Device and method for capturing the thickness of an applied layer and coating machine with capture of the thickness of an applied layer

Abstract

The present invention relates to a device (1) for determining an amount of adhesive (3) applied to a surface (2), in particular to attach an edge strip (5) to a narrow face of a flat workpiece (4) which consists at least partially of a wood, wood material, plastic or the like, in particular by means of an application roller (6), comprising a first measuring unit (7a) for measuring a first property of the applied adhesive (3) and a control unit (8) which is configured to determine the layer thickness (d) of the applied adhesive (3) on the basis of the measured first property, wherein the surface (2) is a surface of the workpiece (4), the edge strip (5) or the application roller (6).

Description

[0001] Device and method for detecting the thickness of an applied layer and machine for coating with a detection of the thickness of an applied layer

[0002] Technical area

[0003] The invention relates to a device and method for detecting the thickness of a layer applied to a surface, in particular an adhesive layer, and to a machine for coating a surface, in particular a narrow surface of a plate-shaped workpiece consisting at least partially of wood, wood-based material, plastic or the like, with adhesive in order to attach an edge band thereto.

[0004] State of the art

[0005] Panel-shaped workpieces made of wood or wood-like materials are typically provided with an edge band, which is bonded to the narrow surface of the workpiece using an adhesive. Thermoplastic hot melt adhesives such as EVA and PO, but also PUR hot melt, are predominantly used for this purpose. In addition to the application temperature of the adhesive, the substrate temperatures of the workpiece or edge band before the adhesive is applied, and the contact pressure, the thickness of the adhesive layer also plays a significant role in the quality of the bond.

[0006] Currently, the difference in weight between a test workpiece coated with adhesive and an uncoated workpiece is measured randomly or before production begins by manually weighing it, and the resulting layer thickness is then calculated. Since no edgeband is glued on, the test workpiece is rejected. Furthermore, continuous monitoring of the production process is not possible. In practice, determining the layer thickness by weighing has proven to be very time-consuming and inaccurate because the applied adhesive mass is relatively small compared to the workpiece mass and the required mechanics make design implementation difficult. Due to discontinuous adhesive removal and the high viscosity of the adhesive, volume flow monitoring is also not practical.

[0007] Wood and wood-like materials are inhomogeneous and do not allow the measurement methods established in the metalworking industry due to the low adhesive layer thicknesses.

[0008] DE 10 2017 122701 A1 discloses a coating device for coating a narrow side of a workpiece, which device controls a detection device for detecting a surface property on the surface of the workpiece to be coated and, based thereon, a device for acting on the adhesive.

[0009] DE 10 2020 129553 A1 further discloses a device for applying adhesive to the narrow side of a plate-shaped workpiece made of wood or wood substitute materials or to edge bands with a device for detecting the amount of adhesive present or consumed in the application device or its change over time.

[0010] Description of the invention

[0011] The invention is based on the object of providing a device, a machine and a method for detecting the thickness of an adhesive layer applied to a surface in a contactless, precise and continuous manner in order to determine and / or regulate the amount of adhesive applied and the amount of adhesive to be applied in the future. A device according to the invention is defined in claim 1. A machine according to the invention is defined in claim 5. A method according to the invention is defined in claim 12. The subclaims relate to specific embodiments.

[0012] The device according to the invention comprises a first measuring unit which is designed to detect a first property of an adhesive layer applied to a narrow surface of a workpiece, a surface of an edge band or a surface of an application roller in a contactless manner, and a control unit which is designed to determine a layer thickness of the applied adhesive on the basis of the first property.

[0013] The contactless recording of the properties makes it possible to determine the thickness of the applied adhesive layer and thus the mass or homogeneity of the applied adhesive layer easily and with high accuracy and even shortly after the adhesive has been applied. This enables seamless quality monitoring of all workpieces and automated control of the adhesive application. In particular, deviations from a specified adhesive quantity or irregularities in the production process can be detected at an early stage so that appropriate measures can be initiated to ensure and document a consistently high quality of the adhesive bond. Since samples no longer have to be taken, weighed manually and then disposed of, time, costs and raw materials can be saved.

[0014] In one embodiment, the device further comprises a second measuring unit which is configured to detect a second property of an adhesive layer applied to a narrow surface of a workpiece, a surface of an edge band or a surface of an application roller or a reference property in a contactless manner, wherein the control unit is configured to determine the layer thickness of the applied adhesive on the basis of the first and second detected properties.

[0015] The contactless detection of the second property makes it possible to determine the thickness of the applied adhesive layer with greater accuracy. The second property can, for example, be a property of the adhesive layer, a property of a reference surface such as the surface to be coated before the adhesive is applied, or a property of a reference medium such as the ambient air. Furthermore, the device can comprise a third measuring unit for detecting a third property, whereby the accuracy of the layer thickness determination can be further improved.

[0016] In one embodiment, the first property and / or the second property is a temperature and / or a distance to a surface and / or can be detected by means of laser triangulation, fluorescence laser scanning, optical coherence tomography, active thermography and / or terahertz radar technology.

[0017] Commercially available coating machines often use adhesive that is first heated to a defined application temperature and then continuously applied to the workpiece surface to be coated at a defined relative speed in the longitudinal direction. The device according to the invention can therefore be set up to be connected to the coating machine in such a way that the first measuring unit is at a defined distance in the longitudinal direction behind the point of adhesive application. The defined relative speed and the defined distance result in a time difference that any point on the workpiece surface or on the adhesive layer needs from the point of adhesive application to the point at which the temperature is detected by the first measuring unit.Based on the known time difference, the known application temperature and the recorded temperature, the cooling rate and consequently the thickness of the applied adhesive layer can be determined.

[0018] The alternative distance measurement also makes it possible to determine the layer thickness of adhesives that are not first heated but are applied directly to the surface to be coated at room temperature. Furthermore, the distance measurement is less susceptible to influences from other factors such as the dimensions, condition, and temperature of the surface before the adhesive is applied, the temperature and humidity of the ambient air, as well as the heat capacity and heat conduction of the adhesive and the material to which the adhesive is applied.

[0019] Temperature fluctuations in the ambient air during storage of uncoated workpieces or during adhesive application can influence the cooling rate of the applied adhesive layer. Therefore, the accuracy of determining the layer thickness based on the cooling behavior of the applied adhesive layer can be improved by recording and considering an appropriate reference temperature.

[0020] Likewise, distance fluctuations between the first measuring unit and the uncoated workpiece surface, for example due to tolerances in relative movement or the parallelism of the workpiece edges, can influence or distort the measured distance to the applied adhesive layer. Therefore, the accuracy of determining the layer thickness based on the distance measurement to the applied adhesive layer can be improved by recording and considering an appropriate reference distance.

[0021] In contrast to conventional measuring methods, layer thickness measurement by means of temperature or distance detection is characterized by high accuracy, speed, cost-effectiveness and practicability, particularly against the background of high tolerances of the transport chain within two measuring points.

[0022] The first property and / or the second property can also be other layer-thickness-dependent properties that can be measured using appropriate measurement methods such as laser triangulation, fluorescence laser scanning, optical coherence tomography, active thermography, or terahertz radar technology. These methods are characterized by high measurement accuracy. For laser triangulation, the light-section technique with linear detection has proven particularly advantageous, while for fluorescence laser scanning, a UV laser with a wavelength of < 400 nm is preferably used.

[0023] In one embodiment, the control unit is configured to determine and / or regulate an adhesive quantity to be applied in the future on the basis of the determined layer thickness, in particular by means of a corresponding interface for controlling a provided adhesive flow and / or a generated relative speed.

[0024] Determining the amount of adhesive to be applied in the future makes it possible to compensate for deviations from the specifications in the form of an adhesive layer that is too thick, too thin, or too inhomogeneous by adjusting the production process accordingly, for example, by adjusting the supplied adhesive flow or the generated relative speed. Automated control via an appropriate machine interface also saves costs and shortens response time, so that deviations from the specifications can be further reduced, thereby improving quality and reducing waste.

[0025] The machine according to the invention comprises a dosing unit for

[0026] Dosing of a provided adhesive stream, an application unit for applying the adhesive to the surface, and the device according to the invention, wherein the application unit is set up to apply the adhesive, e.g. by means of an application nozzle, directly to the narrow surface of the workpiece and / or directly to the surface of the edge band or to apply it first to the surface of an application roller which is set up to then apply the adhesive to the narrow surface of the workpiece and / or to the surface of the edge band.

[0027] The provision of a machine for applying adhesive with the device according to the invention has the advantage that the individual components of the machine and the device can be better coordinated with one another and that possible problems which can arise when retrofitting an existing machine with the device according to the invention can be avoided.

[0028] In one embodiment, the machine according to the invention further comprises a movement unit for generating a relative movement between the surface and the machine at a defined speed in a longitudinal direction of the surface and / or a pressing unit for pressing the edge band against the workpiece and / or an application roller for applying the adhesive to the surface, wherein the application unit is configured to apply the adhesive to the application roller in order to form an adhesive layer thereon, and the application roller is configured to apply the applied adhesive to the surface in order to form an adhesive layer thereon.

[0029] The additional provision of a motion unit has the advantage of enabling automated relative movement at a defined speed between the machine and the surface to be coated. Due to the precise and consistent speed of automated relative movement, resulting deviations from the specified thickness of the applied adhesive layer can be largely avoided.

[0030] The additional provision of a pressing unit has the advantage that the coating of the surface with adhesive and the subsequent joining process can be carried out directly one after the other in the same machine. Since the adhesive is only slightly cured or cooled during the joining process, the quality of the bond is improved compared to a separate joining process. Furthermore, time and costs can be saved, since no additional machines or work steps are required for the joining process.

[0031] In one embodiment, there is a first and / or second defined distance in the longitudinal direction of the surface between the application unit and the first and / or the second measuring unit, there is a relative movement with a defined speed in the longitudinal direction of the surface between the surface and the application unit as well as between the surface and the first and / or the second measuring unit, the adhesive is heated to a defined application temperature for application, the first and / or the second measuring unit are configured to detect a first and / or a second temperature of the applied adhesive and / or the surface before the adhesive is applied and / or the ambient air, and the control unit is configured to determine the thickness of the applied adhesive layer on the basis of the first and / or the second temperature, in particular taking into account the speed of the relative movement,the first and / or second detected distance, the application temperature, the surface temperature before the adhesive is applied, the ambient temperature, the heat capacity and / or heat conduction of the surface and / or the adhesive.

[0032] A temperature measurement has the advantage that the recorded temperature cannot be distorted by fluctuations in the distance between the first measuring unit and the surface to be coated, for example due to tolerances in the relative movement or the parallelism of the workpiece edges. The temperature measurement can be carried out, for example, using a pyrometer that detects a point on the surface of the adhesive layer that moves longitudinally over it at the relative speed, whereby temperature fluctuations and thus fluctuations in the layer thickness in the longitudinal direction can also be recorded. Alternatively, a thermal camera can be used, which detects a larger area of ​​the adhesive layer, so that temperature fluctuations and thus fluctuations in the layer thickness in the height direction can also be recorded.

[0033] In one embodiment, the first measuring unit is configured to detect a first temperature of the applied adhesive at a first defined distance from the application unit, the second measuring unit is configured to detect a second temperature of the applied adhesive at a second defined distance from the application unit, and the control unit is configured to determine the thickness of the applied adhesive layer on the basis of a temperature difference between the first temperature and the second temperature.

[0034] The advantage of recording the second temperature is that the thickness of the applied adhesive layer can be reliably determined even if the original application temperature is unknown or can only be set imprecisely. Since thinner layers cool down more quickly, the difference between the first temperature and the second temperature is greater the thinner the applied layer. Based on the distance between the first measuring unit and the second measuring unit and the difference between the first temperature and the second temperature, the cooling rate and consequently the thickness of the adhesive layer can be determined. If the original application temperature is known, the accuracy can also be improved by taking both the recorded temperatures and their difference into account when determining the cooling rate or the thickness of the adhesive layer.

[0035] In one embodiment, there is a defined distance in the normal direction perpendicular to the surface between the surface and the first and / or the second measuring unit, the first and / or the second measuring unit are configured to detect a first and / or a second distance to the applied adhesive layer and / or to the surface before the adhesive is applied, and the control unit is configured to determine the thickness of the applied adhesive layer on the basis of the first and / or the second detected distance.

[0036] To determine the adhesive layer.

[0037] Distance measurement has the advantage that it is also possible to determine the layer thickness of adhesives that are not first heated but are applied directly to the surface to be coated at room temperature. In addition, distance measurement is less susceptible to influence by other factors such as the dimensions, nature and temperature of the surface before the adhesive is applied, the temperature and humidity of the ambient air, and the heat capacity and heat conduction of the adhesive and the material to which the adhesive is applied. The distance can be recorded, for example, using light section sensors or triangulation sensors. The measuring beam and the measuring surface can have a spatial extension in all spatial axes, whereby the spatial positions of the measuring unit(s) are known or are referenced when the machine is put into operation.

[0038] In one embodiment, the application roller is configured to apply the adhesive to the surface in a region of the application roller, there is a defined distance between the surface of the application roller (6) and the first and / or the second measuring unit (7a, 7b), the first and / or the second measuring unit are configured to detect a first and / or a second distance to the adhesive layer on the application roller, and the control unit is configured to determine the thickness of the applied adhesive layer on the basis of the first and / or the second detected distance.

[0039] Applying the adhesive using an applicator roller ensures that the adhesive is applied to the surface to be coated as evenly as possible. Due to the small position and surface tolerances of the applicator roller, the accuracy of distance measurement is also improved and methods for recording the layer thickness which require a metallic surface can also be used. If all of the adhesive is applied to the surface to be coated in one area of ​​the applicator roller, the thickness of the adhesive layer on the applicator roller before transfer essentially corresponds to the thickness of the adhesive layer that is applied to the surface to be coated. However, if only part of the adhesive is applied to the surface to be coated in one area of ​​the applicator roller, the difference between the thickness of the adhesive layer on the applicator roller before and after transfer orThe depth of a corresponding depression in the adhesive layer on the application roller after transfer essentially corresponds to the thickness of the adhesive layer applied to the surface to be coated. Thus, even in the case of incomplete transfer from the application roller to the surface, the thickness of the applied adhesive layer can be determined from the known thickness of the adhesive layer on the application roller, the known distance of the measuring unit to the surface of the application roller, and the distance to the bottom of the depression in the adhesive layer on the application roller.In one embodiment, the first measuring unit is configured to detect the first distance to a bottom of a depression in the adhesive layer on the application roller, which depression is created after the adhesive is transferred to the surface, and / or the second measuring unit is configured to detect the second distance to the adhesive layer on the application roller before the adhesive is transferred to the surface or in an area in which no adhesive is transferred to the surface.

[0040] The detection of the second distance has the advantage that the thickness of the adhesive layer applied to the surface to be coated can be reliably determined even if the thickness of the adhesive layer on the application roller is unknown or is subject to fluctuations. As long as the distance between the first and second measuring units is known, the exact distance to the application roller does not need to be known, since the thickness of the applied adhesive layer is the difference between the two detected distances. If the distance to the application roller is known, the accuracy can also be improved by taking both the detected distances and their difference into account when determining the layer thickness.

[0041] A method according to the invention for detecting the thickness of an adhesive layer applied to a surface, in particular using a device or machine according to the invention, wherein there is a relative movement at a defined speed in a longitudinal direction of the surface between the surface and a location where the adhesive is applied and an adhesive is heated to a defined application temperature for application, comprises detecting a first and / or a second temperature of the applied adhesive layer at a first and / or a second defined distance in the longitudinal direction after the location where the adhesive is applied, and determining the thickness of the applied adhesive layer on the basis of the application temperature and the first and / or the second temperature.

[0042] A temperature measurement has the advantage that the recorded temperature cannot be distorted by fluctuations in the distance between the first measuring unit and the surface to be coated, for example due to tolerances in the relative movement or the parallelism of the workpiece edges. The temperature measurement can be carried out, for example, using a pyrometer that detects a point on the surface of the adhesive layer that moves longitudinally over it at the relative speed, whereby temperature fluctuations and thus fluctuations in the layer thickness in the longitudinal direction can also be recorded. Alternatively, a thermal camera can be used, which detects a larger area of ​​the adhesive layer, so that temperature fluctuations and thus fluctuations in the layer thickness in the height direction can also be recorded.

[0043] The advantage of recording the second temperature is that the thickness of the applied adhesive layer can be reliably determined even if the original application temperature is unknown or can only be set imprecisely. Since thinner layers cool down more quickly, the difference between the first temperature and the second temperature is greater the thinner the applied layer. Based on the distance between the first measuring unit and the second measuring unit and the difference between the first temperature and the second temperature, the cooling rate and consequently the thickness of the adhesive layer can be determined. If the original application temperature is known, the accuracy can also be improved by taking both the recorded temperatures and their difference into account when determining the cooling rate or the thickness of the adhesive layer.A method according to the invention for detecting the thickness of an adhesive layer applied to a surface, in particular using a device or machine according to the invention, comprises detecting a first and / or a second distance to the applied adhesive layer and / or to the surface before the adhesive is applied, and determining the thickness of the applied adhesive layer on the basis of the first and / or the second detected distance.

[0044] Distance measurement has the advantage that it is also possible to determine the layer thickness of adhesives that are not first heated but are applied directly to the surface to be coated at room temperature. In addition, distance measurement is less susceptible to influence by other factors such as the dimensions, nature and temperature of the surface before the adhesive is applied, the temperature and humidity of the ambient air, and the heat capacity and heat conduction of the adhesive and the material to which the adhesive is applied. The distance can be recorded, for example, using light section sensors or triangulation sensors. The measuring beam and the measuring surface can have a spatial extension in all spatial axes, whereby the spatial positions of the measuring unit(s) are known or are referenced when the machine is put into operation.

[0045] In one embodiment, the method according to the invention further comprises determining and / or regulating an adhesive quantity to be applied in the future on the basis of the determined layer thickness, in particular by means of a corresponding interface for controlling a provided adhesive flow and / or a generated relative speed.

[0046] Determining the amount of adhesive to be applied in the future makes it possible to compensate for deviations from the specifications in the form of an adhesive layer that is too thick, too thin, or too inhomogeneous by adjusting the production process accordingly, for example, by adjusting the adhesive flow provided or the relative speed generated. Automated control via an appropriate machine interface also saves costs and shortens response time, so that deviations from the specifications can be further reduced, thereby improving quality and reducing waste.

[0047] Short description of the drawings

[0048] Further features and advantages of a device, a use and / or a method will become apparent from the following description of embodiments with reference to the accompanying drawings. These drawings show:

[0049] Fig. 1a is a perspective view of a first and second embodiment of a device according to the invention and of a machine according to the invention;

[0050] Fig. 1b is a plan view of the first and second embodiment of an inventive

[0051] Device and a machine according to the invention;

[0052] Fig. 1c shows schematically two cooling curves of adhesive layers with different layer thicknesses:

[0053] Fig. 2a is a perspective view of a third and fourth embodiment of a device according to the invention and a machine according to the invention;

[0054] Fig. 2b is a plan view of the third and fourth embodiment of an inventive

[0055] Device and a machine according to the invention; Fig. 3a is a perspective view of a fifth embodiment of a machine according to the invention

[0056] Device and a machine according to the invention;

[0057] Fig. 3b is a plan view of the fifth embodiment of a device according to the invention and a machine according to the invention;

[0058] Fig. 4 is a perspective view of a sixth embodiment of an inventive

[0059] Device and a machine according to the invention;

[0060] Description of embodiments

[0061] Like reference numerals appearing in different figures indicate identical, corresponding, or functionally similar elements. It will be apparent to those skilled in the art that individual features described in different embodiments may also be implemented in a single embodiment, provided they are not structurally incompatible. Likewise, various features described in a single embodiment may also be provided in multiple embodiments, individually or in any suitable subcombination.

[0062] Fig. 1a and 1b show a first and second embodiment of a device (1) according to the invention for determining a quantity of adhesive (3) applied to a surface (2a) and a machine (10) according to the invention for applying adhesive (3) to a surface (2a).

[0063] The device (1) according to the invention can be retrofitted into an existing machine (10) or already integrated into a machine (10) according to the invention. The described devices, machines, and methods are applicable for applying adhesive to both the workpiece (4) and the edge band (5). Only the adhesive application to the workpiece (4) is described in more detail below.

[0064] The device (1) comprises a first measuring unit (7a) and an optional second measuring unit (7b), which are connected to a control unit (8). The machine (10) comprises a dosing unit (11) for dosing a stream of adhesive to be applied, an application unit (12) for applying the adhesive (3) to a narrow surface (2a, 2b) of a plate-shaped workpiece (4), and the device (1) for determining the amount of adhesive applied. The machine (10) further comprises a movement unit (not shown) for moving the workpiece (4) at a speed (v) in a direction of movement (X) along the narrow surface (2a, 2b) of the workpiece (4). Alternatively, the application unit (12) can be moved along the narrow surface (2a, 2b) of the workpiece (4), both manually and automatically.

[0065] The dosing unit (11) withdraws a defined amount of adhesive (3) per unit of time from a reservoir (not shown) and passes it on to the application unit (12), which then applies the adhesive (3) evenly to the narrow surface (2a, 2b) of the workpiece (4). The dosing unit (11) can be designed, for example, as a valve, pump, or wiping unit (such as a doctor blade) and can be integrated into the application unit (12). The application unit (12) can have a slot-shaped outlet (not shown), the width of which can be adjustable and the height of which extends over the entire height of the narrow surface (2a, 2b) of the workpiece (4).

[0066] While the workpiece (4) is moved along the application unit (12), the adhesive (3) applied by the application unit (12) is evenly distributed over the narrow surface (2a, 2b) of the workpiece (4), so that a uniform adhesive layer (3) is formed thereon. The thickness (d) of the adhesive layer (3) can be adjusted by varying the adhesive flow provided by the dosing unit (11) and / or by varying the relative speed (v) between the workpiece (4) and the application unit (12) generated by the movement unit.

[0067] According to the first embodiment, the adhesive (3) is heated to a defined application temperature (T0) during application. The first measuring unit (7a) can be designed, for example, as a pyrometer or a thermal camera and detects, without contact, a first temperature (Ta) of the applied adhesive layer (3) at a defined distance (Xa) from the application unit (12) in the direction of movement (X). The relative speed (v) and the distance (Xa) result in a defined time difference between the temperature (T0) during application of the adhesive (3) and the first temperature (Ta). The adhesive (3) cools down more slowly the thicker the applied layer is. Based on the application temperature (T0) and the first temperature (Ta), the cooling rate and consequently the thickness (d) of the applied adhesive layer (3) can be determined.

[0068] The advantage of using a thermal camera with an area sensor is that each pixel value represents the temperature of the imaged adhesive layer (at the feed rate at different time intervals). Thus, a thermal camera can capture a large number of temperature values ​​to determine the cooling curve more accurately based on multiple reference values, allowing the layer thickness to be measured more accurately.

[0069] In order to improve the measuring accuracy, in addition to the first measuring unit (7a), a second measuring unit (7b) can optionally be provided, which measures the temperature of the ambient air, the temperature of the surface (2b) before the adhesive is applied (as shown in Fig. 1a and 1b) or the temperature of the adhesive (3) after the adhesive has been applied (not shown). In the second case, the second measuring unit (7b) is arranged at a defined distance (Xb) from the application unit (12) and thus in the direction of movement (X) at a defined distance in front of or behind the first measuring unit (7a). The difference between the first temperature (Ta) and the second temperature (Tb) is greater the thinner the applied layer is, since thinner layers cool down more quickly.Based on the distance between the first measuring unit (7a) and the second measuring unit (7b) and the difference between the first temperature (Ta) and the second temperature (Tb), the cooling rate and consequently the thickness (d) of the adhesive layer (3) can be determined.

[0070] Fig. 1c shows two cooling curves of adhesive layers with different layer thicknesses. At the application time (t0), both layers have the same application temperature (T0). At the first time (ta), at which the first temperature (Ta) is recorded by the first measuring unit (7a), the thick layer has cooled to temperature (Tal) and the thin layer to temperature (Ta2), whereby the temperature of the thick layer is still higher than the temperature of the thin layer (Tal > Ta2). The thickness (d) of the adhesive layer can therefore already be determined based on the application temperature (T0) and the first temperature (Ta).

[0071] At the second time (tb), at which the second temperature (Tb) is detected by the second measuring unit (7b), the thick layer has cooled further to the temperature (Tbl) and the thin layer to the temperature (Tb2), wherein the difference (AT) between the first temperature (Ta) and the second temperature (Tb) of the thin layer is greater than that of the thick layer (AT2 < ATI). On the basis of the first temperature (Ta) and the second temperature (Tb), the thickness (d) of the adhesive layer can thus be determined, even if the original application temperature (TO) is not known or can only be set imprecisely. At a constant speed (v), the first and second times (ta, tb) correspond to the first and second distances (Xa, Xb) of the respective measuring units (7a, 7b) from the application unit (12).

[0072] In addition to the layer thickness, the cooling rate of the adhesive depends on other influencing factors such as the dimensions, condition, and temperature of the surface before the adhesive is applied, the temperature and humidity of the ambient air, as well as the heat capacity and thermal conductivity of the adhesive and the material to which the adhesive is applied. The influence of layer thickness on the cooling rate can be determined through appropriate tests. These influencing factors must be kept as constant as possible or taken into account accordingly.

[0073] According to the second embodiment, which is also shown in Figs. 1a and 1b, the first measuring unit (7a) is arranged at a defined distance in a normal direction (Y) perpendicular to the narrow surface (2a, 2b) of the workpiece (4) and detects a first distance (Da) from the applied adhesive layer (3). The difference between the defined distance from the workpiece surface (2a) and the detected first distance (Da) thus corresponds to the thickness (d) of the applied adhesive layer (3).

[0074] In order to improve the measuring accuracy, a second measuring unit (7b) can optionally be provided in addition to the first measuring unit (7a), which is also arranged at a defined distance in a normal direction (Y) perpendicular to the narrow surface (2a, 2b) of the workpiece (4) and detects a second distance (Db) from the workpiece surface (2b) before the adhesive is applied. The second distance (Db) serves as a reference value in order to detect fluctuations in the distance between the first measuring unit (7a) and the workpiece surface (2a), for example due to relative movement, and to take them into account when determining the layer thickness. In Fig. 1a and 1b, both measuring units (7a, 7b) have the same distance from the workpiece surface (2a, 2b), which essentially corresponds to the second distance (Db), so that the difference between the detected distances (Da, Db) corresponds to the thickness (d) of the applied adhesive layer (3).However, the two measuring units (7a, 7b) can also have different distances from the workpiece (4), which are taken into account when determining the layer thickness.

[0075] The control unit (8) can also be configured to determine and regulate a quantity of adhesive to be applied in the future on the basis of the determined thickness (d) of the applied adhesive layer (3), in particular by controlling the adhesive flow provided by the dosing unit (11) and / or the relative speed (v) generated by the movement unit between the workpiece (4) and the application unit (12).

[0076] Fig. 2a and 2b show a third and fourth embodiment of a device (1) according to the invention for determining an amount of adhesive applied to a surface (2a)

[0077] (3) and a machine (10) according to the invention for applying adhesive (3) to a surface (2a). The third and fourth embodiments comprise essentially the same components and features as the first and second embodiments described above, respectively, and differ therefrom only in that the adhesive (3) is not applied directly by the application unit (12) to the workpiece (4), but indirectly via an application roller (6).

[0078] The application unit (12) first distributes the adhesive (3) evenly with a defined layer thickness on the outer surface of the rotating application roller (6), the length of which in the height direction (Z) is greater than the height of the narrow surface (2a, 2b) of the workpiece (4). When the workpiece

[0079] (4) is moved past the application roller (6), the adhesive layer (3) is applied to the workpiece (4) by the application roller (6) in the region of the narrow surface (2a, 2b), so that in this region of the application roller (6) a depression is formed in the adhesive layer (3), the depth of which depression essentially corresponds to the thickness of the adhesive layer (3) that was applied to the workpiece (4). The depression in the adhesive layer (3) of the application roller (12) is subsequently refilled by the application unit (12). Furthermore, reference is made to the above descriptions of the first and second embodiments.

[0080] 3a and 3b show a fifth embodiment of a device (1) according to the invention for determining a quantity of adhesive (3) applied to a surface (2a), and of a machine (10) according to the invention for applying adhesive (3) to a surface (2a). Except for the arrangement of the first measuring unit (7a) and / or the second measuring unit (7b), the fifth embodiment essentially corresponds to the fourth embodiment described above. For better clarity, the workpiece (4), which is arranged as shown in Fig. 2a, is not shown in Fig. 3a.

[0081] In this embodiment, the first measuring unit (7a) and the optional second measuring unit (7b) are not directed at the workpiece (4), but at an area of ​​the application roller (6) before the adhesive is applied by the application unit (12) and after the adhesive is transferred to the workpiece (4), which area has the recess in the adhesive layer (3).

[0082] The first measuring unit (7a) is arranged at a defined distance from the outer surface of the application roller (6) and detects a first distance (Da) from the bottom of the recess, i.e. from the adhesive layer (3) after it has been transferred to the workpiece (4). If all of the adhesive (3) has been applied to the workpiece (4) in the area of ​​the recess, the first distance (Da) corresponds to the defined distance from the outer surface of the application roller (6). The difference between the defined distance and the defined thickness of the adhesive layer (3) corresponds to the distance between the first measuring unit (7a) and the adhesive layer (3) before it is transferred to the workpiece (4). The thickness (d) of the adhesive layer (3) applied to the workpiece (4) is thus determined from the difference in the distance to the adhesive layer (3) on the application roller (6) before and after the transfer to the workpiece (4).

[0083] In order to improve the measuring accuracy, in addition to the first measuring unit (7a), a second measuring unit (7b) can optionally be provided, which is also arranged at a defined distance from the outer surface of the application roller (6) and detects a second distance (Db) to the adhesive layer (3) on the application roller (6) before transfer to the workpiece (4) or in an area in which no transfer to the workpiece (4) takes place. The second distance (Db) serves as a reference value in order to detect fluctuations in the defined thickness of the adhesive layer (3) on the application roller (6) and to take this into account when determining the thickness (d) of the adhesive layer (3) applied to the workpiece (4).

[0084] In Fig. 3a and 3b, both measuring units (7a, 7b) have the same distance from the outer surface of the application roller (12), so that the difference between the measured distances (Da, Db) corresponds to the thickness (d) of the adhesive layer (3) applied to the workpiece (4). However, the two measuring units (7a, 7b) can also have different distances from the

[0085] application roller (12), which are then taken into account when determining the layer thickness. Furthermore, the first distance (Da) and the second distance (Db) can also be measured with the same measuring unit (7a) (see Fig. 4).

[0086] Fig. 4 shows a sixth embodiment of a device (1) according to the invention for determining a quantity of adhesive (3) applied to a surface (2a), and of a machine (10) according to the invention for fastening an edge band (5) to the narrow side (2a, 2b) of a plate-shaped workpiece (4) by means of adhesive (3). The sixth embodiment essentially corresponds to the fifth embodiment, in which the adhesive (3) is applied to the narrow side of a plate-shaped workpiece (4) by means of a rotating application roller (6), which is moved along the application roller (6) at a defined speed (v). In the sixth embodiment, the dosing unit (11) and the application unit (12) are integrated into the application roller (6). In addition, the machine (10) additionally comprises a pressing unit (14) for pressing the edge band (5) onto the workpiece (4).

[0087] After the adhesive (3) has been applied to the narrow side of the workpiece (4) by the application roller (6), the edge band (5) is pressed by the pressing unit (14) against the narrow side of the workpiece (4) coated with adhesive (3) in order to bond it to the workpiece (4). The first measuring unit (7a) records both the first distance (Da) to the bottom of the recess and the second distance (Db) to the surface of the adhesive layer (3) on the application roller (6) in an area in which no transfer to the workpiece (4) occurs.

[0088] Reference symbol list

[0089] I Device

[0090] 2a / 2b surface / reference surface

[0091] 3 adhesive layer

[0092] 4 Workpiece

[0093] 5 edge band

[0094] 6 application roller

[0095] 7a / 7b first / second measuring unit

[0096] 8 Control unit

[0097] 10 machines

[0098] II Dosing unit

[0099] 12 order units

[0100] 14 Pressing unit

[0101] X Longitudinal direction

[0102] Y normal direction

[0103] Z Altitude direction v Speed ​​of relative movement

[0104] TO Application temperature of the adhesive layer d Thickness of the applied adhesive layer h Height of the surface and the adhesive layer s Depth of the depression in the adhesive layer Xa / Xb Defined distance to the first / second measuring unit

[0105] Da / Db detected first / second distance

[0106] Ta / Tb recorded first / second temperature

Claims

CLAIMS 1. Device (1) for determining an amount of adhesive applied to a surface (2a), in particular for fastening an edge band (5) to a narrow surface of a plate-shaped workpiece (4) made at least partially of wood, wood-based material, plastic or the like, in particular by means of an application roller (6), comprising a first measuring unit (7a) for the contactless detection of a first property of an applied adhesive (3) and a control unit (8) which is set up to determine a layer thickness (d) of the applied adhesive (3) on the basis of the detected first property, wherein the surface (2a) is a surface of the workpiece (4), a surface of the edge band (5) and / or a surface of the application roller (6).

2. Device (1) according to claim 1, further comprising a second measuring unit (7b) for the contactless detection of a second property of a reference surface (2b) or of a reference medium, wherein the reference surface (2b) can be a narrow surface of the workpiece (4) before the adhesive is applied, a surface of the edge band (5) before the adhesive is applied or a surface of the application roller (6) after the adhesive has been transferred to the workpiece (4) or to the edge band (5) and the reference medium can be ambient air, wherein the control unit (8) is set up to determine the layer thickness (d) of the applied adhesive (3) on the basis of the detected first and second properties.

3. Device (1) according to claim 1 or 2, wherein the first property and / or the second property is a temperature (Ta, Tb) and / or a distance (Da, Db) to a surface and / or can be detected by means of laser triangulation, fluorescence laser scanning, optical coherence tomography, active thermography and / or terahertz radar technology.

4. Device (1) according to one of the preceding claims, wherein the control unit (8) is further configured to determine and / or regulate a quantity of adhesive to be applied in the future on the basis of the determined layer thickness (d), in particular by means of a corresponding interface for controlling a provided adhesive flow and / or a generated relative speed (v).

5. Machine (10) for applying adhesive (3) to a surface (2a), in particular for fastening an edge band (5) to a narrow surface of a plate-shaped workpiece (4) consisting at least partially of wood, wood-based material, plastic or the like by means of the adhesive (3), comprising a dosing unit (11) for dosing a provided adhesive stream, an application unit (12) for applying the adhesive (3) to the surface (2a), and a device (1) according to one of the preceding claims, wherein the application unit (12) is configured to apply the adhesive (3), e.g. by means of an application nozzle, directly to the narrow surface of the workpiece (4) and / or directly to the surface of the edge band (5) or to first apply the adhesive (3) to the surface of an application roller (6), and the application roller (6) is arranged to then apply the adhesive (3) to the narrow surface of the workpiece (4) and / or to the surface of the edge band (5).

6. Machine (10) according to claim 5, further comprising a movement unit for generating a relative movement between the surface (2a, 2b) and the machine (10) at a defined speed (v) in a longitudinal direction (X) of the surface (2a, 2b) and / or a pressing unit (14) for pressing the edge band (5) onto the workpiece (4).

7. Machine (10) according to claim 5 or 6, wherein between the application unit (12) and the first and / or the second measuring unit (7a, 7b) there is a first and / or second defined distance (Xa, Xb) in the longitudinal direction (X) of the surface (2a, 2b), between the surface (2a, 2b) and the application unit (12) as well as between the surface (2a, 2b) and the first and / or the second measuring unit (7a, 7b) there is a relative movement with the defined speed (v) in the longitudinal direction (X) of the surface (2a, 2b), the adhesive (3) is heated to a defined application temperature (T0) for application, the first and / or the second measuring unit (7a, 7b) are configured to measure a first and / or a second temperature (Ta, Tb) of the applied adhesive (3) and / or the surface (2b) before the adhesive application and / or the ambient air, and the control unit (8) is set up on the basis of the first and / or the second temperature (Ta,Tb) to determine the thickness (d) of the applied adhesive layer (3), in particular taking into account the speed (v), the relative movement, the first and / or the second defined distance (Xa, Xb), the application temperature (T0), the surface temperature before the adhesive is applied, the ambient temperature, the heat capacity and / or heat conduction of the surface (2a) and / or the adhesive (3).

8. Machine (10) according to claim 7, wherein the first measuring unit (7a) is set up to detect a first temperature (Ta) of the applied adhesive (3) at a first defined distance (Xa) from the application unit (12), the second measuring unit (7b) is set up to detect a second temperature (Tb) of the applied adhesive (3) at a second defined distance (Xb) from the application unit (12), the control unit (8) is set up to determine the thickness (d) of the applied adhesive layer (3) on the basis of a temperature difference (AT) between the first temperature (Ta) and the second temperature (Tb).

9. Machine (10) according to claim 5 or 6, wherein there is a defined distance in the normal direction (Y) perpendicular to the surface (2a, 2b) between the surface (2a, 2b) and the first and / or the second measuring unit (7a, 7b), the first and / or the second measuring unit (7a, 7b) are set up to detect a first and / or a second distance (Da, Db) to the applied adhesive layer (3) and / or to the surface (2b) before the adhesive is applied, and the control unit (8) is set up to determine the thickness (d) of the applied adhesive layer (3) on the basis of the first and / or the second detected distance (Da, Db).

10. Machine (10) according to claim 5 or 6, wherein there is a defined distance between the surface of the application roller (6) and the first and / or the second measuring unit (7a, 7b), the first and / or the second measuring unit (7a, 7b) are set up to detect a first and / or a second distance (Da, Db) to the adhesive layer (3) on the application roller (6), and the control unit (8) is set up to determine the thickness (d) of the applied adhesive layer (3) on the basis of the first and / or the second detected distance (Da, Db).

11. Machine (10) according to claim 9, wherein the first measuring unit (7a) is set up to detect the first distance (Da) to a bottom of a depression in the adhesive layer (3) on the application roller (6) which arises after the adhesive has been transferred to the surface (2a, 2b) and / or the second measuring unit (7b) is set up to detect the second distance (Db) to the adhesive layer (3) on the application roller (6) before the adhesive has been transferred to the surface (2a, 2b) or in a region in which no adhesive has been transferred to the surface (2a, 2b).

12. Method for detecting the thickness (d) of an adhesive layer (3) applied to a surface (2a, 2b), in particular with a device (1) according to one of claims 1 to 4 or a machine (10) according to one of claims 5 to 8, wherein between the surface (2a, 2b) and a location of the Adhesive application a relative movement with a defined Speed ​​(v) in a longitudinal direction (X) of the surface (2a, 2b), an adhesive (3) is heated to a defined application temperature (TO) for application, and the method comprises Detecting a first and / or a second temperature (Ta, Tb) of the applied adhesive layer (3) at a first and / or a second defined distance (Xa, Xb) in the longitudinal direction (X) after the location of the adhesive application, Determining the thickness (d) of the applied adhesive layer (3) based on the application temperature (TO) and the first and / or second temperature (Ta, Tb).

13. Method for detecting the thickness (d) of an adhesive layer (3) applied to a surface (2a, 2b), in particular with a device (1) according to one of claims 1 to 4 or a machine (10) according to one of claims 5, 6 or 9 to 11, wherein the method comprises Detecting a first and / or a second distance (Xa, Xb) to the applied adhesive layer (3) and / or to the surface (2a, 2b) before the adhesive is applied, Determining the thickness (d) of the applied adhesive layer (3) on the basis of the first and / or the second detected distance (Xa, Xb).

14. The method of claim 12 or 13, further comprising Determining and / or regulating a quantity of adhesive to be applied in the future on the basis of the determined layer thickness (d), in particular by means of a corresponding interface for controlling a provided adhesive flow and / or a generated relative speed (v).

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