Device and method for coating a workpiece

Abstract

The invention relates to a device (1) for coating a workpiece (2), preferably with at least sections consisting of wood, wood-based material, plastic or similar, with a coating material (4), wherein the device comprises a pressure unit (6) for pressing the coating material (4) onto the workpiece (2), a conveyor unit (8) for bringing about a relative movement between the pressure unit (6) and the workpiece (2), and an adhesive application unit (10) for applying adhesive (12) to the coating material (4) and / or to the workpiece (2). The adhesive application unit has a plurality of outlet openings (14) for outputting adhesive (12).

Description

[0001] Device and method for coating a workpiece

[0002] Technical area

[0003] The invention relates to a device for coating a workpiece, which preferably consists at least in sections of wood, wood-based material, plastic or the like, with a coating material according to the preamble of claim 1, and to a corresponding method.

[0004] State of the art

[0005] In the furniture and construction component industries, it is common practice to apply a coating material (edge ​​material) to the narrow side of panel-shaped workpieces. Various techniques are used for this, such as gluing using a hot-melt adhesive rolled on during the joining process, or applying a coating material coated with a joining agent and activating the joining agent during the joining process using a suitable energy source.

[0006] Furthermore, WO2020 / 094283 discloses a device and method in which an adhesive is applied to the workpiece or coating material using a drop-on-demand technique. However, it has been shown that the disclosed technology does not always enable a high-quality coating result and is not necessarily suitable for all types of adhesive. Description of the invention

[0007] The invention is based on the object of providing a device and a method of the type mentioned at the outset which enable a high-quality coating result.

[0008] This object is achieved according to the invention by a device for coating a workpiece according to claim 1 and a method for coating a workpiece according to claim 15. Particularly preferred embodiments of the invention are specified in the dependent claims.

[0009] The invention is based on the idea of ​​being able to apply the adhesive more precisely than before. For this purpose, the invention provides that the adhesive application unit has a plurality of outlet openings for dispensing adhesive. This allows the dispensing of adhesive to be precisely tailored to the respective requirements and in particular to the dimensions of the respective workpiece or coating material. In this way, the quality of the joint can be improved. Furthermore, there is less contamination, so that an overall high-quality coating result can be achieved. Furthermore, the more precise application of the adhesive also makes it possible to save adhesive, thus conserving resources.

[0010] According to a development of the invention, the device comprises a control unit for controlling the adhesive application unit, which is preferably configured to control the dispensing of adhesive at at least one outlet opening independently of the dispensing of adhesive at at least one other outlet opening. In this way, the precise dispensing of adhesive described above can be achieved particularly effectively. Furthermore, the dispensing of adhesive can also be adapted in a particularly variable manner to different requirements, such as changing properties of the workpiece. For example, it is possible to apply more adhesive in the edge region of the workpiece than in a core region of the workpiece, which in the case of chipboard, for example, is often unable to build up a strong adhesive force anyway.

[0011] Furthermore, according to a further development of the invention, the adhesive application unit comprises several rows of nozzles, which are preferably arranged offset from one another. In addition to the advantages described above, this allows for particularly good coverage of the surface to be coated with adhesive and an increased application speed.

[0012] Furthermore, according to a development of the invention, the device is provided with a detection unit which is set up to detect the dimensions and / or position of the workpiece and / or the coating material. On the basis of the variables detected by the detection unit, the precise application of adhesive described above can be achieved particularly effectively. It is particularly preferred that the control unit is set up to selectively control the ejection of adhesive by the adhesive application unit on the basis of the detection result of the detection unit. This results in an overall concept in which the advantages described above can be achieved in a diverse, variable and sustainable manner.

[0013] According to a further development of the invention, the device according to the invention can have at least one edge adhesive application unit which is configured to apply adhesive to an edge region of the workpiece. This allows the coating quality to be improved even further, since the edge region of a coating is generally of crucial importance for the coating quality, for example from an optical point of view or with regard to the tightness of the joint. The edge adhesive application unit can make it possible to apply adhesive to this critical region particularly effectively, reliably, and quickly, thus improving the quality of the coating.

[0014] It is particularly preferred that at least one positioning unit is provided, which is configured to position at least one edge adhesive application unit with respect to the workpiece. This ensures that the adhesive is applied with high precision in the desired or required area in order to achieve the advantages described above.

[0015] The positioning unit can be configured in different ways within the scope of the invention. With a view to simple construction and low complexity, a further development of the invention provides that at least one positioning unit has a mechanical sensing element for sensing a surface of the workpiece. Alternatively or additionally, the positioning unit can also have a detection element for preferably optical and / or electronic detection of a surface of the workpiece. This enables not only precise and rapid positioning but also a greater variety of applications.

[0016] Furthermore, it is particularly preferred that at least one positioning unit is configured to move at least one edge adhesive application unit along a surface of the workpiece, preferably also via bearings to move the workpiece. This results in drastically increased application possibilities for the edge adhesive application unit, which, on the one hand, allows for coating of a wider range of workpieces and, on the other hand, enables rapid and trouble-free coating operation.

[0017] Furthermore, according to a further development of the invention, at least one edge adhesive application unit has a plurality of outlet openings for dispensing adhesive, wherein adhesive with at least one different property can be ejected from at least one outlet opening than from at least one other outlet opening. This allows an adhesive with the best possible properties (such as color, resistance to moisture, strength, etc.) to be applied to the edge region, which is often so critical and also crucial for the appearance, thus achieving an optimal coating result.

[0018] According to a further development of the invention, the adhesive application unit and / or the edge adhesive application unit is configured to eject an adhesive which, during ejection, has a viscosity of at least 20 Pa . s, preferably at least 100 Pa . s. This makes it possible for the first time to use not only liquid adhesives, but also conventional adhesives such as hot melt adhesives when coating workpieces made of wood, wood-based materials or the like. These have proven themselves for decades and enable a high-quality and durable coating result.

[0019] Precisely to enable the ejection of such highly viscous adhesives, a further development of the invention provides that the adhesive application unit and / or edge adhesive application unit has at least one ejection element and an associated valve seat, at least one of which is movable in order to eject adhesive through an associated outlet opening. By means of these mechanical components, a wide variety of adhesives can be effectively ejected and finely metered, in particular also highly viscous adhesives. It is particularly preferred that the adhesive application unit and / or edge adhesive application unit has an actuator, in particular a piezo actuator, for moving the ejection element and / or valve seat. This results in a fine response behavior and precise metering and controllability of the (edge) adhesive application unit.

[0020] In order to be able to adapt the device according to the invention to changing requirements as simply and quickly as possible, a further development of the invention provides that the adhesive application unit has a plurality of modules, each of which has at least one outlet opening. This allows both geometric adjustments to be made and adjustments to changing adhesive requirements, ambient conditions, etc. to be taken into account. Repair and maintenance work can also be carried out simply and quickly in this way. This applies in particular if, according to a further development of the invention, at least one module has connecting means, in particular quick-connecting means, for exchanging the module in and out of the adhesive application unit.

[0021] The advantages described above can be realized particularly effectively with a method according to claim 16.

[0022] Short description of the drawings

[0023] Fig . 1 shows schematically a plan view of a

[0024] Embodiment of the device according to the invention;

[0025] Fig. 2 shows schematically a plan view of another

[0026] Embodiment of the device according to the invention; Fig. 3 shows schematically a partial side view of an embodiment of the device according to the invention;

[0027] Fig. 4 shows a schematic side view of various processing steps using the device according to the invention;

[0028] Fig. 5 shows schematically a side view of various processing steps using the device according to the invention;

[0029] Fig. 6 shows schematically a side view of various processing steps using the device according to the invention;

[0030] Fig. 7 shows schematically different application patterns of adhesive.

[0031] Detailed description of preferred embodiments

[0032] Preferred embodiments of the invention are described in detail below with reference to the accompanying drawings.

[0033] A device 1 for coating a workpiece 2 is shown schematically in a plan view in Fig. 1. The workpiece 2 can, for example, be a plate-shaped workpiece made of wood or a wood-based material, as is widely used in the furniture and construction element industry, for example for home furniture, kitchen furniture, doors, but also for interior fittings, etc.

[0034] The workpiece 2 is coated in the device 1 with a coating material 4, preferably in the region of a narrow surface of the workpiece 2. The coating material 4 can be a band- or strip-shaped material, which can consist, for example, of plastic, veneer, metal, and a variety of other materials and composite materials.

[0035] The device 1 comprises a pressing unit 6 for pressing the coating material 4 against the workpiece, such as one or more pressure rollers. Furthermore, the device 1 comprises a conveyor unit 8, which in the present embodiment is a continuous conveyor unit that conveys the workpiece 2 (from right to left in Fig. 1) past the pressing unit 6.

[0036] Finally, the device 1 comprises an adhesive application unit 10 for applying an adhesive 12 to the coating material 4 and / or the workpiece 2. The adhesive can be, for example, a hot melt adhesive, but also a variety of other adhesives. These adhesives often have a high viscosity of, for example, 100 Pa s or more.

[0037] The adhesive application unit can thus be used to apply adhesive to the coating material 4, preferably in the areas of the edge band where the edge regions of the workpiece are located after joining to the panel workpiece 2. This has the advantage that, compared to applying the adhesive to the workpiece, less precision is required and, if necessary, a detection device 44 (which will be described below) can be dispensed with.

[0038] Furthermore, the adhesive application can be made even more flexible by splitting the application of the adhesive onto the two substrates, panel material and coating material 4 or edge band. This is advantageous with regard to the adhesive application, as the application accuracy in the edge area can be less precise and at the same time the guiding options for the coating material are improved. If the adhesive is applied exclusively to the coating material, then with thin coating materials it is possible for the adhesive to "kink" and cause the guide elements to become very dirty, thus reducing the availability of the application device. In addition, it is easy to separate the application materials, e.g. high-quality adhesives for the edge area on the coating material and lower-quality adhesives for the central area.

[0039] Another embodiment of the device 1 according to the invention is shown schematically in a plan view in Fig. 2. This differs from the embodiment shown in Fig. 1 primarily in the conveying concept. In the embodiment shown in Fig. 2, the workpiece 2 is arranged stationary, and the device components shown in Fig. 2, such as in particular the pressing unit 6 and the adhesive application unit 10, can be moved along the workpiece 2 and optionally also around it. For this purpose, the device components shown in Fig. 2 are arranged on a carrier 100, which can be moved in a horizontal plane or freely in space by means of a conveying unit (not shown), such as a traveling gantry or a boom. Mixed forms of the concepts shown in Fig. 1 and Fig. 2 are also possible.

[0040] A possible embodiment of the adhesive application unit 10 is shown schematically in Fig. 3 in a partial side view of the device 1 described above with reference also to Fig. 1 and Fig. 2. It can be seen that the adhesive application unit 10 in the present embodiment has a plurality of modules 16 which are attached to a module carrier 18' via quick-connecting means so that they can be inserted and removed.

[0041] As can be seen in Fig. 3, each of the modules 16 has a plurality of adhesive outlet openings 14, which in the present embodiment face the narrow surface 2' of the workpiece 2 to be coated. The outlet openings 14 are arranged in two rows and offset from one another.

[0042] The modules 16 of the adhesive application unit 10, like the edge adhesive application units 40 shown in Fig. 3, which are described in more detail below, are also designed to eject highly viscous adhesives such as hot melt adhesives, which have a viscosity of at least 20 Pa.s or even at least 100 Pa.s during ejection (i.e., typically in the heated state). To enable this, the modules in the present embodiment each have a special design in which a preferably rod- or needle-shaped ejection element interacts with an associated valve seat, wherein the ejection element and / or the valve seat are movable in an adhesive ejection direction of an associated outlet opening 14. A suitable actuator, such as, in particular, a piezo actuator, ensures the movement.It is therefore a completely different design than, for example, an inkjet print head, in which a chamber is usually compressed by an actuator to eject ink.

[0043] The adhesive application unit 10 is controlled by a control unit 20 shown in Figs. 1 and 2. This control unit is capable of controlling the various outlet openings 14 individually or in groups independently of one another. In this way, individual or multiple outlet openings 14 can be deactivated as needed. Alternatively or additionally, it is also possible to control the ejection behavior of individual or multiple outlet openings 14 with regard to the ejection quantity, the ejection speed, the selection of a suitable adhesive (such as a desired color), and various other parameters.

[0044] This allows the application of the adhesive 12 to the workpiece 2 and / or the coating material 4 to be optimally adapted to the respective requirements. In order to also enable adaptation to the geometry of the workpiece 2 and / or the coating material 4, the device 1 in the present embodiment comprises a detection unit 30 shown in Figs. 1 and 2, which detects the dimensions and / or position of the workpiece 2 and / or the coating material 4. For this purpose, the detection unit 30 can have various sensors such as a camera, but also a variety of other sensors such as simple light barriers.

[0045] Based on the detection result of the detection unit 30, the control unit 20 selectively controls the ejection of adhesive 12 by the adhesive application unit 10, i.e., depending on the dimensions and / or position of the workpiece 2 and / or the coating material 4, only those outlet openings 14 are controlled that are necessary and appropriate for the application of adhesive 12. This also prevents overspray, so that contamination of the workpiece 2, the coating material 4, or the device 1 is minimized and resources can be saved.

[0046] In addition to the adhesive application unit 10, the device 1 in the present embodiment also comprises two edge adhesive application units 40, which are each set up to apply adhesive 12 to an edge region of the surface 2' of the workpiece 2 to be coated. In the embodiment shown in Fig. 3, each of the edge adhesive application units 40 has an outlet opening 46 for adhesive 12 facing the surface 2' to be coated. The lower edge adhesive application unit 40 in Fig. 3 can be arranged stationary in the vertical direction, since the workpiece 2 usually rests with its lower surface on the conveyor unit 8 (Fig. 1) or a workpiece table (not shown in Fig. 2).

[0047] In contrast, the upper edge adhesive application unit 40 in Fig. 3 is coupled to a positioning unit 42 which is set up to position the associated edge adhesive application unit 40 in relation to the work piece 2. In the embodiment shown in Fig. 3, the positioning unit 42 is designed for this purpose, for example, as a linear drive, pneumatic cylinder or other suitable actuator which is controlled by the control unit 20 on the basis of a detection result of a detection element 44. The detection element 44 scans a surface of the workpiece 2 optically and / or electronically, in this case the upper surface of the workpiece 2 in Fig. 3.

[0048] Alternatively, it is also possible to design the positioning unit 42 mechanically, for example as a mechanical scanning element which, as is known, rolls on the surface of the workpiece 2 and thus positions the edge adhesive application unit 40 in relation to the upper edge of the narrow surface 2' to be coated. Such scanning can also be in the form that the upper edge adhesive application device 40, via a suitable scanning, first applies adhesive 12 to the leading edge of the narrow surface 2' to be coated, which runs from bottom to top in Fig. 3, and only then applies adhesive 12 to the upper edge of the narrow surface 2' of the workpiece to be coated. In contrast, the lower adhesive application device 40, as shown in Fig. 3, is responsible for the lower edge of the narrow surface 2' of the workpiece 2 to be coated. A corresponding sequence is shown in Fig. 4 shown in schematic side views .The sequence begins in Fig. 4a), in which the lower edge adhesive application unit 40 applies adhesive 12 to the lower edge of the surface 2' to be coated as the workpiece 2 moves, while the upper edge adhesive application unit 40 is moved from bottom to top by means of the positioning unit 42 such that adhesive is applied to the leading edge of the surface 2' to be coated. This can be done without stopping the workpiece 2, for example by the positioning unit 42 moving along with the workpiece 2 during the application of glue to the leading edge.

[0049] As shown in Fig. 4b), in the next step, the upper edge adhesive application unit 40 applies adhesive 12 to the upper edge of the surface 2' to be coated. The upper edge adhesive application unit 40 can remain stationary or be moved counter to the conveying direction of the workpiece 2.

[0050] In the last step according to Fig. 4c), the lower edge adhesive application unit 40 has already completed the application of adhesive to the lower edge of the surface 2' to be coated, while the upper edge adhesive application unit 40 is still applying adhesive to the trailing edge of the surface 2' to be coated by again moving accordingly by means of the positioning unit 42.

[0051] As can also be seen in Fig. 5, the edge adhesive application units 40 just described can operate simultaneously with the adhesive application unit 10, so that the entire adhesive application to the desired areas of the surface 2 ' to be coated can take place in one operation.

[0052] A further variant is shown schematically in Fig . 6 .

[0053] In this case, the edge adhesive application units 40 each have a plurality of adhesive outlet openings 46, from which adhesives with different properties, in particular different colors, can be ejected. In a further variant, instead of different colors, adhesives with different physical properties such as hydrophobicity, heat resistance, rheology, thixotropy, etc. can be used. This makes it particularly easy and quick to adapt the adhesive application to the respective boundary conditions, for example, applying black adhesive to a black coating material or applying white adhesive to a white coating material. This results in a special optical effect, which is sometimes also referred to as an "optical zero joint".

[0054] Finally, Fig. 7 illustrates various possible application patterns for the adhesive 12, naturally without claiming to be complete. However, it is clear that effective adhesive application is of crucial importance, particularly in the edge areas, while in the interior areas, depending on the requirements and the joining partners involved, areas with less adhesive or no adhesive can be provided, which ultimately also saves resources.

Claims

CLAIMS Device (1) for coating a workpiece (2), which preferably consists at least in sections of wood, wood material, plastic or the like, with a coating material (4), wherein the device comprises: a pressing unit (6) for pressing the coating material (4) onto the workpiece (2), a conveying unit (8) for bringing about a relative movement between the pressing unit (6) and the workpiece (2), and an adhesive application unit (10) for applying Adhesive (12) onto the coating material (4) and / or the workpiece (2), characterized in that the adhesive application unit comprises a plurality of Has outlet openings (14) for dispensing adhesive (12). Device according to claim 1, which has a control unit (20) for controlling the adhesive application unit (10), which is preferably configured to control the dispensing of adhesive (12) at at least one outlet opening (14) independently of the dispensing of adhesive (12) at at least one other outlet opening (14). Device according to claim 1 or 2, wherein the adhesive application unit (10) has a plurality of rows of nozzles, which are preferably arranged offset from one another. Device according to one of the preceding claims, in which a detection unit (30) is provided which is configured to detect the dimensions and / or position of the workpiece (2) and / or the coating material (4). Device according to claim 4, in which the control unit (20) is configured to selectively control the ejection of adhesive (12) by the adhesive application unit (10) on the basis of the detection result of the detection unit (30). Device according to one of the preceding claims, wherein at least one edge adhesive application unit (40) is provided, which is configured to apply adhesive (12) in an edge region of the workpiece (2). Device according to claim 6, wherein at least one positioning unit (42) is provided, which is configured to position at least one edge adhesive application unit (40) with respect to the workpiece (2). Device according to claim 6 or 7, wherein at least one positioning unit (42) has a mechanical sensing element for sensing a surface of the workpiece (2) and / or a detection element (44) for preferably optical and / or electronic detection of a surface of the workpiece (2).Device according to one of claims 6 to 8, in which at least one positioning unit (42) is arranged to move at least one edge adhesive application unit (40) along a surface of the workpiece (2), preferably also superimposed on a movement of the workpiece. Device according to one of claims 6 to 9, wherein at least one edge adhesive application unit (40) has a plurality of outlet openings (46) for dispensing adhesive, wherein adhesive with at least one different property can be ejected from at least one outlet opening (46) than from at least one other outlet opening (46). Device according to one of the preceding claims, wherein the adhesive application unit (10) and / or edge adhesive application unit (40) is designed to eject an adhesive (12) which has a viscosity of at least 20 Pa.s, preferably at least 100 Pa.s during ejection. Device according to one of the preceding claims, wherein the adhesive application unit and / or edge adhesive application unit has at least one Ejection element and an associated valve seat, at least one of which is movable to eject adhesive through an associated outlet opening. Device according to claim 12, in which the adhesive application unit and / or Edge adhesive application unit has an actuator, in particular a piezo actuator, for moving the ejection element and / or valve seat. Device according to one of the preceding claims, in which the adhesive application unit (10) has a plurality of modules (16), each having at least one outlet opening (14). Device according to claim 14, in which at least one Module (16) connecting means (18), in particular Quick connection device, for replacing and replacing the Module (16) into the adhesive application unit (10). Method for coating a workpiece (2), which preferably consists at least partially of wood, wood-based material, plastic or the like, with a coating material (4) using a device (1) according to one of the preceding claims, comprising the steps: Bringing about a relative movement between the pressing unit (6) and the workpiece (2) by means of the conveying unit (8), and Controlling the adhesive application unit (10) and / or the edge adhesive application unit (40) in such a way that adhesive is applied at least in an edge region of a surface (2') of the workpiece (2) or of the coating material (4) to be coated, and Pressing the coating material (4) onto the workpiece (2) by means of the pressing unit (6). Method according to claim 16, wherein the dimensions and / or position of the workpiece (2) and / or of the coating material (4) are detected by means of the detection unit (30) and on this basis the adhesive application unit (10) and / or the Edge adhesive application unit (40) can be controlled.

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