Method for inspecting panels and a device used therefor

Abstract

The invention relates to a method for inspecting panels (1) wherein the panels (1) are provided with profiled edge areas on at least one pair of opposite edges (2-3). In the method, a first set of one or more sensors (15) is employed to record a first part of the contour of a cross-section of the first profiled edge area (2), wherein there is a relative displacement between the first set of one or more sensors (15) and the panel (1) during the recording. The invention further also relates to a device used in such a method.

Description

[0001] Method for inspecting panels and a device used therefor.

[0002] The present invention relates to a method for inspecting panels and a device used in such methods for inspecting panels. In the context of the present invention, the invention is in the first place concerned with the inspection of decorative panels intended to be used as panels of a floating floor covering. Other applications, such as applications with panels that are glued to a subfloor, or with wall or ceiling panels, are not excluded in the present invention.

[0003] WO 2024 / 069284 Al describes a method for inspecting panels, wherein at least a first part and at least a second part of the contour of the cross-section of a profiled edge area are recorded. The recordings obtained from this inspection can then be used to evaluate whether the recorded cross-section of the inspected profiled edge area fits the desired shape. A limitation of the method of WO 2024 / 069284 Al is that it only provides information of the profiled edge area at the inspected cross-section, so that deviations and inaccuracies in the contour of other cross-sections along the profiled edge area will not be observed. Additionally, if the recorded cross-section fulfills a set of requirements in accordance with the desired contour, the panel will be accepted, i.e. it will be labelled as a panel with an acceptable contour. This might lead to false negatives, i.e. incorrectly accepting a panel while it actually should be rejected, since other cross-sections of the same profiled edge area might provide recordings that would not fulfill the set of requirements in accordance with the desired contour. Furthermore, if the panel would have a non-constant contour along the longitudinal direction of the profiled edge area, the method of WO 2024 / 069284 Al would require repeated positioning of the panel’s edge to enable recording of several portions of the non-constant contour. The method of WO’284 requires taking the panel to be inspected outside the production flow. This may be hazardous or require a standstill of the line to take the panel out in a safe way. Further, the separate inspection could lead to a downtime in the production process while recording, to prevent wrong profiling until the production process is adjusted based on the recording, or, could lead to a delay between the detection of wrongly profiled panels and a potential adjustment of the production process. The present invention, in the first place, aims at providing an alternative method for inspecting panels, wherein according to various preferred embodiments a solution is provided for one or more of the problems with the methods of the prior art.

[0004] To this end, according to its first independent aspect, the present invention is a method for inspecting panels, wherein said panels, at least at one pair of opposite edges, are provided with profiled edge areas which are provided with coupling parts allowing two of such panels to be coupled to each other, wherein the method comprises the step of recording at least a first part of the contour of a cross-section of a first of said profiled edge areas, wherein the first part is recorded by means of a first set of one or more sensors, with as a characteristic that the method comprises the step of performing a relative displacement of the panels with respect to the first set of one or more sensors during said step of recording.

[0005] An inspection method in accordance with the present invention can be efficiently incorporated into a panel production line, especially into a panel production line wherein the panels perform one or more continuous movements, for example in a panel production line comprising a double-end tenoner. Because there is a relative displacement during the recording, more information regarding the recorded crosssection is obtained. In other words, the recording of the contour of the cross-section also comprises information regarding the contours of the cross-sections directly adjacent to the recorded cross-section, at least because the recording requires a finite amount of time. This allows for at least a certain degree of averaging of small effects, such as the presence of one or more burrs on the inspected edge, providing a more robust inspection method.

[0006] Preferably, the step of recording comprises at least recording the contour at at least two separate cross-sections along the first profiled edge area. By recording the contour of the cross-section of a panel during the relative displacement, information regarding the contour can thus be obtained at multiple cross-sections along the profiled edge area. This information provides for a complete, or at least more complete, characterization of the shape of the contour along the profiled edge area, which allows for a detailed assessment of the entire profiled edge area for errors or deviations. Preferably, the method comprises the step of evaluating the errors or deviations in the contour along the profiled edge area. Thereby, it is possible thanks to the invention to accept or reject a panel with a higher degree of certainty than with the methods of the prior art. With the method of the invention, even panels with a non-constant contour along the profiled edge area can be efficiently inspected. Additionally, if, during the step of providing said profiled edge areas, for example in a double-end tenoner, the panel does not advance in a straight line, in the plane of the panel and parallel to the profiled edge areas, the recordings may indicate this. Thus, such a swaying of a panel during the step of providing the profiled edge areas may be detected through the method of the invention. Preferably, the method comprises the step of using the information contained in the recordings, and preferably feeding the information back to the means that provide the profiled edge areas. For example, in the case of a double-end tenoner that comprises milling tools, the milling tools are adjusted based on said information. By using this information, for example by feeding this information back to the means that provide said profiled edge areas, the swaying of further panels during the step of providing the profiled edge areas can be avoided.

[0007] In a further preferred embodiment, the information that is fed back to the means that provide the profiled edge areas, is based on deviations detected between the recorded contour and the desired geometry of the profiled edge area. This desired geometry of the profiled edge area may be stored in a digital format, such as a CAD-model or a structured data representation that allows comparison of the recorded contour data and the reference geometry stored in said digital format. Based on such deviations, the position of the means that provide the profiled edge area, for example milling tools, may be adjusted in position with regard to a system used for effecting a relative displacement of a panel with respect to the means for providing the profiled edge area, for example a belt system for conveying the panels, for example in a horizontal and / or vertical direction and / or for example towards and / or away from said system. This adjustment may be carried out manually, for example by providing instructions or visual indicators to a human operator, or automatically, by transmitting control signals to a drive system capable of repositioning the means that provide the profiled edge area. This feedback mechanism enables dynamic correction of the step of providing the profiled edge areas.

[0008] In a preferred embodiment, the step of providing the profiled edge areas is followed directly by the step of recording, preferably within 5 meters, more preferably within 2 meters, even more preferably within 1 meter, most preferably within 0.5 meter. Alternatively, this may be within 2 minutes, more preferably within 1 minute, most preferably within 30 seconds. Alternatively, this may be inside the double-end tenoner at a position after the last operative milling tool of said double-end tenoner. Alternatively, this may be in the double-end tenoner while the panel is moved by the conveyor system of the double-end tenoner. This has the benefit that there is a limited amount of time between the providing of the profiled edge areas and the inspection thereof. This has the further benefit that, if the inspection of the contour of the cross-section indicates that the profile is not satisfactory, there is only a limited amount of panels that will have unsatisfactory profiled edge areas before it is determined that the provided profile is unsatisfactory.

[0009] Preferably, the relative displacement is in a first direction in the plane of the panels. Preferably, the relative displacement is parallel to said one pair of opposite edges. This has the benefit that it can simplify the implementation of the method.

[0010] Preferably, the first set of one or more sensors is stationary and the panels move relative to the first set of one or more sensors. This has the benefit that it could be easily incorporated into a panel production line where the panels are already moving, for example in a double-end tenoner. Additionally, the stationary configuration of the first set of one or more sensors could be beneficial since the addition of the first set of one or more sensors could require only a limited space and can be even incorporated into the double-end tenoner. Alternatively, it is also possible according to the invention that the panels are stationary and that the first set of one or more sensors moves relative to the panels, or that both the panels and the first set of one or more sensors move relative to each other. The relative displacement is preferably effected by means of a conveyor system, such as a belt or a chain. By effecting the relative displacement in such a way, the complexity to incorporate the first set of one or more sensors can be reduced, for example by adding the first set of one or more sensors along the conveyor system. Most preferably, the relative displacement is effected by means of the conveyor system of a double-end tenoner. This has the benefit that the step of providing the profiled edge areas can be performed in-line with the step of recording, making the entire process very efficient since the provided profiled edge areas can be directly inspected.

[0011] Preferably, the method further comprises the step of aligning and / or positioning the to be inspected profiled edge areas in a fixed position in a direction perpendicular to the plane of the corresponding panel with respect to the first set of one or more sensors. This is beneficial to warrant an optimal orientation of the inspected edge with respect to the first set of one or more sensors. Additionally, this also advantageously counteracts possible vibrations of the used machinery, such as for example vibrations resulting from the milling of the profiled edge areas, and thus provides for a more steady recording of the contour of the cross-section. For example, panels with limited bending stiffness, such as for example LVT (Luxury Vinyl Tile) panels, could bend due to gravity or other external forces, which would lead to a sub-optimal orientation for the recording.

[0012] Preferably, said step of aligning and / or positioning is performed at least by a pressure shoe and / or a slide shoe. Preferably, in the case where the relative displacement is provided by the conveyor system of a double-end tenoner, said double-end tenoner comprises said pressure shoe and / or slide shoe. This has the benefit that already existing parts of the double-end tenoner are used, which simplifies the incorporation of the method of the invention with a minimal amount of structural modifications.

[0013] Preferably, the method further comprises the step of aligning and / or positioning the to be inspected profiled edge areas in a fixed position with respect to the first set of one or more sensors, in a direction in the plane of the panel perpendicular to the longitudinal direction of the first pair of opposite edges. For example, this can be obtained in the case the conveyor system of a double-end tenoner provides the relative displacement, by means of the friction provided by a pressure belt above the conveyor system pressing down on the panel. This has the benefit that there is no change in distance along this direction between the profiled edge areas and the first set of one or more sensors, providing a better recording with fewer distortions.

[0014] The recording is preferably performed at a fixed recording frequency. This simplifies the implementation of the step of recording. Further, this also ensures that, if the fixed recording frequency is sufficiently high, all, or at least most, details of each panel may be recorded. Preferably, said fixed recording frequency is selected based on the speed of the relative displacement, wherein a higher frequency is selected for a higher speed, and vice versa. Preferably, at least 2 recordings are made for each panel, more preferably at least 20, even more preferably at least 100, most preferably at least 1000. Additionally, or alternatively, in the case that the relative displacement is at a constant speed, said fixed recording frequency can be selected based on the desired distance, measured along the profiled edge areas, between two consecutively recorded cross-sections. This advantageously makes it possible to select the fixed recording frequency based on a desired level of accuracy for the inspection of each panel. Preferably, each sensor of the first set of one or more sensors preferably has the same recording frequency. This provides for a straightforward implementation, where for example same-timed trigger signals can be employed.

[0015] Alternatively, the recording can be performed at an adaptive frequency. This has the advantage that certain parts of a panel, e.g. critical zones, can be recorded at a higher recording frequency than other parts, thus locally providing a more accurate inspection. Preferably, the adaptive frequency is adapted based on the proximity of one of the extremities of the panel, in the direction of the relative displacement, and the first set of one or more sensors. In other words, the distances between the first set of one or more sensors and the extremities of the panel, i.e. the leading and the trailing edges of the panel, are calculated, and, based on the lowest of said distances, the frequency is adapted, wherein the frequency is adapted inversely to said lowest distance. This has the benefit that the leading and the trailing edges of a panel are recorded at a higher frequency, which provides a more accurate inspection of these zones. Preferably, at least one sensor, and preferably all sensors, comprised in the first set of one or more sensors allow distance and / or profile measurement, e.g. laser distance or laser profile meters. Preferably, such a sensor allows the measurement of distance to multiple points of the corresponding contour part, preferably with a resolution of more than 10 points per millimeter, or even more than 1000 points per millimeter, while the recording angle is constant. This may involve a sensor which is capable of performing a line scan of the corresponding contour part. According to a particular example, the first set of one or more sensors comprises one or more optical 2D triangulation position sensors and / or one or more sensors, namely 2D triangulation position sensors, available on the market under the name Keyence LJ-V7060. Alternatively or additionally to the particular example, the first set of one or more sensors comprises one or more optical 2D triangulation position sensors and / or one or more sensors, namely 2D triangulation position sensors, available on the market under the name scanCONTROL 30xx, preferably scanCONTROL 3000-50.

[0016] Preferably, the sensors used in the first set of one or more sensors are laser-based sensors, more preferably laser-based sensors emitting electromagnetic radiation with a wavelength between 300 and 600 nanometers, preferably with a wavelength between 350 and 500 nanometers or so called blue light lasers, more preferably between 400 and 420 nm, for example 405 nm or 410 nm. Such sensors are especially suitable for panels having a transparent top layer, in particular when this top layer is made of a thermoplastic material. The wavelengths within this range are less prone to penetrating transparent or semi-transparent layers, thereby reducing measurement errors and ensuring accurate detection of the actual surface contour beneath such layers.

[0017] Alternatively or additionally, red light lasers may be used, in particular laser-based sensors emitting electromagnetic radiation with a wavelength between 600 and 700 nanometers, preferably with a wavelength between 640 and 670 nm, for example 658 nm or 660 nm. Such red light lasers may offer improved signal stability, thereby providing a viable complement or alternative to said blue light laser-based sensors. It is remarked that, within the scope of the claimed invention, it is possible that the first set of one or more sensors comprises at least two sensors, wherein said two sensors record the same first part of the contour of a cross-section of the first profiled edge area. Furthermore, it is not excluded, and in certain cases even beneficial, that these at least two sensors record at different wavelengths or in different wavelength bands, for example, in the visible wavelength band, in the infrared wavelength band, or in the ultraviolet wavelength band. According to the claimed invention, it is also possible that at least one sensor of the first set of one or more sensors records at the aforementioned different wavelengths or in the aforementioned different wavelength bands. Recording at different wavelengths or in different wavelength bands can be beneficial since it provides a different way of looking at the same first part of the contour of the crosssection of the first profiled edge area, wherein each one of the sensors can have an increased sensitivity to certain features. Further, the recordings at the different wavelengths and or different wavelength bands are preferably combined in order to provide an improved inspection of the panel. This combination can be done in several ways, such as overlaying the recordings or part of the recordings, or through a mathematical procedure. This is advantageous since certain features can be detected more easily, while other disturbing features might be removed at certain wavelengths or wavelength bands.

[0018] Preferably, the relative displacement is at a constant speed. This allows for a smooth and continuous process. Further, this also advantageously provides for a substantially similar length of the contour of the profiled edge areas that is comprised in a recording, improving the uniformity across different recordings. Of course, it is also possible that the relative displacement is at a non-constant speed, for example an oscillating speed profile or a block-wise speed profile.

[0019] It is noted that the method of the first independent aspect can be used to obtain one or more dimensions of the panel, such as its length, its width, and / or its surface area. The one or more dimensions are preferably obtained based on the constant speed of the relative displacement and on the time duration between two consecutive recordings, which will be both described in greater detail in the following paragraphs. Therefore, the method preferably further comprises the step of obtaining said constant speed of the relative displacement. Preferably, said constant speed is obtained through one, or a combination of two or more, of the three possibilities described hereafter.

[0020] According to a first possibility, said constant speed can be obtained by directly measuring it using one or more speed-measuring devices, such as for example a speedometer, a radar, or a lidar (light detection and ranging).

[0021] According to a second possibility, the conveyor system that provides the relative displacement, preferably the conveyor system of a double-end tenoner, comprises means to read out the constant speed of the relative displacement, wherein the constant speed is read out from said means to read out the constant speed. This is advantageous because this information can be efficiently extracted, for example from an encoder comprised in the conveyor system, without the requirement of additional speed-measurement devices.

[0022] According to a third possibility, the relative displacement is in a first direction in the plane of the panels, parallel to said one pair of opposite edges, wherein there is a first sensor and a second sensor, wherein the first sensor and the second sensor are stationary, wherein it is not necessary that the first sensor is comprised in the first set of one or more sensors nor that the second sensor is comprised in the first set of one or more sensors. It is thus possible that both the first sensor and the second sensor are comprised in the first set of one or more sensors, or that only the first sensor is comprised in the first set of one or more sensors, or that only the second sensor is comprised in the first set of one or more sensors, or that both the first sensor and the second sensor are not comprised in the first set of one or more sensors. Each panel has a leading edge and a trailing edge, wherein the first sensor and the second sensor record at least the passing of said leading edge and / or at least the passing of said trailing edge, wherein there is a time delay between said recording at least the passing of said leading edge and / or at least the passing of said trailing edge. Further, in the longitudinal direction of the first profiled edge area, there is an offset of predefined length between said first sensor and said second sensor. Preferably, said offset of predefined length is less than the length of a panel, more preferably less than half of the length of a panel, even more preferably less than one tenth of the length of a panel, most preferably less than one fiftieth of the length of a panel. This has the benefit that the time delay is reduced, making possible comparisons between the recordings of the first sensor and the second sensor easier. For example, influences from time-dependent effects, like low-frequency vibrations, can be minimized.

[0023] The constant speed of the relative displacement is determined based on at least said offset of predefined length and said time delay.

[0024] There are a multitude of possible implementations wherein said first sensor and said second sensor record at least the passing of said leading edge and / or at least the passing of said trailing edge, of which some are detailed in the following paragraphs. Of course, other implementations are conceivable and thus fall within the scope of the invention.

[0025] According to a first implementation, the first set of one or more sensors comprises at least said first sensor and said second sensor. This is beneficial since all required information for obtaining said constant speed can be done with only one set of sensors, preferably comprised in a single sensor head. This also advantageously means that only one edge area needs to be recorded.

[0026] According to a second implementation, the method further comprises the step of recording a second part of the contour of the cross-section of the first edge area by a second set of one or more sensors, wherein said first set of one or more sensors comprises said first sensor and wherein said second set of one or more sensors comprises said second sensor. Advantageously, recording a second part of the contour of the crosssection provides additional information, which can be used for the evaluation of the provided profile, while, in a synergistic manner, also providing the required sensors for the obtaining of said constant speed.

[0027] According to a third implementation, the method further comprises the step of recording at least a part of the contour of the cross-section of a second of said profiled edge areas using an additional set of one or more sensors, wherein said first set of one or more sensors comprises said first sensor and wherein said additional set of one or more sensors comprises said second sensor. This has the benefit that the additional set of one or more sensors can provide information regarding the quality of the profile on the second profiled edge area, while, in a synergistic manner, also providing the required sensors for the obtaining of said constant speed.

[0028] According to a fourth implementation, the step of recording at least the passing of said leading edge and / or at least the passing of said trailing edge is performed by at least a further set of two or more sensors, wherein said further set of two or more sensors comprise said first sensor and said second sensor. According to this fourth implementation, the first sensor and the second sensor are not comprised in the first set of one or more sensors, nor, if present, in the second set of one or more sensors, nor, if present, in the additional set of one or more sensors. This is beneficial since the time delay can be determined based on relatively basic and inexpensive sensors. Furthermore, this implementation is advantageous since these sensors may be selected from a large variety of sensors, providing the possibility of selecting the sensors based on certain design parameters, such as for example the space available for the sensors. It may further also reduce the complexity of the obtaining of said time delay. Said further set of two or more sensors could for example be pressure sensors connected to a spring, wherein the passing of the panel by a said pressure sensor causes said pressure sensor to alter its position, wherein the altering of the position of said pressure sensor is picked up by said pressure sensor, in this way providing a signal of the passing of the leading and / or trailing edge of the panel. Alternative types of sensors, such as for example sensors using a ray of light, or a plurality of rays of light, might be used, wherein the ray of light is interrupted by the passing of the panel, and remains interrupted for the entire time duration between the passing of the leading edge and the passing of the trailing edge. Said ray of light could be detected in a position on the opposite major flat side of the panel relative to the major flat side where the ray of light is emitted from, or on the same major flat side of the panel. In the case this detection is performed on the same major flat side of the panel, the ray of light could be reflected off of a reflecting surface, for example a mirror, which is positioned on the opposite major flat side of the panel. According to a fifth implementation, the first set of one or more sensors comprises said first sensor and said second sensor is not comprised in the first set of one or more sensors, nor, if present, in the second set of one or more sensors, nor, if present, in the additional set of one or more sensors. Thus, the fifth implementation provides a combination of the first sensor recording the first part of the first profiled edge area, whereas the second sensor records the passing of the leading and / or trailing edge of a panel at another portion on the contour than at the first or second profiled edge areas. This is beneficial in certain scenarios, for example when only the first part of the first profiled edge area is to be inspected, such that a relatively inexpensive second sensor can be used and said time delay can still be obtained. The second sensor can be one of the sensors employed in the fourth implementation, such as for example one of said pressure sensors or light ray sensors.

[0029] As an alternative or addition to the recording of the passing of the leading edge and / or trailing edge with at least two sensors, the method can comprise the further step of recording the passing of at least two markings on the contour of the cross-section of a panel, wherein the at least two markings are positioned at a predefined distance from each other along the longitudinal direction of the first profiled edge area. Such markings can for example be notches, for example in the upper and / or lower surface of the panel parallel to the plane of the panel. This can be beneficial as these marking, besides aiding in the method for determining the constant speed, can also provide for certain effects, such as aesthetic effects, in the inspected panel. It is also conceivable for the at least two markings to be located on the first profiled edge area, for example as locally removed portions of the profile. Similarly as described above for the third possibility, there is a time delay between the recordings of said two markings, wherein the constant speed of the relative displacement is obtained from this time delay and said predefined distance between said two markings. The benefit of this alternative is that the constant speed can be obtained through the use of only one sensor.

[0030] As described before, at least one dimension of the panel, for example its length in the direction of the first pair of opposite edges, can be obtained based on the constant speed and the time duration between two consecutive recordings. In the following, this is explained in more detail.

[0031] Preferably, the method comprises the further step of recording the passing of said leading edge and the passing of said trailing edge of a panel with a panel-detecting sensor, wherein the method further comprises the step of determining the time duration between the passing of said leading edge and the passing of said trailing edge. Said paneldetecting sensor can be the first sensor or the second sensor described before in any of the first to the fifth implementation. This is beneficial as it relies on a sensor that is already available in the method of the invention, and thus does not require further adaptations. Preferably, said panel-detecting sensor recording the passing of said leading edge and the passing of said trailing edge of a panel corresponds to a sensor of the first set of one or more sensors or if present, of the second set of one or more sensors, or if present, of the additional set of one or more sensors. This is beneficial since it synergistically combines any one of the first to the third implementations described before for obtaining the constant speed, and the recording of the panel-detecting sensor, wherein as much information as possible is recorded using as little sensors as possible, greatly simplifying the method and reducing the costs related thereto.

[0032] Preferably, the length of a panel, and preferably of each panel, in the longitudinal direction of the first profiled edge area is obtained based on at least said constant speed and said time duration between the passing of said leading edge and the passing of said trailing edge. This is advantageous since it allows for a good monitoring of the panels, especially when this method is incorporated into a double-end tenoner. Such information is also useful for statistical analyses of the panel production process, for example to determine deviations from the expected lengths. It further provides an independent check of the properties of the panel, which can be used in a possible further step to adjust prior steps in the production process if needed.

[0033] According to some embodiments, the method comprises the further step of recording the passing of the leading or trailing edge of the panel, as well as the passing of at least one additional marking on the contour of the cross-section of a panel, wherein said additional marking is located at a predefined position in relation to the length of the panel in the longitudinal direction of the first profiled edge area, for example at the half-length position of the panel. Said additional marking can for example be a notch, for example in the upper or lower surface of the panel, parallel to the plane of the panel. It is also conceivable for the additional marking to be located on the first profiled edge area, for example a locally removed portion of the profile. Similarly as described above for the third possibility for obtaining the constant speed, the recording of the leading edge or trailing edge and the recording of the additional marking results in a time delay, wherein the distance between the leading edge or trailing edge and the additional marking is obtained based on this time delay and the constant speed of the relative displacement, wherein the length of the panel is obtained based on the distance between the leading edge or trailing edge and the additional marking and said predefined position in relation to the length of the panel. For example, in the case where the additional marking is located at one quarter of the length of the panel, first the length of said one quarter is obtained based on the constant speed and the time delay between the recordings of the leading edge and the particular marking, after which the length of the panel in the direction of the first profiled edge area is obtained by multiplying the length of said quarter by a factor of four. It is clear to a person skilled in the art that selecting the distance between the leading edge, alternatively the trailing edge, and the particular marking is of arbitrary choice.

[0034] Preferably, the method comprises the further step of counting the number of panels that pass the first set of one or more sensors. This can provide useful information regarding the panel production process.

[0035] As aforementioned, the method may comprise the further step of recording a second part of the contour of the cross-section of the first edge area by a second set of one or more sensors, wherein the first part is at least recorded from a first recording angle, and wherein the second part is at least recorded from a second recording angle different from the first recording angle, but each time, from one or more recording directions transverse to the longitudinal direction of the corresponding edge. This provides the advantage that a more complete inspection of the profiled edge area is obtained. Advantageously, a sensor from said second set of one or more sensors can synergistically be used in the third possibility for obtaining the constant speed of the relative displacement, however, this is not required. Preferably, said first recording angle and said second recording angle are at right angles to the longitudinal direction of the edge concerned. In this way, repeatable recordings can be made. Additionally, this ensures a more accurate tracking of the passing of the leading edge and / or the trailing edge of a panel.

[0036] Preferably, said coupling parts are substantially made as a tongue and a groove, wherein the groove is at least delimited by means of a top groove lip and a bottom groove lip. Preferably, the bottom groove lip extends beyond the top groove lip in a distal direction from the panel. Preferably, said tongue and groove are configured such that, in the coupled state, a locking can be obtained between the relevant edges in a direction perpendicular to the plane of the coupled panels. Preferably, said tongue and groove are fitted with locking parts which prevent the tongue and groove from moving apart, wherein, in the coupled state, a locking can be obtained between the relevant edges in a direction in the plane of the coupled panels and perpendicular to the coupled edges. The method of the invention is particularly advantageous for this type of panels, since the accuracy of the provided coupling parts and locking parts is of critical importance for the quality of the locking of two such panels in the coupled state, thus also requiring a highly accurate and robust inspection method.

[0037] The second part preferably comprises a part of the contour of the cross-section of the first edge area which is not comprised in said first part. Preferably, the second part also comprises a portion of the first part, such that there is an overlap between the first part and the second part. Said overlap is beneficial since it provides reference points to combine the recordings of the first part and the second part. Furthermore, by having said overlap, it can be ensured that no part of the contour of the cross-section remains uninspected. For example, in the case of a tongue and groove connection, when inspecting the first profiled edge area comprising the groove, the first part could comprise the upper lip whereas the second part could comprise the lower lip, preferably wherein both the first part and the second part further also have an overlap. As aforementioned, the method may comprise the step of recording at least a part of the contour of the cross-section of a second of said profiled edge areas using an additional set of one or more sensors. Preferably, the first set of one of more sensors and the additional set of one or more sensors are configured such that at least one sensor of the first set of one or more sensors is oriented downwardly and at least one sensor of the additional set of one or more sensors is oriented upwardly, or alternatively, at least one sensor of the first set of one or more sensors is oriented upwardly and at least one sensor of the additional set of one or more sensors is oriented downwardly, wherein downwardly and upwardly are defined relative to the plane of the panel. This configuration may allow for a good inspection of panels with coupling parts and locking parts.

[0038] Preferably, said panel, at least at a second pair of opposite edges, is provided with profiled edge areas which are provided with coupling parts allowing two of these panels to be coupled together, and wherein the method also comprises the step of recording a part of one or both profiled edge areas of the second pair of opposite edges. This allows said panels to be used efficiently in the forming of a floor covering, preferably a floating floor covering. Preferably, the method of the invention comprises the step of providing the profiled edge areas on the second pair of opposite edges, preferably by means of a milling operation, directly prior to the step of recording a part of one or both profiled edge areas of the second pair of opposite edges, preferably within 5 meters, more preferably within 2 meters, even more preferably within 1 meter, most preferably within 0.5 meter. Alternatively, this may be within 2 minutes, more preferably within 1 minute, most preferably within 30 seconds. Alternatively, this may be inside the double-end tenoner at a position after the last operative milling tool of said double-end tenoner. Alternatively, this may be in the double-end tenoner while the panel is moved by the conveyor system of the double-end tenoner. This has the benefit that there is a limited amount of time between the providing of the profiled edge areas and the inspection thereof. This has the further benefit that, if the inspection of the contour of the crosssection indicates that the profile is not satisfactory, there is only a limited amount of panels that will have unsatisfactory profiled edge areas before it is determined that the provided profile is unsatisfactory. Preferably, the step of providing the profiled edge areas on the second pair of opposite edges takes place after the step of recording a first part of the first pair of opposite edges. This allows for a smooth process flow, wherein the first pair of opposite edges is inspected before continuing with the providing of the profiled edge areas on the second pair of opposite edges. As such, if the first pair of opposite edges would not be satisfactory, it would be possible to avoid unnecessary further steps and unnecessary wear of machining tools.

[0039] Preferably, the length of the panel, and preferably of each panel, in the direction of the second pair of opposite edges is obtained. This is advantageous since it allows for a good monitoring of the panels. Such information is also useful for statistical analyses of the panel production process, for example to determine deviations from the expected lengths. It further provides a check of the properties of the panel, which can be used in a possible further step to adjust prior steps in the production process if needed. Preferably, the length of the panel in the direction of the second pair of opposite edges is obtained in a similar manner as for the length of the panel in the direction of the first pair of opposite edges. This simplifies the overall method.

[0040] Preferably, the surface area of the panel, and preferably of each panel, is obtained. Said surface area is preferably obtained based on the lengths of the panel in the direction of the first and second pairs of opposite edges. It is remarked that the obtained surface area can be an approximation of the true surface area of the panel, for example because at the moment of obtaining the length of the panel in the direction of the first pair of opposite edges, the second pair of opposite edges may not yet have been provided with profiled edge areas, thus providing for an overestimation of the length of the panel in the direction of the first pair of opposite edges, and therefore also an overestimation of the surface area of the panel.

[0041] Preferably, the method further comprises the step of saving a set of measurements and / or metrics of each panel in a data storage installation. This provides valuable information and insights into the panel production process as a whole. This information can be used to correct the process where needed, and can also be further used to monitor the amount of panels produced and their sizes.

[0042] The invention, according to its second independent aspect, is a device for use in a method in accordance with the first independent aspect of the invention or any one of the preferred embodiments thereof, with the characteristic that the device comprises at least said first set of one or more sensors, wherein the device is fitted with means for providing the relative displacement of the panels with respect to the first set of one or more sensors.

[0043] Preferred embodiments of the first independent aspect of the invention also apply to the second independent aspect of the invention, and vice versa, as far as this does not lead to contradictions.

[0044] Preferably, said means for providing the relative displacement is a conveyor system, such as a belt or a chain. Preferably, said means for providing the relative displacement is the conveyor system of a double-end tenoner. Preferably, the device is fitted with means for aligning and / or positioning a panel in a fixed position in a direction perpendicular to the plane of the panel with respect to the first set of one or more sensors. Preferably, said means for aligning and / or positioning comprise a sliding shoe and / or pressure shoe. Preferably, said sliding shoe and / or pressure shoe are comprised in a double-end tenoner, preferably the same double-end tenoner as the double-end tenoner comprising the conveyor system for providing the relative displacement. This has the benefit that the device can be made with minimal changes to an already existing double-end tenoner, and that existing components of the double-end tenoner can be used also for the inspection of the panels.

[0045] Preferably, the first set of one or more sensors are positioned stationary.

[0046] Preferably, the device is fitted with a second set of one or more sensors that record at least a second part of the contour of the cross-section of the first of said profiled edge areas. Preferably, said second set of one or more sensors is located downstream of said first set of one or more sensors. This has the benefit that a more complete inspection of the first profiled edge area can be performed.

[0047] Preferably, the device is fitted with an additional set of one or more sensors that record at least a part of the contour of the cross-section of a second of said profiled edge areas. As such, a complete inspection of the provided profiled edge areas can be performed, resulting in a higher degree of certainty regarding the quality of the panels and their profiles.

[0048] Preferably, the device is fitted with means for providing a panel with profiled edge areas on a first pair of opposite edges. Preferably, said means for providing a panel with profiled edge areas on a first pair of opposite edges is located upstream from said first set of one or more sensors, and if present also upstream of said second set of one or more sensors, and if present also upstream of said additional set of one or more sensors. It is advantageous to have the providing of the profiled edge areas and the inspection of the profiled edge areas in one and the same device as this reduces the amount of time between the providing of the profiled edge areas and the recording thereof, resulting in a faster reaction time in case something is wrong with a profiled edge area. This thus leads to an economic advantage, where the amount of scrap material, i.e. panels with a bad profiled edge area, that is produced can be reduced to a minimum.

[0049] According to a first practical possibility, the sensors of the first set of sensors are positioned stationary, wherein the relative movement of the panel is along a propagation direction, wherein the first set of one or more sensors comprises at least a first sensor and a second sensor, wherein the first sensor and the second sensor are positioned at a mutual offset of predefined length in the propagation direction.

[0050] According to a second practical possibility, the sensors of the first set of sensors are positioned stationary, wherein the relative movement of the panel is along a propagation direction, wherein the first set of one or more sensors comprises a first sensor and wherein the second set of one or more sensors comprises a second sensor, wherein the first sensor and the second sensor are positioned at a mutual offset of predefined length in the propagation direction.

[0051] According to a third practical possibility, the sensors of the first set of sensors are positioned stationary, wherein the relative movement of the panel is along a propagation direction, wherein the first set of one or more sensors comprises a first sensor and wherein the additional set of one or more sensors comprises a second sensor, wherein the first sensor and the second sensor are positioned at a mutual offset of predefined length in the propagation direction.

[0052] Any one of the first to third practical possibilities has the advantage that, based on the mutual offset of predefined length in the propagation direction, the constant speed of the relative movement can be determined, by a method which is explained in greater detail in the context of the first independent aspect of the invention.

[0053] Preferably, the device is fitted with means for providing a panel with profiled edge areas on a second pair of opposite edges. Preferably, said means for providing a panel with profiled edge areas on a second pair of opposite edges is located downstream from said first set of one or more sensors, and if present also downstream of said second set of one or more sensors, and if present also downstream of said additional set of one or more sensors. This allows for a streamlined process, where in a first step the first pair of opposite edges is inspected, after which the second pair of opposite edges is provided with profiled edge areas, which on their turn are inspected subsequently.

[0054] Preferably, the device is fitted with at least an extra set of one or more sensors for recording a part of the profiled edge areas of the second pair of opposite edges. Preferably, said extra set of one or more sensors are located downstream of the means for providing a panel with profiled edge areas on a second pair of opposite edges.

[0055] Preferably, the device is fitted with a processing installation and / or a data storage installation. Preferably, said processing installation can evaluate the recording and / or compare the recording to the desired geometry of the corresponding part. Preferably, the processing installation is capable of executing the steps described in the first independent aspect of the invention for the obtaining of the constant speed of the relative displacement. Preferably, the data storage installation at least stores data related to the geometry of a panel, and preferably each panel, such as for example the length of the panel along the first and second pair of opposite edges, the surface area of the panel. Preferably, the data storage installation also stores data related to the number of panels that have passed through the device. Preferably, said processing installation and / or said data storage installation are connected to a computer over a network, preferably over the internet.

[0056] Preferably the recording is handled by a processing installation separate from the processing installation used for evaluating and / or comparing the recording to the desired geometry of the corresponding part. By separating the tasks of data acquisition and data evaluation, each processing installation can be optimized for its specific function. This reduces processing delays and allows for faster overall system performance, especially in high-speed production environments.

[0057] It is generally remarked that the characteristics described for the sensors comprised in the first set of one or more sensors, can be applied equally to the second set of one or more sensors and / or to the additional set of one or more sensors, without it being required that all characteristics are taken over.

[0058] In a preferred embodiment, the device comprises a first series of sensor heads comprising at least two sensor heads for recording at least a part of the cross-section of a first profiled edge area, wherein each sensor head of said first series of sensor heads comprises at least a first set of one or more sensors for recording a first part of the contour of a cross-section of the first profiled edge area, and wherein there is a relative displacement of the panel with respect to each sensor head of said first series of sensor heads in a first direction in the plane of the panel, parallel to the profiled edge area, and wherein said first series of sensor heads is positioned along a line parallel to said direction in the plane of the panel, parallel to the first profiled edge area. Each sensor head of said first series of sensor heads preferably has a similar or identical configuration. Each sensor head of said first series of sensor heads is preferably positioned stationary. The use of multiple sensor heads provides several advantages: it introduces a failsafe mechanism in case one or more sensors malfunction, thereby increasing system reliability; it reduces the number of recordings each individual sensor head must perform in order to get a clear evaluation of the profiled edge quality, which allows for higher line speeds; and it enables the overlay of recorded data from multiple sensor heads, resulting in highly detailed and accurate knowledge of the contour of the cross-section of the profiled edge along its length. Furthermore, the sensor head arrangement allows for easy scaling of the system to accommodate different inspection lengths or resolutions. The identical configuration of the sensor heads simplifies calibration procedures and ensures uniform data quality across the system. Additionally, faulty sensor heads can be individually replaced without halting the entire system, thereby improving maintainability and minimizing downtime. The overlapping coverage of the sensor heads also enhances data redundancy, ensuring that critical contour information is preserved even in the event of isolated sensor failure.

[0059] It is preferred that the relative displacement of the panel is effected by means of a belt system and that the relative displacement of the panel is at a constant velocity. During said relative displacement, said panel passes through and / or underneath said first series of sensor heads, thereby allowing said at least first set of one or more sensors to record a first part of the contour of a cross-section of the first profiled edge area.

[0060] In a further preferred embodiment, the device further comprises a second series of sensor heads comprising at least two second sensor heads for recording at least a part of the cross-section of a second profiled edge area, wherein said second series is configured similarly to the first series. In an even more preferred embodiment, the device may additionally comprise a third series of sensor heads for recording at least a part of the cross-section of a third profiled edge area, and preferably also a fourth series of sensor heads for recording at least a part of the cross-section of a fourth profiled edge area. Each of these series may be arranged in accordance with the principles described for the first series, thereby enabling inspection of multiple profiled edge areas of the panel. It is preferred that said belt system comprises a stationary supporting structure, wherein said first and preferably also said second and / or third and / or fourth series of sensor heads is mounted on said stationary supporting structure of said belt system.

[0061] Preferably, a distance between at least two of said sensor heads of a series of sensor heads may be adjustable along said respective direction in the plane of the panel, parallel to the respective profiled edge area, preferably in such a way that during said relative displacement, it is possible that at least two sensor heads of the respective series of sensor heads can simultaneously record at least the same part of a different cross-section of the respective profiled edge area. This adjustability allows the system to accommodate multiple panel formats on a single line, thereby increasing flexibility and reducing the need for reconfiguration between production runs.

[0062] It is preferred that each series of sensor heads is connected to a separate processing installation and / or a separate data storage installation. This way each series can process its data independently and simultaneously, significantly increasing the overall throughput and enabling real-time analysis even at high line speeds.

[0063] According to a particularly preferred embodiment, the panels are provided with profiled edge areas at a first pair of opposite edge areas, wherein the profiled edge areas are provided by the rotating milling tools of a double-end tenoner, wherein the panels move at a first constant speed in a propagation direction in the plane of the panels, parallel to the first pair of opposite edge areas, wherein the panels are moved at said first constant speed by means of the conveyor system of said double-end tenoner. The contours of the profiled edge areas of at least two cross-sections, perpendicular to the first pair of opposite edges, are recorded by a first sensor and a second sensor, wherein the first sensor and the second sensor are stationary, wherein there is an offset of predefined length in the direction of the first pair of opposite edges between the first sensor and the second sensor. Preferably, the first sensor is oriented to record a part of the contour of the crosssection at a first of said profiled edge areas, and the second sensor is oriented to record a part of the contour of a second of said profiled edge areas. The first sensor and the second sensor record the passing of the leading edge of a panel or the passing of the trailing edge of a panel, in the direction of the first pair of opposite edge areas, wherein there is a time delay between the recording of the passing of the leading edge or the trailing edge with the first sensor and the recording of the passing of the leading edge or the trailing edge with the second sensor, wherein the first constant speed is obtained based on said offset of predefined length and said time delay between the recording of the passing of the leading edge or the trailing edge with the first sensor and the recording of the passing of the leading edge or the trailing edge with the second sensor. The first sensor further records the passing of the leading edge and the passing of the trailing edge of the panels in the direction of the first pair of opposite edges, wherein there is a first time duration between the passing of the leading edge and the passing of the trailing edge of each panel, wherein the length of each panel, in the direction of the first pair of opposite edges, is obtained based on the first constant speed and said first time duration. Preferably, the number of panels passing the first sensor is counted. The panels preferably comprise profiled edge areas at the first pair of opposite edges that allow two of such panels to be coupled to each other, wherein these profiled edge areas substantially correspond to a tongue and a groove profile, wherein the tongue and groove comprise locking parts that, in a coupled condition, prevent two panels from moving apart.

[0064] According to said particularly preferred embodiment, the panels are provided with profiled edge areas at a second pair of opposite edge areas, wherein the second pair of opposite edge areas is preferably substantially perpendicular to the first pair of opposite edge areas, wherein the profiled edge areas at the second pair of opposite edge areas are provided by the rotating milling tools of a second double-end tenoner, wherein the panels move at a second constant speed in a propagation direction in the plane of the panels, parallel to the second pair of opposite edge areas, wherein the panels are moved at said second constant speed by means of the conveyor system of said second double-end tenoner. The contours of the profiled edge areas at a second pair of opposite edges at at least two cross-sections, perpendicular to the second pair of opposite edges, are recorded by a first extra sensor and a second extra sensor, wherein the first extra sensor and the second extra sensor are stationary, wherein there is an offset of predefined length in the direction of the second pair of opposite edges between the first extra sensor and the second extra sensor. Preferably, the first extra sensor is oriented to record a part of the contour of the cross-section at a first of said profiled edge areas at the second pair of opposite edges, and the second extra sensor is oriented to record a part of the contour of a second of said profiled edge areas at the second pair of opposite edges. The first extra sensor and the second extra sensor record the passing of the leading edge of a panel or the passing of the trailing edge, in the direction of the second pair of opposite edge areas, of a panel, wherein there is a time delay between the recording of the passing of the leading edge or trailing edge with the first extra sensor and the passing of the leading edge or trailing edge with the second extra sensor, wherein the second constant speed is obtained based on said offset of predefined length in the direction of the second pair of opposite edges and said time delay between the recording of the passing of the leading edge or the trailing edge with the first extra sensor and the recording of the passing of the leading edge or the trailing edge with the second extra sensor. The first extra sensor further records the passing of the leading edge and the passing of the trailing edge of the panels, in the direction of the second pair of opposite edges, wherein there is a second time duration between the passing of the leading edge and the passing of the trailing edge of each panel, wherein the length, in the direction of the second pair of opposite edges, of each panel is obtained based on the second constant speed and said second time duration. Preferably, the number of panels passing the first extra sensor is counted. The panels preferably comprise profiled edge areas at the second pair of opposite edges that allow two of such panels to be coupled to each other with a downward movement, wherein the profiled edge areas at the second pair of opposite edges comprise locking parts that, in a coupled condition, prevent two panels from moving apart.

[0065] It is remarked that obtaining the length of a panel in the direction of a first pair of opposite edges by means of the time delay between sensor measurements, without the panel necessarily having profiled edge areas, also forms an inventive concept. Therefore, in accordance with a third independent aspect, the invention is a method for inspecting panels, wherein the panels comprise a first pair of opposite edges, wherein the panels move at a constant speed, preferably in a direction in the plane of the panels and parallel to the first pair of opposite edges, wherein the method comprises the step of recording at least a first location on the contour of a cross-section of the panel perpendicular to the first pair of opposite edges using a first further sensor, wherein the method comprises the step of recording the a second location on the contour of the same cross-section of the panel perpendicular to the first pair of opposite edges using a second further sensor, wherein said first location and said second location are preferably the same location, wherein the first further sensor and the second further sensor are stationary, wherein there is a mutual offset of predefined length between said first further sensor and said second further sensor, wherein there is a time delay between the recordings of the first further sensor and the second further sensor, wherein the constant speed of the panels is obtained based on the mutual offset of predefined length and the time delay between the recordings of the first further sensor and the second further sensor, wherein the first further sensor records the passing of the leading edge of each panel and the passing of the trailing edge of each panel, wherein there is a time duration between the recording of the passing of the leading edge of each panel and the passing of the trailing edge of each panel with the first further sensor, wherein the length of the panel in the direction of the first pair of opposite edges is obtained based on the constant speed and on said time duration between the recording of the passing of the leading edge of each panel and the passing of the trailing edge of each panel with the first further sensor. Preferred embodiments of the method of the first independent aspect can equally apply to the method of the third independent aspect, as long as this does not cause any contradictions.

[0066] It is noted that wherever is referred to “constant speed”, this is not meant to be limited to its literal meaning. Instead, this should be interpreted to allow for a deviation of ±10%, preferably ±5%, more preferably ±1%, most preferably less than ±0.5% around the average value of the speed. Preferably, the deviation is of maximum ±5 meter per minute.

[0067] While the invention is described in relation to panels, it is especially useful for the inspection of floor panels, wall panels, ceiling panels or furniture panels. Said floor panels can be any one of the following floor panel types: wood-based floor panels, LVT (Luxury Vinyl Tile), WPC (Wood Plastic Composite), SPC (Stone Plastic Composite), laminate floor panels, parquet floor panels. Preferably, said panels are decorative panels, wherein the panels comprise a substrate and a decorative layer above and / or below said substrate.

[0068] The substrate of the panels can be wood-based, such as fibrous (MDF or HDF) or such as particulate (chipboard or Oriented Strand Board), or polymer-based, such as substrates on the basis of polyvinyl chloride. The method of the first independent aspect of the invention is particularly beneficial for the inspection of panels with a fibrous or particulate substrate, since these substrates might have burrs in the shape of fibers, respectively of particles such as chips or oriented wood flakes that stick out from the profiled edge areas after the providing of the profiled edge areas, such that the method of the first independent aspect provides an improved inspection of panels with such substrates.

[0069] Preferably, the method of the first independent aspect comprises the step of enhancing the recording by means of mathematical operations, preferably by means of mathematical models such as artificial intelligence models, for example one or more neural networks. This has the benefit that, even in the case that the recording would not be of sufficiently high quality, the recording can be artificially enhanced, resulting in an improved inspection of the panels. Preferably, the method further comprises the step of recognizing the profile of the profiled edge areas. Preferably, this step of recognizing is performed by an artificial intelligence model. Usefully, if the profile can be recognized, the recording of the profiled edge area can be added to the training data for artificial intelligence models, further improving their performance.

[0070] In a further preferred embodiment, the data generated by the recording of the profiled edge area is used as training data for one or more artificial intelligence models. These models may include, for example, convolutional neural networks (CNNs) for analyzing spatial patterns in the recorded contour data, or gradient boosted decision trees (such as XGBoost or LightGBM) for structured feature-based classification of defects. The models may be trained to recognize patterns that correlate with known defects or deviations from the desired geometry. By coupling specific recordings to known defect types, and further linking these defects to known causes, such as tool wear, chipping, or misalignment of the means that provide the profiled edge areas (e.g., milling tools) the system can be used not only for defect detection but also for determining the underlying cause of said defects. In addition, autoencoders or isolation forests may be employed for unsupervised anomaly detection, identifying deviations from normal profile patterns even in the absence of labeled defect data. Based on this analysis, the system may suggest corrective actions to resolve the defect or even prevent it from occurring. For example, the artificial intelligence model may detect early signs of tool degradation or damage based on subtle changes in the recorded contour, allowing for preemptive maintenance or tool replacement before a defect manifests in the final product. Over time, the accumulation of labeled and unlabeled data enhances the predictive capabilities of the system, enabling continuous improvement of the profiling process and reducing the occurrence of defects. Furthermore, recurrent neural networks (RNNs) or temporal convolutional networks (TCNs) may be used to analyze time-series data from successive recordings, enabling the prediction of future defects such as tool failures based on historical trends.

[0071] With the intention of better showing the characteristics of the invention, some preferred embodiments are described below, as examples without any limiting character, with reference to the corresponding drawings, wherein:

[0072] Figure 1 in perspective view shows a step in a method for inspecting panels according to the invention;

[0073] Figures 2 and 3 show, on a larger scale, the cross-section according to lines II-II and III-III shown in Figure 1, respectively;

[0074] Figure 4 shows a schematic of the recording of the two sensors of Figure 1;

[0075] Figure 5 shows a schematic of a preferred embodiment of a method of the invention;

[0076] Figures 6 and 7 show alternative embodiments for the step of Figure 1;

[0077] Figure 8 shows an alternative embodiment of a step in a method of the invention; and

[0078] Figure 9 shows, on a larger scale, the cross section according to lines IX-IX shown in Figure 8.

[0079] Figure 10 shows an alternative embodiment of a step in a method of Figure 1; Figure 11 shows a step in a method of the third independent aspect of the invention.

[0080] Figure 1 shows a perspective view of the method for inspecting panels 1 in accordance with the first independent aspect of the invention. The inspected panel 1 is rectangular and oblong, and is on both pairs of opposite edges 2-3 -4-5 provided with profiled edge areas which are provided with coupling parts 6 allowing two of such panels 1 to be coupled to each other. A first part of the contour of a cross-section of the first profiled edge area, here the edge 2, is recorded by means of a first set of one or more sensors 15. In Figure 2, it is shown that a first sensor head 7 comprises a sensor 15A of the first set of one or more sensors 15, a sensor 16A of a second set of one or more sensors 16 and a sensor 17A of a third set of one or more sensors 17. There is a relative displacement between the panel 1 with respect to the first sensor head 7, wherein the panel 1 moves in a first direction DI in the plane of the panel 1, parallel to the first pair of opposite edges 2-3, while the first sensor head 7 and the sensors 15A-16A-17A are positioned stationary and the sensors 15A-16A-17A in the first sensor head 7 are recording the contour of a cross-section of the first profiled edge area 2. The relative displacement of the panel 1 is effected by means of a belt system 8, and the relative displacement of the panel 1 is at a constant velocity.

[0081] It is indicated in dashed lines that there can be a second sensor head 9 comprising sensors 15B-16B-17B, wherein the sensors 15B-16B-17B record the contour of a cross-section of the first profiled edge area 2. The second sensor head 9 preferably has a similar or identical configuration as the first sensor head 7. The sensors 15A-16A-17A comprised in the first sensor head 7 and the sensors 15B-16B-17B comprised in the second sensor head 9 record the contour of separate cross-sections of the first profiled edge area 2. A part of the contour of a cross-section of the second profiled edge area 3 of the first pair of opposite edges 2-3 is recorded by means of sensors 20A-21 A-22A that are comprised in an additional sensor head 10.

[0082] Figures 2 and 3 clearly show that the coupling parts 6 of the profiled edge areas 2-3 of the first pair of opposite edges 2-3 are substantially made as a tongue 11 and a groove 12, wherein the groove 12 is at least delimited by means of a top groove lip 13 and a bottom groove lip 14. Said tongue 11 and groove 12 are configured such that, in the coupled state, a locking can be obtained between the relevant edges in a direction perpendicular to the plane of the coupled panels 1. Said tongue 11 and groove 12 are fitted with locking parts which prevent the tongue 11 and groove 12 from moving apart, wherein, in the coupled state, a locking can be obtained between the relevant edges in a direction in the plane of the coupled panels 1 and perpendicular to the coupled edges. The first profiled edge area 2 of the first pair of opposite edges 2-3 comprises the aforementioned groove 12 and the second profiled edge area 3 of the first pair of opposite edges 2-3 comprises the aforementioned tongue 11.

[0083] Figure 2 shows an enlarged view of the cross-section according to line II-II of Figure 1, wherein the sensors 15A-16A-17A comprised in the first sensor head 7 record the contour of a cross-section of the first profiled edge area 2 of the first pair of opposite edges 2-3. The first set of one or more sensors 15 records a first part of the contour of a cross-section of the first profiled edge area 2, and the second set of one or more sensors 16 records a second part of the contour of a cross-section of the first profiled edge area 2. The first set of one or more sensors 15 records at a first recording angle Al and the second set of one or more sensors 16 records at a second recording angle A2, different than the first recording angle Al, wherein the first and second recording angles A1-A2 are perpendicular to the first direction DI in which the panel 1 is moving. In this scenario, there is also a sensor 17A of a third set of one or more sensors 17, wherein the third set of one or more sensors 17 records a third part of the contour of a cross-section of the first profiled edge area 2 of the first pair of opposite edges 2-3. In the depicted embodiment, all sensors 15A-16A-17A comprised in the first sensor head 7 are located in the same plane perpendicular to the first profiled edge area 2, such that all sensors 15A-16A-17A comprised in the first sensor head 7 record their respective parts on the contour of one and the same cross-section of the first profiled edge area 2. It is also possible, according to a not-represented alternative, that at least two of the sensors 15A-16A-17A comprised in the first sensor head 7 record a part of the contour of separate cross-sections. Preferably, these sensors 15A-16A-17A together record the entire contour of the crosssection of the first profiled edge area 2 of the first pair of opposite edges 2-3. The inspected profiled edge area 2 of the panel 1 is aligned and positioned in a fixed position in a direction perpendicular to the plane of the corresponding panel 1 with respect to the sensor 15A of the first set of one or more sensors 15 by means of a first pressure shoe 18A and a first slide shoe 19 A.

[0084] The first set of one or more sensors 15 is stationary, and records at a fixed recording frequency, wherein the fixed recording frequency is preferably set to 100 frames per panel 1 or more, preferably more than 1000 frames per panel 1. A good value for the fixed recording frequency is about 5000 frames per second. The second set of one or more sensors is stationary, and records at a second fixed recording frequency, preferably at the same fixed recording frequency as the fixed recording frequency of the first set of one or more sensors.

[0085] Figure 3 shows an enlarged view of the cross-section according to line III-III of Figure 1, wherein the sensors 20A-21 A-22A comprised in the additional sensor head 10 record the contour of a cross-section of the second profiled edge area 3 of the first pair of opposite edges 2-3, in this case the tongue 11. The additional sensor head 10 comprises three sensors 20A-21A-22A, of which sensor 20 A forms part of an additional set of sensors 20. The sensors 20A-21A-22A comprised in the additional sensor head 10 all record a part of the contour of one and the same cross-section of the second profiled edge area 3 of the first pair of opposite edges 2-3, wherein these sensors 20A-21A-22A together preferably record the entire contour of this cross-section of the second profiled edge area 3 of the first pair of opposite edges 2-3. The inspected profiled edge area 3 of the panel 1 is aligned and positioned in a fixed position in a direction perpendicular to the plane of the corresponding panel 1 with respect to the sensor 20A of the additional set of one or more sensors 20 by means of a second pressure shoe 18B and a second slide shoe 19B.

[0086] The first set of one of more sensors 15 and the additional set of one or more sensors 20 are configured such that at least one sensor of the first set of one or more sensors 15, in this case sensor 15 A, recording a part of the groove 12, is oriented upwardly and at least one sensor of the additional set of one or more sensors 20, in this case sensor 20A, recording a part of the tongue 11, is oriented downwardly, wherein downwardly and upwardly are defined relative to the plane of the panel 1.

[0087] Figure 4 shows a schematic view of the recordings 23-24 of a first sensor and a second sensor, wherein, in this case, the first sensor head 7 comprises the first sensor and the additional sensor head 10 comprises the second sensor. Preferably, the first sensor corresponds to a sensor of the first set of one or more sensors 15, however, the first sensor can in principle be any one of the sensors 15A-16A-17A in the first sensor head 7, for example the sensor 16A of the second set of one or more sensors 16 comprised in the first sensor head 7. There is a distance of predefined length AX, in the direction of the first pair of opposite edges 2-3, between the first sensor and the second sensor. Both the first sensor and the second sensor record at least the passing of the leading edge 4 or at least the passing of the trailing edge 5 of each panel 1. The graphical representation of Figure 4 depicts the evolution of a recorded signal S in function of the time t, wherein the recordings 23-24 of the first sensor and the second sensor start at the same reference time tO. The recorded signals 23-24 can, for example, be the resulting value of a crosscorrelation calculation between the recording of the first sensor or second sensor and the expected recording, wherein the expected recording can be based on the expected contour of the recorded cross-section. Before the leading edge 4 is recorded by the first sensor, the first sensor does not detect a panel 1 and therefore provides a minimum recorded signal. Upon arrival of the leading edge 4, the first sensor starts detecting the panel, leading to an increase in the recorded signal 23, until reaching a substantially constant maximum value. Similarly, when the trailing edge 5 passes the first sensor, the recorded signal 23 reduces from said substantially constant maximum value down to a minimum recorded signal. This applies similarly to the recording 24 of the second sensor. As a result of the offset of predefined length AX between the first and second sensors, there is a time delay At between the recorded signal 23 of the first sensor and the recorded signal 24 of the second sensor. The longer the offset of predefined length AX, the larger the time delay At, and vice versa. Possibly, there is also an offset in the values, such as the maximum value, of the recorded signals 23-24 between the first sensor and the second sensor. The time delay At can be obtained in many ways known to a person skilled in the art of signal processing, such as for example a comparison of the time instance at which the recorded signals of the first sensor and the second sensor reach a value equal, or at least substantially equal, to half their maximum value. Other possibilities, such as techniques based on the cross-correlation between the recorded signals 23-24 of the first sensor and the second sensor, are equally applicable. Based on the obtained time delay At and the offset of predefined length AX, the constant speed of the relative displacement can be determined, or at least can be estimated.

[0088] It is noted that, as described in greater detail in the third possibility in the introduction, multiple configurations for the first sensor and second sensor are feasibly for obtaining the constant speed.

[0089] The time duration TD between the passing of the leading edge 4 and the passing of the trailing edge 5 is obtained from the recording 23 of the first sensor or from the recording 24 of the second sensor. The length LI of the panel 1, in the direction of the first pair of opposite edges 2-3, is subsequently obtained based on said time duration At and said constant speed.

[0090] Figure 5 shows a very preferred embodiment of the method of the first independent aspect of the invention. A panel 1 is provided with profiled edge areas on a first pair of opposite edges 2-3, wherein said profiled edge areas comprise coupling parts 6 allowing two of such panels 1 to be coupled to each other. In the case of a decorative panel, the panel 1 is positioned such that its decorative side is at the bottom side of the panel. The profiled edge areas on the first pair of opposite edges 2-3 are provided with the milling tools 25 of a first double-end tenoner 26. The panel 1 moves in the first direction DI at a first constant speed, wherein it is the conveyor system of said first double-end tenoner 26 that moves the panel 1. Directly after providing the panel 1 with profiled edge areas on the first pair of opposite edges 2-3, the first profiled edge area 2 is inspected with a first sensor 27A, wherein the first sensor 27A is a sensor comprised in the first sensor head 27, and the second profiled edge area 3 is inspected with a second sensor 28A, wherein the second sensor 28A is a sensor comprised in the additional sensor head 28. The first sensor 27A and second sensor 28A are stationary, and are built into the first double-end tenoner 26. The first double-end tenoner 26 comprises pressure shoes and slide shoes, not shown, that align and position the first profiled edge area 2 on the first pair of opposite edges 2-3 in a fixed position in a direction perpendicular to the plane of the panel 1 with respect to the first sensor 27A, as well as the second profiled edge area 3 on the first pair of opposite edges 2-3 in a fixed position in a direction perpendicular to the plane of the panel 1 with respect to the second sensor 28A. There is a first offset of predefined length AX1 between the first sensor head 27and the second sensor head 28. Based on the time delay between the recordings of the first sensor 27A and the second sensor 28A and on the first offset of predefined length AX1, the first constant speed is obtained. Based on the first constant speed and the time duration between the passing of the leading edge 4 and the passing of the trailing edge 5 of the panel 1 in the direction of the first pair of opposite edges 2-3, the length LI of the panel 1 in the direction of the first pair of opposite edges 2-3 is obtained. The amount of panels 1 passing the first sensor 27A is also counted.

[0091] Next, the panel 1 is provided with profiled edge areas on the second pair of opposite edges 4-5, wherein said profiled edge areas comprise coupling parts 6 allowing two of such panels 1 to be coupled to each other. The profiled edge areas on the second pair of opposite edges 4-5 are provided with the milling tools 29 of a second double-end tenoner 30. The panel 1 moves in a second direction D2 in the plane of the panel 1 and parallel to the second pair of opposite edges 4-5 at a second constant speed, wherein it is the conveyor system 31 of said second double-end tenoner 30 that moves the panel 1. Directly after providing the panel 1 with profiled edge areas on the second pair of opposite edges 4-5, the first profiled edge area 5 on the second pair of opposite edges 4- 5 is inspected with a first extra sensor 32 A, wherein the first extra sensor 32 A is a sensor comprised in a first extra sensor head 32, and the second profiled edge area 4 on the second pair of opposite edges 4-5 is inspected with a second extra sensor 33A, wherein the second extra sensor 33A is a sensor comprised in a second extra sensor head 33. The first extra sensor 32A and second extra sensor 33A are stationary, and are built into the second double-end tenoner 30. The second double-end tenoner 30 comprises pressure shoes and slide shoes, not shown, that align and position the first profiled edge area 5 on the second pair of opposite edges 4-5 in a fixed position in a direction perpendicular to the plane of the panel 1 with respect to the first extra sensor 32A, as well as the second profiled edge area 4 on the second pair of opposite edges 4-5 in a fixed position in a direction perpendicular to the plane of the panel 1 with respect to the second extra sensor 33A. There is a second offset of predefined length AX2 between the first extra sensor 32A and the second extra sensor 33A. Based on the time delay between the recordings of the first extra sensor 32A and the second extra sensor 33A and on the second offset of predefined length AX2, the second constant speed is obtained. Based on the second constant speed and the time duration between the passing of the leading edge 2 and the passing of the trailing edge 3 of the panel 1 in the direction of the second pair of opposite edges 4-5, the length L2 of the panel 1 in the direction of the second pair of opposite edges 4-5 is obtained. The amount of panels 1 passing the first extra sensor 32A is also counted.

[0092] The surface area of the panel 1 is then obtained based on the length LI of the panel 1 in the direction of the first pair of opposite edges 2-3 and the length L2 of the panel 1 in the direction of the second pair of opposite edges 4-5.

[0093] The entire system is preferably connected to a data storage installation 100, such as a laptop, which can store one or more of the following: the recordings of at least the first sensor 27A, the second sensor 28A, the first extra sensor 32A and the second extra sensor 33A, the first constant speed, the second constant speed, the length LI of a panel 1, the length L2 of a panel, or the surface area of a panel 1. Further, the data storage installation 100 preferably can also perform the calculations and measurements to obtain at least one of the first constant speed, the second constant speed, the length LI of a panel 1, the length L2 of a panel, and the surface area of a panel 1.

[0094] Figure 6 shows an alternative embodiment of the method for inspecting panels 1 of the first independent aspect of the invention, which differs from the embodiment in Figure 1 in that the constant speed of the relative displacement is obtained by means of a further set of two or more sensors 34. This embodiment is an example of the fourth implementation of the third possibility to obtain the constant speed of the relative displacement described in the context of the first independent aspect wherein the first sensor and the second sensor are two pressure sensors 34A-34B. The length LI of the panel 1 in the direction of the first pair of opposite edges 2-3 is obtained based on the constant speed and the time duration between the passing of the leading edge 4 and the passing of the trailing edge 5, which is recorded by either one of the two pressure sensors 34A-34B.

[0095] Figure 7 shows an alternative embodiment of the method for inspecting panels 1 of the first independent aspect of the invention, which differs from the embodiment in Figure 1 in that the presence of two markings 35A-35B are employed for obtaining the speed of the relative displacement of the panel 1 and the length LI of said panel. In the shown embodiment, the markings 35A-35B are two notches in the upwardly directed surface 36. The two notches 35A-35B are positioned at a predefined distance 37 from each other in the direction of the first pair of opposite edges 2-3, for example at 100 cm. The first notch 35 A is positioned at a portion 38 of the length LI of the panel 1, in this example one quarter the length LI of the panel 1, in the direction of the first pair of opposite edges 2-3, from the leading edge 4 of the panel 1. Based on the predefined distance 37 between the two notches 35A-35B and the time delay between the recording of the first notch 35 A and the second notch35B , the constant speed of the relative displacement of the panel 1 can be obtained. Based on the constant speed, the time duration between the recording of the passing of the leading edge 4 and the recording of the passing of the first notch 35 A, and the portion 38 of the length LI of the panel, the length LI of the panel 1 in the direction of the first pair of opposite edges 2-3 can be obtained.

[0096] Figure 8 shows an alternative embodiment of the method of the first independent aspect of the present invention, wherein a stack of panels 39 with profiled edge areas at at least a first pair of opposite edges 2-3 is inspected by means of a cluster of sensors 40, wherein the cluster of sensors 40 records one of said profiled edge areas of each of the panels 1 in the stack of panels 39. In this embodiment, all panels 1 in the stack of panels 39 are oriented in the same direction, such that their profiled edge areas 2-3 are all parallel and that the inspected profiled edge areas 2 all comprise substantially the same contour. Of course, it is also possible that at least one of the panels 1 of the stack of panels 39 has a different contour at the inspected profiled edge area 2 from the other panels 1 in the stack of panels 39. It is possible that the cluster of sensors 40 moves, preferably in the direction in the plane of one of the panels 1 in said stack of panels 39 and parallel to the profiled edge areas 2-3 of the plane of one of the panels 1 in said stack of panels 39. Additionally, or alternatively, it can be the entire stack of panels 39 that is moved, such as by means of two belts 41. While here only one cluster of sensors 40 is depicted, it is of course possible and even preferential to also inspect the second profiled edge areas 3 at the first pair of opposite edges 2-3, preferably by means of a second cluster of sensors. Furthermore, here the stack of panels 39 consists of five panels 1, however, it can of course that the stack of panels 39 comprises more than five panels 1 or less than five panels 1, for example a stack of ten panels 1. It is noted that this embodiment can be useful to perform a final check of the profiled edge areas before packaging the stack of panels 39 for selling, for example in order to make sure that the provided profiles correspond to the desired ones.

[0097] Figure 9 shows the cross-section along the lines IX-IX of the embodiment shown in Figure 8, wherein the cluster of sensors 40 are positioned such that at least two sensors comprised in the cluster of sensors 40 record a part of the contour of the cross-section of each panel 1 of the stack of panels 39.

[0098] Figure 10 shows an alternative embodiment of the method for inspecting panels 1 of the first independent aspect of the invention, which differs from the embodiment in Figure 1 in that the speed of the relative displacement of the panel 1 is determined by means of one and the same sensor 42, here depicted as a pressure-wheel sensor which can move along a vertical axis V. The pressure-wheel sensor 42 comprises a wheel 43, wherein the wheel 43 can rotate around its rotation axis, wherein the wheel 43 comprises means for reading out the constant speed. The wheel 43 is connected to a suspension system 44 which allows for a movement along the vertical axis V, wherein the suspension system 44 comprises a spring that presses the wheel 43 down. The pressure-wheel sensor 42 is positioned above the conveyor system 8 in such a manner that the wheel 43 contacts the conveyor system 8, and thus at any given moment provides the speed, in fact even the instantaneous speed. Alternatively, the pressure wheel 43 does not contact the conveyor system 8, but is position such that, upon passing of a panel 1, the wheel 43 makes contact with the panel 1 and starts rotating at the speed of the relative displacement of the panel 1, thus providing the speed, in fact even the instantaneous speed, only at times when the panel 1 passes by the pressure-wheel sensor 42. The passing of the leading edge 4 of a panel 1 by the pressure-wheel sensor 42 causes the pressure-wheel sensor 42 to change its vertical position, more particularly to a higher position, which can detected by the pressure-wheel sensor 42. Similarly, the passing of the trailing edge 5 of a panel 1 by the pressure-wheel sensor 42 causes the pressure-wheel sensor 42 to change its vertical position, more particularly to a lower position, which can be detected by the pressurewheel sensor 42. The length LI of the panel 1 can then be obtained based on the speed, preferably the instantaneous speed, and the time duration between the passing of the leading edge 4 and the trailing edge 5 of a panel. In the case of a non-constant speed, the average value of the speed during said time duration may be used. It is noted that the speed in this embodiment is not necessarily a constant speed, however, this is preferred.

[0099] Figure 11 shows a preferred embodiment of the method for inspecting panels of the third independent aspect of the invention, which differs from the embodiment in Figure 6 in that the panel 1 does not have profiled edge areas and there are thus no sensors recording profiled edge areas. According to this embodiment, the length LI of the panel 1 in the direction of the first pair of opposite edges 2-3 is obtained by means of only the two pressure sensors 45A-45B, as explained in more detail in the detailed description of Figure 6.

Claims

Claims1.- Method for inspecting panels (1), wherein said panels (1), at least at one pair of opposite edges (2-3 -4-5), are provided with profiled edge areas which are provided with coupling parts (6) allowing two of such panels (1) to be coupled to each other, wherein the method comprises the step of recording at least a first part of the contour of a crosssection of a first of said profiled edge areas, wherein the first part is recorded by means of a first set of one or more sensors (15), characterized in that the method comprises the step of performing a relative displacement of the panels (1) with respect to the first set of one or more sensors (15) during said step of recording.2.- Method according to claim 1, characterized in that the method comprises the step of providing the profiled edge areas, preferably by means of a milling operation, prior to the step of recording.3.- Method according to any one of the preceding claims, characterized in that the relative displacement is in a first direction (DI) in the plane of the panels, preferably parallel to said one pair of opposite edges (2-3).4.- Method according to any one of the preceding claims, characterized in that the first set of one or more sensors (15) is stationary and the panels (1) move relative to the first set of one or more sensors (15).5.- Method according to any one of the preceding claims, characterized in that the relative displacement is effected by means of a conveyor system (8), such as a belt or a chain.6.- Method according to claim 5, characterized in that the relative displacement is effected by means of the conveyor system (8) of a double-end tenoner (26).7.- Method according to any one of the preceding claims, characterized in that the method further comprises the step of aligning and / or positioning the to be inspected profiled edgearea in a fixed position in a direction perpendicular to the plane of the corresponding panel with respect to the first set of one or more sensors (15).8.- Method according to claim 7, characterized in that said step of aligning and / or positioning is performed at least by a pressure shoe (18A) and / or a slide shoe (19A).9.- Method according to claims 6 and 8, characterized in that said double-end tenoner (26) comprises said pressure shoe (18A) and / or slide shoe (19A).10.- Method according to any one of the preceding claims, characterized in that the recording is performed at a fixed recording frequency, wherein each sensor of the first set of one or more sensors (15) preferably has the same recording frequency.

11. - Method according to any one of the claims 1 to 9, characterized in that the recording is performed at an adaptive frequency, preferably wherein the adaptive frequency is adapted based on the proximity of one of the extremities of the panel (1), in the direction of the relative displacement, and the first set of one or more sensors (15).12.- Method according to any one of the preceding claims, characterized in that the relative displacement is at a constant speed.13.- Method according to claim 12, characterized in that the method further comprises the step of obtaining said constant speed of the relative displacement.14.- Method according to claim 13, characterized in that the relative displacement is in a first direction (DI) in the plane of the panels (1), parallel to said first pair of opposite edges (2-3), wherein the first set of one or more sensors (15) is stationary and the panels (1) move relative to the first set of one or more sensors (15), wherein each panel (1) has a leading (4) edge and a trailing edge (5), wherein at least a first sensor and a second sensor record at least the passing of said leading edge (4) and / or at least the passing of said trailing edge (5), wherein there is a time delay (At) between said recording at least the passing of said leading edge (4) and / or at least the passing of said trailing edge (5).15.- Method according to claim 14, characterized in that, in the longitudinal direction of the first profiled edge (2), there is an offset of predefined length (AX) between said first sensor and said second sensor.16.- Method according to claim 15, characterized in that the constant speed of the relative displacement is determined based on at least said offset of predefined length (AX) and said time delay(At).17.- Method according to claim 16, characterized in that the first set of one or more sensors (15) comprises at least said first sensor and said second sensor.18.- Method according to claim 16, characterized in that the method further comprises the step of recording a second part of the contour of the cross-section of the first profiled edge area (2) by a second set of one or more sensors (16), wherein said first set of one or more sensors (15) comprises said first sensor and wherein said second set of one or more sensors (16) comprises said second sensor.19.- Method according to claim 16, characterized in that the method further comprises the step of recording at least a part of the contour of a cross-section of a second of said profiled edge areas (3) using an additional set of one or more sensors (20), wherein said first set of one or more sensors (15) comprises said first sensor and wherein said additional set of one or more sensors (20) comprises said second sensor.20.- Method according to any one of claims 13 to 19, characterized in that the method comprises the further step of recording the passing of said leading edge (4) and the passing of said trailing edge (5) of a panel (1) with at least one panel-detecting sensor, wherein the method further comprises the step of determining the time duration (TD) between the passing of said leading edge (4) and the passing of said trailing edge (5).21.- Method according to claim 20, characterized in that said panel-detecting sensor recording the passing of said leading edge (4) and the passing of said trailing edge (5) ofa panel (1) corresponds to a sensor of the first set of one or more sensors (15) or if present, of the second set of one or more sensors (15), or if present, of the additional set of one or more sensors (20).22.- Method according to any one of claims 20 or 21, characterized in that the length (LI) of a panel (1) in the longitudinal direction of the first profiled edge area (2) is obtained based on at least said constant speed and said time duration (TD).23.- Method according to any one of the preceding claims, characterized in that the method comprises the further step of recording a second part of the contour of the crosssection of the first profiled edge area (2) by a second set of one or more sensors (16), wherein the first part is at least recorded from a first recording angle (Al), and wherein the second part is at least recorded from a second recording angle (A2) different from the first recording angle (Al), but each time, from one or more recording directions transverse to the longitudinal direction of the corresponding edge.24.- Method according to claim 23, characterized in that said first recording angle (Al) and said second recording angle (A2) are at right angles to the longitudinal direction of the edge concerned.25.- Method according to any one of the preceding claims, characterized in that said coupling parts (6) are substantially made as a tongue (11) and a groove (12), wherein the groove (12) is at least delimited by means of a top groove lip (13) and a bottom groove lip (14).26.- Method according to claim 25, characterized in that said tongue (11) and groove (12) are configured such that, in the coupled state, a locking can be obtained between the relevant edges in a direction perpendicular to the plane of the coupled panels (1).27.- Method according to claim 26, characterized in that said tongue (11) and groove (12) are fitted with locking parts which prevent the tongue (11) and groove (12) from moving apart, wherein, in the coupled state, a locking can be obtained between therelevant edges in a direction in the plane of the coupled panels (1) and perpendicular to the coupled edges.28.- Method according to any one of the preceding claims, characterized in that the method further includes the step of recording at least a part of the contour of a crosssection of a second of said profiled edge areas (3) using an additional set of one or more sensors (20), wherein the first set of one of more sensors (15) and the additional set of one or more sensors (20) are configured such that at least one sensor of the first set of one or more sensors (15) is oriented downwardly and at least one sensor of the additional set of one or more sensors (20) is oriented upwardly, or alternatively, at least one sensor of the first set of one or more sensors (15) is oriented upwardly and at least one sensor of the additional set of one or more sensors (20) is oriented downwardly, wherein downwardly and upwardly are defined relative to the plane of the panel (1).29.- Method according to any one of the preceding claims, characterized in that said panel (1), at least at a second pair of opposite edges (4-5), is provided with profiled edge areas which are provided with coupling parts (6) allowing two of these panels (1) to be coupled together, and wherein the method also comprises the step of recording a part of one or both profiled edge areas of the second pair of opposite edges (4-5).30.- Method according to claim 29, characterized in that the method comprises the step of providing the profiled edge areas on the second pair of opposite edges (4-5), preferably by means of a milling operation, prior to the step of recording a part of one or both profiled edge areas of the second pair of opposite edges (4-5).

31. - Method according to claim 30, characterized in that the step of providing the profiled edge areas on the second pair of opposite edges (4-5) takes place after the step of recording a first part of the first pair of opposite edges (2-3).32.- Method according to any one of claims 29 to 31, characterized in that the length (L2) of the panel in the direction of the second pair of opposite edges (4-5) is obtained.33.- Method according to any one of the preceding claims, characterized in that the method further comprises the step of saving a set of measurements and / or metrics of each panel in a data storage installation (100).34.- Device for use in a method in accordance with any one of the preceding claims, characterized in that the device comprises at least said first set of one or more sensors (15), wherein the device is fitted with means for providing the relative displacement of the panels (1) with respect to the first set of one or more sensors (15).35.- Device in accordance with claim 34, characterized in that said means for providing the relative displacement is a conveyor system (8), such as a belt or a chain.36.- Device in accordance with claim 35, characterized in that said means for providing the relative displacement is the conveyor system (8) of a double-end tenoner (26).37.- Device in accordance with any one of claims 34 to 36, characterized in that the device is fitted with means for aligning and / or positioning a panel (1) with respect to said first set of one or more sensors (15).38.- Device in accordance with any one of claims 34 to 37, characterized in that the first set of one or more sensors (15) are positioned stationary.39.- Device in accordance with any one of claims 34 to 38, characterized in that the device is fitted with a second set of one or more sensors (16) that record at least a second part of the contour of the cross-section of the first of said profiled edge areas, wherein said second set of one or more sensors (16) is preferably located downstream of said first set of one or more sensors (15).40.- Device in accordance with any one of claims 34 to 39, characterized in that the device is fitted with an additional set of one or more sensors (20) that record at least a part of the contour of the cross-section of a second of said profiled edge areas.41.- Device in accordance with any one of claims 34 to 40, characterized in that the device is fitted with means for providing a panel (1) with profiled edge areas on a first pair of opposite edges (2-3).42.- Device in accordance with claim 41, characterized in that the means for providing a panel (1) with profiled edge areas on a first pair of opposite edges (2-3) is located upstream from said first set of one or more sensors (15), and if present also upstream of said second set of one or more sensors (16), and if present also upstream of said additional set of one or more sensors (20).43.- Device in accordance with any one of claims 34 to 42, characterized in that the sensors of the first set of sensors (15) are positioned stationary, wherein the relative movement is along a propagation direction, wherein the first set of one or more sensors (15) comprises at least a first sensor and a second sensor, wherein the first sensor and the second sensor are positioned at an offset of predefined length (AX) in the propagation direction.44.- Device in accordance with any one of claims 39 to 42, characterized in that the sensors of the first set of sensors (15) are positioned stationary, wherein the relative movement is along a propagation direction, wherein the first set of one or more sensors (15) comprises a first sensor and wherein the second set of one or more sensors (16) comprises a second sensor, wherein the first sensor and the second sensor are positioned at an offset of predefined length (AX) in the propagation direction.45.- Device in accordance with any one of claims 40 to 42, characterized in that the sensors of the first set of one or more sensors (15) are positioned stationary, wherein the relative movement is along a propagation direction, wherein the first set of one or more sensors (15) comprises a first sensor and wherein the additional set of one or more sensors (20) comprises a second sensor, wherein the first sensor and the second sensor are positioned at an offset of predefined length (AX) in the propagation direction.46.- Device in accordance with any one of claims 41 to 45, characterized in that the device is fitted with means for providing a panel (1) with profiled edge areas on a second pair of opposite edges (4-5).47.- Device in accordance with claim 46, characterized in that the means for providing a panel (1) with profiled edge areas on a second pair of opposite edges (4-5) is located downstream from said first set of one or more sensors (15), and if present also downstream of said second set of one or more sensors (16), and if present also downstream of said additional set of one or more sensors (20).48.- Device in accordance with any one of claims 46 to 47, characterized in that the device is fitted with at least an extra set of one or more sensors for recording a part of the profiled edge areas of the second pair of opposite edges (4-5).49.- Device in accordance with claim 48, characterized in that said extra set of one or more sensors are located downstream of the means for providing a panel with profiled edge areas on a second pair of opposite edges (4-5).50.- Device in accordance with any one of claims 34 to 49, characterized in that the device is fitted with a processing installation and / or a data storage installation (100).51.- Method for inspecting panels (1), wherein the panels (1) comprise a first pair of opposite edges (2-3), wherein the panels (1) move at a constant speed, preferably in a direction in the plane of the panels (1) and parallel to the first pair of opposite edges (2- 3), wherein the method comprises the step of recording at least a first location on the contour of a cross-section of the panel (1) perpendicular to the first pair of opposite edges (2-3) using a first further sensor, wherein the method comprises the step of recording the a second location on the contour of the same cross-section of the panel (1) perpendicular to the first pair of opposite edges (2-3) using a second further sensor, wherein said first location and said second location are preferably the same location, wherein the first further sensor and the second further sensor are stationary, wherein there is a mutual offset of predefined length (AX) between said first further sensor and said second further sensor, wherein there is a time delay (At) between the recordings of the first further sensor and the second further sensor, wherein the constant speed of the panels (1) is obtained based on the mutual offset of predefined length (AX) and the time delay (At) between the recordings of the first further sensor and the second further sensor, wherein the first further sensor records the passing of the leading edge (4) of each panel (1) and the passing of the trailing edge (5) of each panel (1), wherein there is a time duration (TD) between the recording of the passing of the leading edge (4) of each panel and the passing of the trailing edge (5) of each panel (1) with the first further sensor, wherein the length (LI) of the panel (1) in the direction of the first pair of opposite edges (2-3) is obtained based on the constant speed and on said time duration (TD) between the recording of the passing of the leading edge (4) of each panel (1) and the passing of the trailing edge (5) of each panel (1) with the first further sensor.

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