Abstract
Floor panels are shown, which are provided with a mechanical locking system that may be locked with a vertical displacement of a first panel against a second panel. The locking system includes a first rigid and a second flexible joint edge section with different locking functions. The first edge section provides a horizontal locking and the second section provides a vertical locking.
Claims
1. A set of essentially identical floor panels provided with a mechanical locking system comprising a strip extending horizontally from a lower part of a first edge of a first panel and a downwardly open locking groove formed in an adjacent second edge of a second panel, the strip comprising an upwardly protruding locking element which is configured to cooperate with the locking groove for locking the first edge and the second edge in a horizontal direction parallel to a main plane of the panels and in a vertical direction perpendicularly to the horizontal direction, wherein the locking element and the locking groove comprise an upper and a lower locking surface which are configured to lock the panels vertically, wherein the strip comprises slits located along the first edge, and a slit wall is configured to be bended horizontally inwardly towards an inner part of the first panel during locking, wherein the locking system in a locked position and along the edges comprises a first rigid edge section and a second flexible edge section comprising one of the slits, and that the first rigid edge section is configured such that the locking element is in contact with the locking groove and the second flexible edge section is configured such that there is a space (S) between an inner surface of the locking element and an outer groove wall of the locking groove.
2. The set as claimed in claimed in claim 1, wherein a cross section of the locking groove (14) or a cross section of the locking element varies along the first and the second edge.
3. The set as claimed in claim 1, wherein the slit wall is further configured to be bended at least partly back to an initial position of the slit wall during a final stage of the locking.
4. The set as claimed in claim in claim 1, wherein the edge of the first panel comprises upper and lower stabilizing surfaces that in the locked position overlap each other and prevent an upward bending of the slit wall.
5. The set as claimed in claim 1, wherein the first edge and the second edge are locked with vertical pretension between upper and lower support surfaces and between the upper and lower locking surfaces.
6. A set of essentially identical floor panels provided with a mechanical locking system comprising a strip extending horizontally from a lower part of a first edge and a downwardly open locking groove formed in an adjacent second edge, wherein the strip comprises a first and a second upwardly protruding locking element, the first locking element being located closer to an upper edge of the first edge than the second locking element, wherein the first locking element comprises an upper locking surface at its upper and outer part, wherein the second edge comprises a downwardly extending protrusion comprising a lower locking surface at its outer and lower part, the second locking element being configured to cooperate with the locking groove and to lock the first and the second edge in a horizontal direction parallel to a main plane of a first and a second panel and the upper and lower locking surfaces being configured to lock the adjacent edges in a vertical direction perpendicularly to the horizontal direction, wherein that the first and the second edge in a locked position comprise a first edge section and a second edge section along the first and the second edge, that a cross section of the first locking element or a cross section of the protrusion varies along the first and/or the second edge, that the second edge section comprises a first and a second slit extending side by side along the edge, that the first slit is located closer to the upper part of the first edge than the second slit, that the second slit is formed between the first and the second locking elements, that the locking system is configured to be locked with a vertical displacement of the second edge against the first edge, and that a part of the first locking element and a slit wall of the first and the second slits during an initial stage of the vertical displacement is configured to bend horizontally inwards towards an inner part of the first panel and during a final stage of the vertical displacement is configured to bend outwards towards an initial position of said part.
7. The set as claimed in claim 6, wherein the first edge comprises upper and lower stabilizing surfaces that in the locked position overlap each other and prevent an upward bending of one of the slit walls.
8. A set of essentially identical floor panels provided with a mechanical locking system comprising a strip extending horizontally from a lower part of a first edge and a downwardly open locking groove formed in an adjacent second edge, wherein the strip comprises an upwardly protruding locking element comprising an upper locking surface at its upper and inner part and the locking groove comprises a lower locking surface at its outer and lower part, the locking element being configured to cooperate with the locking groove and to lock the first and the second edge in a horizontal direction parallel to a main plane of a first and a second panel, the upper and lower locking surfaces being configured to lock the adjacent edges in a vertical direction perpendicularly to the horizontal direction, wherein that the first and the second edge in a locked position comprise a first edge section and a second edge section along the first and the second edge, that a cross section of the locking element (8) or a cross section of the locking groove varies along the first and/or the second edge, that the strip of the second edge section comprises a slit extending along at least a part of the first edge, the slit being located between the locking element and an upper edge of the first edge, that the locking system is configured to be locked with a vertical displacement of the second edge against the first edge, and that a part of the locking element and a slit wall during an initial stage of the vertical displacement is configured to bend horizontally outwardly and during a final stage of the vertical displacement is configured to bend inwardly towards an initial position of said part.
9. The set as claimed in claim 8, wherein the first edge comprises upper and lower stabilizing surfaces that in the locked position overlap each other and prevent an upward bending of a part of the locking element.
10. A set of essentially identical floor panels provided with a mechanical locking system comprising a strip extending horizontally from a lower part of a first edge and a downwardly open locking groove formed in an adjacent second edge, wherein the strip comprises an upwardly protruding locking element and the second edge comprises a downwardly extending protrusion comprising a lower locking surface at its lower and outer part, the locking element being configured to cooperate with the locking groove and to lock the first and the second edge in a horizontal direction parallel to a main plane of a first and a second panel, characterized in wherein that the first and the second edge in a locked position comprise a first edge section and a second edge section along the first and the second edge, that a cross section of the protrusion varies along the first and/or the second edge, that the second edge section comprises a first and a second slit extending side by side along the first edge, the first slit being located closer to an upper part (25) of the first edge than the second slit, that the second slit is configured to accommodate the protrusion and the lower locking surface such that the lower locking surface locks against an upper locking surface located at a lower and inner part of the second slit and locks the first and second edges in a vertical direction, that the locking system is configured to be locked with a vertical displacement of the second edge against the first edge, and that a flexible strip part located between the first and the second slit during an initial stage of the vertical displacement is configured to bend horizontally inwardly and during a final stage of the vertical displacement is configured to bend outwardly towards an initial position of the flexible strip part.
11. The set as claimed in claim 10 wherein the first edge comprises upper and lower stabilizing surfaces that in locked position overlap each other and prevent an upward bending of the flexible strip part.
12. A set of essentially identical floor panels provided with a mechanical locking system comprising a strip extending horizontally from a lower part of a first edge and a first and a second downwardly open locking grooves formed in an adjacent second edge, wherein the first locking groove is located closer to an upper edge of the first edge than the second locking groove, wherein the strip comprises a first upwardly protruding locking element and a second locking element, the first locking element being located closer to the upper edge than the second locking element, wherein the second edge comprises a downwardly extending protrusion comprising a lower locking surface at its lower and inner part, the first locking element being configured to cooperate with the first locking groove and to lock the first and the second edge in a horizontal direction parallel to a main plane of a first and a second panel, wherein that the first and the second edge in a locked position comprise a first edge section and a second edge section along the first and the second edge, that a cross section of the protrusion varies along the first and/or the second edge, that the second edge section comprises a slit configured to accommodate the protrusion and the lower locking surface such that the lower locking surface locks against an upper locking surface located at a lower and inner part of the second locking element and locks the edges in a vertical direction, that the locking system is configured to be locked with a vertical displacement of the second edge against the first edge, and that the second locking element during an initial stage of the vertical displacement is configured to bend horizontally and outwardly and during a final stage of the vertical displacement is configured to bend inwardly towards an initial position of the second locking element.
13. The set as claimed in claim 12, wherein the first edge comprises upper and lower stabilizing surfaces that in locked position overlap each other and prevent an upward bending of the second locking element.
14. A set of essentially identical floor panels provided with a mechanical locking system comprising a strip formed in one piece with a core of a first panel and extending horizontally from a lower part of a first edge of the first panel and a downwardly open locking groove formed in an adjacent second edge of a second panel, the strip comprising an upwardly protruding locking element which is configured to cooperate with the locking groove for locking the first edge and the second edge in a horizontal direction parallel to a main plane of the panels and in a vertical direction perpendicularly to the horizontal direction, wherein the locking element and the locking groove comprise an upper and a lower locking surface which are configured to lock the panels vertically, wherein the strip comprises slits located along the first edge, and a slit wall is configured to be bended horizontally inwardly towards an inner part of the first panel during locking, wherein the core has a higher content of cured resins at a lower and outer part than at a lower and inner part.
15. The set as claimed in claim 14, wherein the resin is a thermosetting resin.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0097] The disclosure will in the following be described in connection to exemplary embodiments and in greater detail with reference to the appended exemplary drawings, wherein:
[0098] FIGS. 1a-d illustrates main principles according to an embodiment of the invention.
[0099] FIGS. 2a-e illustrate production methods to form locking systems.
[0100] FIGS. 3a-b illustrate production methods to form locking systems.
[0101] FIGS. 4a-b illustrate production methods to form locking systems.
[0102] FIGS. 5a-b illustrates punching and carving of core material.
[0103] FIGS. 6a-e illustrate an embodiment of a first principle of the invention.
[0104] FIGS. 7a-f illustrate locking according to a first principle.
[0105] FIGS. 8a-h illustrate forming a locking system designed according to the first principle.
[0106] FIGS. 9a-d illustrate forming a locking system designed according to the first principle.
[0107] FIGS. 10a-d illustrate an edge of a panel comprising a locking system according to an embodiment of the first principle.
[0108] FIGS. 11a-d illustrate an edge of a panel comprising a locking system according to an embodiment of the first principle.
[0109] FIGS. 12a-c illustrate an edge of a panel comprising a locking system according to an embodiment of the first principle.
[0110] FIGS. 13a-c illustrate an edge of a panel comprising a locking system according to an embodiment of the first principle that is formed with punching.
[0111] FIGS. 14a-g illustrate an embodiment of a locking system according to a second principle of the invention.
[0112] FIGS. 15a-b illustrate embodiments with increased locking strength and reduced friction.
[0113] FIGS. 16a-f illustrate an embodiment of a locking system according to a third principle of the invention.
[0114] FIGS. 17a-g illustrate an embodiment of a locking system according to the third principle of the invention.
[0115] FIGS. 18a-d illustrate an embodiment of a locking system according to a fourth principle of the invention.
[0116] FIGS. 19a-b illustrate an embodiment of a locking system according to the fourth principle of the invention.
[0117] FIGS. 20a-f illustrate an embodiment of a locking of a locking system according to the fourth principle of the invention.
[0118] FIGS. 21a-d illustrate an embodiment of a locking system according to a fifth principle of the invention.
[0119] FIGS. 22a-h illustrate a locking and a forming of a locking system according to the fifth principle of the invention.
[0120] FIGS. 23a-h illustrate embodiments according to the fifth principle of the invention.
[0121] FIGS. 24a-f illustrate an embodiment of a locking system according to a sixth principle of the invention.
[0122] FIGS. 25a-f illustrate an embodiment a locking system according to a seventh principle of the invention.
[0123] FIGS. 26a-d illustrate forming of locking systems with screw cutters, jumping tools, rotating tools and carving according to an embodiment of the invention.
[0124] FIGS. 27a-b illustrate an embodiment of a locking system for furniture components according to an eighth principle of the invention.
[0125] FIGS. 28a-d illustrate a method to strengthen edge portions according to an embodiment.
DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION.
[0126] The embodiments in FIGS. 1a-1d are used to explain some main problems related to flexible locking elements made in one piece with a core and some basic principles of the inventive concept.
[0127] Locking systems comprising flexible and bendable parts formed in one piece with the core are to a major extent dependent of the material properties and thickness of the core that may vary between various core materials and between the same type of core materials. Each locking system must be formed with a specific geometry that is optimized in relation to the properties and thickness of the specific floor panel. This means that a locking system must provide a variety of alternative geometries and principles that could be combined in order to meet the requirements of normal tolerances used in a cost efficient high speed production, locking strength, easy and reliable installation. The inventive concept provides several principles that may be combined and may be used to form a locking system in a specific floor panel.
[0128] FIG. 1a is a plan view of an edge of a first 1 and a second 1′ panel according to an embodiment. A cutting tool, for example a jumping tool head, a rotating carving tool or a punch, may be used to cut an upwardly and downwardly open slit 20 in the core material 5 and a flexible tongue 10 comprising a locking surface 11 may be formed adjacent to the slit 20. The flexible tongue 10 is provided outwardly of the slit 20. The slit 20 comprises an outer slit wall 20a, an inner slit wall 20b and two slit sidewalls 20c, 20d. The slit and the tongue have a length direction L along the joint and a thickness T in the vertical direction as shown in FIG. 1c. The flexible tongue 10 has a width W in a horizontal direction that is perpendicular to the length direction and to the thickness direction. According to the present embodiment, the width W varies along the first edge in an unlocked position of the panels 1, 1′. Indeed, the width W is larger at a location of the locking surface 11, which protrudes outwardly in the horizontal direction, than at a location along the edge next to the locking surface 11. Moreover, the open slit 20 has a width W′ in a horizontal direction which is perpendicular to the length direction and to the thickness direction. According to the present embodiment, in an unlocked position the width W′ is constant along the first edge as well as in the thickness direction.
[0129] FIG. 1b shows the flexible tongue 10 in FIG. 1a in a bended position when an edge of the second panel 1′ presses the flexible tongue 10 and the outer slit wall 20a inwardly during locking. During locking the locking surface 11 engages with the edge of the second panel 1′. Tests of various core materials, especially wood based core materials such as HDF, show that the tongue 10 generally comprises three tongue portions P1, P2, P3 with essentially different properties that will be described next in non-limiting embodiments. The two end portions P1 located close to the slit sidewalls 20c, 20d are only possible to bend slightly inwardly and cannot be used to accommodate a locking surface 11 that must be displaced over a specific distance in order to provide a sufficient locking strength. The middle section P3 may accommodate a locking surface but such tongue part is very easy to bend inwardly but also upwardly as shown in the embodiments in FIGS. 1c and 1d and the locking strength in this part of the flexible tongue is generally not sufficient. According to the present embodiment, only the two active portions P2 located between the end portions P1 and the middle portion P3 comprises sufficient flexibility and sufficient locking strengths. Known flexible tongues are such that only about 20% of the length L of the flexible tongue may be used for a vertical locking of adjacent edges. The major part of the tongue 10 is either not possible to bend or is too weak to provide a sufficient locking strength.
[0130] One solution to this problem would be to form a lot of small flexible tongues along the edge configured such that they are rather easy to bend horizontally inwardly during the vertical folding but hard to bend vertically upwards in locked position. This may be accomplished with several small flexible tongues that are not possible to form with the known production methods and especially not tongues which must be formed by rotating tools that form deep cavities in a core material and that are only open in one direction vertically or horizontally. One solution is to form the small tongues with a thickness T that is larger than the width W and this provides a horizontal flexibility that exceeds the vertical flexibility. Removal of material that may be accomplished by forming an open slit 20 or just by removing material from an edge provides major advantages related to forming of an appropriate joint geometry.
[0131] Another solution to this problem would be to form a locking system comprising a stabilizing edge section 17 as shown in FIG. 1c that may be used to prevent upward bending of the flexible tongue 10 in locked position. This may be accomplished with a locking system comprising a flexible tongue 10 that in a final locked position is slightly bended such that a part of the tongue 10 overlaps a stabilizing part 17 located above a part of the tongue. An advantage is that the stabilizing part will be most active at the weak middle portion P3 that may be most bended in locked position. Such geometry makes it possible to form flexible tongues 10 comprising sufficient locking strengths and flexibility along 50% or more of the tongue length L.
[0132] The locking system according to embodiments of the invention is three dimensional and comprises preferably a first rigid edge section 7a having a vertically protruding locking element 8 for horizontal locking and a second flexible edge section 7b comprising a flexible slit 20 that may be bended inwardly such that a distance between the outer 20a and inner 20b slit walls decreases during bending and/or outwardly such that the distance between the slit walls 20a, 20b increases during bending. The distance may be a minimal distance between the outer 20a and inner 20b slit walls. The first rigid edge section 7a and the second flexible edge section 7b are provided along the edges of the first 1 and second 1′ panels. In FIGS. 1a-d the second flexible edge section 7b is provided in a centre section of the edges of the panels 1, 1′ and first rigid edge sections 7a are provided on both sides of the second flexible edge section 7b. The first rigid edge sections 7a may be provided at corner sections of the edges. According to the present embodiment, there is no locking element 8 provided in the second flexible edge section 7b.
[0133] FIGS. 2-5 show production methods that may be used to form three-dimensional locking systems according to embodiments of the invention. In particular, the production methods may be used for producing cavities, protrusions, grooves and slits according to any of the principles of the present disclosure. FIG. 2a shows a tool comprising several rotating saw blades 40 that are displaced against a panel edge 1 and back again. Alternatively, the panel 1 may be displaced against the saw blades 40 and back again. This production method may be used to form cavities 37 or protrusions 36 as shown in FIGS. 2b and 2c.
[0134] FIG. 2d shows a top view of a so-called screw cutter 41. This is an advanced production technology that allows high precision and cost efficient forming of protrusions 36 and cavities 37 perpendicular to a panel edge 1 that is displaced in high speed against the screw cutter. WO 2010/087752 provides a detailed description of the screw cutter principle. The resulting protrusions 36 and cavities 37 are shown in FIG. 2e.
[0135] FIGS. 3a and 3b show a panel 1 with a surface 2 pointing downwards and carving tool 44 that may be used to formed an undercut groove 38 that is not possible to form with large rotating tools since a tangent line TL to a part of the undercut groove intersects the panel edge. The carving tool is fixed and the panel 1 is displaced against the carving tool. A more detailed description of carving may be found in WO 2013/191632.
[0136] FIG. 4a shows a so-called rotating jumping tool head 43 that may be displaced vertically or horizontally against a moving panel edge 1 and that may be used to form a slit 20. FIG. 4b is a side view of a jumping tool head that is displaced vertically up and down but also along the feeding direction of a panel 1. The jumping tool head may move horizontally parallel with the panel edge and with a speed that is somewhat lower than the speed of the panel. Several slits 20 may be formed one after each other in the feeding direction and at high speed. Several jumping tools may also be used. One jumping tool may form a first, a third and a fifth slit 20 and another jumping tool may form a second and a fourth slit.
[0137] FIG. 5a shows a rotating punching tool set 45 comprising a punching wheel 45a and a die wheel 45b. Such tools may be used to punch slits 20 or to remove material from a panel 1 comprising for example LVT, WPC or HDF material. The punching process produces residual material 21 that may be recycled. The punched slits may have various shapes, for example oval, circular or rectangular and the walls are preferably vertical. FIG. 5b shows another cost efficient method to form slits 20 with a rotating carving tool 48. The tool rotation is synchronized with the displacement of the panel 1 and each tooth 49 forms one slit at a predetermined position and with a predetermined horizontal extension along an edge of a panel 1. It is not necessary to displace the carving tool vertically. A carving tool 48 may have several sets of teeth 49 and each set may be used to form one cavity. The cavities may have different cross sections depending on the geometry of the teeth. The panel 1 may be displaced along or against the tool rotation.
[0138] FIG. 6a shows vertical folding of a second panel 1′ that is angled against a previously installed panel 1″ in a previous row and wherein this angling action also connect a short edge of the second panel 1′ to a short edge of a first panel 1. The short edges of the first 1 and the second 1′ panels are locked with a scissor like movement wherein the short edges are gradually locked from one long edge to the other long edge. The adjacent short edges of the first and the second panels 1, 1′ have along its edges a first joint edge section 7a that preferably becomes active during a first initial step of the folding action and a second joint edge 7b section that becomes active during a second stage of the folding action. It is clear that there may be additional joint edge sections 7a, 7b that subsequently become active. For example, the first joint edge section 7a and the second joint edge section 7b may be arranged alternately, e.g. as {7a, 7b, 7a, . . . , 7a, 7b, 7a} with first joint edge sections 7a at corner sections of the edges. As will be described below, the first joint edge section may be a first rigid edge section 7a and the second joint edge section may be a second flexible edge section 7b.
[0139] FIGS. 6b-6e show an embodiment according to a first principle of the invention. A set of similar floor panels 1, 1′ is provided wherein each floor panel preferably comprises a surface layer 2, a core 5, a balancing layer 3 and a first and a second short edge. As shown in FIG. 6b, the adjacent edges are initially formed with a geometry that only allows a locking with a sideways sliding action where the panel edges are inserted into each other with a horizontal displacement along the short edges. The panels are not possible to lock with angling, horizontal snapping or vertical snapping.
[0140] The edges are in a second step adjusted and a part of the material at the edges is removed as shown in FIGS. 6c and 6d such that a first short edge of a first floor panel 1 may be locked to an adjacent second edge of a similar second floor panel 1′ with a vertical displacement of the second edge against the first edge. The vertical displacement is a vertical scissor movement caused by the same angling action that is used to connect the long edges of the panels. The first edge comprises a horizontally protruding strip 6 with a vertically protruding locking element 8 at its outer part that cooperates with a downwardly open locking groove 14 formed in the adjacent second edge.
[0141] The locking element comprises an inner surface 8a, an outer surface 8b and an upper surface 8c. The inner surface 8a is closer to the upper edge 25 of the first panel 1 than the outer surface 8b. By upper edge 25 of the first panel 1 is meant an upper part of the first edge of the first floor panel 1. The locking groove 14 comprises an outer groove wall 14a, an inner groove wall 14b and an upper groove wall 14c. The outer groove 14a wall is closer to the upper edge 25′ of the second panel 1′ than the inner groove wall 14b. By upper edge 25′ of the second panel 1′ is meant an upper part of the second edge of the second floor panel 1′. The locking element 8 comprises an upper locking surface 11a formed in the outer surface 8b of the locking element 8 that in a locked position of the panels 1, 1′ cooperates with a lower locking surface 11b formed in the inner groove wall 14b and that locks the adjacent edges in a vertical direction. According to the present embodiment, the upper 11a and lower 11b locking surfaces are inclined against a horizontal plane. In non-limiting examples, the inclination angle may be between 0° and 45°, more preferably between 5° and 25°, e.g. 20°. The locking element 8 comprises a first locking surface 12a formed in the inner surface 8a of the locking element 8 that in a locked position cooperates with a second locking surface 12b formed in the outer groove wall 14a and that locks the adjacent edges in a horizontal direction. According to the present embodiment, the first 12a and second 12b locking surfaces are essentially vertical walls. The second edge comprises a projection 26 that is adapted to engage with an indentation 28 in the first edge in a locked position. The edges comprise lower and upper support surfaces 15, 16 that in a locked position cooperate with the upper and lower locking surfaces 11a, 11b and prevent the edges to be displaced vertically downwards and vertically upwards. According to the present embodiment, the lower support surface 15 is provided in the first panel 1 between the upper edge 25 and an inner surface 28a of the indentation 28, and the upper support surface 16 is provided in the second panel 1′ between the upper edge 25′ and an outer surface 26a of the projection 26. Moreover, the lower support surface 15 is provided adjacent to the upper edge 25 and the upper support surface 16 is provided adjacent to the upper edge 25′. According to the present embodiment, the lower and upper support surfaces 15, 16 are horizontal but it is understood that inclined lower and upper support surfaces are equally conceivable.
[0142] Adjacent edges comprise in locked position a first essentially rigid edge section 7a and a second flexible edge section 7b as shown in FIGS. 6c and 6d, respectively. The edge sections are characterized in that a cross section of the locking groove 14 and/or a cross section of the locking element 8 varies at a horizontal plane H along the adjacent edges 1, 1′ which are formed with a basic geometry as shown in FIG. 6b that is thereafter modified such that the first 7a and the second 7b cooperating edge sections are formed with different geometries and different locking functions as shown in FIGS. 6c and 6d.
[0143] It is understood that according to alternative embodiments the geometries according to FIGS. 6c and 6d may be formed directly without first forming a basic geometry as in FIG. 6b.
[0144] The first edge section 7a is preferably a start section that becomes active during a first initial step of the folding action and the second edge section 7b is preferably a section that becomes active during a second step of the folding action.
[0145] FIG. 6c shows a first cooperating edge section 7a that is used to prevent edge separation during locking and to lock adjacent edges horizontally in the locked position. The first edge section 7a has no vertical locking function since one of the locking surfaces, the upper 11a or as shown in this preferred embodiment the lower locking surface 11a, has been removed. The first 12a and the second 12b locking surfaces are preferably vertical and they are used to guide the second panel 1′ during the vertical displacement along a vertical plane VP that intersects the upper and outer edge of the first panel 1.
[0146] FIG. 6d shows the second edge section 7b that is used to lock the adjacent edges vertically. The second edge 7b section cannot prevent horizontal edge separation and has no horizontal locking function since a part of the locking element 8 and/or the locking groove 14 has been removed in order to form a space S along a horizontal plane H and a slit 20 adjacent to the locking element allows the locking element 8 to be displaced inwardly during locking. The slit 20 is preferably located closer to the upper edge 25 of the first panel 1 than the locking element 8. This inward displacement enables the upper 11a and lower 11b locking surfaces to overlap and lock against each other when the second edge 1′ is displaced vertically along the vertical plane VP until a final position where lower 15 and upper 16 support surfaces are in contact with each other. All shown and described locking systems are primarily intended to be used on the short edges. However, it is not excluded that the disclosed embodiments of locking systems may be used on short and/or long edges and the panels may be locked with a vertical displacement of long and/or short edges.
[0147] In FIGS. 6c and 6d the cross section in the first rigid edge section 7a is different from the cross section in the second flexible edge section 7b due to the space S and/or the slit 20 and therefore the cross section varies along the edges.
[0148] The panel edges may also comprise a second horizontally extending tongue 50 and a tongue groove 51 formed in the upper part of the panels as shown in FIG. 6d and inclined first and second locking surfaces 12a, 12b (not shown) such that they may be locked with an angling action wherein the upper and lower locking surfaces 11a, 11b may prevent the strip to bend down when a horizontal separation force is applied after locking. This may be used to increase the locking strength at for example at the long and/or short edges, especially in soft LVT material.
[0149] FIG. 6e shows that it may be a major advantage to lock the edges with vertical pretension between lower and upper support surfaces 15, 16 and between upper and lower locking surfaces 11a, 11b. The locking element 8 with its upper locking surface 11a at the second edge section 7b will only partly snap back to its original position, preferably less than about 80% of the first inward displacement, and will in locked position be displaced upwardly in relation to an unlocked position due to the inclined upper and lower locking surfaces 11a, 11b. This may increase the locking strength considerably, even in the case when the locking element in locked position is only pressed inwardly about 0.1-0.2 mm.
[0150] FIGS. 7a-7c show locking of the first adjacent edge sections 7a. The second panel 1′ is displaced essentially along a vertical plane VP until the first and second locking surface 12a, 12b are in contact with each other and a horizontal edge separation is prevented until the edges are in a final locked position.
[0151] FIGS. 7d-7f show locking of the second edge section 7b. A lower part of the second panel slides against a sliding surface 27 formed on the outer surface 8b, which is an outer part of the locking element 8. The separation forces are prevented by the first edge section 7a that is in a locking stage with overlapping first and second locking surfaces 12a, 12b. The locking element 8 adjacent to the slit 20 is pressed inwardly by the lower part of the second panel 1′ until the edges are in a final locking position when the locking element 8 snaps back towards its initial position such that the upper 11a and the lower 11b locking surfaces lock against each other and prevent vertical separation of the adjacent panel edges 1, 1′.
[0152] FIGS. 8a-8c show that a screw cutter 41 may be used to remove the outer part of the locking element 8 from a first panel edge 1 in order to form a part of first edge section 7a.
[0153] FIGS. 8d-8f show that a jumping tool 43 may be used to form the second flexible section 7b by removing a part of the inner surface 8a of the locking element 8 and a part of the strip 6 in in order to create a space S and to form a slit 20. The jumping tool is initially positioned above the strip 6.
[0154] FIGS. 8g and 8h show that similar removal may be obtained with a jumping tool 43 that initially is positioned below the strip. The difference between these two production methods is mainly the fact that more material is removed at the entrance side where the tool initially is positioned than at the exit side. This may be used to form locking systems with a geometry that may be suitable for a strong vertical locking or a strong horizontal locking and the locking system may be adapted to various material properties of the core material. FIG. 8h shows that the thickness T of the flexible locking element 8 may be larger than the width W and such a locking element is easier to bend horizontally inwardly than vertically upwards. Low locking resistance during vertical folding may be combined with a strong vertical locking force in locked position.
[0155] FIGS. 9a-9d show that the first rigid edge section 7a may be formed with a jumping tool 43 or a screw cutter 41 that removes a lower part of the locking groove 14 and the lower locking surface 11b.
[0156] FIGS. 10a-10b show an embodiment of a first panel 1 comprising two long edges 4a, 4b and a short edge 4c. The panel may be a laminate floor panel comprising an HDF core with a thickness of 6-9 mm. FIG. 10a is a plan view of the panel 1. The short edge 4c may have a width of about 18-20 cm. Four slits 20-1, 20-2, 20-3, 20-4 may be formed in the strip 6 with a jumping tool head comprising a rotating cutting tool with a diameter of for example 4-10 cm. Such rotating cutting tools may have a sufficient capacity to form slits in high speed especially if the vertical displacement of the cutting tool may be as small as about 3-5 mm. FIG. 10b shows a cross section of a part of the first rigid edge section 7a that is located between the slits 20-1, 20-2, 20-3, 20-4 along the edge and preferably at the end portions of the strip 6 adjacent to the long edges 4a, 4c. The outer part of the locking element 8 is removed by a screw cutter 41. FIG. 10c shows a cross section of the second flexible edge section 7b that comprises a slit 20 and an upper locking surface 11a. The shown embodiment comprises five rigid first edge sections 7a and four flexible second edge sections 7b and this is sufficient to provide a strong vertical and horizontal locking especially when the locking element 8 preferably has a thickness that exceeds the width. It is clear, however, that any number of rigid first edge sections 7a and flexible second edge sections 7b may be used. FIGS. 10c and 10d shows that the slit 20-3 may be formed with a jumping tool head 43 that initially is located above the strip 6. According to the present embodiment, a length L2 of an upper part of the slit 20 is larger than a length L1 of the lower part of the slit 20 and a length L3 of the space S. Such joint geometry may be favourable in some core materials and some core thicknesses.
[0157] FIGS. 11a-11d show the same basic embodiment as FIGS. 10a -10d. The only difference is that the jumping tool 43 is initially located below the strip 6. The length L2 of the upper part of the slit 20 is smaller than the length L1 of the lower part of the slit 20 and the length L3 of the space S.
[0158] A slit 20 that may be formed from above and/or from below provides the advantages that relationships between vertical and horizontal locking surfaces and the flexibility of the flexible edge section may be adjusted in an easy way and adapted to the properties of the core material.
[0159] FIGS. 12a-12c show a panel that may be a LVT or WPC floor panel having a core comprising thermoplastic material and fillers with a thickness of about 3-5 mm. The short edge 4c may have a width of about 18-20 cm. The small thickness makes it possible to form more than four slits in the strip 6 with a jumping tool head, for example six slits as shown in FIG. 12a. The shown non-limiting embodiment may comprise preferably up to seven rigid first edge sections 7a and up to six flexible second edge sections 7b and this is sufficient to provide a strong vertical and horizontal locking over essentially the whole short edge 4c in thin core material.
[0160] FIGS. 13a-13c show that the number of sections 7a, 7b may be increased further if a punching wheel 45 is used that may remove material such that the slits 20 and protrusions 36 may be formed with essentially vertical walls and with advanced geometries. Such forming is especially suitable for floor panels comprising a core of thermoplastic material such as LVT and WPC core material. Such a locking system may comprise a slit 20 with a length L that is smaller than 2-3 times the floor thickness FT. A short edge may comprise more than ten slits 20.
[0161] FIGS. 14a-14g show a second principle of the invention. A locking system is initially formed with a geometry that is not possible to lock even when the edges are displaced sideways along the joint since the horizontal distance from the vertical plane VP to the upper locking surface 11a is larger than the distance from the vertical plane VP to the lower locking surface 11b as shown in FIG. 14a. Material is thereafter removed from the locking element 8 as in the first principle. According to the present embodiment, the outer surface 8b in the first edge section 7a has a concave shape so that a horizontal extension of an upper and a lower portion of the locking element from the vertical plane VP is larger than a horizontal extension of a middle portion of the locking element between the upper and lower portion. Alternatively, however, the outer surface 8b may be planar in a vertical direction. Moreover, a slit 20 is formed in the second edge section 7b, preferably with a very small opening 20e that may be as small as for example 0.05-0.5 mm, e.g. 0.1 mm, or practically even non-existent as long as material above the slit may be separated. FIGS. 14d, 14f show that the first edge section 7a is locked in a similar way as shown in FIGS. 7a-7c. The upper part of the slit 20 comprises an upper stabilizing surface 18 and the upper part of the strip 6 comprises a lower stabilizing surface 19 as shown in FIG. 14e. In an unlocked position of the panels 1, 1′, the upper stabilizing surface 18 is provided inwardly of the lower stabilizing surface 19. The flexible part of the strip 6 is during locking displaced inwardly and the stabilizing surfaces 18, 19 will overlap each other horizontally as shown in FIG. 14e. The flexible part of the strip 6 will during the final stage of the vertical displacement slide back partly towards its initial position but not completely until the upper 11a and lower 11b locking surfaces are in contact with each other and the locking system will be locked with a horizontal pretension and with overlapping upper 18 and lower 19 stabilizing surfaces. There is a space S provided in the second flexible edge section 7b into which the locking element is displaced during locking. In a locked position of the panels 1, 1′, the space is provided between an inner surface 8a of the locking element 8 and an outer groove wall 14a of the locking groove 14. For example, the space S may be formed by removal of material.
[0162] As shown in FIG. 1b the bending of a flexible tongue is at its maximum position in the middle portion P3 where the vertical locking strength is low and this middle section may be stabilized with stabilizing surfaces that may overlap each other with for example 0.1-0.5 mm. This is sufficient to stabilize a flexible part formed by a slit 20.
[0163] Stabilizing surfaces allow that the length of the slit may be increased and in some applications only one or two slits may be sufficient.
[0164] FIGS. 15a and 15b show that a wax layer 22 may be applied on all parts that are in contact with each other, especially on surfaces adjacent to the upper 11a and lower 11b locking surfaces for example the sliding surface 27 and on first 12a and second 12b locking surfaces. This may reduce friction forces during locking. Core material adjacent to the upper and lower locking surfaces 11a, 11b may also be reinforced with for example resins that are injected into the core or applied on the contact surfaces. The present embodiment may be combined with all principles in the disclosure.
[0165] FIG. 16a-16f show an embodiment of a locking system according to a third principle of the invention. Such a locking system may be used when a high horizontal strength is needed for example in a floating floor that is installed in a large commercial area. The slit 20 may be formed in the locking element 8 and the first and the second edge section 7a, 7b may comprise a rigid locking element 8′ that is continuous and that extends essentially along the whole edge. FIG. 16c shows a slit 20 that is formed with a jumping tool from above and FIG. 16f shows a slit 20 that is formed from below. Punching may also be used. The present embodiment may be combined with all principles in the disclosure.
[0166] FIGS. 17a-17c show that a preformed groove 30 may be formed along essentially the whole locking element 8 and a slit 20 may be formed from below in the second edge section. FIGS. 17d-17f show that the preformed groove may be formed in the lower part of the strip 6 and the slit 20 may be formed from above the locking element. FIG. 17g shows an edge of a first panel 1 comprising a continuous locking element 8′ located between the slit 20 and the upper edge 25 of the first panel 1. According to alternative embodiments (not shown) the preformed groove 30 may extend along a part of the locking element 8. In a first non-limiting example, an extension of the preformed groove 30 is the same or larger than an extension of the slit 20. In a second non-limiting example, the preformed groove 30 extends side by side with the slit 20. The present embodiment may be combined with all principles in the disclosure.
[0167] FIGS. 18a-18d show a locking system according to a fourth principle of the invention. The strip 6 in the first panel 1 comprises a first 8 and a second 8′ upwardly protruding locking element. The first locking element 8 is located closer to the upper edge 25 of the first panel 1 than the second locking element 8′. The edge of the second panel 1′ comprises a downwardly extending protrusion 36a. The downwardly extending protrusion 36a is provided outside of a locking groove 14 provided in the second panel 1′. The locking groove 14 is configured to engage with the second locking element 8′ in a locked position of the panels 1, 1′. An upper locking surface 11a is formed in an upper and outer part of the first locking element 8 and a lower locking surface 11b is formed at a lower and outer part of the protrusion 36a.
[0168] There is provided a first rigid edge section 7a and a second flexible edge section 7b along the edges of the first 1 and second 1′ panels. The first 7a and second 7b edge sections may be arranged according to any of the embodiments described in the above. FIG. 18b shows that the first rigid edge section 7a may be formed such that the upper 11a or the lower 11b locking surface is removed. The second edge section 7b may be formed with a jumping tool 43 or punching. FIGS. 18c and 18d show the second edge section 7b that comprises a first and a second slit 20, 20′ located horizontally side-by-side. The first slit 20 is located closer to the upper edge 25 of the first panel 1 than the second slit 20′. The slits allow the first locking element 8 and the upper locking surface 11a to be displaced inwardly during locking. The locking system is configured to be locked with a vertical displacement of the second edge against the first edge wherein a part of the first locking element 8 and a slit wall of the first and the second slits during an initial stage of the vertical displacement is configured to bend horizontally inwards towards an inner part of the first panel 1 and during a final stage of the vertical displacement is configured to bend outwards towards an initial position of the part of the first locking element 8.
[0169] Preferably, a preformed groove 30 is formed adjacent to the vertical plane VP that intersects the upper edge 25 of the first panel edge 1.
[0170] FIGS. 19a, 19b show a plan and perspective view of a short edge of a first panel 1 comprising a locking system according to the fourth principle of the invention. According to this embodiment, there are a five first rigid edge sections 7a and four second flexible edge sections 7b provided alternately along the edge of the first panel 1. The first 7a and second 7b edge sections are illustrated in cross-section along a line A-A and a line B-B, respectively, in the enlargements in FIG. 19a. FIG. 19b illustrates a perspective view of a second edge section 7b. The first 20 and the second 20′ slits are provided along portions of the edge of the first panel 1. According to the present embodiment, the first 20 and the second 20′ slits are provided side by side and have substantially the same extension along the edge, but it is understood that according to alternative embodiments they may have different extensions. In a first example, the first slit 20 has a longer extension than the second slit 20′ along the edge. In a second example, the first slit 20 has a smaller extension than the second slit 20′ along the edge.
[0171] FIGS. 20a-20f show that the principles of the invention may be combined, for example the fourth and the second principle. The upper locking surface 11a is formed in an edge of a first panel 1 and is located above the strip 6 and between the locking element 8 and the upper edge 25 of the first panel 1 and the lower locking surface 11b is formed in an edge of a second panel 1′ between the locking groove 14 and the upper edge 25′ of the second panel 1′. There is provided at least one first rigid edge section 7a and at least one second flexible edge section 7b along the edges of the first 1 and second 1′ panels in accordance with any of the embodiment of the disclosure. The second flexible edge section 7b comprises a strip 6 having two slits 20, 20′ and the locking is made with pretension and overlapping upper and lower stabilizing surfaces 18, 19 as described above in relation to the second principle of the invention.
[0172] FIGS. 21a-21d show a locking system of edges of a first 1 and a second 1′ panel according to a fifth principle. There is provided at least one first rigid edge section 7a and at least one second flexible edge section 7b along the edges of the first 1 and second 1′ panels in accordance with any of the embodiment of the disclosure. The upper locking surface 11a is formed on the inner surface of the locking element 8 in the second flexible edge section 7b and the lower locking surface 11b is formed on the outer groove wall 14a of the locking groove 14 along the entire edge of the second panel 1′. As shown in FIG. 21b, the first rigid edge section 7a does not comprise any upper locking surface 11a and provides horizontal locking of the panels since the edge of the second panel 1′ comprises a projection 26 that is adapted to engage with an indentation 28 in the edge of the first panel 1 in a locked position. More specifically, a first locking surface 12a in an inner surface 8a of the locking element 8, which is a vertical wall in the first rigid edge section 7a, engages with a second locking surface 12b in an outer groove wall 14a of the locking groove 14, and an upper edge 25 of the first panel 1 engages with an upper edge 25′ of the second panel 1′ for providing horizontal locking. The upper 11a and lower 11b locking surfaces provide vertical locking of the panels 1, 1′. A part of the locking element 8 and a slit wall of the slit 20 is during an initial stage of a vertical displacement of the panels 1, 1′ configured to bend horizontally outwardly and during a final stage of the vertical displacement configured to bend inwardly towards an initial position of the part of the locking element 8. A space S and a slit 20 are provided in the second flexible edge section(s) 7b as shown in FIG. 21c. The space S that preferably extends along essentially the whole edge and that allows a horizontal displacement outwardly of the locking element 8 is formed between an inner groove wall 14b of the locking groove 14 and the locking element 8 in a locked position of the panels 1, 1′. FIG. 21d illustrates a perspective view of the first panel 1 in the first rigid edge section 7a and the second flexible edge section 7b. The upper 11a and lower 11b locking surfaces are preferably essentially horizontal and comprises a locking angle against the horizontal plane that is less than 45 degrees, e.g. 10, 15, 20 or 25 degrees. Such locking surfaces are preferably formed with carving tools.
[0173] FIGS. 22a-22c show locking of the first rigid edge section 7a and FIGS. 22d-22f show locking of the flexible second edge section 7b when the locking element 8 is initially displaced outwardly, and inwardly during the final stage of the vertical displacement of the edge of the second panel 1′ against the edge of the first panel 1. As shown in FIG. 22e, the locking element 8 is horizontally displaced outwardly into the space S during locking. FIGS. 22g and 22h show that the slit 20 may be formed with a jumping tool head from above or below, respectively.
[0174] FIGS. 23a-23h show embodiments of the invention. FIGS. 23a-23d show that the fifth principle may be combined with the second principle and that a crack 23 in the core material may be used to form upper and lower 18, 19 stabilizing surfaces. In a non-limiting example, the core material may comprise an HDF board that comprises an essentially horizontal fibre orientation. Due to the crack 23, an inner and an outer portion of the strip 6 which initially are joined may be separated during locking when the locking element 8 is displaced outwardly. FIGS. 23e and 23f show that two slits 20, 20′ may be formed in a locking system according to the fifth principle. FIGS. 23g and 23h show that as an alternative the lower locking surfaces 11b may be removed with a jumping tool 43 or a screw cutter 41 in a locking system according to the fifth principle in order to form the rigid first edge section 7a. More generally, it is emphasized that embodiments of all the principles of the invention may be combined.
[0175] FIGS. 24a-24f show a sixth principle of the invention. An edge of a first panel 1 comprises a strip 6 with a locking element 8 and an edge of a second panel 1′ comprises a downwardly open locking groove 14. The locking element 8 is configured to engage with the downwardly open locking groove 14 in a locked position. Upper 11a and lower 11b locking surfaces that lock the edge of the first panel 1 to the edge of the second panel 1′ vertically are located at a lower part of the strip 6 and at an outer and lower part 32 of an downwardly extending protrusion 36a, respectively, wherein the protrusion 36a is formed between the locking groove 14 and the upper edge 25′ of the second panel 1′ as shown in FIG. 24a. A part of the protrusion 36a and the lower locking surface 11b is removed by for example a screw cutter or jumping saw blades and a first rigid edge section 7a is formed as shown in FIG. 24b. A second flexible edge section 7b comprises a first slit 20 and a second slit 20′. The first slit 20 is located closer to the upper edge 25 of the first panel 1 than the second slit 20′. The first slit 20 and the second slit 20′ extend along the edge of the second panel 1′. The first 20 and second 20′ slit may extend side by side along the edge. An extension of the first slit 20 may be the same as an extension of the second slit 20′. However, it is equally conceivable that the slits have different extensions along the edge as has been explained above in relation to other principles. The upper locking surface 11a is located at a lower and inner part of the second slit 20′. The first slit 20 provides flexibility such that a flexible strip part 31 located between the first and the second slit may be displaced horizontally inwardly and back again during locking as shown in FIGS. 24d and 24e. The second slit 20′ is used to accommodate the protrusion 36a that during a vertical displacement of the edge of the second panel 1′ towards the edge of the first panel 1 is inserted into the second slit such that the upper 11a and the lower 11b locking surfaces overlap each other and lock the edges of the first 1 and the second 1′ panel vertically. FIG. 24f show that the sixth principle may be combined with the second principle and that the locking system may comprise a flexible strip part 31 that is locked with pretension and upper and lower stabilizing surfaces 18, 19 that stabilize the flexible strip part 31 and prevent upward bending. The locking system is particularly suitable for thin LVT and WPC floors but may also be used in HDF floors and other floor types. An advantage is that the protrusion 36a and the locking element 8 may be strong and rigid since no flexibility of such parts is required to lock the edges with a vertical displacement.
[0176] FIGS. 25a-25f show a seventh principle of the invention that is a modification of the sixth principle. An edge of a first panel 1 comprises a strip 6 with a first 8 and a second 8′ locking element 8. The first locking element 8 is located closer to the upper edge 25 of the first panel 1 than the second locking element 8′. An edge of a second panel 1′ comprises a first downwardly open locking groove 14 and a second downwardly open locking groove 14′. The first locking groove 14 is located closer to the upper edge 25′ of the second panel 1′ than the second locking groove 14′. The first locking element 8 and the first locking groove 14 lock the edges horizontally in a locked position of the panels 1, 1′. An upper locking surface 11a is located at a lower and inner part of the second locking element 8′ and a lower 11b locking surface is located at a lower and inner part 33 of a downwardly extending protrusion 36a formed on an edge of the second panel 1′ between the first 14 and the second 14′ locking groove. The upper 11a and lower 11b locking surfaces lock the edges vertically in a locked position of the panels 1, 1′. A part of the protrusion 36a and the lower locking surface 11b is removed by for example a screw cutter or jumping saw blades and a first rigid edge section 7a is formed as shown in FIG. 25b. A second flexible edge section 7b comprises a slit 20 that provides flexibility such that the second locking element 8′ may be displaced horizontally outwardly and at least partly back again during locking as shown in FIGS. 25d and 25e. The slit 20 is used to provide flexibility and to accommodate the protrusion 36a that during a vertical displacement of the edge of the second panel 1′ towards the edge of the first panel 1 is inserted into the slit 20 such that the upper 11a and the lower 11b locking surfaces overlap each other and lock the edges of the first 1 and the second 1′ panel vertically. FIG. 25f shows that the seventh principle may be combined with the second principle as shown in FIG. 23e and the locking system may comprise a flexible outer stabilizing strip part 34 and a second locking element 8′ that is locked with pretension against the protrusion 36a such that upper and lower stabilizing surfaces 18, 19 overlap each other.
[0177] FIG. 26a shows an edge of a first panel 1 that is positioned between a chain 46 and a belt 47 of a double-end tenor with its surface 2 pointing downwards. A screw cutter 41 may be used to remove material at an outer part of a strip 6. FIG. 26b shows a jumping tool 43 that is used to form slits 20. FIG. 26c shows rotating tools 42 that are used to form vertical grooves from above and below and FIG. 26d shows that essentially horizontal upper 11a and lower 11b locking surfaces may be formed with carving tools 44 in the vertical grooves formed by rotating tools.
[0178] FIGS. 27a and 27b show that all embodiments of the invention disclosed in the above may be used to lock for example furniture components where a second panel 1′ comprising a locking groove 14 is locked vertically and perpendicularly to a first panel 1 comprising a strip 6 and with a locking element 8. The locking groove 8 is configured to engage with the locking groove 14 in a locked position of the panels 1, 1′. The panels 1, 1′ may have a first rigid edge section 7a providing horizontal locking of the panels 1, 1′ and a second flexible edge section 7b comprising a slit 20 and upper 11a and lower 11b locking surfaces as described in the embodiments above. According to the embodiment in FIGS. 27a-b there is a space S provided in the second flexible edge section 7b between an inner surface 8a of the locking element 8 and a groove wall 14a of the locking groove 14. In a locked position, a horizontal distance between the groove wall 14a and an upper part 25 of the first panel 1 is smaller than a horizontal distance between an outer surface 8b of the locking element 8 and the upper part 25 of the first panel 1. Stabilizing surfaces may also be formed according to the embodiments in the above-described principles. An edge of second panel 1′ is preferably covered in an edge banding equipment with an edge material prior to the forming of the locking system such that the lower and outer edge 35 of the second panel is covered with an edge material. Such edges may be used in all embodiments of this disclosure but also in other locking system, which are intended to lock a second panel 1′ perpendicularly to a first panel 1. It is stressed that any, or any combination, of the principles above which mainly have been described in relation to floor panels also are applicable to furniture components or furniture panels. One difference, however, is that front surfaces of the first 1 and the second 1′ panels do not necessarily have to be flush or aligned with each other in a locked position of the panels 1, 1′, as preferably is the case in the case of floor panels. Rather, in the case of furniture components, outer surfaces 52, 52′ as well as inner surfaces 53, 53′ of the panels 1, 1′ are preferably arranged perpendicularly to each other in a locked position. In a non-limiting embodiment, a first and a second pair of furniture components are configured to be locked to each other by means of a locking system according to any or any combination of the principles of the invention. The furniture components of each pair may be parallel to each other. The first and the second pair may be arranged perpendicularly to each other in a locked position of the panels. It is equally conceivable, however, that according to alternative embodiments, the first and the second pair are arranged at an angle to each other in a locked position.
[0179] FIGS. 28a-28d show that a core material 5 of a panel 1 may be locally modified such that it becomes more suitable to form flexible and strong edges portions of a locking system. FIG. 28a shows that a resin, for example a thermosetting resin 24 such as for example melamine formaldehyde, urea formaldehyde or phenol formaldehyde resin, may be applied in liquid or dry powder form on for example a melamine formaldehyde impregnated balancing paper 3 or directly on a core material 5. The resin may also be locally injected into the core with high pressure. The resin may also be applied on the upper part of the core 5 in order to improve moisture properties of the upper edges. FIG. 28b shows that a core material 5, preferably a wood based panel for example a HDF board or a particle board, may be applied on the impregnated paper 3 with the added resin 24 prior to lamination. Alternatively, a powder layer may be applied on the resin 24. FIG. 28c shows a floor board after lamination when the surface layers 2 and the balancing layer 3 have been laminated to the core 5. The resins 24 have penetrated into the core 5 and cured during lamination under heat and pressure. FIG. 28d shows an edge of a first panel 1 and a second panel 1′ with upper and lower parts that are locally strengthened with increased resin content. The first edge 1 comprises a strip 6 formed in one piece with the core 5. The material of the strip 6 is more flexible and comprises a higher resin content than other parts of the core 5. The increased resin content provides a material that is suitable to form a strong and flexible edge parts. A locking system according to one embodiment of the invention comprises a core 5 having a higher content of cured resins, preferably thermosetting resins, at a lower and outer part than at a lower and inner part. A locking system according to another embodiment of the invention comprises a core 5 having a higher content of cured resins, preferably thermosetting resins, at an upper and outer part than at an upper and inner part. These methods may be used also in other locking systems, preferably locking systems that comprise a horizontally protruding strip with a locking element at a lower part of a panel edge. In particular, the locking systems according to any of the principles in this disclosure may be provided with a higher content of cured resins according to the above.
