads of one and the same printing unit are directly adjacent to one another in the lateral direction. Thus, the area that can be printed by one printing unit is maximized. In a particularly advantageous embodiment, the print heads are arranged laterally relative to one another in such a way that the individual printing areas of the print heads slightly overlap. Thus, errors in the printed image due to geometrical tolerances can be avoided.

[0016] It is advantageous for the print heads of the printing units to be arranged offset in the material flow direction, so that the print heads and their mounting parts can be constructed simply and sufficiently robustly, in particular with the print areas laterally adjacent to one another.

[0017] Particularly advantageous is the curved contour of the printing units in plan view from the printing plane. In this case, the print heads of each printing unit are arranged on one leg of the curve, offset from one another in the longitudinal and transverse directions. In this way, by using a common guide rail, the printing units can be positioned relative to one another in the transverse direction, so that adjacent printing units together form a continuous printing area without interruptions. Thus, a very high variability of the printing area is achieved with a compact construction.

[0018] The feed device allows the printing units to be positioned laterally independently and automatically. For this purpose, the printing units each have a feed drive with a controllable motor. Alternatively, a single feed drive can be used which temporarily acts on each individual printing unit.

[0019] The invention will now be described by way of example with reference to the drawings, to which reference is made for all details not specifically mentioned in the description. [Brief description of the drawings]

[0020] [Figure 1] 1 shows a perspective view of a printing device having three printing units of the same kind; [Diagram 2] 1 shows a printing device with three printing units of the same kind, viewed against the printing direction. [Diagram 3] 1 shows the printing unit in a lateral view. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] In Fig. 1 three printing units 2.1, 2.2, 2.3 of identical construction are shown in a printing machine. The drawing of the three printing units 2.1, 2.2, 2.3 is merely exemplary. Depending on the situation of use, the printing machine may have two or any number of printing units 2.1, 2.2, 2.3.

[0022] The printing units 2.1, 2.2, 2.3 are arranged in fixed positions in the machine frame 1 in relation to the printing process. The printing substrate, not shown, is moved along the print heads 23, 24 in a material flow direction 100, which runs horizontally and defines the longitudinal axis of the printing device. To feed the printing substrate forward, a transport device 60 of known type is provided. Figures 1 and 2 only partially show this transport device 60 arranged in the machine frame 1.

[0023] The printing units 2.1, 2.2, 2.3 are accommodated in the machine frame 1 by means of linear guides 31. In this case, a guide carriage 33 is attached to the printing units 2.1, 2.2, 2.3. The guide carriages 33 are supported together on two mutually parallel guide rails 32. The guide rails 32 are oriented transversely to the material flow direction 100. This allows the printing units 2.1, 2.2, 2.3 and thus the printing areas 201, 202, 203, 204 of the printing units to be positioned in the transverse direction 200. The position changes are represented by double arrows in FIG. 2. The printing units 2.1, 2.2, 2.3 are arranged next to each other with respect to the material flow direction 100.

[0024] The print heads 23, 24 of the printing units 2.1, 2.2, 2.3 form a common printing plane, which is identical to the substrate plane 1000 defined by the substrate. In the exemplary embodiment shown in Fig. 1, a vertical printing direction 300 from bottom to top is set. A different printing direction, for example from top to bottom, is also possible.

[0025] The structure of the individual printing units 2, 2.1, 2.2, 2.3 is explained below by way of example on the basis of FIG. 3. Two identical printing heads 23, 24 are accommodated in a common frame 20 in the same orientation. The printing units 23, 24 are each suitable for simultaneously producing a number of printing dots located next to each other in a common printing direction 300. The array of these printing dots extends in the transverse direction 200 as rows and defines a printing width 201, 202, 203.1, 203.2, 203.3. The two printing heads 23, 24 are arranged offset from one another both in the material flow direction 100 and in the transverse direction 200.

[0026] On the frame 20 is attached a primary printing agent reservoir 21. The primary printing agent reservoir 21 consists of a number of containers, as shown in figures 1 and 3. The primary reservoir 21 is connected by a suction line, not shown, to a pump 25 arranged in the frame 20 configured as a housing. On the printing side, the pump 25 is connected by a line, also not shown, to a secondary printing agent reservoir 22. The printing agent reservoir 22 supplies the print heads 23, 24 with printing agent via lines, not shown.

[0027] The time variation of the current release of printing agent by the print heads 23, 24 can be significantly greater than the drive system of the pump 25 allows, depending on the print image to be produced and the transport speed of the substrate. The secondary reservoir 22, which is arranged at the same vertical height as the print heads 23, 24, is suitable for buffering such short-term fluctuations in the printing agent demand. This allows a more uniform and therefore smoother operation of the pump 25. In this case, the secondary reservoir 22 is significantly smaller than the primary reservoir 21.

[0028] On the side of the frame facing the material flow direction 100, two guide carriages 33 of a linear guide 31 are mounted. The guide carriages 33 are arranged one above the other and are oriented parallel to one another.

[0029] Via the feed device 30, the printing units 2, 2.1, 2.2, 2.3 can be positioned in the lateral direction 200 along the linear guide 31. For this purpose, a rack 35 is arranged on the machine frame parallel to the linear guide 31. A gear 36 of a feed drive 34 meshes with the rack 35, which is fixed to the frame. The gear 36 is arranged on the frame 20 of the printing units 2, 2.1, 2.2, 2.3 and is driven by a controllable motor 37. The controllable motor 37 of the feed drive 34 is mounted in the printing units 2, 2.1, 2.2, 2.3. Via a cable, the controllable motor 37 is connected to the central control 70 of the printing device.

[0030] Mutually adjacent printing units 2, 2.1, 2.2, 2.3 can be positioned relative to one another in the lateral direction 200 by the feed device 30 such that the printing areas 201, 202, 203, 204 have a predetermined distance 205 from one another. If two mutually adjacent printing units 2, 2.1, 2.2, 2.3 are moved in close contact with one another, the smallest possible distance is achieved.

[0031] In this close contact state, due to manufacturing and assembly tolerances, the printing areas 203.1, 203.2, 203.3 of the printing units 2, 2.1, 2.2, 2.3 will occupy different lateral positions relative to each other. To compensate for these deviations, spacer plates 38 are provided, which are arranged between the printing units 2, 2.1, 2.2, 2.3. The spacer plates 38 are attached to the frames 20 of the printing units 2, 2.1, 2.2, 2.3, respectively. The thickness of the spacer plates 38 is selected such that the lateral positioning of the printing areas 203.1, 203.2, 203.3 of two adjacent printing units 2, 2.1, 2.2, 2.3 relative to each other corresponds to a predetermined dimension.

[0032] Alternatively, the spacer plates 38 may be configured to be adjustable, for example by jack bolts, or other adjustable spacer elements may be used, such as, for example, clampable eccentrics.

[0033] The frame 20, which is also configured as a housing, accommodates electronic components 26 which are necessary for controlling the print heads 23, 24. These electronic components 26 are in turn connected to a control unit 70 of the printing device.

[0034] Each print head 23, 24 forms a transverse track 221, 222 by sliding along the linear guide 31. The transverse tracks 221, 222 represent a printable range. The first print head 23 forms a first transverse track 221, and the second print head 24 forms a second transverse track 222. Both tracks 221, 222 are forcedly parallel to each other and to the linear guide 31. In the material flow direction 100, the tracks 221, 222 have a spacing 220 that is set by the arrangement of the print heads 23, 24 in the printing units 2, 2.1, 2.2, 2.3 relative to each other. In this case, the first tracks 221 of the mutually adjacent printing units 2, 2.1, 2.2, 2.3 are identical. Similarly, the second tracks 222 of the mutually adjacent printing units 2, 2.1, 2.2, 2.3 are identical.

[0035] Within the tracks 221, 222 of the print heads 23, 24, the print areas 201, 202 of the print heads 23, 24 result from the shape of the print heads 23, 24 and the lateral position of the print heads 23, 24. The print heads 23, 24 of the printing units 2, 2.1, 2.2, 2.3 are arranged in such a way that the print areas 201, 202 of the print heads 23, 24 are adjacent to one another in the lateral direction 200. To ensure that printing errors are eliminated, the two print areas 201, 202 of the printing units 2, 2.1, 2.2, 2.3 overlap slightly, thus forming a first overlap 211.

[0036] If two adjacent printing units 2, 2.1, 2.2, 2.3 are positioned close to each other, the printing units 2, 2.1, 2.2, 2.3 form a common printing area 204. This arrangement is shown in FIG. 2 on the basis of two printing units 2.1, 2.2 and can be transferred to all mutually adjacent printing units 2, 2.1, 2.2, 2.3. The printing areas 203.1, 203.2, 203.3 of adjacent printing units 2, 2.1, 2.2, 2.3 are directly adjacent to each other, as are the first printing area 201 of the first print head 23 and the second printing area 202 of the second print head 24 of the same printing unit 2, 2.1, 2.2, 2.3. The printing areas overlap and form a second overlap 212, which avoids error spots in the printed image.

[0037] The printing units 2, 2.1, 2.2, 2.3 each have a bent contour 27 in the substrate plane, which is shown in dotted lines in Fig. 2. The bend allows the printing units 2, 2.1, 2.2, 2.3 to be arranged offset in the material flow direction and transverse direction 200 relative to the printing heads 23, 24, respectively, such that the printing area 201 of the first printing head 23 adjoins the second printing area 202 of the second printing head 24 of the directly adjacent printing unit 2.2, as shown in Fig. 2. As an alternative to a simple bent shape, the contour 27 may have a toothed shape. [Explanation of symbols]

[0038] 1 frame 2 Printing unit 2.1 First printing unit 2.2 Second printing unit 2.3 The third printing unit 20 Frames 21 First Reservoir 22 Second Reservoir 23 First Print Head 24 Second Print Head 25 Pump 26 Electronic Components 27 Contours in the plane of the substrate 30 Feeder 31 Linear guide 32 Guide rail 33 Guide Carriage 34 Feed drive unit 35 Rack 36 Gears 37 Controllable Motors 38 Spacer plate 60 Transport Equipment 70 Control section 100 Material flow direction 200 Horizontal 201 Printing range of the first print head 202 Printing range of the second print head 203.1 Printing area of ​​the first printing unit 203.2 Printing area of ​​the second printing unit 203.3 Printing area of ​​the third printing unit 204 Common 4th Print Range 205 Spacing between adjacent print areas 211 First overlap within one printing unit 212 Second overlap between two printing units 220 Material flow direction spacing 221 First lateral track 222 Second lateral track 300 Print direction 1000 Substrate plane

Claims

1. A printing device for printing individually on a web-like or sheet-like printing substrate based on the inkjet principle, the printing substrate defining a substrate plane, The printing device is at least A machine frame (1); a conveying device (60) configured to convey the substrate in a substantially linear material flow direction (100) in a substrate plane; two identical printing units (2, 2.1, 2.2, 2.3) arranged one after the other in a transverse direction (200) relative to the material flow direction (100), each of the at least two printing units (2, 2.1, 2.2, 2.3) having a frame (20) and arranged in said frame (20); Equipped with The printing units (2, 2.1, 2.2, 2.3) comprise at least a first print head (23) adapted and controllable to eject and transfer a liquid printing agent in a predetermined manner to a substrate; a primary reservoir (21) for storing a first amount of liquid printing agent; a secondary reservoir (22) for storing a second amount of liquid printing agent; A pump (25) for pumping the liquid printing agent; having the at least one primary reservoir (21), the at least one secondary reservoir (22) and the at least one pump (25) are connected to each other and to the at least one first print head (23) in a pumping manner with respect to the liquid printing agent, thereby supplying the at least one first print head (23) with the liquid printing agent; A printing device, in which at least two printing units (2, 2.1, 2.2, 2.3) each have at least one second printing head (24), and the first printing head (23) and the second printing head (24) of each printing unit (2, 2.1, 2.2, 2.3) are accommodated in a common frame (20) of the printing unit (2, 2.1, 2.2, 2.3), and the printing planes of the at least two printing heads (23, 24) of one printing unit (2, 2.1, 2.2, 2.3) are identical to a same substrate plane (1000), 1. A printing device, characterized in that, at least temporarily, the printing areas (203.1, 203.2) of at least two printing units (2.1, 2.2) which are directly adjacent to one another form a common uninterrupted printing area (204) at least in the lateral direction (200), and the individual printing areas (203.1, 203.2) of at least two printing units (2.1, 2.2) which are directly adjacent to one another directly follow one another or partially overlap one another and each form a second overlap area (212).

2. 2. The device according to claim 1, characterized in that at least two print heads (23, 24) of one and the same printing unit (2, 2.1, 2.2, 2.3) are arranged offset from one another in the lateral direction (200) such that the printing areas (201, 202) of the print heads (23, 24) partially overlap in the lateral direction (200) to form a first overlap area (211).

3. 3. The device according to claim 2, characterized in that the printing area (201, 202) of one printing unit (2, 2.1, 2.2, 2.3) corresponds in each case to several times the overlap (211) of said printing areas (201, 202) in the lateral direction (200).

4. 2. The device according to claim 1, characterized in that at least two print heads (23, 24) of one and the same printing unit (2, 2.1, 2.2, 2.3) are arranged transversely (200) relative to one another in such a way that the printing areas (201, 202) of the print heads (23, 24) are directly adjacent to one another in the transverse direction (200).

5. 5. Apparatus according to claim 1, characterized in that at least two printing units (2, 2.1, 2.2, 2.3) are accommodated in a common machine frame (1) so as to be movable laterally (200) independently of each other.

6. 6. The apparatus according to claim 5, wherein at least one feed device (30) is provided for each of the at least two printing units (2, 2.1, 2.2, 2.3), each feed device (30) having at least one controllable motor (37), said motor (37) being in communication with a control unit (70) of the printing apparatus.

7. 6. The apparatus according to claim 5, further comprising a common feed device for at least two printing units (2, 2.1, 2.2, 2.3) having at least one controllable motor, said motor being in communication with a control unit (70) of the printing apparatus, the common feed device being alternately operatively connected to one of the at least two printing units (2, 2.1, 2.2, 2.3).

8. 8. The device according to claim 1, wherein the at least one secondary reservoir (22) of each of the at least two printing units (2, 2.1, 2.2, 2.3) is arranged in the vertical direction at the height of the at least two print heads (23, 24) of substantially the same printing unit (2, 2.1, 2.2, 2.3).

9. 9. The device according to claim 5, wherein at least one of the frames (20) of at least one first printing unit (2.1) of the at least two printing units (2, 2.1, 2.2, 2.3) has at least one spacer holder (38), which is arranged towards a second printing unit (2.2) adjacent to the first printing unit (2.1), and which limits the changeable distance between the printing head (23, 24) of the first printing unit (2.1) and the printing head (23, 24) of the adjacent second printing unit (2.2) to a minimum dimension.

10. 10. The apparatus according to claim 1, wherein at least two print heads (23, 24) of one and the same printing unit (2, 2.1, 2.2, 2.3) are offset from one another in the material flow direction (100) on the common frame (20) such that the printing areas of the printing units (2, 2.1, 2.2, 2.3) have a distance (220) from one another in the material flow direction (100).

11. 11. The device according to claim 1, wherein at least two printing units (2, 2.1, 2.2, 2.3) each have a curved or toothed contour (27) in the substrate plane (1000) such that the contours (27) of two adjacent printing units (2, 2.1, 2.2, 2.3) engage with each other.

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