DEVICE AND METHOD FOR PATTERNING A WORKPIECE

Description

Technical field

[0001] The invention relates to a device and a method for patterning a workpiece, which preferably consists at least partially of wood, wood-based materials, plastic or the like. State of the art

[0002] In the furniture and construction industry, workpieces are often made of wood or wood-based materials, such as chipboard, which are coated and patterned on their surface. The coating itself may already be patterned, eliminating the need for a separate patterning process. On the other hand, it is also known to apply the desired decoration to the coating shortly before or after it is applied to the workpiece, for example, using an inkjet printing process (e.g., EP 1 867 488 A).

[0003] This typically involves the use of print heads that eject ink drops of different colors and overlay them to create the desired color or pattern.

[0004] However, it has been shown that conventional printing units require considerable space. Furthermore, conventional printing units are usually optimized for applying complex patterns, but not for additional functions required in the furniture and construction component industries, such as the variable adjustment of the physical and geometric properties of the printing layer. Furthermore, conventional printing units are not ideally suited for printing solid colors.

[0005] Further printing processes are known from EP 1 935 659 A1 and EP 2 097 265 B1.

[0006] Furthermore, the publication WO 2021 / 144353 A1 is known, in which a printing device for printing on a surface, in particular the surface of a workpiece, is described, wherein the printing device has an ink supply device which has at least two ink containers each holding a printing ink, and an ink feed through which the printing inks can be fed to at least one print head in order to carry out a printing process with at least one of the printing inks, wherein a rinsing device is provided by which at least the ink feed and / or the at least one print head can be rinsed with a rinsing liquid for a printing ink change, and a method for changing printing inks (19) in a printing device.

[0007] Furthermore, US 2014 / 198168 A1 is known. Description of the invention

[0008] It is an object of the invention to provide a device and a method for patterning a workpiece, which preferably consists at least partially of wood, wood-based materials, plastic or the like, by means of which diverse geometric and physical properties of the printing layer can be achieved with little space requirement and also an improved printing of solid colors can be achieved.

[0009] This object is achieved according to the invention by a device for patterning a workpiece according to claim 1 and a method for patterning a workpiece according to claim 10. Particularly preferred developments of the invention are specified in the dependent claims.

[0010] The invention is based on the idea of ​​providing a completely different preparation of the printing material (for example, an ink) for the patterning of workpieces. For this purpose, the device according to the invention comprises a feed unit for feeding at least two printing components to a printing unit, as well as a mixing unit upstream of the printing unit for mixing the components fed by the feed unit and for delivering the mixture to the printing unit.

[0011] In this way, it is possible to provide a print layer with the desired geometric and physical properties in a very targeted and individual manner, if necessary even differently for each workpiece. At the same time, the number of required printing units or print heads can be reduced, since the targeted mixing of the components means that separate print heads are no longer required for specific overlay processes. Furthermore, the device according to the invention is particularly well suited for the rapid and economical printing of solid colors, since the desired solid color can already be produced upstream of the printing unit. As a result, the device according to the invention opens up completely new and diverse possibilities for the patterning of workpieces in the furniture and construction element industries, which preferably consist at least partially of wood, wood-based materials, plastic or the like.

[0012] A further increased variety of achievable properties of the subsequent printed layer results from the fact that the mixing unit according to the invention is configured to temperature-control, in particular to heat, the supplied components. Thus, by temperature-controlling the mixing unit, not only can the mixing of the individual components be optimized, but also certain substances and properties of the printed component can be activated or their activation behavior can be temporally controlled and optimized.

[0013] In order to enable the printing components to be supplied to the printing unit in the most targeted, precise and variable manner possible, a further development of the invention provides that the supply unit has a plurality of pumps which are connected to at least one printing component container.

[0014] Within the scope of the invention, the printing component containers can contain and provide a wide variety of components. According to a further development of the invention, at least one printing component container contains a stock liquid. The provision of a stock liquid creates, in a sense, the basis for providing a very wide variety of printing materials without being restricted to a specific type of ink or a specific ink base material. Furthermore, the stock liquid can also have neutral or even cleaning properties, so that it can be used, if necessary, to rinse or even clean specific areas of the device.

[0015] Furthermore, according to a further development of the invention, at least one printing component container contains dyes, such as color pigments. This allows, for example, in combination with a base liquid, to produce printing materials of any desired color, resulting in an extremely wide range of possible printing inks. A particularly advantageous feature is that setting a desired color of the printing material upstream of the printing unit also results in particularly high-quality, yet also rapid and cost-effective solid-color printing.

[0016] Alternatively or additionally, according to a further development of the invention, at least one printing component container comprises at least one additive, wherein the additive is preferably selected from physically changeable additives, matting additives, foamable additives, structure-forming additives, and fluorescent additives. Thanks to these additives, it is possible to impart a wide variety of physical and geometric properties to the subsequent printing layer on the workpiece. For example, structured surfaces, luminous surfaces, reflective surfaces, matte surfaces, particularly thick surfaces, particularly impact-resistant surfaces, and many other surfaces can be created. At the same time, this effect is achieved in a flexible and variable manner with the invention, since the desired properties can be individually adjusted for the respective workpiece depending on the supply of additives.

[0017] The mixing unit can be configured in various ways within the scope of the invention. However, a particularly rapid, effective, and trouble-free mixing of the printing components is achieved if the mixing unit, according to a further development of the invention, has at least one movable mixing element, preferably with at least one drive for driving the movable mixing element.

[0018] In this context, according to a further development of the invention, the mixing unit can also be configured to dispense the supplied components only after a certain dwell time. Thus, the mixing unit can also serve as an intermediate buffer, allowing the components to achieve optimal mixing and / or develop additional properties, such as a particular viscosity or strength or other physical properties, over time and, if necessary, under the influence of temperature control.

[0019] Furthermore, according to a further development of the invention, at least one printing unit has a secondary circuit for circulating and, if necessary, buffering a supplied printing material mixture. In this way, the operation of the mixing unit and the printing unit can be at least partially decoupled from each other, which is advantageous, for example, during interruptions in printing operations or during dwell times on the part of the mixing unit, and minimizes printing material waste.

[0020] Furthermore, according to a further development of the invention, multiple printing units are provided, particularly for sequential printing, wherein preferably multiple printing units are connected to a mixing unit. By providing multiple printing units, special optical and physical effects can be achieved, such as multi-layer printing, multiple partial-area printing to achieve special patterns, or even a layered structure in which each layer has different properties and fulfills different functions.

[0021] The above-mentioned advantages can be achieved particularly effectively with a method for patterning a workpiece according to claim 10. The advantages of the invention are particularly evident when the surface of the workpiece to be printed consists at least partially of plastic. Printing on plastics places particularly high demands on the printing process and the printing material used, and the invention also enables particularly high-quality and diverse printing results here.

[0022] Furthermore, according to a further development of the method according to the invention, the printing unit and / or the mixing unit are cleaned by supplying a printing component, in particular a stock liquid, via the supply unit. This makes it possible to actually utilize the high flexibility and variability of the invention for changing workpieces without requiring a complex and separate cleaning technique. Short description of the drawings

[0023] Fig. 1 shows schematically a plan view of an apparatus for patterning a workpiece according to an embodiment of the invention. Description of embodiments

[0024] Preferred embodiments of the invention are described below with reference to the accompanying drawings.

[0025] A device 1 for patterning a workpiece 2 is shown in Fig. 1 shown schematically in a top view.

[0026] The device 1 is used for the patterning of workpieces 2, such as those used in the furniture and construction element industry, such as furniture fronts, carcass parts, door leaves, etc. These are usually made of wood or wood-based materials and are often coated in the area of ​​their surface 2' with a covering layer, which can be made of plastic or various composite materials, but also of paper or veneer. Fig. 1 A plate-shaped workpiece 2 is shown as an example, which is to be printed in the area of ​​its narrow surface 2'. A so-called edge can be glued to this narrow surface, for example. However, it should be noted that the device according to the invention can also be used for patterning a wide surface or any other surface 2' of the workpiece.

[0027] As in Fig. 1As can be seen, the device 1 in the present embodiment comprises a conveyor device 4 in the form of a continuous device, which may, for example, have a conveyor belt, a conveyor chain, or other suitable conveyor elements. However, it should be noted that other conveyor concepts may also be used within the scope of the present invention, for example so-called stationary machines in which the workpiece 2 is stationary and components of the device are moved relative to the workpiece 2. Mixed forms of both concepts are also possible within the scope of the invention.

[0028] For patterning the surface 2' of the workpiece, the device 1 has a printing unit 10, which in the present embodiment is designed as a drop-on-demand printing unit. Thus, the printing unit 10, as indicated by an arrow 10' in Fig. 1illustrated, ink drops onto the surface of the workpiece 2 to be patterned. Otherwise, however, other, possibly continuous, printing processes are also possible.

[0029] Upstream of the printing unit 10, the device 1 initially comprises a feed unit 20, which in the present embodiment has a plurality of printing component containers 24 and 26. These printing component containers are connected via respective pumps 22 to a mixing unit 30, the output of which is in turn connected to the printing unit 10.

[0030] In the present embodiment, the printing component container 24 contains a stock liquid, which can be, for example, a water-based liquid or a liquid designed for later UV curing, suitable for absorbing dyes or additives. A water-based stock liquid can also contain solvents, for example. A stock liquid designed for later UV curing can contain an acrylate-monomer mixture.

[0031] Furthermore, the stock fluid has the most neutral properties possible and is preferably free of dyes or pigments, so it is not suitable for producing permanent printing surfaces on its own. It can therefore also be used for rinsing or cleaning, for example, the mixing unit 30 or the printing unit 10.

[0032] The printing component containers 26 contain various colorants, such as color pigments or additives, as required. Examples include physically modifiable additives (e.g., polymers), matting additives (e.g., lime), foamable additives (e.g., polyurethanes), structure-forming additives (e.g., granules), or fluorescent additives.

[0033] In the present embodiment, the mixing unit comprises, for example, a worm-shaped mixing element 32, which is provided in a cavity within the mixing unit and is rotatable about a longitudinal axis. In this embodiment, the mixing element 32 is connected to a rotary drive 34 and can thus be driven to rotate about its longitudinal axis. Thanks to the worm shape of the mixing element, it can be used for mixing, but also for conveying and dispensing the supplied pressure components. As shown in Fig. 1 can be seen, these are then passed on to the printing unit 10 in order to be used from there for printing the workpiece 2.

[0034] Although in Fig. 1Not shown, the mixing unit 30 in the present embodiment has a heating unit by means of which the supplied components can be heated. Alternatively or additionally, a cooling unit would also be conceivable. Furthermore, the mixing unit 30 can also be configured to mix the supplied components and then deliver them to the printing unit 10 only after a certain dwell time. For this purpose, a closure can be provided at the outlet of the mixing unit 30, or other types of mixing elements or various other measures can be used.

[0035] As in Fig. 1 can be seen, the Fig. 1Furthermore, in the area of ​​the printing unit 10, there is a secondary circuit 12 with a secondary pump 14, which serves to circulate and, if necessary, buffer a supplied printing material mixture. This can be advantageous, for example, if no workpiece is to be printed at the moment, but the mixing unit 30 continues to supply printing material. Furthermore, the secondary circuit 12 can temporarily supply the printing unit 10 with printing material if the mixing unit 30 is not supplying any printing material mixture at the moment, for example, due to a dwell time.

[0036] Although in Fig. 1Not shown, the printing device 1 can also have a plurality of printing units 10 arranged sequentially along the conveyor device 4. These can all be connected to the mixing unit 30 or at least one separate mixing unit. In any case, the arrangement of a plurality of sequential printing units enables multi-stage and, if necessary, multi-layer printing of the workpiece 2, whereby a wide variety of physical and optical surface properties can be achieved.

[0037] During operation of the device 1, the base liquid from the printing component container 24 and one or more dyes and / or additives from the printing component containers 26 are first fed to the mixing unit 30 and mixed there by means of the mixing element 32. The printing material mixture is then dispensed to the printing unit 10 and used for printing the surface 2' of the workpiece.

[0038] As soon as different surface properties of the workpiece are required, or if the material composition of the workpiece or the surface of the workpiece has changed, either continuous adjustments to the printing material mixture can be made, or printing operation can be stopped in order to rinse and, if possible, clean both the mixing unit 30 and the printing unit 10. For this purpose, for example, stock liquid is supplied from the container 24 by means of the pump and dispensed into a collecting container at the printing unit 10. Subsequently, a new mixture can be determined based on the changed requirements and provided by the mixing unit 30.

[0039] In order to control the above-mentioned functions and components, the device may comprise a suitable control device.

Claims

1. Device (1) for patterning a workpiece (2) which preferably consists at least in part of wood, wood-based materials, plastics material or the like, comprising: at least one printing unit (10) for printing on a surface (2'), in particular a narrow surface, of the workpiece (2), a conveying means (4) for bringing about a relative movement between the workpiece (2) and the printing unit (10), and a supply unit (20) for supplying at least two printing components to the printing unit (10), wherein a mixing unit (30) is provided upstream of the printing unit (10) for mixing the components supplied by means of the supply unit (20) and for discharging the mixture to the printing unit (10), characterised in that the mixing unit (30) is configured to control the temperature of the supplied components.

2. Device according to claim 1, wherein the supply unit (20) comprises a plurality of pumps (22) which are each connected to at least one printing component container (24, 26).

3. Device according to claim 2, wherein at least one printing component container (24) comprises a mother liquid.

4. Device according to claim 2 or 3, wherein at least one printing component container (26) comprises dyes, in particular colour pigments, and / or at least one additive, wherein the additive is preferably selected from physically modifiable additives, matting additives, foamable additives, structure-forming additives, fluorescent additives.

5. Device according to any of the preceding claims, wherein the mixing unit (30) comprises at least one movable mixing element (32), wherein preferably at least one drive (34) is provided for driving the movable mixing element (32).

6. Device according to any of the preceding claims, wherein the mixing unit (30) is configured to heat the supplied components.

7. Device according to any of the preceding claims, wherein the mixing unit (30) is configured to only dispense the supplied components after a dwell time.

8. Device according to any of the preceding claims, wherein at least one printing unit (10) comprises a secondary circuit (12) for circulating and, if applicable, buffering a supplied printing material mixture.

9. Device according to any of the preceding claims, wherein a plurality of printing units are provided for printing, in particular sequentially, wherein preferably a plurality of printing units are connected to a mixing unit.

10. Method for patterning a workpiece (2) which preferably consists at least in part of wood, wood-based materials, plastics material or the like, using a device (1) according to any of the preceding claims, comprising the steps of: bringing about a relative movement between the workpiece (2) and the printing unit (10) by means of the conveying means (4), mixing and controlling the temperature of components in the mixing unit (30) that were supplied by means of the supply unit (20) and discharging the mixture to the printing unit (10), and printing on a surface (2'), in particular a narrow surface, of the workpiece (2) by means of the printing unit (10).

11. Method according to claim 10, wherein the surface (2') of the workpiece (2) to be printed on consists at least in portions of plastics material.

12. Method according to claim 10 or 11, wherein the printing unit (10) and / or the mixing unit (30) are cleaned, in that a printing component, in particular a mother liquid, is supplied by means of the supply unit (20).