PANEL

Abstract

The panel includes a first pair of opposite edges; these comprise male and female coupling parts - in the form of a tongue and groove and locking elements - in order to couple two such panels to each other on their first pair of opposite edges. The panel and coupling parts thereof are configured so that in a covering formed with these panels, the expansion and contraction of the panels in the coupling zone on the first pair of opposite edges is compensated in this coupling zone itself.

Claims

1-62. (canceled)

63. A panel, wherein the panel comprises a first pair of opposite edges, namely a first edge and a second edge; wherein the first edge comprises a male coupling part, wherein the second edge comprises a female coupling part, wherein the male coupling part and the female coupling part are configured in such a way that two such panels, can, by means of their male and female coupling parts, be coupled to each other in one plane and a coupled state can thus be realized between the panels; wherein the male coupling part comprises a tongue; wherein the female coupling part comprises a groove, wherein the groove is delimited by an upper lip and a lower lip; wherein the lower lip extends in the distal direction beyond the open or free end of the upper lip; wherein the tongue and the groove, in the coupled state, form a tongue-and-groove joint, which produces a mechanical locking between the panels in the direction perpendicular to the plane of the panels; wherein the male coupling part and the female coupling part each comprise a locking element, said locking elements, in the coupled state, produce a mechanical locking between the panels in the direction in the plane of the panels and perpendicular to the first pair of opposite edges; wherein the tongue and the upper lip are configured with overlapping contours, so that in the coupled state of two such panels, on their first pair of opposite edges a pretension is formed between the tongue of the panel and the upper lip of said coupled panel.

64. The panel as in claim 63, wherein the overlap of the overlapping contours in the direction perpendicular relative to the surface of the panel is at least 0.03 millimetre; and at least 0.05 millimetre.

65. The panel as in claim 63, so that, on account of this pretension, the lower lip in the coupled state is bent downwards at any degree of humidity.

66. The panel as in claim 63, wherein owing to the pretension, the tongue bends, and not the upper lip.

67. A panel, wherein the panel comprises a first pair of opposite edges, namely a first edge and a second edge; wherein the first edge comprises a male coupling part, wherein the second edge comprises a female coupling part, wherein the male coupling part and the female coupling part are configured in such a way that two such panels can be coupled to each other in one plane by means of their male and female coupling parts, and a coupled state can thus be realized between the panels; wherein the male coupling part comprises a tongue; wherein the female coupling part comprises a groove, wherein the groove is delimited by an upper lip and a lower lip; wherein the lower lip extends in the distal direction beyond the open or free end of the upper lip; wherein the tongue and the groove, in the coupled state, form a tongue-and-groove joint, which produces a mechanical locking between the panels in the direction perpendicular to the plane of the panels; wherein the male coupling part and the female coupling part each comprise a locking element, said locking elements, in the coupled state, produce a mechanical locking between the panels in the direction in the plane of the panels and perpendicular to the first pair of opposite edges; wherein the panel comprises a bevel - straight and/or curved - on the top of its first edge; wherein the top edge of the tongue comprises a contact surface being parallel to the upper side of the panel for coming into contact with the bottom edge of the upper lip of another such panel to which the panel is coupled on its first edge; wherein the tongue comprises a slot, wherein this slot is located between the bevel on the first edge and the contact surface on the top edge of the tongue, wherein the slot has a depth relative to the uppermost point of the tongue of at least 0.05 millimetre.

68. The panel as in claim 67, wherein the width of the slot is greater than its depth, wherein the depth is measured relative to the uppermost point of the tongue.

69. The panel as in claim 67, wherein, in the coupled state just after coupling the panel on its first edge to the second edge of a second such panel, at least one part of the slot is visible from above.

70. The panel as in any claim 67, wherein the panel comprises a substrate and a decorative design; wherein the decorative design runs continuously from the upper surface over the bevel on the first edge of the panel up to at least a part of the slot; and over the entire slot.

71. The panel as in claim 70, wherein the decorative design on the tongue does not run beyond the slot.

72. The panel as in claim 70, wherein the decorative design on the first edge does not run onto the contact surface on the top edge of the tongue.

73. The panel as in claim 72, wherein the contact surface on the top edge of the tongue is a milled contact surface.

74. The panel as in claim 70, wherein the panel comprises a substrate and a decorative design, wherein the contact surface on the top edge of the tongue is formed from substrate.

75. The panel as in claim 70, wherein the decorative design on the first edge runs up to, but not onto the contact surface on the top edge of the tongue.

76. The panel such in claim 70, wherein the decorative design on the tongue runs continuously to beyond the slot.

77. The panel as in claim 67, wherein the panel comprises a bevel - straight and/or curved - on the top of its second edge; wherein the contact surface of the top of the first edge, in the coupled state of the panel on its first edge to the second edge of another such, is located completely under the bevel on the top of the second edge of the other such panel.

78. A panel, wherein the panel comprises a first pair of opposite edges, namely a first edge and a second edge; wherein the first edge comprises a male coupling part, wherein the second edge comprises a female coupling part, wherein the male coupling part and the female coupling part are configured in such a way that two such panels can, by means of their male and female coupling parts, be coupled to each other in one plane and a coupled state can thus be realized between the panels; wherein the male coupling part comprises a tongue; wherein the female coupling part comprises a groove, wherein the groove is delimited by an upper lip and a lower lip; wherein the lower lip extends in the distal direction beyond the open or free end of the upper lip; wherein the tongue and the groove, in the coupled state, form a tongue-and-groove joint, which produces a mechanical locking between the panels in the direction perpendicular to the plane of the panels; wherein the male coupling part and the female coupling part each comprise a locking element, said locking elements, in the coupled state, produce a mechanical locking between the panels in the direction in the plane of the panels and perpendicular to the first pair of opposite edges; wherein the panel comprises a substrate and a decorative design; wherein the panel comprises a bevel - straight and/or curved - on the top of its first edge and on its second edge; wherein the decorative design runs continuously from the upper surface over the bevel to the first edge of the panel up to at least a part of the upper surface of the tongue; wherein the decorative design runs continuously from the upper surface up to the bevel on the second edge of the panel; wherein the second edge comprises a second bevel - straight and/or curved - under the bevel on the second edge, wherein the second bevel, viewed from top to bottom, is directed inwards; wherein the decorative design does not run onto the second bevel; wherein the second bevel has a height, measured perpendicular to the plane of the panel, of at least 0.10 millimetre.

79. The panel as in claim 78, wherein the decorative design comprises a decorative layer, wherein the decorative layer comprises a decorative print.

80. The panel as in claim 78, wherein, in the cross-section perpendicular to the first pair of opposite edges, the second bevel has, in at least one point thereof, a tangent which, relative to the upper surface of the panel, makes an angle of more than 40°.

81. The panel as in claim 78, wherein in the cross-section perpendicular to the first pair of opposite edges, the second bevel is flat over at least one part thereof.

82. The panel as in claim 78, wherein in the coupled state of the panel with its first edge on the second edge of another such panel, in the direction perpendicular to the plane of the panel the upper lip of the other such panel lies partly above a portion of the tongue of the panel containing a decorative design.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0102] For the purpose of better clarification of the features of the invention, some preferred embodiments are described hereunder, as examples without any limiting character, referring to the appended drawings.

[0103] FIG. 1 shows schematically an example of a floor covering according to one aspect of the invention, with panels according to the invention.

[0104] FIG. 2 shows a top view of an example of a panel according to the invention used in the floor covering in FIG. 1.

[0105] FIG. 3 shows a cross-section through III-III of the panel in FIG. 2.

[0106] FIG. 4 shows a cross-section of an alternative panel according to the invention.

[0107] FIG. 5 shows panels according to the invention coupled on their first pair of opposite edges, in the situation just after coupling and moreover at average relative humidity.

[0108] FIG. 6 shows the coupled panels from FIG. 5 in a state at low relative humidity in the room where they are installed.

[0109] FIG. 7 shows the coupled panels from FIG. 5 in a state at very high relative humidity in the room where they are installed.

[0110] FIG. 8 illustrates steps of a production process that can be used for producing examples of panels according to the invention.

[0111] FIG. 9 shows a detail from FIG. 8.

DESCRIPTION OF EXAMPLES OF EMBODIMENTS

[0112] FIG. 1 shows schematically an example of a floor covering according to one aspect of the invention, with panels (1) according to the invention. FIG. 2 shows a top view of an example of a panel (1) according to the invention used in the floor covering in FIG. 1. The panels (1) of the floor covering in FIG. 1 are rectangular and elongated. The panels possess, on their long sides, a first pair of opposite edges (2, 3). The covering has, in the direction perpendicular to the first pair of opposite edges (2, 3) of the panels, a length of at least 15 metres, and preferably of at least 20 metres. Over this length, all adjacent panels are coupled to each other on their first pair of opposite edges (2, 3) by means of their respective coupling parts, without fitting separate profiles between the panels to compensate expansion and contraction of the covering in the transverse direction on the first pair of opposite edges (2, 3). The panels may be coupled to each other on their first pair of opposite edges (2, 3) by means of a rotating movement (R).

[0113] The panels (1) comprise a second pair of opposite edges (94, 95), more specifically a third edge (94) and a fourth edge (95). The panels possess, on their second pair of opposite edges, coupling parts that allow the panels to be coupled, on their third edge, to the fourth edge of another such panel, wherein a locking occurs in the direction in the plane of the thus coupled panels and perpendicular to the thus coupled edges; as well as perpendicular to the plane of the coupled panels. The coupling parts of the second pair of opposite edges (94, 95) may be designed in such a way that the panel can be coupled on its third edge (94) to the fourth edge (95) of another such panel by means of one or more of: a rotating movement, pushing the panel parallel to the plane of the panel with a snap effect, or movement of the third edge of the panel perpendicular to the plane of the panel.

[0114] FIG. 3 shows a cross-section through III-III of the panel (1) according to the invention from FIG. 2.

[0115] FIG. 5 shows the panels according to the invention from FIGS. 2 and 3 coupled on their first pair of opposite edges (2, 3), in the situation just after coupling and moreover at average relative humidity in the floor covering.

[0116] FIG. 6 shows the coupled panels from FIG. 5 in a state at very low relative humidity in the room where they are installed. This signifies that the panels have shrunk to a considerable extent.

[0117] FIG. 7 shows the coupled panels from FIG. 5 in a state at very high relative humidity in the room where they are installed. This signifies that the panels have expanded to a considerable extent.

[0118] The panel (1) illustrated in FIGS. 1-3 and 5-7 comprises a first pair of opposite edges (2, 3), namely a first edge (2) and a second edge (3). The first edge (2) comprises a male coupling part (5). The second edge (3) comprises a female coupling part (6). The male coupling part (5) and the female coupling part (6) are configured in such a way that two such panels (1) can, by means of their male and female coupling parts (5, 6), be coupled to each other in one plane and a coupled state can thus be realized between the panels (1). The male coupling part (5) comprises a tongue (7). The female coupling part (6) comprises a groove (8), wherein the groove (8) is delimited by an upper lip (10) and a lower lip (11). The lower lip (11) extends in the distal direction beyond the open or free end (13) of the upper lip (10). The tongue (7) and the groove (8) form, in the coupled state, a tongue-and-groove j oint, which produces a mechanical locking between the panels (1) in the direction perpendicular to the plane of the panels (1). The male coupling part (5) and the female coupling part (6) each comprise a locking element (15, 16). These locking elements (15, 16) produce, in the coupled state, a mechanical locking between the panels (1) in the direction in the plane of the panels (1) and perpendicular to the first pair of opposite edges (2, 3).

[0119] The locking element (15) of the male coupling part (5) is provided on the underside of the tongue (7). The locking element (16) of the female coupling part (6) is provided on the upper side of the lower lip (11).

[0120] The tongue (7) and the upper lip (10) are configured with overlapping contours (18, 19), so that in the coupled state of two such panels, on their first pair of opposite edges (2, 3) a pretension is formed between the tongue (7) of the panel and the upper lip (10) of said coupled panel. FIGS. 5, 6 and 7 show these overlapping contours, admittedly not in the state such as occurs in the coupled state. In the coupled state, the surfaces of the overlapping contours in fact come into contact with each other so that a bending occurs in the panel. In the panels according to this example, the lower lip (11) is bent downwards by the aforementioned pretension at any degree of humidity in the room where the coupled panels are located. In panels according to this example, the tongue (7) bends owing to the aforementioned pretension; and not the upper lip (10).

[0121] The overlap of the overlapping contours (18, 19) in the direction perpendicular relative to the surface of the panel may be at least 0.03 millimetre; and preferably at least 0.05 millimetre.

[0122] The panel (1) comprises, on the top of its first edge (2), a bevel (21). The top edge of the tongue comprises a contact surface (22) - in this example parallel to the upper side of the panel - for coming into contact with the bottom edge of the upper lip (10) of another such panel to which the panel is coupled on its first edge. The tongue (7) comprises a slot (27) that is located between the bevel (21) on the first edge (2) and the contact surface (22) on the top of the tongue. The slot preferably has a depth relative to the uppermost point of the tongue of at least 0.05 millimetre, more preferably of at least 0.1 millimetre, even more preferably of at least 0.15 millimetre.

[0123] The width of the slot (23) is greater than its depth, wherein the depth is measured relative to the uppermost point of the tongue.

[0124] In the coupled state, just after coupling the panel on its first edge to the second edge of a second such panel, at least one part of the slot is visible from above; this is shown in FIG. 5. The state as shown in FIG. 5 is also the state of the coupled panels on their first pair of opposite edges (2, 3) in non-extreme situations of relative humidity in the room where these coupled panels are located.

[0125] The panel comprises a substrate (24) and a decorative design (25). The substrate may be or may comprise an MDF (Medium Density Fibreboard) or an HDF (High Density Fibreboard) substrate. The decorative design runs continuously through from the upper surface over the bevel (21) on the first edge (2) of the panel up to at least a part of the slot (23); and in the example over the entire slot (23). For this purpose the decorative design comprises a decorative layer, which comprises a decorative print. The decorative layer of the example panel comprises a layer of paper, which is printed and is melaminized. The panel of the example is formed as a DPL (Direct Pressure Laminate).

[0126] The decorative design (25) on the first edge (2), in the example panel, does not run through onto the contact surface (22) on the top edge of the tongue (7). In order to achieve this, in this example the contact surface (22) on the top edge of the tongue is a milled contact surface. Therefore the contact surface (22) on the top edge of the tongue is formed by substrate (24).

[0127] In the example panel, the decorative design (25) on the first edge (2) runs through up to, but not onto the contact surface (22) on the top edge of the tongue (7).

[0128] The panel comprises a bevel (27) on the top of its second edge (3). The contact surface (22) of the top of the first edge (2) is located, in the coupled state of the panel on its first edge (2) to the second edge (3) of another such, completely under the bevel (27) on the top of the second edge (3) of the other such panel.

[0129] The decorative design (25) runs continuously through from the upper surface up to the bevel (27) on the second edge of the panel. The second edge (3) comprises a second bevel (28), situated under the bevel (27) on the second edge. The second bevel (28), viewed from top to bottom, is directed inwards. The decorative design (25) does not run through up to the second bevel (28). In the example, this second bevel (28) has a height measured perpendicular to the plane of the panel of 0.25 millimetre. The second bevel (28) may be formed by a milling operation.

[0130] In the cross-section perpendicular to the first pair of opposite edges (2, 3), the second bevel (28) is flat over at least one part thereof. In this flat part, the second bevel (28) has a tangent, which makes an angle of 75° relative to the upper surface of the panel.

[0131] In the coupled state of the panel with its first edge (2) on the second edge (3) of another such panel, in the direction perpendicular to the plane of the panel, the upper lip (10) of the other such panel, lies partly above a decorative design (25) comprising a portion of the tongue (7) of the panel.

[0132] As illustrated in FIG. 5, which shows two panels according to the invention immediately after coupling, in the coupled state directly after the coupling of the panel on its first edge (2) to the second edge (3) of a second such panel, a part of the tongue (7) is visible from above. There is a space (30) between the lowest point of the tongue of the panel and the lower lip (11) of the second such panel.

[0133] Underneath the tongue (7) there is a first contact surface (32), a first inclined abutting surface (33) and a second inclined abutting surface (34). In the distal direction of the panel, the first contact surface (32) lies farther than the first inclined abutting surface (33), and the first inclined abutting surface (33) lies farther than the second inclined abutting surface (34). On top of the lower lip (11) there is a first counter-contact surface (37), a first inclined counter-abutting surface (38), and a second inclined counter-abutting surface (39). In the distal direction of the panel, the second inclined counter-abutting surface (39) lies farther than the first inclined counter-abutting surface (38), and the first inclined counter-abutting surface (38) lies farther than the first counter-contact surface (37).

[0134] The first contact surface (32) is located, relative to the first inclined abutting surface (33) as well as relative to the second inclined abutting surface (34) in the direction perpendicular to the surface of the panel, closer to the upper surface of the panel.

[0135] In the coupled state of the panel with another such panel, the first contact surface (32) comes into contact with the first counter-contact surface (37). On expansion or contraction of these coupled panels, the first contact surface (32) of the panel and the first counter-contact surface (37) of the other such panel can move over one another. Depending on the extent of expansion or contraction of the panel and the other such panel to which the panel is coupled on its first edge (2) to the second edge (3) of the other such panel, there can be contact between the first inclined abutting surface (33) of the panel with the first inclined counter-abutting surface (38) of the other such panel (see FIGS. 5 and 7, with non-extreme humidity and with very high relative humidity, respectively), or of the second inclined abutting surface (34) of the panel with the second inclined counter-abutting surface (39) of the other such panel (see FIG. 6, which shows the state at very low relative humidity). There is not, in any situation of temperature or humidity at all, contact both between the first inclined abutting surface (33) of the panel with the first inclined counter-abutting surface (38) of the other such panel and between the second inclined abutting surface (34) of the panel with the second inclined counter-abutting surface (39) of the other such panel.

[0136] The first edge (2) and the second edge (3) are configured so that on contact between the first inclined abutting surface (33) of the panel with the first inclined counter-abutting surface (38) of another such panel to which the panel is coupled, in the direction perpendicular to the first pair of opposite edges (2, 3) there is a distance of more than 0.3 mm between the second inclined abutting surface (34) of the panel and the second inclined counter-abutting surface (39) of the other such panel.

[0137] The first edge (2) and the second edge (3) are configured so that on contact between the second inclined abutting surface (34) of the panel with the second inclined counter-abutting surface (39) of another such panel to which the panel is coupled, in the direction perpendicular to the first pair of opposite edges, there is a distance of more than 0.3 mm between the first inclined abutting surface (33) of the panel and the first inclined counter-abutting surface (38) of the other such panel.

[0138] In the panels in the example, the contact in the coupled state between the first contact surface (32) of the panel and the first counter-contact surface (37) of the other such panel is parallel to the upper surface of the panel.

[0139] Underneath the tongue (7) there is an inclined sliding surface (35). In the distal direction of the panel, the second inclined abutting surface (34) lies farther than the inclined sliding surface (35).

[0140] The slope of the inclined sliding surface (35) is smaller than the slope of the second inclined abutting surface (34) and smaller than the slope of the first inclined abutting surface (33).

[0141] On top of the lower lip (11) there is an inclined counter-sliding surface (40). In the distal direction of the panel, the inclined counter-sliding surface (40) lies farther than the second inclined counter-abutting surface (39). The slope of the inclined counter-sliding surface (40) is smaller than the slope of the second inclined counter-abutting surface (39) and smaller than the slope of the first inclined counter-abutting surface (38). The inclined sliding surface (35) is located, relative to the first inclined abutting surface (33) and relative to the second inclined abutting surface (34) in the direction perpendicular to the surface of the panel, closer to the upper surface of the panel.

[0142] As illustrated in FIG. 5, the inclined sliding surface (35) of the panel is provided for coming into contact with the inclined counter-sliding surface (40) of the other such panel in the coupled state just after coupling the panel to the other such panel, so that a locking of these coupled panels is obtained in the plane of the coupled panels and perpendicular to their first pair of opposite edges.

[0143] The first pair of opposite edges (2, 3) is designed so that just after coupling there is an overlap between the inclined sliding surface (35) of the panel and the inclined counter-sliding surface (40) of another such panel with which the panel is coupled on its first edge (2) (this state is shown in FIG. 5); so that in this coupled state, the inclined sliding surface (35) of the panel with pretension comes into contact with the inclined counter-sliding surface (40) of the other such panel.

[0144] In the coupled state of the panel on its first edge (2) with the second edge (3) of another such panel, there is a space (42) under the tongue (7) and between the first inclined abutting surface (33) and the second inclined abutting surface (34) and above the lower lip (11).

[0145] The slopes of the first inclined abutting surface (33) and of the second inclined abutting surface (34) run in opposite directions.

[0146] The first edge (2) and the second edge (3) are configured so that on contact between the first inclined abutting surface (33) of the panel with the first inclined counter-abutting surface (38) of another such panel to which the panel is coupled, on further expansion of the panels a stress develops between this first inclined abutting surface (33) and the first inclined counter-abutting surface (38) with which the first inclined abutting surface (33) comes into contact, which causes a bending of the lower lip (11) of the other such panel. This is illustrated in FIG. 7, which shows the state of the coupled panels in a room that has reached a very high relative humidity, so that the coupled panels have expanded considerably.

[0147] The first edge (2) and the second edge (3) are configured so that on contact between the second inclined abutting surface (34) of the panel with the second inclined counter-abutting surface (39) of another such panel to which the panel is coupled, on further contraction of the panels a stress develops between this second inclined abutting surface (34) and the second inclined counter-abutting surface (39) with which the second inclined abutting surface (34) comes into contact, which causes a bending of the lower lip (11) of the other such panel. This is illustrated in FIG. 6, which shows the state of coupled panels in a room that has reached a very low relative humidity, so that the coupled panels have shrunk considerably.

[0148] The panel (1) in the example has, on the first edge (2) above the tongue (7), a first closing face (44). The second edge (3) has a second closing face (45). Directly after coupling of the panel on its first edge (2) to the second edge (3) of the other such panel, between the first closing face (44) of the panel and the second closing face (45) of the other such panel in the direction perpendicular to the first pair of opposite edges (2, 3) of the thus coupled panels, there is at least a distance of 0.35 millimetre. FIG. 5 shows the state after coupling of two panels on their first pair of opposite edges (2, 3). At a certain expansion of the panel and of the other such panel with which the panel is coupled on its first edge (2) to the second edge (3) of the other such panel, there is contact between the first closing face (44) of the panel and the second closing face (45) of the other such panel. This is illustrated in FIG. 7, which shows the coupled panels when the relative humidity is very high in the room where the panels are installed, and thus considerable expansion of the panels occurs.

[0149] The first edge (2) and the second edge (3) are configured so that on contact between the first inclined abutting surface (33) of the panel with the first inclined counter-abutting surface (34) of another such panel to which the panel is coupled, in the direction perpendicular to the first pair of opposite edges, there is a distance of more than 0.3 mm; and preferably more than 0.35 mm between the second inclined abutting surface (34) of the panel and the second inclined counter-abutting surface (39) of the other such panel.

[0150] The first edge (2) and the second edge (3) are configured so that on contact between the second inclined abutting surface (34) of the panel with the second inclined counter-abutting surface (39) of another such panel to which the panel is coupled, in the direction perpendicular to the first pair of opposite edges, there is a distance of more than 0.3 mm; and preferably more than 0.35 mm between the first inclined abutting surface (33) of the panel and the first inclined counter-abutting surface (38) of the other such panel.

[0151] The included angle of inclination (β) of the second inclined counter-abutting surface (39) to the plane of the panel is greater than the included angle of inclination (α) of the first inclined counter-abutting surface (38) to the plane of the panel; in the example this difference is 35°.

[0152] Underneath the tongue (7), there is a zone between the first contact surface (32) and the first inclined abutting surface (33). In all conditions of humidity and temperature, in the coupled state on the first edge (2) of the panel to the second edge (3) of another such panel in the direction parallel to the surface of these coupled panels, there is a space (47) between this zone and the lower lip (11) of the other such panel to which the panel is coupled on its first edge.

[0153] In the case of the panel in the example shown in FIGS. 1-3 and 5-7, the second edge (3) comprises a notch (49) under the lower lip (11). The length of the notch (49), measured in the plane parallel to the surface of the panel and perpendicular to the second edge, is smaller than the distance between the most distal point of the upper lip (10) and the most distal point of the lower lip (11).

[0154] The lower lip (11) possesses a most proximal contact surface at the top. This most proximal contact surface comes into contact, in the coupled state, with the underside of the tongue of a coupled panel, wherein, in the coupled state of the panel, on its second edge there is no contact surface at the top of the lower lip more proximal than the most proximal contact surface. The notch (49) does not extend from the distal end of the second edge (3) beyond the most proximal contact surface.

[0155] The panel in the example that comprises an MDF or an HDF substrate, under the influence of temperature changes and/or changes in air humidity, in relative terms, changes less in dimension in the direction parallel to the first pair of opposite edges (2, 3) than in the direction perpendicular to the first pair of opposite edges (2, 3).

[0156] FIG. 4 shows a cross-section of an alternative panel according to the invention. The panel in FIG. 4 is thinner than the panel illustrated in FIGS. 3 and 5-7. Instead of a notch, the second edge comprises an undercut (50) under the lower lip of the panel in FIG. 4. This undercut (50) has the same function as the notch of the panel in FIG. 3. The length of the undercut (50), measured in the plane parallel to the surface of the panel and perpendicular to the second edge, is smaller than the distance between the most distal point of the upper lip (10) and the most distal point of the lower lip (11). Moreover, the panel in FIG. 4 is configured like the panel in FIG. 3. However, variations might well occur in the configuration of the panel according to the various aspects and embodiments of the invention described.

[0157] FIG. 8 illustrates steps of a production process that can be used for producing examples of panels according to the invention. FIG. 9 shows a detail from FIG. 8. FIGS. 8 and 9 show an already pressed board (78) - with its decorative side (62) -from which panels according to the invention can be produced. The pressed board (78) consists of a substrate (64), preferably an HDF (High Density Fibreboard) substrate, on which a melaminized printed paper sheet (71) and optionally overlays (e.g. melaminized paper sheets that contain particles in order to increase the wear resistance of the panel) have been placed. Grooves (73), for applying the melaminized printed paper sheet and the optional overlays, have already been milled in the substrate. By means of a pressing element (58), the layers that are then applied (melaminized printed paper sheet and the optional overlays) are pressed onto the substrate. This takes place by means of the so-called DPL (Direct Pressure Laminate) process. FIGS. 7 and 8 show the board (78) after pressing by means of the pressing element (58). The pressing element (58) has a pressing side (59), which will form the sections (56), which will then form the surface of the panels.

[0158] During the pressing operation, the applied layers (melaminized printed paper sheet and the optional overlays) will display a split (80) in the zones where the grooves (73) were milled beforehand. As will be seen later, this split is located in zones of the board that will be removed, and thus will not form part of the panels.

[0159] The pressing side (59) of the pressing element (58) may comprise irregularities or projections (63), which by means of indentations (68) will form a relief on the surface of the pressed board (78), and thus on the panels. During this pressing, the slot (23) and the bevels (75) are also formed; these are covered with the melaminized printed paper sheet. In this process, the bevels are partially pressed into the substrate, and a so-called “pressed bevel” can thus be formed. The slot (23) is a component of the tongue (7), which can be provided over an extensive upper surface with melaminized printed paper.

[0160] The pressed board (78) is then sawn along sawing lines (60, 61), after which the coupling parts (66) can be formed on the edges of the panels, preferably by means of milling operations. It is also possible to mill a contact surface on the top edge of the tongue; narrow tolerances for this contact surface can be achieved in this way. If this contact surface is milled on the top edge of the tongue, then during milling, the melaminized printed paper at this position is milled away.