Device and method for coating a workpiece

Abstract

The invention relates to a device (1) for coating a workpiece (2), preferably made at least in sections of natural wood, artificial wood, plastic or the like, by means of a coating material (4), said device comprising: a pressing unit (6) for pressing the coating material (4) onto the workpiece (2); a conveying unit (8) for causing a relative movement between the pressing unit (6) and the workpiece (2); and an adhesive application unit (10) for applying an adhesive (12) to the coating material (4) and / or the workpiece (2). The adhesive application unit has a plurality of exit openings (14) for dispensing the adhesive (12).

Description

Field of the Invention

[0001] The present invention relates to an apparatus for coating a workpiece with a cladding material according to the preamble of claim 1, wherein the workpiece is preferably at least partially composed of natural wood, artificial wood, plastic, etc., and to a corresponding method. Background Art

[0002] In the field of the furniture and building component industries, it is known to provide a cladding material (edge material) for a plate-shaped workpiece in the region of its narrow side. For this purpose, different techniques are used, such as gluing by means of a hot melt adhesive rolled during the joining process or conveying a cladding material provided with an adhesive and activating the adhesive during the joining process by means of a suitable energy source.

[0003] Furthermore, WO2020 / 094283 discloses an apparatus and a method in which an adhesive is applied to a workpiece or a cladding material by means of a Drop-on-Demand technique. However, it has been found that the disclosed technique does not always enable high-quality cladding results and is not necessarily suitable for all types of adhesives. Summary of the Invention

[0004] The object underlying the present invention is to provide an apparatus and a method of the type mentioned at the beginning, which enable high-quality cladding results.

[0005] According to the present invention, this object is achieved by an apparatus for coating a workpiece according to claim 1 and a method for coating a workpiece according to claim 15. Particularly preferred embodiments of the present invention are given in the dependent claims.

[0006] The concept underlying the present invention is that the adhesive coating can be carried out more precisely than hitherto. For this purpose, according to the present invention, it is proposed that the adhesive coating unit has a plurality of outlet openings for outputting the adhesive. Thereby, the output of the adhesive can be precisely coordinated with the respective requirements and in particular with the dimensions of the respective workpiece or cladding material. In this way, the quality of the joint connection can be improved. Furthermore, less contamination is also generated, so that overall high-quality cladding results can be achieved. In addition, by coating the adhesive more precisely, the adhesive can also be saved, thereby protecting resources.

[0007] According to a further development of the invention, the device has a control unit for controlling an adhesive application unit, which is preferably configured to control the output of adhesive to at least one exit opening independently of the output of adhesive to at least one other exit opening. The precise output of adhesive described above can thus be achieved particularly effectively. In addition, the output of adhesive can also be particularly variably adapted to different requirements, such as variable properties of the workpiece. Thus, for example, it is possible to apply more adhesive in the edge region of the workpiece than in the core region of the workpiece, which core region, for example in a chipboard, is generally not able to form a strong adhesive anyway.

[0008] Furthermore, according to a further development of the invention, the adhesive coating unit has a plurality of rows of nozzles which are preferably arranged offset from one another. In addition to the advantages described above, this allows particularly good coverage of the surface to be coated with adhesive or an increased coating speed.

[0009] Furthermore, according to an improved solution of the present invention, the device has a detection unit, which is configured to detect the size and / or position of the workpiece and / or the coating material. According to the variables detected by the detection unit, the precise adhesive coating described above can be achieved particularly effectively. It is particularly preferred that the control unit is configured to selectively control the spraying of the adhesive by the adhesive coating unit based on the detection result of the detection unit. This leads to the following general concept, in which the advantages described above can be achieved in a variety of ways, variably and sustainably.

[0010] 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 in the edge region of the workpiece. This can further improve the coating quality, since the edge region of the coating is usually of decisive importance for the coating quality, for example in terms of optics or in terms of the tightness of the joint connection. The edge adhesive application unit can achieve particularly effective, reliable and smooth application of adhesive in this critical region, thereby improving the quality of the coating.

[0011] It is particularly preferred that at least one positioning unit is provided, which is configured to position at least one edge adhesive application unit relative to the workpiece, so as to ensure that the adhesive is applied with high precision in the desired or required area in this way, in order to achieve the advantages described above.

[0012] Within the scope of the present invention, the positioning unit can be designed in different ways and methods. In terms of simple construction and low complexity, according to an improvement of the present invention, at least one positioning unit has a mechanical probing element for probing the surface of the workpiece. Alternatively or additionally, the positioning unit can also have a detection element for preferably optically and / or electronically detecting the surface of the workpiece. In addition to precise and rapid positioning, this also enables more diverse usage scenarios.

[0013] Furthermore, it is particularly preferred that at least one positioning unit is configured to move at least one edge adhesive application unit along the surface of the workpiece, more precisely preferably also superimposed on the movement of the workpiece. This results in a significantly increased usability of the edge adhesive application unit, whereby on the one hand, more diverse workpieces can be coated, and on the other hand, a smooth and interference-free coating operation can be achieved.

[0014] In addition, according to an improvement of the present invention, at least one edge adhesive application unit has a plurality of outlet openings for outputting the adhesive, wherein an adhesive having different properties compared to that from at least one other outlet opening can be ejected from at least one of the outlet openings. Thereby, an adhesive having the best possible properties (such as color, resistance to moisture, strength, etc.) can always be applied in the usually critical and also decisive edge region for the appearance, so that an optimal coating result is obtained.

[0015] According to an improvement of the present invention, the adhesive application unit and / or the edge adhesive application unit is configured to eject an adhesive that has a viscosity of at least 20 Pa·s, preferably at least 100 Pa·s during ejection. Thereby, for the first time, it is possible to use not only liquid adhesives but also common adhesives such as hot melt adhesives when coating workpieces made of natural wood, wood materials, etc. The adhesive has been proven suitable for decades and can achieve high-quality and durable coating results.

[0016] Also, in order to be able to eject such a highly viscous adhesive, according to an improved embodiment of the present invention, the adhesive coating unit and / or the edge adhesive coating unit have at least one ejection element and an associated valve seat, and at least one of the ejection element and the valve seat can move so as to eject the adhesive through an associated outlet opening. Different adhesives, especially highly viscous adhesives, can be effectively ejected and precisely metered by means of the mechanical members. Here, it is particularly preferred that the adhesive coating unit and / or the edge adhesive coating unit have an actuator, especially a piezoelectric actuator, for moving the ejection element and / or the valve seat. This results in a fine response performance, precise metering ability, and controllability of the (edge) adhesive coating unit.

[0017] In order to enable the device according to the present invention to be matched to changing requirements as simply and smoothly as possible, according to an improved embodiment of the present invention, the adhesive coating unit has a plurality of modules, each of which has at least one outlet opening. This enables not only geometric matching but also consideration of matching to changing adhesive requirements, environmental conditions, etc. Therefore, repair and maintenance work can also be carried out simply and smoothly. This is particularly applicable if, according to an improved embodiment of the present invention, at least one module has a connection mechanism, especially a quick-connection mechanism, for inserting the module into the adhesive coating unit and removing it therefrom.

[0018] The advantages described above can be achieved particularly effectively by means of the method according to claim 16. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A top view schematically showing an embodiment of the device according to the present invention;

[0020] Figure 2 A top view schematically showing another embodiment of the device according to the present invention;

[0021] Figure 3 A partial side view schematically showing an embodiment of the device according to the present invention;

[0022] FIG. 4 schematically shows a side view of different processing steps using the device according to the present invention;

[0023] Figure 5 A side view schematically showing different processing steps using the device according to the present invention;

[0024] Figure 6 A side view schematically showing different processing steps using the device according to the present invention;

[0025] Figure 7 Schematically shows different coating patterns of an adhesive or glue. Detailed description of specific embodiments

[0026] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0027] In Figure 1 a top view schematically shows a device 1 for cladding a workpiece 2. The workpiece 2 can be, for example, a plate-shaped workpiece made of natural wood or wood-based materials, such as plate-shaped workpieces widely used in the fields of the furniture and building component industries, for example, plate-shaped workpieces for residential furniture, kitchen furniture, doors, but also plate-shaped workpieces for interior decoration, etc.

[0028] The workpiece 2 is clad with a cladding material 4 in the device 1, more precisely preferably in the region of the narrow sides of the workpiece 2. The cladding material 4 can be, for example, a strip-shaped or ribbon-shaped material composed of plastic, plywood, metal, and various other materials and composite materials.

[0029] The device 1 includes a pressing unit 6 for pressing the cladding material 4 onto the workpiece, for example one or more pressing rollers. In addition, the device 1 includes a conveying unit 8, and in the present embodiment, the conveying unit is a continuous conveying unit that conveys the workpiece 2 (in Figure 1 from right to left) past the pressing unit 6.

[0030] Finally, the device 1 includes an adhesive coating unit 10 for coating an adhesive 12 onto the cladding material 4 and / or the workpiece 2. The adhesive can be, for example, a hot melt (hot melt, melt body), but can also be various other adhesives. Generally, the adhesive has a high viscosity of, for example, 100 Pa·s or higher.

[0031] Therefore, the adhesive coating unit can be used to coat the adhesive onto the cladding material 4 so as to preferably coat the glue in the following region of the edge strip: where the edge region of the workpiece is located after being joined to the plate workpiece 2. This has the advantage that lower precision is required compared to coating the glue onto the workpiece, and a detection device 44 (which will also be described below) can be omitted if necessary.

[0032] Furthermore, the adhesive application can be further flexibilized by applying the adhesive separately to two substrates, namely the panel material and the cladding material 4 or the edge strip, which is advantageous with regard to adhesive application because the coating accuracy in the edge region can have a lower precision and at the same time the guiding feasibility of the cladding material is improved. If the adhesive is only applied to the cladding material, in the case of a small thickness of the cladding material, "einknicken" may occur due to the amount of adhesive, such that the guiding element is severely contaminated, thereby reducing the usability of the coating device. In addition, the separation of the coating materials can be simply achieved, for example, a high-quality adhesive for the edge region is used for the cladding material, while an adhesive of less quality is used for the central region.

[0033] In Figure 2 a further embodiment of the device 1 according to the invention is schematically shown in a top view. The difference between this embodiment and the embodiment shown in Figure 1 mainly lies in the conveying concept. Thus, in the embodiment shown in Figure 2 the workpiece 2 is fixedly arranged, and the device components shown in Figure 2 , such as in particular the pressing unit 6 and the adhesive application unit 10, can move along the workpiece 2 and, if necessary, also around the workpiece. For this purpose, the device components shown in Figure 2 are arranged on a carrier 100, which can be moved in a horizontal plane by means of a conveying unit (not shown), such as a traveling gantry (Fahrportal) or a cantilever, or can also move freely in space. In Figure 1 and Figure 2 a hybrid form of the concept shown is also feasible.

[0034] In Figure 3 a possible design of the adhesive application unit 10 is schematically shown in a partial side view of the device 1 which has also been referred to above with reference to Figure 1 and Figure 2 . It can be seen that the adhesive application unit 10 in this embodiment has a plurality of modules 16, which are arranged at the module carrier 18' in a loadable and removable manner via a quick-connect mechanism.

[0035] As can be seen in Figure 3 , each of the modules 16 has a plurality of adhesive discharge outlets 14, which in this embodiment are directed towards the narrow face 2' of the workpiece 2 to be clad. Here, the adhesive discharge outlets 14 are arranged in two rows and staggered from each other.

[0036] The module 16 of the adhesive application unit 10 and the Figure 3The edge adhesive application unit 40 shown in FIG. is configured to also eject a highly viscous adhesive, such as hot melt adhesive, which has a viscosity of at least 20 Pa·s or even at least 100 Pa·s during ejection (i.e., usually in a heated state). To enable this, the modules in the present embodiment each have a specific construction, in which preferably rod-shaped or needle-shaped ejection elements cooperate with associated valve seats, and the ejection elements and / or valve seats can move in the adhesive ejection direction away from the associated outlet opening 14. Here, a suitable actuator, such as a piezoelectric actuator in particular, ensures the movement. Therefore, it involves a completely different construction from, for example, an inkjet print head, in which the cavity is usually compressed by an actuator to eject ink.

[0037] The adhesive application unit 10 is controlled by the control unit 20 shown in Figure 1 and Figure 2 . The adhesive application unit can individually or in groups control different outlet openings 14 in an independent manner. In this way, it is possible to deactivate single or multiple outlet openings 14 as required. Alternatively or additionally, it is also feasible to manipulate the ejection characteristics of single or multiple outlet openings 14 in terms of ejection volume, ejection speed, selection of a suitable adhesive (such as the desired color), and various other parameters.

[0038] Thereby, the application of the adhesive 12 to the workpiece 2 and / or the cladding material 4 can be optimally matched to the corresponding requirements. To also be able to achieve a match to the geometry of the workpiece 2 and / or the cladding material 4, the device 1 in the present embodiment includes the detection unit 30 shown in Figure 1 and Figure 2 , which detects the dimensions and / or positions of the workpiece 2 and / or the cladding material 4. For this purpose, the detection unit 30 can have different sensors, such as cameras, but can also have various other sensors, such as simple gratings.

[0039] The control unit 20 selectively controls the ejection of the adhesive 12 through the adhesive application unit 10 based on the detection results of the detection unit 30, that is, according to the dimensions and / or positions of the workpiece 2 and / or the cladding material 4, only controls those outlet openings 14 that are required and meaningful for the application of the adhesive 12. This also prevents "overspray", minimizing the contamination of the workpiece 2, the cladding material 4, or the device 1, and can also save resources.

[0040] In addition to the adhesive application unit 10, the device 1 in the present embodiment also includes two edge adhesive application units 40, which are configured to apply the adhesive 12 to the edge regions of the surface 2' of the workpiece 2 to be clad. In Figure 3In the embodiment shown, each edge adhesive application unit 40 in the edge adhesive application unit has a discharge opening 46 for the adhesive 12 facing the surface 2' of the layer to be coated. In Figure 3 the lower edge adhesive application unit 40 can be fixedly arranged in the vertical direction here, because the workpiece 2 is usually placed flat on the conveying unit 8 ( Figure 1 ) or the workpiece table (not shown in Figure 2 ) with its lower surface.

[0041] In contrast, the upper edge adhesive application unit 40 in Figure 3 is coupled to the positioning unit 42, which is configured to position the associated edge adhesive application unit 40 with respect to the workpiece 2. In the embodiment shown in Figure 3 , the positioning unit 42 is designed, for this purpose, as a linear drive, a pneumatic cylinder or other suitable actuator, which is controlled by the control unit 20 based on the detection result of the detection element 44. The detection element 44 probes the surface of the workpiece 2 optically and / or electronically, in which case the upper surface of the workpiece 2 is probed in Figure 3 .

[0042] Alternatively, it is also possible to design the positioning unit 42 mechanically, for example as a mechanical probing element, which can also roll on the surface of the workpiece 2 in a known manner, so as to position the edge adhesive application unit 40 with respect to the upper edge of the narrow surface 2' of the layer to be coated. Such probing can also be configured such that the upper edge adhesive application device 40 first loads the front edge of the narrow surface 2' of the layer to be coated with the adhesive 12 via a suitable probe, which extends from bottom to top in Figure 3 , and only then applies the adhesive 12 to the upper edge of the narrow surface 2' of the layer to be coated of the workpiece. In contrast, the lower adhesive application device 40 is responsible for the lower edge of the narrow surface 2' of the layer to be coated of the workpiece 2 as shown in Figure 3 . The corresponding process is shown in a schematic side view in FIG. 4. The process starts in FIG. 4a), where the lower edge adhesive application unit 40 applies the adhesive 12 to the lower edge of the surface 2' of the coating during the movement of the workpiece 2, while the upper edge adhesive application unit 40 moves from bottom to top by means of the positioning unit 42, so that the adhesive is applied to the front edge of the surface 2' of the layer to be coated. This can be done without stopping the workpiece 2, for example by moving the positioning unit 42 together with the workpiece 2 during the gluing at the front edge.

[0043] As shown in Fig. 4b), in the next step, the upper edge adhesive coating unit 40 coats the adhesive 12 onto the upper edge of the surface 2' of the layer to be coated. Here, the upper edge adhesive coating unit 40 can remain fixed or can also move against the conveying direction of the workpiece 2.

[0044] In the last step according to Fig. 4c), the lower edge adhesive coating unit 40 has completed coating the adhesive onto the lower edge of the surface 2' of the layer to be coated, while the upper edge adhesive coating unit 40 is still coating the adhesive onto the rear edge of the surface 2' of the layer to be coated, in such a way that the upper edge adhesive coating unit is correspondingly moved again by means of the positioning unit 42.

[0045] As can be seen Figure 5 from the above, the edge adhesive coating unit 40 described just now can work simultaneously with the adhesive coating unit 10, so that all the adhesive coating onto the desired area of the surface 2' of the layer to be coated can be completed in one process.

[0046] In Figure 6 Fig. 11 another variant is schematically shown. In this case, the edge adhesive coating unit 40 respectively has a plurality of adhesive discharge openings 46, from which adhesives with different properties, such as especially different colors, can be respectively ejected. In another variant, instead of different colors, adhesives with different physical properties, such as hydrophobicity, thermal stability, rheology, thixotropy, etc., can also be used. Therefore, it is particularly simple and feasible to make the adhesive coating match the corresponding boundary conditions, for example, coating a black adhesive in the case of a black coating material, or coating a white adhesive in the case of a white coating material. Thereby, a special optical effect is obtained, which is sometimes also called "optical zero joint (Nullfuge)".

[0047] Figure 7 Finally, different feasible coating patterns for the adhesive or glue 12 are also shown, of course without claiming completeness. However, it is clear that especially in the edge region, effective glue coating is of decisive significance, while in the inner region, depending on the requirements and the mating joining parts involved, regions with less glue or no glue can also be provided, thereby also saving resources.

Claims

1. An apparatus (1) for coating a workpiece (2) with a coating material (4), wherein the workpiece is preferably at least partially made of natural wood, artificial wood, plastic, etc., and the apparatus has: A pressing unit (6) for pressing the coating material (4) onto the workpiece (2), A conveying unit (8) for causing relative movement between the pressing unit (6) and the workpiece (2), and An adhesive coating unit (10) for applying an adhesive (12) to the coating material (4) and / or the workpiece (2), Characterized in that The adhesive coating unit has a plurality of outlet openings (14) for outputting the adhesive (12).

2. The apparatus according to claim 1, which has a control unit (20) for controlling the adhesive coating unit (10), and the control unit is preferably configured to control the output of the adhesive (12) to at least one outlet opening (14) independently of the output of the adhesive (12) to at least one other outlet opening (14).

3. The apparatus according to claim 1 or 2, Wherein the adhesive coating unit (10) has a plurality of rows of nozzles preferably arranged offset from each other.

4. The apparatus according to any one of the above claims, Wherein a detection unit (30) is provided, and the detection unit is configured to detect the dimensions and / or position of the workpiece (2) and / or the coating material (4).

5. The apparatus according to claim 4, Wherein the control unit (20) is configured to selectively control the spraying of the adhesive (12) through the adhesive coating unit (10) based on the detection result of the detection unit (30).

6. The apparatus according to any one of the above claims, Wherein at least one edge adhesive coating unit (40) is provided, and the edge adhesive coating unit is configured to apply the adhesive (12) in the edge region of the workpiece (2).

7. The apparatus according to claim 6, Wherein at least one positioning unit (42) is provided, and the positioning unit is configured to position at least one edge adhesive coating unit (40) with respect to the workpiece (2).

8. The apparatus according to claim 6 or 7, Wherein at least one positioning unit (42) has a mechanical probing element for probing the surface of the workpiece (2) and / or a detection element (44) for preferably optically and / or electronically detecting the surface of the workpiece (2).

9. The apparatus according to any one of claims 6 to 8, Wherein at least one positioning unit (42) is configured to move at least one edge adhesive coating unit (40) along the surface of the workpiece (2), more precisely preferably also superimposed on the movement of the workpiece.

10. The apparatus according to any one of claims 6 to 9, At least one edge adhesive application unit (40) has a plurality of outlet openings (46) for outputting an adhesive (12), and an adhesive having at least one different property compared to that from at least one other outlet opening (46) can be ejected from at least one of the outlet openings (46).

11. The apparatus according to any one of the preceding claims, wherein the adhesive application unit (10) and / or the edge adhesive application unit (40) is configured to eject an adhesive (12) having a viscosity of at least 20 Pa·s, preferably 100 Pa·s during ejection.

12. The apparatus according to any one of the preceding claims, wherein the adhesive application unit and / or the edge adhesive application unit has at least one ejection element and an associated valve seat, and at least one of the ejection element and the valve seat is movable to eject the adhesive through the associated outlet opening.

13. The apparatus according to claim 12, wherein the adhesive application unit and / or the edge adhesive application unit has an actuator, in particular a piezoelectric actuator, for moving the ejection element and / or the valve seat.

14. The apparatus according to any one of the preceding claims, wherein the adhesive application unit (10) has a plurality of modules (16), and each module has at least one outlet opening (14).

15. The apparatus according to claim 14, wherein at least one module (16) has a connection mechanism (18), in particular a quick-connection mechanism, for loading the module (16) into and removing the module (16) from the adhesive application unit (10).

16. A method for cladding a workpiece (2) with a cladding material (4) by means of the apparatus (1) according to any one of the preceding claims, the workpiece preferably being at least partially composed of natural wood, artificial wood, plastic, etc., the method having the following steps: causing 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) such that an adhesive is applied at least to the surface (2') of the workpiece (2) to be clad or to the edge region of the cladding material (4), and pressing the cladding material (4) onto the workpiece (2) by means of the pressing unit (6).

17. The method according to claim 16, wherein the dimensions and / or positions of the workpiece (2) and / or the cladding 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) is controlled.

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