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Title:
PANELS COMPRISING A MECHANICAL LOCKING DEVICE AND AN ASSEMBLED PRODUCT COMPRISING THE PANELS
Document Type and Number:
WIPO Patent Application WO/2019/182505
Kind Code:
A1
Abstract:
A set of panels including a first panel (2) with a first main plane and a second panel (4) with a second main plane. The first and the second panel includes a mechanical locking device which is configured for locking a first edge of the first panel (2) to a second edge of the second panel (4) at a junction plane (J). The first main plane is essentially perpendicular to the second main plane and the junction plane is extending between the first main plane and the second main plane. The mechanical locking device includes at the first edge an edge tongue (22) which extends from the junction plane (J) and at the second edge includes an edge groove (21) at the junction plane. The edge tongue is configured to cooperate with the edge groove for locking together the first and the second edges in a first direction (D1) which is perpendicular to the first main plane. The mechanical locking device includes a dowel (91) at the first edge and a dowel groove (92) at the second edge. The dowel (91) is configured to cooperate with the dowel groove (92). A centreline (97) of the dowel (91) is positioned at a first distance (93) in the first direction from an outer corner (95) of the first panel (2). The dowel groove (92) is positioned at a second distance (94) in the first direction from an outer corner (96) of the second panel (4) and the second distance (94) is greater than the first distance (93).

Inventors:
DERELÖV, Peter (Lärkvägen 4 A, HELSINGBORG, 252 84, SE)
SVENSSON, Johan (Bunkegatan 10, Nyvång, SE-265 50, SE)
GUNNARSSON, Lars (Västergatan 19A, ÅSTORP, SE-265 34, SE)
Application Number:
SE2019/050259
Publication Date:
September 26, 2019
Filing Date:
March 22, 2019
Export Citation:
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Assignee:
VÄLINGE INNOVATION AB (Prästavägen 513, VIKEN, SE-263 65, SE)
International Classes:
F16B12/24; A47B47/02; F16B5/00
Domestic Patent References:
WO2017131574A12017-08-03
Foreign References:
US20130071172A12013-03-21
DE202004017486U12006-04-13
US20160174704A12016-06-23
DE102014110124A12016-01-21
US20120279161A12012-11-08
Attorney, Agent or Firm:
ENGSTRAND, Ola (Välinge Innovation AB, Prästavägen 513, VIKEN, SE-263 65, SE)
Download PDF:
Claims:
CLAIMS

1. A set of panels comprising a first panel (2) with a first main plane and a second panel (4) with a second main plane, wherein the first and the second panel comprises a mechanical locking device which is configured for locking a first edge of the first panel (2) to a second edge of the second panel (4) at a junction plane (J), wherein the first main plane is essentially perpendicular to the second main plane and the junction plane is extending between the first main plane and the second main plane, wherein the mechanical locking device comprises:

at the first edge, an edge tongue (22) which extends from the junction plane (J); and

at the second edge, an edge groove (21) at the junction plane, wherein the edge tongue is configured to cooperate with the edge groove for locking together the first and the second edges in a first direction (D1) which is perpendicular to the first main plane, characterized in

that the mechanical locking device comprises a dowel (91) at the first edge and a dowel groove (92) at the second edge,

that the dowel (91) is configured to cooperate with the dowel groove (92),

that a centreline (97) of the dowel (91) is positioned at a first distance (93) in the first direction from an outer corner (95) of the first panel (2),

that the dowel groove (92) is positioned at a second distance (94) in the first direction from an outer corner (96) of the second panel (4), and

that the second distance (94) is greater than the first distance (93).

2. The set as claimed in claim 1 , wherein a difference between the second distance (94) and the first distance (93) is within the range of about 0,1 mm to about 0,5mm, or is about 0,3mm.

3. The set as claimed in claim 1 or 2, the dowel (91) is attached to another dowel groove (99) at the first edge.

4. The set as claimed in any one of the claims 1-3, wherein the dowel (91) is of a cylindrical shape.

5. The set as claimed in any one of the claims 1-4, wherein the dowel (91) made from one or more of a wood based material, a polymer material, preferably with a

reinforcement, such as glass fibre or a metal.

6. The set as claimed in any one of the claims 1-5, wherein edge tongue (22) is formed of a core material of the first panel and/or the edge groove (21) is formed of a core material of the second panel.

7. The set as claimed in any one of the claims 1-6, wherein the edge tongue (22) comprises a tongue groove (10) and the edge groove (21) comprises a flexible tongue (30), preferably arranged in an insertion groove (20), and wherein said flexible tongue is configured to cooperate with the tongue groove (10) for locking together the first and the second edges in a second direction (D2 ) which is perpendicular to the second main plane.

8. The set as claimed in any one of the claims 1-7, wherein the angle between the junction plane and the first main plane is about 45°.

9. The set as claimed in any one of the claims 1-8, wherein edge tongue (22) extends, from the junction plane, essentially in the second direction.

10. The set as claimed in any one of the claims 1-9, wherein the edge tongue (22) extends along essentially the entire length of the first edge in a longitudinal direction of the first edge and ends at a distance from a front edge (81) of the first panel (2).

1 1 The set as claimed in any one of the claims 1 -10, wherein the dowel (91) is positioned between the front edge (81) of the first panel (2) and the edge tongue (22).

12 The set as claimed in any one of the claims 1 -11 , wherein the edge groove (21) extends along essentially the entire length of the second edge in a longitudinal direction of the second edge and ends at a distance from a front edge (82) of the second panel (4).

Description:
PANELS COMPRISING A MECHANICAL LOCKING DEVICE AND AN ASSEMBLED PRODUCT COMPRISING THE PANELS

Technical Field

Embodiments of the present invention relate to panels that may be arranged perpendicular to each other and locked together with a mechanical locking device. The panels may be assembled and locked together to obtain a furniture product, such as a bookshelf, a cupboard, a wardrobe, a box, a drawer or a furniture component. The locking device may comprise a flexible tongue.

Background

A furniture product provided with a mechanical locking device is known in the art, as evidenced by WO 2017/131574. The furniture comprises a first panel connected perpendicular to a second panel by a mitre joint which includes a mechanical locking device.

Summary

One object of certain embodiments of the present invention is to provide an

improvement over the above described technique and the known art. A specific objective is to improve assembling of panels, such as furniture panels, locked together by a mechanical locking device and to increase the strength of the mechanical locking device or reduce visible gaps in the joint. The panels may be a part of a furniture product, such as a furniture component, a drawer, a cupboard, a bookshelf, a wardrobe, a kitchen fixture, or a box.

At least some of these and other objects and advantages that will be apparent from the description have been achieved by a first aspect of the invention that includes a set of panels comprising a first panel with a first main plane and a second panel with a second main plane. The first panel and the second panel comprise a mechanical locking device which is configured for locking a first edge of the first panel to a second edge of the second panel at a junction plane. The first main plane is essentially perpendicular to the second main plane and the junction plane is extending between the first main plane and the second main plane. The mechanical locking device comprises: at the first edge, an edge tongue which extends from the junction plane; and, at the second edge, an edge groove at the junction plane, wherein the edge tongue is configured to cooperate with the edge groove for locking together the first and the second edges in a first direction which is perpendicular to the first main plane. The mechanical locking device further comprises a dowel at the first edge and a dowel groove at the second edge. The dowel is configured to cooperate with the dowel groove. A centreline of the dowel is positioned at a first distance in the first direction from an outer corner of the first panel. The dowel groove is positioned at a second distance in the first direction from an outer corner of the second panel. The second distance is greater than the first distance.

The dowel and the dowel groove and their positions are configured such that the first edge is pressed against the second edge. This may have the effect that a gap at the junction plane is avoided or diminished when the first edge and/or the second edge have/has a curved shape. Such a gap is particularly undesired at the front edges of the panels.

A difference between the second distance and the first distance may be within the range of about 0, 1 mm to about 0,5mm, or is about 0,3mm.

The dowel may be attached to another dowel groove at the first edge.

The dowel may be attached to the dowel groove at the second edge before the first and the second panels are assembled and locked together with the mechanical locking device. Thus, the dowel is in this embodiment inserted in said another dowel groove, at the first edge, during the assembling.

The dowel may be of a cylindrical shape.

The dowel may comprise locking elements, such as flanges, barbs or ribs.

The dowel may be made from one or more of a wood based material, a polymer material, preferably with a reinforcement, such as glass fibre or a metal.

The edge tongue may be formed of a core material of the first panel and/or the edge groove may be formed of a core material of the second panel.

The edge tongue may comprise a tongue groove and the edge groove may comprise a flexible tongue, preferably arranged in an insertion groove, and wherein said flexible tongue is configured to cooperate with the tongue groove for locking together the first and the second edges in a second direction which is perpendicular to the second main plane.

The angle between the junction plane and the first main plane may be about 45°.

The edge tongue may extend, from the junction plane, essentially in the second direction.

The edge tongue may extend along essentially the entire length of the first edge in a longitudinal direction of the first edge and ends at a distance from a front edge of the first panel. The dowel may be positioned between the front edge of the first panel and the edge tongue.

The edge groove may extend along essentially the entire length of the second edge in a longitudinal direction of the second edge and ends at a distance from a front edge of the second panel.

The flexible tongue may be displaceable in the insertion groove.

A core material of the first and the second panel may comprise a wood fibre based board, such as a HDF, MDF, plywood, solid wood or particleboard, or a reinforced plastic board or a wood fibre composite board. The core may be provided with a decorative layer.

The locking device may comprise a bevel or rounding at an opening of the tongue groove. This may facilitate disassembling as the bevel or the rounding may prevent that the flexible tongue got stuck during the disassembling.

The locking device is preferably configured such that the flexible tongue moves out of the tongue groove when a tool is inserted into the tongue groove and pushed back into the insertion groove.

The first panel and the second panel are preferably configured to be assembled by displacing the first panel relative the second panel in the second direction, wherein the first panel is perpendicular to the second panel. The edge tongue is inserted into the edge groove, wherein the flexible tongue is pushed back into the insertion groove and springs back into the tongue groove to obtain a locked position.

The flexible tongue may be according to the flexible tongue described and shown in FIGS 2A-2F or FIG 3A-3B in WO 2015/105449. FIGS 2A-2F or FIG 3A-3B, and accompanying disclosure in the specification, in WO 2015/105449 are hereby expressly incorporated by reference.

The set of panels may be furniture panels.

A second aspect of the invention includes an assembled furniture product comprising a corner of a frame comprising the set of panels as described above.

Brief description of the drawings

These and other aspects, features and advantages of which embodiments of the invention are capable of, will be apparent and elucidated from the following description of embodiments of the present invention, reference being made to the accompanying drawings, in which FIG 1 shows an embodiment of an assembled furniture product

FIG 2 shows an embodiment of the first panel and the second panel locked together with an embodiment of the mechanical locking device.

FIG 3 shows an enlargement of the encircled area in FIG 2 without the flexible tongue.

FIGS 4A-4F show a part of an embodiment of the invention comprising an embodiment of the flexible tongue.

FIG 5A shows an embodiment of two panels assembled with a mitre joint.

FIG 5B shows an enlargement of the encircled area in FIG 5A.

FIG 6A shows an embodiment of the first panel in a bottom view.

FIG 6B shows an embodiment of the first panel in a side view.

FIG 6C shows an embodiment of the first panel in a 3D view.

FIG 7A shows an embodiment of the second panel in a bottom view.

FIG 7B shows an embodiment of the second panel in a side view.

FIG 7C shows an embodiment of the second panel in a 3D view.

FIG 8 shows an embodiment of the first panel and the second panel locked together with an embodiment of the mechanical locking device.

FIG 9 shows an enlargement of a corner part of an embodiment of the first panel and the second panel, without the flexible tongue, before assembling.

FIG 10 shows an enlargement of a corner part of an embodiment of the first panel and the second panel, without the flexible tongue, before assembling.

Detailed description

Specific embodiments of the invention now will be described with reference to the accompanying drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. The terminology used in the detailed description of the embodiments illustrated in the accompanying drawings is not intended to be limiting of the invention. In the drawings, like numbers refer to like elements. An embodiment of an assembled product, such as a furniture product, comprising panels joined together with mitre joints is shown in FIG 1.

Embodiments of the invention concern a set of panels, comprising a mechanical locking device, for an assembled product, such as illustrated in FIG 1 in a 3D view.

FIG 2 shows an embodiment including a set of panels comprising a first panel 2 with a first main plane and a second panel 4 with a second main plane. FIG 3 shows an enlargement of the encircled area in FIG 2 without the flexible tongue. The first panel and the second panel are provided with a mechanical locking device for locking a first edge of the first panel 2 to a second edge of the second panel 4 at a junction plane J. The first main plane is essentially perpendicular to the second main plane and the junction plane is extending between the first main plane and the second main plane.

The panels are shown in a locked position in a crosscut view. A longitudinal direction of the first edge and the second edge extends perpendicular to the view shown. The first edge comprises an edge tongue 22 that extends from the junction plane J. The second edge comprises an edge groove 21 at the junction plane, wherein the edge tongue is configured to cooperate with the edge groove for locking together the first and the second edges in a first direction D1 which is perpendicular to the first main plane.

The edge tongue 22 comprises a tongue groove 10. The edge groove 21 comprises a flexible tongue 30 arranged in an insertion groove 20, said flexible tongue is configured to cooperate with the tongue groove 10 for locking together the first and the second edges in a second direction D2 which is perpendicular to the second main plane.

The mechanical locking device may comprise a first space 46 between the edge tongue 22 and the edge groove 21 at an opening of the edge groove 21 and at the junction plane in a locked position of the first and the second edge. The first space 46 may have the advantage that a loading of a part of the second edge at the opening of the edge groove is avoided. This part of the second edge may be a weak part, since little material is available to absorb a load. The angle 74 between the junction plane and the first main plane may be about 45°. The edge tongue 22 preferably extends, from the junction plane, essentially in the second direction.

The first panel 2 has a first thickness 65 and the second panel 4 has a second thickness 64. The first and the second thickness may be essentially the same. The first panel 2 comprises an inner half 66, at a first side of a central plane 68 of the first panel, and an outer half 67, at second side of the central plane 68 of the first panel, in a direction of the thickness of the first panel. The entire edge tongue 22 is preferably at the inner half of the first panel. This may have the effect that more material is obtained between the edge groove 21 and an outer corner, in a locked position of the first and the second panel, which may increase the strength of the mechanical locking device. The first panel comprises an inner face 60 and an outer face 61 . The second panel comprises an inner face 62 and an outer face 63.

FIG 3 shows that a first side of the edge tongue 22 may comprise, at the junction plane J, a first locking surface 41 , and the edge groove 21 may comprises, at the junction plane J, a second locking surface 40. The first locking surface and the second locking surface are essentially parallel and are configured to cooperate for locking in the first direction. The first locking surface and the second locking surface preferably extend essentially in the second direction. The edge tongue 22 at a second side, which is opposite the first side, may comprise a third locking surface 43 and the edge groove 21 may comprise a fourth locking surface 42, wherein the third locking surface and the fourth locking surface are essentially parallel and are configured to cooperate at a distance from the junction plane for locking in the first direction. The third locking surface and the fourth locking surface are preferably extending essentially in the second direction. Said parallel first, second, third and fourth locking surface may have the advantage that panels are easy to assemble and that, e.g., a furniture comprising said set of panels may be more stable. The fourth locking surface 42 is preferably closer to the central plane 68 than the second locking surface 40.

The third locking surface 43 and the fourth locking surface 42 may cooperate, to absorb a load, at an area extending over a first distance 47 in the second direction. The third locking surface and the fourth locking surface are preferably displaced from the junction plane by a second distance 48. This may have the effect that more material is obtained, in the first direction D1 , between the fourth locking surface 42 and the junction plane, which may increase the strength of the mechanical locking device. The first distance 47 may be within the range of about 20% to about 200% of the second distance 48 or within the range of about 50% to about 150% of the second distance 48. The first 47 distance is essentially the same as the second distance 48 in the embodiment shown in FIG 3.

The first side of the edge tongue 22, at a distance from the junction plane, may comprise a fifth locking surface 45 and the edge groove 21 may comprise a sixth locking surface 44 at a distance from the junction plane J. The fifth locking surface and the sixth locking surface are essentially parallel and are preferably configured to cooperate for locking in the first direction. The fifth locking surface and the sixth locking surface are preferably extending essentially in the second direction. The insertion groove 20 is, in the embodiment shown FIG 3, positioned between the sixth locking surface 44 and the second locking surface 40. The tongue groove 10 may be positioned between the fifth locking surface 45 and the first locking surface 41.

The first panel 2 and the second panel 4 are preferably configured to be assembled by displacing the first panel 2 relative the second panel 4 in the second direction D2, wherein the first panel is perpendicular to the second panel. The edge tongue 22 is inserted into the edge groove 21 , wherein the flexible tongue 30 is pushed back into the insertion groove and springs back into the tongue groove 10 to obtain a locked position. The set of panels may be furniture panels.

The insertion groove 20 may extend along essentially the entire length of the edge groove.

FIG 5A shows panels 102, 104 that are joined with a mitre joint and FIG 5B shows an enlargement of the encircled area in FIG 5A. The panels 102, 104 may show a gap 85 at the mitre joint at the front edges 81 , 82 of the panels if one of the panels has a curved shape 86 along an edge at the mitre joint. The panels may have obtained the curved shape due to a load and, e.g., wood based panels may have obtained the curved shape due to a humidity change.

FIG 6A-C shows an embodiment of the first panel in a bottom view, in a side view, and in a 3D view, respectively. The embodiment of the first panel comprises an embodiment of the edge tongue 22 which extends along essentially the entire length of the first edge in a longitudinal direction of the first edge and ends at a front end 87 at a distance from a front edge 81 of the first panel 2. The dowel 91 may be positioned at distance from the front edge 81 of the first panel 2. The dowel 91 may be positioned between the front end 87 of the edge tongue 22 and the front edge 81 of the first panel 2.

FIG 7A-C shows an embodiment of the second panel in a bottom view, in a side view, and in a 3D view, respectively. The edge groove 21 may extend along essentially the entire length of the second edge in a longitudinal direction of the second edge and end at a front end 88 at a distance from a front edge 82 of the second panel 4. The dowel groove 92 may be positioned at distance from the front edge 82 of the second panel 4. The dowel groove 92 may be positioned between the front end 88 of the edge groove 21 and the front edge 82 of the second panel 4.

FIG 8 shows an embodiment of the first panel and the second panel locked together with an embodiment of the mechanical locking device and FIG 9 and 10 shows an enlargement of a corner part of an embodiment of the first panel and the second panel, without the flexible tongue 30, before assembling. The embodiment shown in FIG 6-8 comprises a first panel with a first main plane and a second panel with a second main plane, wherein the first and the second panel comprises a mechanical locking device which is configured for locking a first edge of the first panel 2 to a second edge of the second panel 4 at a junction plane J. The first main plane is essentially perpendicular to the second main plane and the junction plane is extending between the first main plane and the second main plane. The mechanical locking device comprises at the first edge an edge tongue 22 which extends from the junction plane J and at the second edge comprises an edge groove 21 at the junction plane. The edge tongue is configured to cooperate with the edge groove for locking together the first and the second edges in a first direction D1 which is perpendicular to the first main plane.

FIG 9 shows an embodiment of the mechanical locking device which comprises a dowel 91 at the first edge and a dowel groove 92 at the second edge, wherein the dowel 91 is configured to cooperate with the dowel groove 92. A centreline 97 of the dowel 91 is positioned at a first distance 93 in the first direction from an outer corner 95 of the first panel 2. The dowel groove 92 is positioned at a second distance 94 in the first direction from an outer corner 96 of the second panel 4, and the second distance 94 is greater than the first distance 93.

A difference between the second distance 94 and the first distance 93 may be within the range of about 0,1 mm to about 0,5mm, or is about 0,3mm.

FIG 10 shows an embodiment of the mechanical locking device which comprises a dowel 91 at the first edge and a dowel groove 92 at the second edge. An outer surface 105 of the dowel 91 is configured to cooperate with an outer surface 106 of the dowel groove 92. The outer surface 105 of the dowel 91 is positioned at a third distance 107 in the first direction from an outer corner 95 of the first panel 2. The outer surface 106 of the dowel groove 92 is positioned at a fourth distance 108 in the first direction from an outer corner 96 of the second panel 4, and the fourth distance 108 is greater than the third distance 107.

The outer surface 105 of the dowel 91 may be parallel to the outer surface 61 of the first panel 2.

The outer surface 105 of the dowel 91 may be the surface of the dowel which is closest, in the first direction, the outer corner 95 of the first panel 2.

The outer surface 106 of the dowel groove 92 may be perpendicular to the outer surface 63 of the second panel 4. The outer surface 106 of the dowel groove 92 may be the surface of the dowel groove which is closest, in the first direction, the outer corner 96 of the second panel 4.

A difference between the fourth distance 108 and the third distance 107 may be within the range of about 0,1 mm to about 0,5mm, or is about 0,3mm

The dowel 91 may be attached to another dowel groove 99 at the first edge.

The dowel may be attached to the dowel groove 92 at the second edge before the first 2 and the second 4 panels are assembled and locked together with the mechanical locking device. Thus, the dowel is, in this embodiment, inserted in said another dowel groove 99, at the first edge, during the assembling.

The dowel 91 may be of a cylindrical shape. The diameter may be in the range of about 5mm to about 8 mm.

The dowel groove 92 and/or the said another dowel groove 99 may be of an essentially cylindrical shape, such as a drill hole or a bottomed drill hole. The diameter may be in the range of about 5 mm to about 8 mm

The dowel 91 may be made from one or more of a wood based material, a polymer material, preferably with a reinforcement, such as glass fibre or a metal.

The edge tongue 22 may formed of a core material of the first panel and or at least partly in a surface layer of the first panel. The edge groove 21 may be formed of a core material of the second panel and/or at least partly in a surface layer of the second panel. The edge tongue 22 may formed of material separate from the core material of the first panel. The edge groove 21 may be formed of a material separate from the core material of the second panel.

The edge tongue 22 may comprises a tongue groove 10 and the edge groove 21 may comprise a flexible tongue 30, preferably arranged in an insertion groove 20, and wherein said flexible tongue is configured to cooperate with the tongue groove 10 for locking together the first and the second edges in a second direction D2 which is perpendicular to the second main plane.

The angle between the junction plane and the first main plane may be about 45°.

The edge tongue 22 may extend, from the junction plane, essentially in the second direction.

The edge tongue 22 may extend along essentially the entire length of the first edge in a longitudinal direction of the first edge and ends at a distance from a front edge 81 of the first panel 2. The dowel 91 may be positioned between the front edge 81 of the first panel 2 and the edge tongue 22.

The edge groove 21 may extend along essentially the entire length of the second edge in a longitudinal direction of the second edge and ends at a distance from a front edge 82 of the second panel 4.

The flexible tongue 30 may be displaceable in the insertion groove.

The locking device is preferably configured such that the flexible tongue 30 moves out of the tongue groove 10 when a tool is inserted into the tongue groove and pushed back into the insertion groove.

The insertion groove 20 may be parallel to the second main plane or at an acute angle 75 to the second main plane, such that a bottom of the insertion groove 20 is at a greater distance from an inner face 62 of the second panel than an opening of the insertion groove to the edge groove.

The locking device may comprise a bevel or rounding at an opening of the tongue groove. This may facilitate disassembling as the bevel or the rounding may prevent the flexible tongue from getting stuck during the disassembling.

The set of panels as described above may be a part of an assembled furniture product, such as a corner of a frame. The tongue groove 10 may be open at a backside of the furniture, such that a tool may be inserted into the tongue groove to push back the flexible tongue 30 into the insertion groove 20 and unlock the locking device.

A core material of the first and the second panel may comprise a wood fibre based board, such as a HDF, MDF, plywood, solid wood or particleboard, or a reinforced plastic board or a wood fibre composite board. The core may be provided with a decorative layer. Parts of the locking device may be formed, preferably by mechanical cutting, such as milling, of material of the first and the second panel.

An embodiment of the flexible tongue 30, which is displaceable in an insertion groove 20, is shown in FIGS 4A-4D. FIGS 4A-4B show the flexible tongue 30 in a locked potion and FIGS 4C-4D show the flexible tongue 30 during assembling of the first panel 2 and the second panel 4. FIG 4B shows a cross section of the flexible tongue 30 in FIG 4A. FIG 4D shows a cross section of the flexile tongue 30 in FIG 4C. The flexible tongue 30 comprises bendable protruding parts 24. A space 23 is provided between the flexible tongue 30 and a bottom wall of the insertion groove 20. FIG 4C shows that the flexible tongue 30 is pushed into the insertion groove 20 and towards the bottom wall of the insertion groove 20 during an assembly of the first panel 2 with the second panel 4. The flexible tongue 30 springs back toward its initial position when the first panel 2 and the second panel 4 have reached a locked position. A recess 25 is preferably arranged at each bendable protruding part.

The flexible tongue 30 may have a first displacement surface 26 and an opposite second displacement surface 27, configured to be displaced along a third displacement surface 28 and a fourth displacement locking surface 29, respectively, of the insertion groove 20.

An alternative embodiment of the flexible tongue 30, without the protruding bendable parts 24, is shown in FIGS 4E-4F. FIG 4F shows a cross section of the flexible tongue 30 shown in FIG 4E. The alternative embodiment is bendable in its length direction in order to accomplish the same function as the embodiment shown in FIGS 4A-4D.