DIGITAL PRINTING MACHINE AND PRINTING PROCEDURES

Description

[0001] The invention relates to a digital printing machine, in particular for printing on textiles, comprising a frame, at least one receiving carriage for receiving and holding a print material, in particular a textile, wherein the receiving carriage is movable in a horizontal direction along the frame in a longitudinal direction, and at least one printing carriage with a print head having one or more inkjet nozzles, wherein the printing carriage is movable on the frame in a transverse direction, according to the preamble of claim 1.

[0002] The invention further relates to a printing method for printing a substrate with a digital printing machine, which has a frame, at least one receiving carriage for receiving and holding a substrate, in particular a textile, wherein the receiving carriage is moved in a horizontal direction in a longitudinal direction of the frame, and at least one printing carriage with a print head having one or more inkjet nozzles, wherein the printing carriage is moved in a transverse direction on the frame during printing, according to the preamble of claim 7.

[0003] A textile printing machine of this type is described, for example, in EP 3 184 313 A1. Two receiving carriages are arranged parallel to each other and movable in a longitudinal direction on a frame. The receiving carriages are designed to pick up and hold a textile, such as a T-shirt or a sweatshirt. Above the receiving carriages, two printing carriages are mounted on a crossbeam in a transverse direction to the longitudinal direction. Each printing carriage has a plurality of inkjet nozzles with which a desired printed image is applied to the respective textile. For this purpose, the receiving carriages with the textile are moved longitudinally below the printing carriages, [2] whereby the printed image is applied line by moving the printing carriages and the receiving carriages in a coordinated manner relative to each other.

[0004] EP 2 461 982 B1, US 2006 / 0152568 A1 and WO 2021 / 132448 A1 each disclose a generic pressure device with the features from the preamble of independent claim 1.

[0005] US Patent 2021 / 229472 discloses a printing device with a printhead holder that can be positioned relative to the printhead via a lifting unit. For correct height adjustment, this printer includes a height sensor that scans the object to be printed, thus preventing potential collisions between the printhead and the object. The object thickness is also indirectly measured via this height sensor. US Patent 2018 / 304645 discloses a printing device and proposes replacing the conventional cylindrical slide, which must be rotated to feed the objects to be printed, with a plate-shaped slide. However, this plate-shaped slide still requires a translational feed axis to move the clamped object relative to the printhead.During the exchange, the movement of the rotating slide is thus converted into a linear movement of the plate-shaped slide. Finally, US 2004 / 017 456 also shows a printing device with feed rollers or feed belts that slide the object to be printed onto a receiving table and feed it to the print head.

[0006] For the quality of the printed image, a defined distance between the print nozzles and the printing area on the textile is crucial. If the distance is too small, too much ink can be applied to each area of ​​the textile, which can lead to color bleeding. Furthermore, this can result in excessive ink consumption.

[0007] If the distance between the print nozzle and the textile is too high, contour sharpness is lost and the applied printed image can appear blurry and indistinct.

[0008] It is common practice to set up a printing machine for printing on a specific type of textile. Typically, this setup is used to print as many similar items as possible. However, if the type of item to be printed changes, for example from a relatively thin T-shirt to a thicker sweatshirt or sweater, the machine's setup must be manually adjusted, sometimes requiring the modification or replacement of components. This is time-consuming and labor-intensive. Therefore, it is standard practice to print as many similar items as possible in a single setup, thus minimizing the frequency of these complex changeovers.

[0009] The invention is based on the objective of providing a printing machine and a printing process with which printed materials with different wall thicknesses can be printed particularly efficiently.

[0010] The problem is solved, firstly, by a digital printing machine with the features of claim 1 and, secondly, by a printing method with the features of claim 7. Preferred embodiments are specified in the dependent claims.

[0011] The printing press according to the invention is characterized in that the receiving carriage has a base carriage and a receiving table which is adjustable in a vertical direction relative to the base carriage, which is perpendicular to the horizontal, and that the vertical adjustment of the receiving table relative to the base carriage is carried out by means of a drive.

[0012] A fundamental aspect of the invention is to arrange the mounting table adjustably on a base carriage of the mounting carriage. The height adjustability of the mounting table allows for efficient compensation of any changes in the thickness of the material to be printed, particularly textiles.

[0013] According to a further aspect of the invention, this is made particularly easier by the fact that the height adjustment is effected by means of a drive. The drive motor causes a change in the position of the receiving table relative to the base slide. This is done quickly and without requiring any effort from the machine operator.

[0014] This allows for easy height adjustment of the infeed table while loading or unloading a print material, enabling the processing and printing of materials with varying thicknesses with virtually no downtime. This increases the operational flexibility of the printing press and simultaneously ensures that the optimal distance between the print nozzles and the print material is always maintained.

[0015] In principle, adjustment can be made manually by a machine operator or a control device. A particularly efficient printing operation is achieved according to a further development of the invention by providing a control device that is designed for automatically adjusting the receiving table in the vertical direction.

[0016] In principle, the control unit, which is conventionally designed with buttons or a display with control panels, can show the machine operator a selection of possible printable materials, especially textiles, for pre-selection. Upon the operator's selection, the control unit then adjusts the height of the loading table relative to the base carriage according to a predefined and stored setting. The drive is directly controlled by the control unit.

[0017] According to one embodiment of the invention, it is preferred that at least one sensor device is provided by which the thickness of the material being printed, in particular a textile, which is held on the receiving table, can be determined, and that the sensor device is connected to the control device, wherein a vertical adjustment of the receiving table is carried out depending on the thickness of the material being printed. The sensor device can directly detect the thickness. Alternatively, the sensor device can also detect the type of material being printed, in particular a textile, wherein a corresponding thickness is assigned to a specific material by means of data stored in a memory. The control device can thus control the drive and make a necessary height adjustment according to the stored data on thickness or material thickness.

[0018] In principle, the positioning of the receiving table relative to the base slide can be achieved directly by adjusting elements, such as vertically oriented actuating cylinders. A preferred embodiment of the invention consists in providing an adjusting mechanism between the base slide and the receiving table, with which a vertical adjustment is effected. The adjusting mechanism can include mechanical elements, such as levers and / or gears, with which a particularly precise and reliable adjustment can be achieved.

[0019] A further development of the invention offers a particular advantage: the adjustment mechanism can incorporate a scissor mechanism. A scissor mechanism consists of at least two levers articulated to each other, which can be pivoted towards and away from each other in a scissor-like manner. The scissor mechanism can, in particular, also have more than two levers, which are arranged parallel and / or one behind the other. By means of a suitable transmission or reduction gear, a change in the actuating force and also in the actuating stroke can be achieved, even with respect to an actuator. Particularly in the latter case, very fine and precise adjustment in the vertical direction is possible.

[0020] According to one embodiment of the invention, it is particularly advantageous that the drive is designed as a linear drive, which is arranged on the receiving slide in the longitudinal or transverse direction. This allows for a particularly compact arrangement.

[0021] It is particularly advantageous that the drive is designed as an actuating cylinder or a spindle drive. The actuating cylinder can be pneumatically or, preferably, hydraulically driven. A spindle drive allows a threaded spindle driven by the actuator to mesh with a corresponding threaded bore or threaded sleeve of a linear drive element, thus enabling its linear movement.

[0022] Further flexibility in the printing press according to the invention can be achieved by providing the receiving table with an adapter element to which a plate-shaped receiving element is detachably and easily interchangeable. The adapter element can have a base table to which different plate-shaped receiving elements can be interchangeably attached. The different plate-shaped receiving elements can be adapted to a specific printing material, in particular a textile. A holding device, in particular a movable holding frame, can also be provided on the receiving element for holding or fixing, in particular, a textile to the receiving element. This allows for particularly good adaptation of the receiving table, and thus of the printing press, to different printing materials not only in height, but also in width and length.

[0023] A further improvement in flexibility is achieved according to the invention by providing a detection device that can detect the plate-shaped receiving element attached to the adapter element. The receiving element can, for example, be provided with an RFID chip or other identifier, which can be detected and / or queried by the detection device in order to identify the exact type of receiving element. Depending on the receiving element thus detected, the control unit can then automatically set and adjust further operating parameters of the printing press.

[0024] A particularly advantageous embodiment of the invention consists in the fact that the control unit allows the travel range of the print carriage and / or the inkjet nozzles to be adjusted depending on detected values. For example, if a plate-shaped receiving element for a small textile element is applied, the travel path of the print carriage in the transverse direction can be shortened accordingly.

[0025] If, however, a mounting element for a larger textile size is used, the travel distance of the print carriage can be increased accordingly. By shifting the reversal points of the print carriage, unnecessary idle travel during the line-by-line back-and-forth movement of the inkjet nozzles can be reduced. The same applies to setting and adjusting the longitudinal travel distance of the mounting carriage. This increases the efficiency of the machine and reduces required printing times.

[0026] A further improvement can be achieved by further developing the invention by mounting the printhead with the inkjet nozzles on the print carriage in a way that allows for vertical adjustment. Height adjustment can therefore be achieved not only by adjusting the mounting table, but also by adjusting the inkjet nozzles relative to the print carriage. This provides a relatively large adjustment range in the vertical direction, further increasing the flexibility of the printing machine for printing on different materials.

[0027] The invention further comprises a printing method for printing a substrate, characterized in that the receiving carriage has a base carriage and a receiving table, which is adjusted in a vertical direction relative to the base carriage before printing, which is perpendicular to the horizontal, and that the vertical adjustment of the receiving table relative to the base carriage is carried out by means of a drive.

[0028] The printing process according to the invention can be carried out, in particular, by the printing press according to the invention described above in the different embodiments described above. The advantages described in each case can be achieved in this way.

[0029] The invention is further explained below with reference to a preferred embodiment, which is shown schematically in the drawings.

[0030] The drawings show: Fig. 1 is a partial perspective view of a printing press according to the invention before printing; and Fig. 2 is a perspective view of the printing press from Fig. 1 during printing.

[0031] A printing press 10 according to the invention Figure 1 and 2 The frame 12, shown only schematically, has a horizontally mounted receiving carriage 20 on which it is movable in a longitudinal direction. A guide beam 14 is arranged on the frame 12 in a transverse direction, i.e., essentially perpendicular to the longitudinal direction, above the receiving table 20. A print carriage 40 with a print head 42 and a plurality of inkjet nozzles 44 is mounted transversely along the guide beam 14.

[0032] The mounting carriage 20 has a base carriage 22 and a mounting table 30 mounted thereon so that its height can be adjusted. An adjustment mechanism 36 for adjusting the height of the mounting table 30 is arranged between the base carriage 22 and the mounting table 30.

[0033] The adjusting mechanism 36 has a scissor mechanism formed by levers 37, wherein the levers 37 cross each other in a scissor-like manner and are pivotably connected to each other via a central joint 38. Part of the levers 37 is articulated to a movable slide 39, which is slidably mounted on the preferably flat or plate-shaped base slide 22.

[0034] For height adjustment of the receiving table 30, a drive 24 with a rotatable threaded spindle 25 is arranged on the receiving slide 20. The threaded spindle 25 meshes with a threaded section (not shown) on the slide 39 to convert a rotary movement of the threaded spindle 25 into a longitudinal movement of the slide 39 for adjusting the adjustment mechanism 36. The scissor mechanism translates the longitudinal movement into a vertical movement.

[0035] In the illustrated embodiment, the receiving table 30 has an adapter element 31 which is connected or coupled to the adjustment mechanism 36. A plate-shaped receiving element 32 can be detachably and easily interchangeably attached to the adapter element 31. The plate-shaped receiving element 32 can thus be adapted to the size of a printable material 5.

[0036] A detection device 52 for detecting the type and / or size of the receiving element 32 to be applied or already applied can be arranged on the adapter element 31. For this purpose, a marker 54, in particular an RFID chip, can be attached to the plate-shaped receiving element 32.

[0037] A sensor device 50, shown only schematically and preferably located on the frame 12 or the print carriage 40, can detect the substrate 5 and / or its thickness on the receiving table 30. Depending on the detected thickness, the adjustment mechanism 36 can be automatically adjusted by means of the drive 24 via a control device (not shown) so that a suitable distance for the printing process is set between the substrate 5 and the inkjet nozzles 42. This allows the printing machine 10 to print on different substrates 5 with varying material thicknesses, with the appropriate distance between the print nozzles 42 and the substrate 5 being automatically adjusted.

Claims

1. Digital textile printing machine for printing textiles, with - a frame, - at least one receiving carriage (20) for receiving and holding a printing product (5), in the form of a textile, wherein the receiving carriage (20) is displaceable in a horizontal in a longitudinal direction along the frame (12), and - at least one printing carriage (40) with a print head (42) having one or several ink jet nozzles (44), wherein the printing carriage (40) is displaceable on the frame (12) in a transverse direction, - wherein the receiving carriage (20) has a base carriage (22) and a receiving table (30) which is adjustable relative to the base carriage (22) in a vertical direction which is perpendicular to the horizontal, - wherein a drive (24) is provided for vertical adjustment of the receiving table (30) with respect to the base carriage (22), wherein the receiving table (30) has an adapter element (31), on which a plate-shaped receiving element (32) is attached in a releasable and easily changeable manner, wherein a detection means (52) is arranged, by which the plate-shaped receiving element (32) attached on the adapter element (31) can be detected, and wherein by the control means a displacement range of the printing carriage (40) and / or the ink jet nozzles (44) can be set depending on detected values on the type of the applied receiving element (32), in that characterized in that at least one sensor means (50) is provided, by which a thickness of the textile can be determined which is held on the receiving table (30), and in that the sensor means (50) is connected to the control means, wherein a vertical adjustment of the receiving table (30) takes place depending on the thickness of the textile (5) received.

2. Digital textile printing machine according to claim 1, characterized in that between the base carriage (22) and the receiving table (30) an adjustment mechanism (36) is provided, with which a vertical adjustment takes place.

3. Digital textile printing machine according to claim 2, characterized in that the adjustment mechanism (36) has a scissor mechanism.

4. Digital textile printing machine according to any one of claims 1 to 3, characterized in that the drive (24) is designed as a linear drive which is arranged on the receiving carriage (30) in the longitudinal direction or the transverse direction.

5. Digital textile printing machine according to any one of claims 1 to 4, characterized in that the drive (24) is designed as a positioning cylinder or a spindle drive.

6. Digital textile printing machine according to any one of claims 1 to 5, characterized in that the print head (42) with the ink jet nozzles (44) is supported on the printing carriage (40) by being adjustable in the vertical direction.

7. Printing method for printing a printing product (5), in the form of textiles, with a digital textile printing machine (10) according to any one of claims 1 to 6, which has - a frame (12), - at least one receiving carriage (20) for receiving and holding a textile, wherein the receiving carriage (20) is displaced in a horizontal in a longitudinal direction along the frame (12), and - at least one printing carriage (40) with a print head (42) having one or several ink jet nozzles (44), wherein during printing the printing carriage (40) is displaced on the frame (12) in a transverse direction, - wherein the receiving carriage (20) has a base carriage (22) and a receiving table (30) which, prior to printing, is adjusted relative to the base carriage (22) in a vertical direction which is perpendicular to the horizontal, and - wherein vertical adjustment of the receiving table (30) with respect to the base carriage (22) is carried out by means of a drive (24).