Mechanical locking system for floor panels

Abstract

Floor panels are shown, which are provided with a vertical folding locking system on short edges that only locks vertically and a mechanical locking system on long edges that prevents displacement along the long edges.

Claims

1. A flooring system comprising a plurality of rectangular floor panels with short edges and long edges, the panels are adapted to be installed on a sub floor and connected to each other with a long edge mechanical locking system for locking the panels vertically and horizontally, said locking system comprising a tongue and a tongue groove for mechanically locking together adjacent edges vertical to the horizontal plane, forming a vertical mechanical connection between the panels, and a locking element at a first long edge and a locking groove at an opposite second long edge thereby forming a first horizontal mechanical connection between adjacent long edge locking the panels to each other in a direction parallel to the horizontal plane and at right angles to said adjacent long edges, wherein the panels are provided with a short edge locking connection comprising a short edge tongue groove and a separate tongue, for locking adjacent short edges in a first vertical direction, inserted in a fixation groove at a short edge of a panel, wherein the separate tongue is at least one of flexible and displaceable, and a locking strip and a locking cavity for locking adjacent short edges in a second vertical direction, wherein the separate tongue comprises a lower surface, wherein the lower surface contacts a portion of the short edge tongue groove on an adjacent short edge for locking the adjacent short edges in the first vertical direction, wherein the short edge locking connection is configured to lock the adjacent edges in the vertical directions only, wherein the long edges are provided with a second horizontal mechanical connection locking the panels to each other along said adjacent long edges, in a direction parallel to the horizontal plane and parallel to said adjacent long edges, when the panels are laying flat on the sub floor.

2. The flooring system as claimed in claim 1, wherein said second horizontal mechanical connection at the long edges comprises a locking element and locking groove with two sets of cooperating locking surfaces wherein a first set is located closer to a vertical plane and upper joint edges than a second set.

3. The flooring system as claimed in claim 2, wherein the two sets of locking surfaces are inclined such that a lower part of the locking element is larger than an upper part.

4. The flooring system as claimed in claim 2, wherein the vertical extension of the second set of locking surfaces is essentially the same or larger than the vertical extension of the first set of locking surfaces.

5. The flooring system as claimed in claim 2, wherein the long edge locking system further comprises a third set of cooperating locking surfaces located at the outer and lower part of a strip having the locking element.

6. The flooring system as claimed in claim 2, wherein there is a space between the upper part of the locking element and the locking groove.

7. The flooring system as claimed in claim 1, wherein said second horizontal mechanical connection comprises a flexible material which is applied in an essentially vertical groove.

8. The flooring system as claimed in claim 7, wherein said flexible material is compressed horizontally in two opposite directions.

9. The flooring system as claimed in claim 7, wherein said essentially vertical groove is complementary with a wedge shaped locking element.

10. The flooring system as claimed in claim 1, wherein said second horizontal mechanical connection comprises a friction element located on the upper part of the locking element that cooperates with a friction groove.

11. The flooring system as claimed in claim 10, wherein the friction groove comprises a flexible material.

12. The flooring system as claimed in claim 1, wherein said second horizontal mechanical connection comprises friction cavities located on the locking element.

13. The flooring system as claimed in claim 1, wherein said second horizontal mechanical connection comprises compressible material that is applied in the locking system at surfaces that do not comprise cooperative active locking surfaces which lock the panels vertically to the horizontal plane and horizontally in a direction parallel to the horizontal plane and at right angles to said adjacent long edges.

14. The flooring system as claimed in claim 1, wherein the short edge locking connection is locked with a vertical snap action where the separate tongue is displaced in the fixation groove during vertical displacement.

15. The flooring system as claimed in claim 1, wherein the short edge locking connection is locked when the separate tongue is displaced in the fixation groove along the short edge.

16. A flooring system comprising a plurality of rectangular floor panels with short edges and long edges, the panels are adapted to be installed on a sub floor and connected to each other with a long edge mechanical locking system for locking the panels vertically and horizontally, said locking system comprising a tongue and a tongue groove for mechanically locking together adjacent edges vertical to the horizontal plane, forming a vertical mechanical connection between the panels, and a locking element at a first long edge and a locking groove at an opposite second long edge thereby forming a first horizontal mechanical connection between adjacent long edges locking the panels to each other in a direction parallel to the horizontal plane and at right angles to said adjacent long edges, wherein the panels are provided with a short edge locking connection comprising a short edge tongue groove and a separate tongue, for locking adjacent short edges in a first vertical direction, inserted in a fixation groove at a short edge of a panel, wherein the separate tongue is at least one of flexible and displaceable, and a locking strip and a locking cavity for locking adjacent short edges in a second vertical direction, wherein the separate tongue comprises a lower surface, wherein the lower surface contacts a portion of the short edge tongue groove on an adjacent short edge for locking the adjacent short edges in the first vertical direction, wherein the short edge locking connection is configured to lock the adjacent edges in the vertical directions only, wherein the long edges are provided with a second horizontal mechanical connection locking the panels to each other along said adjacent long edges, in a direction parallel to the horizontal plane and parallel to said adjacent long edges, when the panels are laying flat on the sub floor, wherein said second horizontal mechanical connection at the long edges comprises a locking element and locking groove with two sets of cooperating locking surfaces wherein a first set is located closer to a vertical plane and upper joint edges than a second set, wherein the two sets of locking surfaces are inclined such that a lower part of the locking element is larger than an upper part.

17. The flooring system as claimed in claim 16, wherein the vertical extension of the second set of locking surfaces is essentially the same or larger than the vertical extension of the first set of locking surfaces.

18. A flooring system comprising a plurality of rectangular floor panels with short edges and long edges, the panels are adapted to be installed on a sub floor and connected to each other with a long edge mechanical locking system for locking the panels vertically and horizontally, said locking system comprising a tongue and a tongue groove for mechanically locking together adjacent edges vertical to the horizontal plane, forming a vertical mechanical connection between the panels, and a locking element at a first long edge and a locking groove at an opposite second long edge thereby forming a first horizontal mechanical connection between adjacent long edges locking the panels to each other in a direction parallel to the horizontal plane and at right angles to said adjacent long edges, wherein the panels are provided with a short edge locking connection comprising a short edge tongue groove and a separate tongue, for locking adjacent short edges in a first vertical direction, inserted in a fixation groove at a short edge of a panel, wherein the separate tongue is at least one of flexible and displaceable, and a locking strip and a locking cavity for locking adjacent short edges in a second vertical direction, wherein the separate tongue comprises a lower surface, wherein the lower surface contacts a portion of the short edge tongue groove on an adjacent short edge for locking the adjacent short edges in the first vertical direction, wherein the short edge locking connection is configured to lock the adjacent edges in the vertical directions only, wherein the long edges are provided with a second horizontal mechanical connection locking the panels to each other along said adjacent long edges, in a direction parallel to the horizontal plane and parallel to said adjacent long edges, when the panels are laying flat on the sub floor, wherein said second horizontal mechanical connection at the long edges comprises a locking element and locking groove with two sets of cooperating locking surfaces wherein a first set is located closer to a vertical plane and upper joint edges than a second set, wherein the long edge locking system further comprises a third set of cooperating locking surfaces located at the outer and lower part of a strip having the locking element.

19. A flooring system comprising a plurality of rectangular floor panels with short edges and long edges, the panels are adapted to be installed on a sub floor and connected to each other with a long edge mechanical locking system for locking the panels vertically and horizontally, said locking system comprising a tongue and a tongue groove for mechanically locking together adjacent edges vertical to the horizontal plane, forming a vertical mechanical connection between the panels, and a locking element at a first long edge and a locking groove at an opposite second long edge thereby forming a first horizontal mechanical connection between adjacent long edges locking the panels to each other in a direction parallel to the horizontal plane and at right angles to said adjacent long edges, wherein the panels are provided with a short edge locking connection comprising a short edge tongue groove and a separate tongue, for locking adjacent short edges in a first vertical direction, inserted in a fixation groove at a short edge of a panel, wherein the separate tongue is at least one of flexible and displaceable, and a locking strip and a locking cavity for locking adjacent short edges in a second vertical direction, wherein the separate tongue comprises a lower surface, wherein the lower surface contacts a portion of the short edge tongue groove on an adjacent short edge for locking the adjacent short edges in the first vertical direction, wherein the short edge locking connection is configured to lock the adjacent edges in the vertical directions only, wherein the long edges are provided with a second horizontal mechanical connection locking the panels to each other along said adjacent long edges, in a direction parallel to the horizontal plane and parallel to said adjacent long edges, when the panels are laying flat on the sub floor, wherein said second horizontal mechanical connection comprises a flexible material which is applied in an essentially vertical groove that is complementary with a wedge shaped locking element, wherein said flexible material is compressed horizontally in two opposite directions.

20. A flooring system comprising a plurality of rectangular floor panels with short edges and long edges, the panels are adapted to be installed on a sub floor and connected to each other with a long edge mechanical locking system for locking the panels vertically and horizontally, said locking system comprising a tongue and a tongue groove for mechanically locking together adjacent edges vertical to the horizontal plane, forming a vertical mechanical connection between the panels, and a locking element at a first long edge and a locking groove at an opposite second long edge thereby forming a first horizontal mechanical connection between adjacent long edges locking the panels to each other in a direction parallel to the horizontal plane and at right angles to said adjacent long edges, wherein the panels are provided with a short edge locking connection comprising a short edge tongue groove and a separate tongue, for locking adjacent short edges in a first vertical direction, inserted in a fixation groove at a short edge of a panel, wherein the separate tongue is at least one of flexible and displaceable, and a locking strip and a locking cavity for locking adjacent short edges in a second vertical direction, wherein the separate tongue comprises a lower surface, wherein the lower surface contacts a portion of the short edge tongue groove on an adjacent short edge for locking the adjacent short edges in the first vertical direction, wherein the short edge locking connection is configured to lock the adjacent edges in the vertical directions only, wherein the long edges are provided with a second horizontal mechanical connection locking the panels to each other along said adjacent long edges, in a direction parallel to the horizontal plane and parallel to said adjacent long edges, when the panels are laying flat on the sub floor, wherein said second horizontal mechanical connection comprises a friction element located on the upper part of the locking element that cooperates with a friction groove.

21. The flooring system as claimed in claim 20, wherein the friction groove comprises a flexible material.

22. A flooring system comprising a plurality of rectangular floor panels with short edges and long edges, the panels are adapted to be installed on a sub floor and connected to each other with a long edge mechanical locking system for locking the panels vertically and horizontally, said locking system comprising a tongue and a tongue groove for mechanically locking together adjacent edges vertical to the horizontal plane, forming a vertical mechanical connection between the panels, and a locking element at a first long edge and a locking groove at an opposite second long edge thereby forming a first horizontal mechanical connection between adjacent long edges locking the panels to each other in a direction parallel to the horizontal plane and at right angles to said adjacent long edges, wherein the panels are provided with a short edge locking connection comprising a short edge tongue groove and a separate tongue, for locking adjacent short edges in a first vertical direction, inserted in a fixation groove at a short edge of a panel, wherein the separate tongue is at least one of flexible and displaceable, and a locking strip and a locking cavity for locking adjacent short edges in a second vertical direction, wherein the separate tongue comprises a lower surface, wherein the lower surface contacts a portion of the short edge tongue groove on an adjacent short edge for locking the adjacent short edges in the first vertical direction, wherein the short edge locking connection is configured to lock the adjacent edges in the vertical directions only, wherein the long edges are provided with a second horizontal mechanical connection locking the panels to each other along said adjacent long edges, in a direction parallel to the horizontal plane and parallel to said adjacent long edges, when the panels are laying flat on the sub floor, wherein said second horizontal mechanical connection comprises friction cavities located on the locking element.

23. A flooring system comprising a plurality of rectangular floor panels with short edges and long edges, the panels are adapted to be installed on a sub floor and connected to each other with a long edge mechanical locking system for locking the panels vertically and horizontally, said locking system comprising a tongue and a tongue groove for mechanically locking together adjacent edges vertical to the horizontal plane, forming a vertical mechanical connection between the panels, and a locking element at a first long edge and a locking groove at an opposite second long edge thereby forming a first horizontal mechanical connection between adjacent long edges locking the panels to each other in a direction parallel to the horizontal plane and at right angles to said adjacent long edges, wherein the panels are provided with a short edge locking connection comprising a short edge tongue groove and a separate tongue, for locking adjacent short edges in a first vertical direction, inserted in a fixation groove at a short edge of a panel, wherein the separate tongue is at least one of flexible and displaceable, and a locking strip and a locking cavity for locking adjacent short edges in a second vertical direction, wherein the separate tongue comprises a lower surface, wherein the lower surface contacts a portion of the short edge tongue groove on an adjacent short edge for locking the adjacent short edges in the first vertical direction, wherein the short edge locking connection is configured to lock the adjacent edges in the vertical directions only, wherein the long edges are provided with a second horizontal mechanical connection locking the panels to each other along said adjacent long edges, in a direction parallel to the horizontal plane and parallel to said adjacent long edges, when the panels are laying flat on the sub floor, wherein said second horizontal mechanical connection comprises compressible material that is applied in the locking system at surfaces that do not comprise cooperative active locking surfaces which lock the panels vertically to the horizontal plane and horizontally in a direction parallel to the horizontal plane and at right angles to said adjacent long edges.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) 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:

(2) FIGS. 1a-1f illustrate locking systems according to known technology.

(3) FIGS. 2a-2d illustrate a short edge locking system according to the invention.

(4) FIGS. 3a-3f illustrate a long edge locking system according to preferred embodiments of the invention.

(5) FIGS. 4a-4c illustrate an preferred embodiment of short edge locking system.

(6) FIGS. 5a-5f illustrate separate tongues that may be used in to lock short edges.

(7) FIGS. 6a-6f illustrate preferred embodiments of the invention.

(8) FIGS. 7a-7c illustrate a long edge locking system according to the invention.

(9) FIGS. 8a-8b illustrate vertical folding with a conventional locking system and a locking system according to the invention. FIGS. 8a-8b

(10) FIGS. 9a-9d illustrate preferable embodiments of the invention.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

(11) To facilitate understanding, several locking systems in the figures are shown schematically. It should be emphasised that improved or different functions may be achieved using combinations of the preferred embodiments.

(12) The inventor has tested all known and especially all commercially used locking systems on the market that are installed with vertical folding in all type of floor panels, especially laminate and wood floorings and the conclusion is that at least all these known locking systems which have one or more locking elements cooperating with locking grooves may be adjusted to a system with a slide lock on the long edges which prevents displacement along the adjacent edges and with fold down locking system on short edges that only locks vertically.

(13) The most preferable embodiments are however based on floorboards with a surface layer of laminate, powder based paper free surfaces or wood surfaces, a core of HDF or wood and a locking system on the long edge with a strip extending beyond the upper edge which allows locking by angling combined with a tongue and groove joint on the short edges comprising a separate tongue which preferably only locks vertically.

(14) All embodiments may be used separately or in combinations. Angles, dimensions, rounded parts, spaces between surfaces etc. are only examples and may be adjusted within the basic principles of the invention.

(15) FIGS. 2a-2d show a first preferred embodiment of a short edge locking system provided with a flexible and displaceable tongue 30 in a first edge 1 inserted in a fixation groove 40 that cooperated with a tongue groove 20 in an adjacent second panel 1′ and locks the panels in a first vertical direction according to known technology. The first panel 1 (strip panel) comprises a protruding strip 6 that extends outwardly beyond a vertical plane VP. The second panel 1′ comprises a locking cavity 7 that cooperates with the locking strip 6 and locks the panels in a second vertical direction. FIG. 2d shows that the panels are only locked vertically and that they may be released or connected horizontally in essentially the same plane since there is no locking element on the strip and no hook connections in the locking system that prevents such horizontal displacement.

(16) FIGS. 3a and 3b show a slide lock system according to one preferred embodiment comprising a tongue 10 and a tongue groove 9, a locking strip 6, a locking element 8 and a locking groove 14. A flexible and compressible material 16 such as synthetic or natural rubber or plastic foam is applied in the upper part of the locking groove 14 as a layer or in local spots. The upper part of the locking element 8 is formed such that preferably two horizontally opposite edges press against the compressible material 16a, 16b. In a wood floor with a lamella core the locking element and the locking groove will be formed across the fibre orientation. The swelling and shrinking in the horizontal direction along the wood fibres is extremely small and will not cause any dimensional changes of the fitting tolerances between the locking element 8 and the locking groove 14. The counter pressure will not have any effect on the locking tolerances and swelling and shrinking of this part of the locking system will easily be compensated by the flexibility of the compressible material even in other wood based materials such as HDF. It is preferred that the upper part of the locking element is wedge formed and that it cooperates with a complementary groove 14. It is preferred that the inner part of the groove 14 is smaller than the groove opening. This design may be used to create a friction connection even without compressible material.

(17) FIGS. 3c and 3d show a locking system with at least three sets of cooperative locking surfaces between the locking element 8 and the locking groove 14. The first 11,12 and the second 21,22 sets are located in the upper part of the locking element wherein the first set is closer to the upper edges 4,5 than the second set. The third set 23,24 is located on the lower and outer part of the strip 6. The locking surfaces are essentially flat but they may also be curved. The locking surfaces are preferably inclined. Preferably the angle A1 against a horizontal plane of the first set of cooperated surfaces should be slightly smaller than the angle A3 of the third set. This geometry may be used to accomplish an easy locking with angling and a strong press fit between the locking element 8 and the locking groove 14 and the panels will be tightly secured to each other such that displacement along the long edges and perpendicular to the short edges will be prevented. Preferably all or some of the cooperating sets of surfaces are made with angles A1, A2, A3 that are between 40-80 degrees against the horizontal plane or even more preferably between 45 and 75 degrees.

(18) In wood cores, such as plywood or wood lamella core, it is preferred the fibre orientation is mainly perpendicular to

(19) the length direction of the edges. Layers in the plywood core may be adapted such that at least one set of cooperation surfaces comprises such fibre orientation that will provide a very high friction and a strong locking along the joint.

(20) Such a locking system with a press fit with or without additional preferably flexible friction increasing materials between the locking element and the locking groove, may be made much stronger than conventional locking systems with hooks at the short edges. A horizontally extending groove 35 may be formed in a wall or the locking groove 14 in order to increase the flexibility of one of the locking surfaces 23 in the third set of locking surfaces. A similar mainly vertical groove 35a may also be formed in the strip 6. The forming may be made with rotating tools or carving tools.

(21) The locking element and the locking groove may be formed in a very precise manner if high precision profiling is used where several tools are positioned at the same tool station such that the upper edge 4 and the locking element are formed at the same time in order to eliminate turning of the panels during machining. The locking groove and the upper edge 5 may be formed in the same way. The locking system may also be formed partly or completely with carving tools that allow forming of more complex geometries with undercuts.

(22) The above described slide lock systems are preferably used on long edges and in combination with a fold down locking system on short edges as shown in FIGS. 2a-2d.

(23) FIGS. 3e and 3f show that the flexible material may be combined with or replaced by with a flexible and preferable displaceable tongue 30 in one of the edges that is inserted in a fixation groove 40 and comprises a part, preferably an outer part, that is in contact with an adjacent edge and prevents displacement of the edges along the joint. The flexible tongue 30 is preferably inserted in a fixation groove 40 that is formed in the locking groove 14. The outer part of the tongue preferably comprises small and sharp locking protrusions that increase the longitudinal friction. The tongue may be fixed into the fixation groove 40 with friction and/or glue. One or several tongues 30 may be attached to one edge, preferably the long edge of a floor panel.

(24) FIG. 3e shows a locking system comprising a tongue 10 and a strip on the same edge 2. This geometry saves material when the locking system is formed. The adjacent panel 2′ comprises a tongue groove 9 with an upper 9a and a lower lip 9b that cooperates with the tongue 10 for vertical locking. The locking groove 14 comprises a fixation groove 40 that may be inclined in order to facilitate easy insertion of the flexible tongue 30 into the fixation groove 40. An outer sliding surface 30a of the flexible tongue 30 is during angling sliding against a siding surface 8a on the locking element and the flexible tongue is displaced inwardly and outwardly in the fixation groove. All types of tongues, which comprise at least one part that is flexible, may be used. The outer part of the flexible tongue may be wedge formed and may in locked position press with pre tension into the tongue groove 20a. The upper part of the tongue groove 20a is in this embodiment inclined upwards and outwardly such that the panels may be unlocked with an angling action.

(25) The fixation groove may be formed in the outer part of the strip 6 and it is also possible the replace the flexible tongue 30 with a sharp nail made of for example plastic or metal, preferably aluminium.

(26) FIG. 3f shows a locking system with a flexible tongue that presses against an upper part 21 of the locking element 8. Such a locking system may have a flexible tongue that may is only be displaced with a distance of less than 0.5 mm. Even 0.1-0.2 mm may be sufficient to provide a locking.

(27) All described embodiments may be combined. The slide lock system may also be combined with a conventional one piece tongue 10 and groove 9 system on the short edges. The flexible tongue may be designed such that it allows some displacement especially if a hammer and a tapping block is used. Two panels may also be connected with the short edges partly or completely and may thereafter be angled into a locked position at long edges.

(28) The fixation groove may extend along the whole length or may be a local groove with a length that may be slightly longer than the length of the flexible tongue 30.

(29) The slide lock system may also be used independently to lock panels at one pair of opposite edges and may be combined with any type of locking system at another pair of edges, preferably short edges. The slide lock system may be used to improve the overall locking of the panels and to increase the locking strengths at another pair of edges. This may be an advantage in thin panels or soft core material such as for example PVC where it is difficult to form large locking element. It is also suitable for narrow panels where the length of the locking element is rather small. Material savings may be obtained in for example a lamella core wood material where a separate, stronger and more expensive material usually is used at the short edges to form the strip and the locking element.

(30) FIGS. 4a-4c show that the separate tongue may be attached to the fold panel 1′.

(31) FIGS. 5a-5d show that all known tongues may be used in the short edge locking system. FIG. 5a shows a bow shaped tongue and FIG. 5b shows a bristle tongue. Such tongues are bended in length direction during locking. FIG. 5c shows a wedge tongue that is displaced with a side push action from the long edge such that it is displaced both along and perpendicular to the edge into the tongue groove 20. FIG. 5d shows as side push rigid tongue that is only displaced along the edge such that the protrusions on the tongue overlap the protrusions formed in the tongue groove 20.

(32) FIG. 5e shows a flexible tongue 30 that may be used to prevent displacement along the edge. The tongue comprises friction connections 31 that are located in the inner part of the fixation groove 40 and locking protrusion 32 that may be in contact with the adjacent edge, preferably an outer part of the locking element 8. Tongues as shown in FIGS. 5a and 5b may also be used

(33) FIG. 5f shows a locking system that comprises a flexible tongue 30 and that is in a locking position whereby one of the edges 2′ is angled to the sub floor. The flexible tongue 30 is in contact with the outer part of the strip when the locking element 8 and the locking groove 14 overlaps each other. This specific geometry prevents separation of the edges during angling.

(34) FIGS. 6a-6f show that all known fold down systems may be adapted to a locking system according to the invention by removing a part the locking element and preferably a part of the strip 6. This will provide cost savings due to less waste and a stronger joint. It is also possible to form a fold down system in very thin floorboards for example with a thickness of 4-6 mm. FIG. 6d shows a side push system with a wedge shaped tongue and FIG. 6e shows a side push system with a tongue comprising protrusions. Even one-piece systems with a machined tongue as shown in FIG. 6f may be used. A short strip provides a much easier machining of the undercut groove 41.

(35) FIG. 6d shows that all shown fold down locking systems may be adjusted such that the edge 6a may be formed without a protruding strip 6 and the tongue 30 may lock vertically upwards and downwards.

(36) FIGS. 7a-7b show preferred embodiments. The long side locking system comprises a friction element 15, which in this embodiment is located on the upper part of the locking element 8, and that cooperates with a friction groove 17. The advantage is that no compressible material 16 is applied in the active locking surfaces 9a,9b,10a,10b,3,4,11,12 that lock the panels vertically and horizontally.

(37) FIG. 7c shows that the friction may be improved if friction cavities 18 are formed on the upper part of the locking element 8 or in the friction element 15. Such cavities form expansion spaces for the flexible material 16 that may be applied with lower requirements on production tolerances. The cavities are preferably formed with a screw cutter as describe in WO2010087752. Friction cavities 18′ may also be formed on other parts of the locking system for example the outer part of the strip 6.

(38) FIGS. 8a and 8b show that present locking systems, as shown in FIG. 8a may easily be converted to a locking system according to the invention, as shown in FIG. 8b, and that the new locking system may be compatible with the old locking system. Friction cavities 18 are formed in the upper part of the locking element with a screw cutter, compressible material 16 is preferably inserted essentially in the groove along the whole long edge or in parts thereof and the locking element on the short edges is removed.

(39) The panels are installed such that a long edge 2″ of a new panel in a second row is put at an angle against a long edge 2 of a first panel installed in a previous row and displaced until its short edge 1′ is in contact with a short edge 1 of a second panel installed in the second row. The new panel is angled down whereby the flexible tongue locks 30 the short edges 1,1′ vertically. The long edges comprise a locking system with a friction connection that prevents displacement of the panels along the long edges 2, 2′, 2″.

(40) FIG. 9a shows that several friction elements 15, 15′ and friction grooves 17,17′ with compressible material 16,16, may be provided.

(41) FIG. 9b shows that the strip 6 may be replaced by overlapping upper edges 32, 33 above the separate tongue 30. It is of course possible to use both overlapping edges and a locking strip 6 cooperating with a locking cavity 7.

(42) FIG. 9c shows that flexible and compressible material 16 may be applied on the friction element 15.

(43) The long edge locking along the edge may be accomplished with a tight fit, with high friction or with all known methods to prevent displacement along the joint.

(44) Wood floor with a lamella core that generally has a rough surface may be formed with a locking system with tight fit and with rather large cooperating locking surfaces. No flexible materials are needed to obtain sufficient friction. Such long side locking system is extremely difficult to displace, especially when the floor boards are long, for example 1.8-2.4 m and the friction force is generally sufficient to accomplish a locking which keeps the short edges together during the lifetime of the floor.

(45) The locking strength of the slide lock may be increased considerably with a locking strip that is slightly bended and that causes a permanent vertical pressure as shown in FIG. 9d. Sufficient friction may be created even in HDF material that generally is formed with rather smooth surfaces. A strip 6 that in locked position is bended backwards will press the locking element 8 into the locking groove 14 when people walk on the floor or when furniture is applied on the surface. This will increase the locking strength of the second horizontal connection along the long edges. The locking strength may be increased further if for example a pressing protrusion 23 is formed on the lower part of the strip, preferably under the locking element. Such pressing protrusion 23 may be applied as a separate material on essentially the whole strip 6 or on separate parts along the edge.

(46) Wedge shaped locking elements 8 that are pressed into a cooperating locking groove 14 as shown in FIG. 9d may create a sufficient friction even without a compressible friction material. FIG. 9d shows embodiment that comprises a locking element 8 and locking groove with two sets of cooperating locking surfaces. A first set 11,12 is located closer to the vertical plane than a second set 21,22. The locking surfaces are preferably inclined such that a lower part of the locking element is larger than an upper part. The locking surfaces may be essentially plane or curved. It is preferred that there is a space S between the upper part of the locking element and the locking groove. Such a space S may be used to give more production tolerances. The angle A1,A2 of the cooperating surfaces, or tangent line in case the surfaces are curved, should preferably be larger than about 45 degrees. Preferably the vertical extension of the second set 21,22 of locking surfaces is essentially the same or larger than the vertical extension of the first set 11,12 of locking surfaces. The second set should preferably extend downwards to a level, which is below the first set.

(47) A flexing groove 34, 34′ may be formed in the locking element 8 and/or behind the locking groove 14 in order to increase the flexibility of the walls of the locking element 8 or the locking groove 14. Such flexing groove may also be filled with a flexible material that increases the flexibility further.

(48) A wedge shaped locking element as described above may be used to position the upper edges with a small play of for example of about 0.01-0.10 mm. Such a play will allow the top edges to swell and damages on the upper edges or squeaking sound will be eliminated. Such locking system is also very suitable to use in glue down floor installations or in combination with bevels between the upper joint edges.

(49) The above-described embodiment may of course be combined with friction cavities 18 and flexible material 16 may be inserted between the locking element and the locking groove.

(50) The locking system may be formed with two or more sets of locking elements and locking grooves in order to increase the friction. Small friction grooves 23 parallel with the joint edge may also increase the friction.

(51) Glue or wax that cures after some time is also possible to use and may eliminate problems with shrinking and swelling of a pre tensioned locking system. Wax mixed with aluminium oxide particles, which are applied in the locking system, increases the friction considerably.

(52) The long edge locking system may be used with all known vertical folding systems that lock the short edges vertically and horizontally.

(53) The separate tongues are generally factory connected into an edge. Separate lose tongues that are inserted prior to folding or when two short edges are laying flat on the sub floor are not excluded.

(54) The long edge locking system may be formed such that it is displaceable in an angle of 3-5 degrees. This facilitates installation around doors and similar.