A leak-proof and break-resistant panel with a locking element and a method for manufacturing such a panel

Description

[0001] The invention relates to a panel with high breaking strength and high resistance to liquid penetration to an underside of the panel, which can cover a surface of a room by means of panels interlocked together via a locking element, in particular to improve the optical appearance of the room and / or to cover the surface of the room with a material layer better suited to the intended function, and to a method by which such a panel can be manufactured.

[0002] From WO 2007 / 079845 A1 it is known to provide a retaining groove on a short side of a panel over the entire transverse extent of the panel, into which a locking element designed as a snap clip can be inserted in a movement-proof manner.

[0003] From WO 2010 / 087752 A1 it is known to saw a semicircular groove into a partial area on a short side of a panel, in which a projection of a locking element otherwise provided outside the groove can be moved in a transverse direction, wherein the projection can slide off the rounded edges of the semicircular groove and thereby press the locking element with a movement component in the longitudinal direction into an opposite groove of another panel.

[0004] There is a constant need to improve the breaking strength and the resistance to liquid penetration from panels.

[0005] EP 2 946 047 B1 discloses a floor panel for forming a floor covering, wherein the floor panel has coupling parts on at least one pair of opposite edges, which make it possible for two such floor panels to be connected by a downward movement of one floor panel relative to the other floor panel, wherein these connecting parts enable locking in a first direction perpendicular to the plane of the floor panels and in a second direction perpendicular to the respective edge and in the plane of the floor panels, wherein at least one of the edges has a longitudinal recess below the upper surface with a locking element, characterized in that the shape and / or the position of the recess and / or the configuration of the connecting parts is such that deformations are avoided.

[0006] EP 2 2346 694 A1 discloses a fastening system for joining two plates together, comprising a first plate with a first edge having an undercut that receives a fastening element, and a second plate with a second edge having a locking area. The first and second edges are adjacent when the plates are fastened together using the fastening system. The fastening element comprises a movable activation section and a locking section that is movable relative to the first plate by rotation about a pivot axis when the activation section is displaced, such that the locking section engages in the locking area of ​​the second plate when the plates are fastened together using the fastening system. The pivot axis is spaced from a wall of the undercut.

[0007] US 7,131,473 B1 discloses a copy cutter that can be easily modified to cut profiles with tenons of varying lengths. The cutter comprises an axially extending main drive shaft and a first cutting element attached to the main drive shaft. An axially extending secondary drive shaft, with an upper and a lower portion, is detachably mounted on the primary drive shaft for rotation with it, and a second cutting element is mounted on the secondary drive shaft at a distance from the first cutting element when the secondary drive shaft is mounted on the primary drive shaft.

[0008] The purpose of the invention is to demonstrate measures that enable a break-resistant and wear-resistant panel.

[0009] The problem is solved by a panel having the features of claim 1 and a method having the features of claim 10. Preferred embodiments of the invention are specified in the dependent claims and the following description.

[0010] One embodiment of the invention relates to a panel for covering a surface of a room, comprising a panel body extending in a longitudinal and a transverse direction for transferring service loads introduced at a top surface of the panel body to a bottom surface of the panel body facing the surface of the room, wherein the top surface is spaced apart from the bottom surface in a thickness direction, and a retaining groove extending transversely in a short end face of the panel body and a locking element inserted in the retaining groove, in particular in a substantially movement-resistant manner, wherein for a transverse extension b 0 of the retaining groove with respect to a nominal width B of the panel body between a longitudinally extending first edge and a longitudinally extending second edge of the panel body, 0.50 ≤ b 0 / B ≤ 0.97, in particular 0.75 ≤ b 0 / B ≤ 0.95, preferably 0.85 ≤ b 0 / B ≤ 0.93 and particularly preferably b 0 / B = 0.90 ± 0,02 applies, wherein a first reinforcement area (24) with a transverse extension t1 is formed between a first end of the retaining groove (20) pointing towards the first edge in the transverse direction (32), and wherein a second reinforcement area (26) with a transverse extension t2 is formed between a second end of the retaining groove (20) pointing towards the second edge in the transverse direction (32), and wherein for the first reinforcement area (24) 0.005 ≤ t1 / B ≤ 0.090, in particular 0.015 ≤ t1 / B ≤ 0.050, preferably 0.020 ≤ t1 / B ≤ 0.030 and particularly preferably t1 / B = 0.025 ± 0.002 and / or for the second amplification range (26) 0.005 ≤ t 2 / B ≤ 0.090, in particular 0.015 ≤ t 2 / B ≤ 0.050, preferably 0.020 ≤ t 2 / B ≤ 0.030 and particularly preferably t 2 / B = 0.025 ± 0.002, provided that t 1 + b 0 + t 2 = B holds,wherein for a transverse extension b 1 of the locking element (22) with respect to the nominal width B of the panel body (28) 0.40 ≤ b 1 / B ≤ 0.95, in particular 0.50 ≤ b 1 / B ≤ 0.90, preferably 0.60 ≤ b 1 / B ≤ 0.80 and particularly preferably b 1 / B = 0.70 ± 0.05 applies.

[0011] The panel can have a panel body based on a cuboid as its basic shape, whose longitudinal extent is generally significantly greater than its transverse extent, while the thickness of the panel body is generally less than its transverse extent. The panel body can have a tongue-and-groove joint on one long side, extending continuously along the length and projecting transversely, and a tongue-and-groove joint on the other side, allowing essentially identical panels to be joined together along their long sides via a tongue-and-groove connection.In particular, a locking hook can project longitudinally from the transverse short side of the panel body, while a spring element can project from the other short side of the panel body, defining a receiving groove, so that substantially identical panels can also be interlocked at their short sides via a tongue-and-groove connection. In addition to or as an alternative to the tongue-and-groove connection formed by the locking hook and the receiving groove of the spring element, the locking element can be inserted, in particular in a movement-resistant manner, into the retaining groove provided on the short side of one panel, and can engage in a detent groove provided on a short side of another panel, in particular one of substantially identical design, facing the locking element.For this purpose, the locking element, designed in particular as a snap-in clip, can have a locking tab with a locking lug that can be elastically pushed aside as the panels move past it during assembly. In the designated final position of the panels to be interlocked, this locking element snaps elastically, at least partially, particularly with the locking lug, into the locking groove, thus securing the interlocked panels against unintentional release. During assembly, one panel can lie flat on a surface defining a working plane, such as a floor, a side wall, or the ceiling of a room. The other panel can optionally be positioned, for example, at an angle of approximately...The panel is positioned at a slight angle of 30° with a pre-mounted panel running alongside it on the long side and then pivoted onto the substrate, thereby creating at least one locking mechanism between the panels facing each other on their short sides. During locking, the locking hook engages in the receiving groove of the next panel, and the locking element inserted in the retaining groove engages in the locking groove of the next panel, essentially simultaneously. The transverse extent of the locking groove corresponds in particular to the transverse extent of the retaining groove. In particular, for an extension c 0 of the locking groove in the transverse direction with respect to the nominal width B of the panel body, 0.50 ≤ c 0 / B ≤ 0.97 applies, more particularly 0.75 ≤ c 0 / B ≤ 0.95, preferably 0.85 ≤ c 0 / B ≤ 0.93 and most preferably c 0 / B = 0.90 ± 0.02 applies.Preferably, the locking groove is identical in design to the retaining groove and / or manufactured using the same manufacturing process, thereby simplifying the simultaneous and / or identical production of the locking groove and the retaining groove. The retaining groove, which receives the pre-assembled locking element, can be provided on one short side of the panel, while the locking groove is provided on the other short side of the panel.

[0012] Since the retaining groove and / or locking groove is not provided across the entire transverse dimension of the panel body, but only in a partial area, it is possible to avoid weakening the panel body at the corners in the transition area between the short and long sides. This design utilizes the understanding that with a continuous transverse retaining groove, both the retaining groove and a tongue and groove can terminate at a corner of the panel body, resulting in a significant loss of material in the transition area between the short and long sides and potentially compromising the panel's strength. Furthermore, this design avoids openings at the longitudinal edges of the panel through which water could seep downwards. Instead, the bottom of the tongue and groove is closed even on the short side, thus providing an effective barrier against water penetration.Since the retaining groove running transversely along the short side can end at a distance from the tongue-and-groove running longitudinally along the long side, sufficient material of the panel body remains between the retaining groove and the tongue-and-groove to prevent a significant reduction in the panel body's strength in the transition area between the short and long sides compared to the strength of the remaining tongue-and-groove and / or the retaining groove. This at least reduces the risk of damage to the panel in the corners under heavy, especially localized, stress, for example, when an office chair is rolled over a corner or a table leg rests against it.If the locking element is fixed in the retaining groove and not movable, an air gap between the locking element and at least part of the surfaces of the retaining groove facing the locking element can be minimized, and in particular eliminated by an interference fit. This prevents the material bounding the retaining groove from breaking off. Instead, the locking element can fill a large portion of the volume of the retaining groove, in particular over 50%, preferably over 75%, more preferably over 85%, and most preferably over 95%, thereby transferring loads acting on the material of the panel body bounding the retaining groove via the locking element. This improves the tensile strength of the panel, especially in the corner areas.

[0013] Simultaneously, hydraulic communication between the retaining groove and the tongue groove can be avoided or at least reduced. This prevents a larger collection volume at a T-joint of three panels, where otherwise two tongue grooves and one retaining groove would open, compared to the flow cross-section along the retaining groove in the transverse direction and / or along the tongue groove in the longitudinal direction. A drop in capillary forces acting on any liquids that have penetrated the T-joint can be avoided, allowing the liquid to evaporate more easily at a later time and / or escape from a joint between the panels.This reduces or even prevents the accumulation of liquid in the collection volume, from which it can reach the underside of the panel body, particularly due to increasing hydrostatic pressure over time caused by incoming liquid. This, in turn, can lead to mold growth. The risk of liquid seeping through the joints between the panels to the underside is thus reduced, thereby improving the panel's resistance to liquid penetration.

[0014] The permeability of the panel can be measured by filling a container, open at both ends, with a predefined volume of liquid, particularly water, so that the liquid reaches a defined level in the container and consequently a defined hydrostatic pressure. The container is placed centrally on the top surface of a T-shaped joint intersection formed between three interlocking panels. The liquid level remaining in the container after a predefined time is a measure of the permeability against liquid penetrating the joint between the interlocking panels.

[0015] Since the retaining groove does not extend across the entire transverse dimension of the panel body, the locking element can also have a transverse dimension that is less than the total transverse dimension of the panel body. This design utilizes the fact that, even with a smaller transverse dimension, the locking element, in the form-fitting clip configuration, can provide sufficiently secure locking due to the positive locking clip connection. Therefore, it is not necessary to provide locking across the entire transverse dimension of the panel body. At the same time, the transverse dimension of the locking element is still large enough to distribute the forces acting on it during locking over a larger area, thus keeping the local mechanical loads on the locking element low.The chosen ratio of the transverse extension b0 of the retaining groove to the nominal width B of the panel body results in improved fracture resistance and improved shear resistance in the corner areas of the panel body, while simultaneously ensuring a secure locking mechanism with minimal stress on the locking element. The retaining groove, which extends only over a larger portion of the short side, and the locking element integrated within this groove, create a fracture-resistant and shear-resistant panel with a secure and material-friendly locking mechanism.

[0016] The locking element is inserted into the retaining groove in such a way that movement of the locking element in the transverse direction is blocked by friction and / or positive locking. In particular, it can be provided that, during transverse movement, the locking element abuts the corresponding end of the retaining groove and cannot be moved further. Preferably, a clearance fit is formed between the retaining groove and the locking element in the transverse direction. Particularly preferably, an interference fit is formed between the retaining groove and the locking element in the thickness direction, which stiffens the material of the panel body forming the retaining groove. Suitable locking elements are described, for example, in WO 2007 / 079845 A2.

[0017] According to the invention, a first reinforcement area with a transverse extent t1 is formed between a first end of the retaining groove, which is to be directed transversely towards the first edge, and a second reinforcement area with a transverse extent t2 is formed between a second end of the retaining groove, which is to be directed transversely towards the second edge, wherein for the first reinforcement area 0.005 ≤ t1 / B ≤ 0.090, in particular 0.015 ≤ t1 / B ≤ 0.050, preferably 0.020 ≤ t1 / B ≤ 0.030 and particularly preferably t1 / B = 0.025 ± 0.002 and / or for the second reinforcement area 0.005 ≤ t2 / B ≤ 0.090, in particular 0.015 ≤ t2 / B ≤ 0.050, preferably 0.020 ≤ t 2 / B ≤ 0.030 and particularly preferably t 2 / B = 0.025 ± 0.002 applies, provided that t 1 + b 0 + t 2 = B applies.The respective reinforcement area adjoins the corresponding edge of the panel body and extends transversely along the short side to the corresponding end of the retaining groove. This means the reinforcement area is free of the retaining groove. Instead of the retaining groove that would otherwise be present in the reinforcement area, the volume of the otherwise existing retaining groove is filled by the material of the panel body. This accumulation of material in the reinforcement area results in increased stability and fracture resistance in the corner area of ​​the panel body. At the same time, the respective reinforcement area is short enough that a sufficiently large proportion of the transverse extent of the short side remains for the retaining groove and the locking element inserted in the retaining groove.

[0018] Preferably, the panel body has a tongue and groove extending into the panel body at the first edge and a tongue and groove extension projecting from the panel body at the second edge, where t1 < t2, in particular 0.75 ≤ t1 / t2 ≤ 0.99, preferably 0.80 ≤ t1 / t2 ≤ 0.95, and most preferably 0.85 ≤ t1 / t2 ≤ 0.90. It can be taken into account that the tongue and groove extension makes the panel body more stable and stronger at the second edge than at the first edge, where the tongue and groove is provided. This allows the second reinforcement area to be correspondingly shorter in the transverse direction than the first reinforcement area.In the area of ​​the joint between two essentially identically designed panels adjoining each other on their long sides, an equally large joint reinforcement area of ​​t 1 + t 2 results on both long sides of the respective panel, in which the first reinforcement area is provided by one panel and the second reinforcement area by the other panel.

[0019] This allows for good fracture resistance in the area of ​​the tongue and groove, while simultaneously achieving good fracture resistance at the tongue and groove joint formed on the long sides. The tongue and groove is located within the panel body between the first and second edges. The tongue and groove extension protrudes from the rest of the panel body, with which it can be integrally formed, and is therefore positioned outside the nominal width B of the panel body, measured from the first to the second edge. Consequently, the extension of the tongue and groove extension does not contribute to the nominal width B of the panel body.

[0020] According to the invention, the transverse extent b1 of the locking element, relative to the nominal width B of the panel body, is 0.40 ≤ b1 / B ≤ 0.95, in particular 0.50 ≤ b1 / B ≤ 0.90, preferably 0.60 ≤ b1 / B ≤ 0.80, and most preferably b1 / B = 0.70 ± 0.05. The transverse extent of the locking element can, in particular, substantially correspond to the transverse extent of the retaining groove. However, it is also possible for the transverse extent of the locking element to be somewhat or significantly less than the extent of the retaining groove. The extension of the locking element can, for example, be dimensioned essentially solely with regard to the locking functionality and the ability to withstand the forces expected in this process, which makes it quite possible for the extension of the locking element to be chosen to be smaller compared to the extension of the retaining groove.In this case, it is theoretically possible to adjust the transverse extent of the retaining groove to the required smaller extent of the locking element. However, if the transverse extent of the retaining groove is chosen to be significantly larger than the extent of the locking element, alternative manufacturing options become available. Instead of producing the retaining groove with a pin-shaped milling cutter moving transversely, whose diameter corresponds in particular to the transverse extent of the retaining groove, it is possible to produce the retaining groove using a circular saw or peripheral milling cutter plunging into the panel body, since a rounded entry area at the ends of the retaining groove can be permitted. This allows for faster and more cost-effective production of the retaining groove.

[0021] In particular, the locking element is held in the retaining groove by friction solely through clamping forces acting in the thickness direction. The locking element can be clamped between an upper surface of the retaining groove and a lower surface of the retaining groove. Preferably, hooks and / or pins projecting from the locking element are driven into the material of the locking element that defines the retaining groove in a form-fitting manner. Clamping in the transverse direction is specifically avoided. This prevents unnecessary shear forces acting on the locking element. Furthermore, it is possible for the locking element to yield slightly in the transverse direction when inserted into the retaining groove, thus facilitating the pressing of the locking element into the retaining groove and / or the driving of hooks and / or pins into the material of the retaining groove.

[0022] Preferably, the locking element has a detent lug that can be bent elastically, at least partially, into the retaining groove. The locking element can thus be designed as a detent clip. When two panels are being locked together, if one panel is moved past the other, particularly during a pivoting movement, the panel can bend the detent lug elastically towards the retaining groove of the locking element and / or at least partially away into the retaining groove of the locking element, so that the panel can be moved past the locking element. In the intended final position, the locking element, in particular a detent lug of the detent lug, can elastically snap into a detent groove of the moving panel and create the locking connection. The detent lug of the panel can engage at least partially in the detent groove of the other panel, thereby forming a tongue-and-groove connection.

[0023] The retaining groove particularly preferably comprises a receiving space adjoining an end face of the short side for receiving a portion of the locking element, in particular for temporarily receiving an elastically bendable detent lug of the locking element, and a fastening space adjoining the side of the receiving space facing away from the end face for frictionally and / or positively locking a fastening projection of the locking element, wherein the extent of the fastening space in the thickness direction is smaller than the extent of the receiving space in the thickness direction. The fastening of the locking element in the retaining groove, which is particularly resistant to movement, can be achieved largely or entirely via the fastening projection of the locking element that extends into the fastening space.At the same time, the locking element can provide sufficient clearance within the volume of the receiving space of the retaining groove into which the elastically bendable locking tab of the locking element, or another component that brings about a locking action, can engage when the panel to be locked is moved. The relative movement of the panels intended for locking them together is not blocked by the locking element.

[0024] In particular, the locking element rests against both thickness-oriented surfaces of the receiving space, especially with a clamping force, wherein the locking element has a receiving pocket extending into the receiving space for the temporary reception of an elastically flexible locking tab of the locking element. This allows for a movement-resistant and / or, in particular, load-bearing fastening of the locking element in the retaining groove. It can even be permitted for the locking element to yield elastically in the thickness direction within the volume of the receiving space. This allows the locking element to be manufactured more cost-effectively. Since the locking element rests against the thickness-oriented surfaces, at least a certain degree of frictional engagement is present, which can make it more difficult for the locking element to slip out of the retaining groove.A free volume can be provided between the material areas of the locking element that contact the surfaces, forming the receiving pocket. This allows sufficient pivoting of the elastically connected locking bar into the receiving pocket as a panel to be locked passes by, and ensures a good frictional engagement of the locking element within the retaining groove. Preferably, the panel body has a locking hook projecting longitudinally from the short side forming the retaining groove on the panel body's short side, for locking into a receiving groove of another panel. This allows one panel to be locked to another panel either by means of the locking element engaging in a locking groove of the other panel or by means of the locking hook engaging in a retaining groove of the other panel.Suitable locking hooks and suitable spring bodies having a retaining groove are described in WO 2006 / 133690 A1, the relevant content of which is hereby incorporated by reference as part of the invention.

[0025] Particularly preferably, the retaining groove in a cutting plane spanned by the longitudinal and transverse directions has a cross-sectional area, producible by rotary machining, with rounded run-out areas at the transversely facing ends of the retaining groove. Rotary machining is understood to be a machining process involving a rotary cutting motion on a workpiece that is stationary relative to it, using a rotating cutting tool with a geometrically defined cutting edge, for example, circular saws with a circular saw blade or milling with a peripheral cutter. In rotary machining, machining can take place with a circular cutting motion associated with the tool and an arbitrary feed motion, whereby the axis of rotation of the cutting motion maintains its position relative to the tool independently of the feed motion.The three-dimensional shape of the locking element can be adapted to the shape of the retaining groove, so that corresponding surfaces can face each other and, in particular, lie flat against each other. Preferably, the locking element is essentially based on a cuboid shape, so that, outside the rounded run-out areas of the retaining groove, the locking element is installed in the retaining groove in a way that prevents movement, thus reducing the cost of manufacturing the locking element. This approach utilizes the fact that a smaller transverse extent of the locking element may be sufficient to provide the locking functionality.The extent of the locking element can, for example, be dimensioned primarily with regard to its locking functionality and its ability to withstand the forces expected during this process. This allows the locking element to be smaller than the retaining groove. Instead of machining the retaining groove with a transversely moving, pin-shaped milling cutter whose diameter corresponds to the groove's thickness, it is possible to machine the groove using a circular saw or peripheral milling cutter that plunges into the panel body, as rounded entry areas at the groove's ends are permissible. This makes manufacturing the retaining groove faster and more cost-effective.

[0026] In a further embodiment, the retaining groove has a rectangular cross-sectional area, produced by milling, particularly one that is substantially right-angled, in a cross-sectional plane spanned by the longitudinal and transverse directions. This allows the entire transverse extent of the retaining groove to be used to accommodate the locking element, for example, in the case of very narrow panels. This avoids the need for unused, rounded entry areas.

[0027] Another embodiment of the invention relates to a method for manufacturing a panel, which can be designed and further developed as described above, in which the retaining groove is produced by rotary machining with a cutting tool that is inserted into the panel body at the short side and rotates about an axis of rotation extending in the thickness direction, wherein the cutting tool enters the panel body at a distance from the first and second edges, is subsequently moved linearly in a transverse direction relative to the panel body, and subsequently emerges from the panel body at a distance from the first and second edges. The method can be designed and further developed, in particular, as explained above with reference to the panel.The retaining groove, which extends over a larger portion of the short side due to rotary machining, and the locking element integrated into the retaining groove, enable a break-resistant and throughput-proof panel with a secure and material-friendly locking mechanism. Specifically, the cutting tool features cutting teeth with a main cutting edge oriented essentially radially relative to the axis of rotation and two secondary cutting edges oriented essentially in opposite axial directions. In addition to the main cutting edge, the two secondary cutting edges engage the panel body by removing material and / or smoothing it to create the retaining groove. The thickness of the cutting teeth can be substantially wedge-shaped in the circumferential direction, allowing the thickness-oriented tooth flanks of the cutting teeth to form clearance surfaces for a suitable wedge angle of the secondary cutting edges.The secondary cutting edges and the main cutting edge can share a common rake face. Using the secondary cutting edges, the surfaces of the retaining groove produced by the main cutting edge and oriented in the thickness direction can be smoothed in the same machining step, thus facilitating the insertion of the locking element into the retaining groove. Smoothing the opposing surfaces with the secondary cutting edges reduces variations in surface roughness and coefficients of friction. Preferably, the cutting tool has cutting teeth with radial extensions of varying lengths in the axial direction relative to the axis of rotation, wherein the cutting teeth, in particular, have a radial profile to simultaneously create both a receiving space and a mounting space for the retaining groove.This allows part of the cutting tooth to penetrate less deeply into the material of the panel body, for example to create part of the receiving space, while another part of the cutting tooth, offset in the axial direction, can penetrate deeper into the material of the panel body, for example to additionally create the mounting space. The invention is explained below by way of example with reference to the accompanying drawings and preferred embodiments. Fig. 1 : a schematic top view of an end area of ​​a panel, Fig. 2 : a schematic cutaway side view of the panel made of Fig. 1 , Fig. 3 : a schematic cutaway side view of the panel made of Fig. 2 during manufacturing and Fig. 4 : a schematic cutaway side view of a detail of the panel made of Fig. 1 with an inserted locking element.

[0028] The in Fig. 1 The illustrated panel 10 can be used, for example as flooring laminate, to cover a room surface. The panel 10 can have a tongue and groove 12 on one side and a tongue and groove projection 14 on the other, on each of its long sides extending in the longitudinal direction 30. A nominal width B is provided between the long sides of the panel 10, whereby the tongue and groove 12 and the tongue and groove projection 14 are disregarded and considered non-existent for the nominal width B between the edges of the panel 10 on the long sides. In particular, the panel 10 has a locking hook 16 on one side and a spring element 18 that can interact with such a locking hook 16 on the other, on its short sides extending in the transverse direction 32. For example, a retaining groove 20 is provided on the short side with the locking hook 16, into which a locking element 22 can be inserted in a movement-resistant manner.The retaining groove 20 does not extend over the entire nominal width B, but only over a partial section b0, so that a first reinforcement area 24 with a transverse extent t1 remains between the retaining groove 20 and the long side with the tongue groove 12, and a second reinforcement area 26 with a transverse extent t2 remains between the retaining groove 20 and the long side with the tongue extension 12. The retaining groove 20 can be produced by a slot cutter 40, designed like a circular saw or peripheral cutter, which is plunged into the short side of a panel body 28 of the panel 10, so that rounded run-out areas 31 with a transverse extent b2 are formed at the ends of the retaining groove 20. The remaining extension b 1 of the retaining groove 20 between the outlet areas 31 can essentially correspond to the extension of the locking element 22 in the transverse direction 32.

[0029] As in Fig. 2 As shown, the retaining groove 20 can have different depths in the longitudinal direction 30 at different heights in a thickness direction 34 of the panel body 28. The retaining groove 20 thus has a receiving space 36 adjoining the short side of the panel body 28 in the longitudinal direction 30 and a fastening space 38 projecting from the receiving space 36 in the longitudinal direction 30 into the interior of the panel body 28, the extent of which differs in the thickness direction 34. The extent of the receiving space 36 in the thickness direction 34 is greater than the extent of the fastening space 38 in the thickness direction 34.

[0030] As in Fig. 3 As shown, the stepped retaining groove 20 can be produced using a slot cutter 40 designed in the manner of a circular saw or a peripheral milling cutter. For this purpose, the slot cutter 40 has a cutting tool 42 with cutting teeth 44 on its radial outer surface. The cutting teeth 44 have a radially stepped profile, resulting in radially offset main cutting edges 46. The receiving space 36, with the shorter extension in the longitudinal direction 30, and the mounting space 38, with the longer extension in the longitudinal direction 30, can thus be produced in a single manufacturing step. In addition, the cutting teeth 44 have secondary cutting edges 48 pointing in the thickness direction 34, so that the entire retaining groove 20 can be produced with a defined surface finish.The retaining groove 20 can be spaced far enough away from a top surface 52 of the panel body 28 in the thickness direction 34 to allow the cutting tool 42 of the slot cutter 40 to pass the locking hook 16. Simultaneously, the retaining groove 20 is spaced far enough away from a bottom surface 50 of the panel body 28 in the thickness direction 34 to ensure sufficient strength of the panel body 28 even in the area of ​​the retaining groove 20. Preferably, the retaining groove 20 is produced using the slot cutter 40, while the top surface 52 of the panel 10 faces downwards and the bottom surface 50 of the panel 10 faces upwards, so that the locking hook 16, which covers the cutting teeth 44 above, can guide the cut chips downwards.

[0031] As in Fig. 4As shown, the locking element 22 can have a fastening projection 60 pressed into the mounting space 38 of the retaining groove 20. Optionally, the locking element 22 can also be pressed into a portion of the receiving space 36 of the retaining groove 20 that faces the mounting space 38. The locking element 22 has a locking web 54 with a locking lug 56, which, when locked to another panel, can slide off the outside of the other panel and, in doing so, can be elastically pivoted towards the receiving space 36 of the retaining groove 20 and, if necessary, fully or partially pivoted into a receiving pocket held clear by the locking element 22. When the designated relative position of the panel 10 to the other panel is assumed, the locking web 54 can elastically snap out of the receiving space 36, so that the locking lug 56 can engage in a corresponding locking groove 58 and bring about a locking action.

Claims

1. Panel for covering a surface of a room, comprising a panel element (28) extending in a longitudinal direction (30) and in a transverse direction (32) for transferring use loads introduced at an upper side (52) of the panel element (28) to a lower side (50) of the panel element (28) facing the surface of the room, wherein the upper surface (52) is spaced apart from the lower side (50) in a thickness direction (34); a retaining groove (20) extending in an end face short side of the panel element (28) in the transverse direction (32); and a locking element (22) inserted into the retaining groove (20), in particular immovably, wherein for an extension b0 of the retaining groove (20) in the transverse direction (32) with respect to a nominal width B of the panel element (28) between a first edge of the panel element (28) extending in the longitudinal direction and a second edge of the panel element (28) extending in the longitudinal direction 0.50 ≤ b0 / B ≤ 0.97, in particular 0.75 ≤ b0 / B ≤ 0.95, preferably 0.85 ≤ b0 / B ≤ 0.93 and particularly preferably b0 / B = 0.90 ± 0.02, wherein a first reinforcing area (24) with an extension t1 in the transverse direction (32) is formed in the transverse direction (32) between a first end of the retaining groove (20) pointing in the transverse direction (32) toward the first edge, wherein a second reinforcement region (26) with an extension t2 in the transverse direction (32) is formed in the transverse direction (32) between a second end of the retaining groove (20) pointing in the transverse direction (32) towards the second edge, a second reinforcement area (26) with an extension t2 in the transverse direction (32) is formed, wherein for the first reinforcing area (24) 0.005 ≤ t1 / B ≤ 0.090, in particular 0.015 ≤ t1 / B ≤ 0.050, preferably 0.020 ≤ t1 / B ≤ 0.030 and particularly preferably t1 / B = 0.025 ± 0.002 and / or for the second reinforcement area (26) 0.005 ≤ t2 / B ≤ 0.090, in particular 0.015 ≤ t2 / B ≤ 0.050, preferably 0.020 ≤ t2 / B ≤ 0.030 and, particularly preferably, t2 / B = 0.025 ± 0.002, with the proviso that t1 + b0 + t2 = B, and in that for an extension b1 of the blocking element (22) in the transverse direction relative to the nominal width B of the panel body (28), 0.40 ≤ b1 / B ≤ 0.95, in particular 0.50 ≤ b1 / B ≤ 0.90, preferably 0.60 ≤ b1 / B ≤ 0.80 and particularly preferably b1 / B = 0.70 ± 0.05 applies.

2. Panel according to claim 1, characterized in that the panel element (28) comprises at the first edge a bung groove (12) extending into the panel element (28) and at the second edge a bung projection (14) projecting from the panel element (28), wherein t1 < t2, in particular 0.75 ≤ t1 / t2 ≤ 0.99, preferably 0.80 ≤ t1 / t2 ≤ 0.95 and particularly preferably 0.85 ≤ t1 / t2 ≤ 0.90.

3. Panel according to any one of claims 1 or 2, characterized in that a frictional engagement of the locking element (22) in the retaining groove (20) is achieved exclusively by means of clamping forces point in the thickness direction (34).

4. Panel according to any one of claims 1 to 3, characterized in that the locking element (22) comprises a latching web (54) which can be elastically bent at least partially in the direction into the retaining groove (20).

5. Panel according to any one of claims 1 to 4, characterized in that the retaining groove (20) comprises a receiving space (36) adjoining an end face of the short side for receiving a part of the locking element (22), in particular for temporary receiving an elastically flexible latching web (54) of the locking element (22), and a fastening space (38) adjoining the side of the receiving space (36) facing away from the end face for fastening a fastening projection (60) of the locking element (22) in a frictional and / or form-fitting manner, wherein the extension of the fastening space (38) in the thickness direction (34) is smaller than the extension of the receiving space (36) in the thickness direction (34).

6. Panel according to claim 5, characterized in that the locking element (22) abuts at both surfaces of the receiving space (36) facing in the thickness direction (34), in particular with a clamping force, wherein in particular the locking element (22) comprises a receiving pocket extending into the receiving space (36) for temporarily receiving an elastically bendable latching web (54) of the locking element (22).

7. Panel according to any one of claims 1 to 5, characterized in that the panel element (28) comprises at the short side forming the retaining groove (20) a locking hook (16) projecting in the longitudinal direction (30) from the short side of the panel element for latching into a retaining groove (20) of a further panel.

8. Panel according to any one of claims 1 to 7, characterized in that the retaining groove (20) comprises in a cross-sectional plane spanned by the longitudinal direction (30) and the transverse direction (32) at the ends of the retaining groove (20) facing in the transverse direction (32) a rounded feed-out area which can be produced by rotary machining.

9. Panel according to any one of claims 1 to 7, characterized in that the retaining groove (20) comprises in a cross-sectional plane spanned by the longitudinal direction (30) and the transverse direction (32) an in particular rectangular cross-sectional area which can be produced by milling.

10. Method of producing a panel according to any one of claims 1 to 9, in which the retaining groove (20) is formed by rotary machining by use of a chip-removing tool (42) engaging into the panel element (28) at the short side of the panel element and rotating about an axis of rotation extending in the thickness direction (34), wherein the cutting tool (42) engages into the panel element (28) at a distance from the first edge and the second edge, subsequently is linearly moved in the transverse direction (32) relative to the panel element (28), and subsequently the cutting tool (42) exits from the panel element (28) spaced from the first edge and the second edge, characterized in that the cutting tool (42) has cutting teeth (44) with a main cutting edge (46) pointing substantially in a radial direction relative to the axis of rotation and two secondary cutting edges (48) pointing substantially in opposite axial directions, wherein, in addition to the main cutting edge (46), the two secondary cutting edges (48) engage the retaining groove (20).

11. Method according to claim 10, wherein the cutting tool (42) comprises cutting teeth (44) having radial extensions of different widths in the axial direction with respect to the axis of rotation, wherein in particular the cutting teeth (44) have a radial profiling for simultaneously producing both a receiving space (36) and a fastening space (38) of the retaining groove (20).