# Patent

## Title
Mechanical locking system for floor panels

## Abstract

Floor panels (1b, 1c) are shown which are provided with a mechanical locking system comprising a tongue with rocker arms that allows locking by a vertical turning motion.

## Background
CROSS REFERENCE TO RELATED APPLICATIONS
The present application claims the benefit of U.S. Provisional Application No. 61/301,402, filed on Feb. 4, 2010. The entire contents of U.S. Provisional Application No. 61/301,402 are hereby incorporated herein by reference.


TECHNICAL FIELD
Embodiments of the invention generally relate to the field of mechanical locking systems for floor panels and building panels especially floor panels with mechanical locking systems, which are possible to lock with a vertical folding.
FIELD OF APPLICATION OF THE INVENTION
Embodiments of the present invention are particularly suitable for use in floating floors, which are formed of floor panels which are joined mechanically with a locking system integrated with the floor panel, i.e. mounted at the factory, that are made up of one or more upper layers of veneer, decorative laminate, solid powder based surfaces, decorative plastic material and similar surfaces, an intermediate core of wood fibre based material or plastic material and preferably a lower balancing layer on the rear side of the core. The following description of known technology, problems of known systems and objects and features of the invention will therefore, as a non restrictive example, be aimed above all at this field of application and in particular at floating flooring formed as rectangular floor panels with long and shorts sides intended to be mechanically joined on both long and short sides. The long and short sides are mainly used to simplify the description of the invention. The panels can be squared and can have more than four sides, which are not parallel or perpendicular to each other.
It should be emphasized that the invention can be applied to any floor panel and it could be combined with all types of known locking system, where the floor panels are intended to be joined using a mechanical locking system connecting the panels in the horizontal and/or vertical directions on at least two adjacent sides. The invention can thus also be applicable to, for instance, solid wooden floors, parquet floors with a core of wood or wood fibre based material and a surface of wood or wood veneer and the like, floors with a printed and preferably also varnished surface, floors with a surface layer of plastic or cork, linoleum, rubber or similar and with core material that do not comprise wood material for example plastic or mineral fibres and similar. Even floors with hard surfaces such as stone, ceramics and similar are included and floorings with soft wear layer, for instance needle felt glued to a board. The invention can also be used for joining building panels which preferably contain a board material for instance wall panels, ceilings, furniture components and similar.
BACKGROUND OF THE INVENTION
Laminate flooring usually comprises a core of 6-12 mm fibreboard; a 0.1-0.8 mm thick upper decorative surface layer of laminate and a 0.1-0.6 mm thick lower balancing layer of laminate, plastic, paper or like material. A laminate surface may comprise a melamine impregnated paper. Recently printed surfaces and wood fibre based paper free laminate surfaces have been developed. The most common core material is fibreboard with high density and good stability usually called HDF—High Density Fibreboard. Sometimes also MDF—Medium Density Fibreboard—is used as core.
Floating laminate and wood floor panels are generally joined mechanically by means of so called mechanical locking systems. These systems comprise locking means, which lock the panels horizontally and vertically. The mechanical locking systems are usually formed by machining the core of the panel. Alternatively, parts of the locking system can be formed of separate materials, which are integrated with the floor panel, i.e. joined with the floor panel in connection with the manufacture thereof.
The main advantages of floating floors with mechanical locking systems are that they are easy to install. They can also easily be taken up again and used once more at a different location. Although many improvements of production cost and function have been accomplished over the years, there is still a need for further improvements.
DEFINITION OF SOME TERMS
In the following text, the visible surface of the installed floor panel is called “front side”, while the opposite side of the floor panel, facing the sub floor, is called “rear side”. The edge between the front and rear side is called “joint edge”. By “horizontal plane (HP) or principal plane” is meant a plane, which extends parallel to the outer part of the surface layer. Immediately juxtaposed upper parts of two adjacent joint edges of two joined floor panels together define a “vertical plane (VP)” perpendicular to the horizontal plane. By “horizontally” is meant parallel to the horizontal plane and by “vertically” parallel to the vertical plane. By “up or upwardly” is meant towards the front side and by “down or downwardly” is meant towards the rear side. By “inwardly” is meant essentially horizontally towards the inner part of the panel and by “outwardly” is meant essentially horizontally and away from the inner part of the panel. By “strip panel” is meant a panel comprising a strip and a locking element. By “groove panel” is meant a panel with a locking groove intended to cooperate with a locking element for horizontal locking.
KNOWN TECHNOLOGY AND PROBLEMS THEREOF
The description of the known technology below is in applicable parts also used in embodiments of the invention.
For mechanical joining of long sides as well as short sides in the vertical and horizontal direction several methods and locking systems could be used. One of the most used methods is the angle-snap method and one of the most used locking systems is a system made in one piece with the core. The long sides are installed and locked by angling. The panel is then displaced, while in the in locked position, along the long side. The short sides are locked by horizontal snapping.
An alternative method is the so-called angling-angling method whereby long and short sides are locked with angling.
Recently a new and simpler method has been developed where all floor panels can be joined with just an angling of the long edges. This installation method generally referred to as vertical folding, is described in FIGS. 1-4.
A new panel 1c is locked to a previously installed first panel 1a with angling. This angling action connects automatically one short edge of the new panel 1c with an adjacent short edge of a second panel 1b, which is installed and locked to the first panel 1a. The vertical and horizontal locking of the short edges 1b, 1c takes place with a vertical turning scissors like motion where a flexible tongue 30 is displaced inwardly gradually from one edge to the other edge when a long side of a new panel 1c is connected by angling to a long edge of a first panel 1a previously installed in an adjacent row. The flexible tongue, which in most cases is made of a plastic section, snaps and locks automatically during folding of the new panel 1c when it is angled down to the subfloor. The displaceable tongue is displaced twice, first inwardly into a displacement groove 32 and than outwardly into a tongue grove 31. The flexibility is caused by a horizontal bending of the tongue along the joint. A part of the flexible tongue is during folding pressed to its inner position, as shown in FIG. 2 and other parts are in a completely unlocked position. The flexible tongue snaps into a final locked position when both edges 1b, 1c are in the same plane as shown by FIG. 3 and locks vertically. A strip 6 with a locking element 8 cooperates with a locking groove 14 and locks the panels horizontally.
The flexible tongue is generally connected to an edge of the strip panel 1b. It could also be connected to the groove panel 1c. One of the most used tongues on the market is a bristle tongue 30, as shown in FIG. 4, that has an inner part comprising several flexible protrusions 10 and an outer rigid part 30′.
The main problems with know flexible tongues are that the tongue must be made of materials that are rather flexible, that the snapping creates a resistance during folding and that the major part the tongue must be displaced in a groove during locking.
The function of a fold down locking system of the kind described above could be improved if locking could be made without a two-ways snapping action described above and with only limited displacement and material bending. It would be an advantage if the tongue could be connected into a groove in a rather fixed manner.
There are known systems that could be locked with vertical turning combined with twisting as shown in for example WO 2008/004960, FIG. 6 (Välinge Innovation AB). There are several disadvantages related to such locking systems. The tongue is difficult to connect into a groove since the whole tongue must turning vertically during locking. A major part of the tongue is exposed towards an open groove. This makes the whole locking system very sensitive to cutting of the panel across the joint and the tongue could easily be damaged or fall out from the groove. The tongue could also turn during transportation and material handling. A considerable amount of material must be removed in order to form cavities or groove that could house such turn snap systems. This affects the stability of the edge in a negative way.
SUMMARY OF THE INVENTION
A basic objective of embodiments of the present invention is to provide an improved mechanical locking system comprising a tongue that locks automatically during folding without any snapping parts that are displaced inwardly and outwardly during locking.
A first specific objective of embodiments is to create a non-snapping tongue with a simple cross section that could be connected in a horizontally extending fixation groove with limited depth, which surrounds and protects a major part of the tongue.
A second specific objective of embodiments is to create a tongue where the main part of the tongue could be fixed firmly into a groove and were only parts of the tongue are displaced inside and/or outside the fixation groove.
The above objects of embodiments of the invention are achieved wholly or partly by a mechanical locking systems and floor panels, according to the independent claim. Embodiments of the invention are evident from the dependent claims and from the description and drawings.
According to a first aspect of the invention, a set of floor panels are provided which are mechanically connectable to each other along one pair of adjacent edges by a vertical turning motion, so that upper joint edges of said floor panels in the connected state define a vertical plane. Each of said floor panels comprising a tongue on a first edge of a panel having a length direction extending parallel with the first edge and a tongue groove on a second opposite edge of the panel for receiving the tongue of an adjacent panel for mechanically locking together said adjacent edges in a vertical direction. The tongue has an inner part mounted in a sideward open fixation groove in the first edge and an outer part extending beyond the vertical plane. The inner part is fixed in the sideward open fixation groove. The tongue comprises one or several rocker arms extending in the length direction of the tongue. Each rocker arm comprises a displaceable pressing protrusion that during locking is in contact with the second edge and a displaceable locking protrusion that in locked position cooperates with the tongue groove.
Said floor panels may further comprise a locking element formed in one piece with the panel at the first edge and a locking groove at the opposite second edge. The locking groove is open towards a rear side of the panel that faces a subfloor. The locking element and the locking groove form a horizontal mechanical connection perpendicularly to the vertical plane. The tongue preferably comprises resilient parts, formed of a separate material than the core. The panels may be mechanically joined together with vertical folding by displacement of said two panels towards each other with a combined vertical and turning motion. The pressing and the locking protrusion of each rocker arm are preferably positioned at different vertical and horizontal positions.
According to a second aspect of the invention a tongue is provided comprising a main tongue body having an elongated shape and a length direction. The tongue is intended to be connected into a groove formed in a building panel wherein the tongue comprises one or several rocker arms located along its length and extending in the length direction of the tongue and wherein the rocker arms are displaceable such that one part of the rocker arm is displaceable inwardly towards the main tongue body and another part of the rocker arm is displaceable outwardly away from the main tongue body.
The above described locking system and the tongue allows that panels could be locked automatically during vertical folding or vertical displacement without any snapping parts that are active and that create snapping resistance. A strong locking could be obtained with a tongue that has limited flexibility and that is fixed into the fixing groove during production, transport and installation. Only a rather limited horizontal turning of the rocker arms is required to lock the panels vertically.
The embodiments and principles related to vertical locking could also be used to connect building panels with a horizontal displacement.
The tongue is preferably factory connected but it could of course be delivered separately in blanks or as a separate loose component and inserted into a groove during installation.



BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1-4 illustrate known art.
FIGS. 5a-d illustrate embodiments of the invention.
FIGS. 6a-f illustrate vertical folding with rotating tongue parts.
FIGS. 7a-d illustrate a tongue blank and a second embodiment with an inclined displacement groove.



DESCRIPTION OF EMBODIMENTS OF THE INVENTION
To facilitate understanding, several locking systems in the figures are shown schematically. It should be emphasized that improved or different functions can be achieved using combinations of the preferred embodiments.
FIGS. 5a-5d show a tongue 30 according to an embodiment of the invention. FIGS. 5a and 5b show a tongue 30, which is inserted into a fixation groove 32 of a panel 1b, comprises an inner part IP with a main tongue body 29 and a rocker arm 20 which is connected with a fastening device 21 to the main tongue body 29.
FIG. 5c shows that the rocker arm comprises a pressing protrusion 22 located on a pressing arm 26 and a locking protrusion 23 located on a locking arm 27. The rocker arm is designed such that the locking protrusion 23 is displaced outwardly away from the main tongue body 29 when the pressing protrusion 22 is pressed and displaced inwardly towards the main tongue body 29. The rocker arm is preferably designed such that it could turn horizontally about 3-10 degrees during locking. The turning is facilitated by a cavity 51, which is formed between the main tongue body 29 and the pressing arm 26 allowing the pressing arm to be turned and displaced inwardly towards the main tongue body. A cavity 52 is preferably also formed between the locking arm 27 and the main tongue body 29
Several rocker arms are preferably located along the length direction L of the tongue as shown in FIGS. 5b and 5d. The rocker arms could have different shapes and lengths and some could be mirror shaped and oriented in different directions along the tongue. It is preferred that the rocker arms have a length, which exceeds the depth of the fixation groove 32.
The tongue is preferably connected to the fixation groove 32 with friction connections 28. Several tongues could be connected into a groove along the edge but also over and under each other. The friction connections 28 could be designed such that the tongue is connected in a rather loose way or in a rather fixed way with firm friction. Even glue or snapping connections, where the core material is bended or compressed, could be used to fix the tongue into the fixation groove 32. The friction 28 connections could be located on protruding parts that could flex vertically in order to eliminate production tolerances.
FIGS. 6a-f show vertical folding and a connection of two adjacent edges 1b, 1c with a combined vertical and turning motion. The tongue is preferably connected to the strip panel 1b comprising a strip 6 with a locking element 8 that cooperates with a locking groove 14 in an adjacent panel edge for horizontal locking of the edges. The tongue could also be connected to the groove panel comprising the locking groove 14 and a tongue groove 31. FIG. 6d shows two cross sections A-A and B-B of two adjacent edges 1b and 1c in an unlocked position. A-A is a cut at the locking protrusion 23 and B-B is a cut at pressing protrusion 22 that is also shown in FIGS. 6b and 6c. The locking protrusion 23 is in its inner position and the pressing protrusion 22 is in its outer position and protrudes beyond the vertical plane VP. The groove panel 1c comprises preferably a lower sliding surface 41, preferably formed as a bevel, that cooperates with a preferably inclined or rounded upper surface 42 of the pressing protrusion 22.
FIG. 6e shows that the pressing protrusion 22 is pressed inwardly by a lower part of the grove panel 1c, preferably the lower sliding surface 41 and causes a turning motion of the rocker arm 20, as shown in FIGS. 6b and 6c, such that the locking protrusion 23 is displaced outwardly towards a tongue groove 31 formed in the adjacent edge. The turning is mainly accomplished with a bending of the resilient fastening device 21.
FIG. 6f shows cross sections of the edges in the locked position when the locking protrusion 23 is in contact with the tongue groove 31 and locks the edges in a vertical direction parallel to the vertical plane VP. The pressing protrusion 22 is locked horizontally against a locking edge 45 of the groove panel 1c. The outer part 46 of the pressing protrusion 22 is preferably located below the outer part 47 of the locking protrusion 23.
The locking could be accomplished essentially with only a turning motion in essentially a horizontal plane. The pressing and locking protrusions are preferably turning in essentially the same plane. Such turning is facilitated if the tongue groove 31 and the locking protrusion 23 preferably have contact surfaces 43, 44 that are inclined in relation to the horizontal plane. Such inclination is preferably 10-50 degrees. It is an advantage if the tongue groove locking surface 44 is more inclined than the locking surface 43 of the locking protrusion 23.
The locking could also be combined with bending of the pressing and locking arms. The locking system could also be designed such that the locking protrusion creates a pressure against the adjacent edge during locking whereby the rocker arm is slightly bended during locking and/or in locked position. This pressure is released partly or completely when the tongue groove 31 is in a position that allows the outer part 47 of the locking protrusion to enter into the tongue groove 31.
It is preferred that the final locking is made with horizontal pre tension between the locking protrusion and the tongue groove. Such pre tension is used to overcome production tolerances and to press the adjacent edges 1b, 1c vertically towards each other in order to preferably accomplish a tight vertical fit between the strip 6 and the adjacent joint part 53 of the groove panel 1c. 
The configuration of the rocking arms could be adapted to the contact angles of the adjacent edges during folding. FIG. 6a shows that a pressing against a pressing protrusion located close to the long side edge 1b′ and at a distance from the other pressing protrusions starts at a higher angle than the pressing against a pressing protrusion located close to the opposite free long side edge 1b′′. 
Long and short edges are used to simplify the description. The panels could be square.
FIGS. 7a, 7b show a tongue and a tongue blank 50 comprising several tongues. Very advanced tongue shapes could be formed with injection moulded plastic components and each rocker arm could have an individual design. The cross section of a pressing and/or locking protrusion may vary between the rocking arms located along the tongue.
It is an advantage if the rocker arms are compacts and located close to each other such that a lot of locking protrusions are active during locking. In small and thick panels only one rocker arm could be sufficient. In most applications several rocker arms should be used. The distance D between the fastening devices 21 should preferably not exceed four times the floor thickness T. Very compact tongues could be made where the distance D between the fastening devices 21 is only about 2 times the floor thickness. This means that a locking system in a 7-10 mm laminate flooring could comprise several locking protrusion with a distance of about 2 cm and this gives a very strong vertical locking.
The distance between the fastening devices 21 along the tongue is preferably larger than the distance between the pressing and locking protrusions 22, 23.
It is an advantage if the locking protrusion 23 is very compact as shown in FIG. 7c. The length of the pressing protrusion along the edge is preferably smaller than the floor thickness.
FIG. 7d show that it could be an advantage if the fixation groove 32 is inclined against the horizontal plane HP. This facilitates the insertion of the tongue into the fixation groove and the turning of the pressing extension could be made with a lower pressing force. This embodiment comprises a locking element 8 and a locking groove 14 that have inclined cooperating locking surfaces. Such an embodiment could also be locked and unlocked with angling.
The principles described above could be used to provide locking systems that snaps in the same way as the known systems. The pressing and/or locking protrusion could be formed such that they are displaced inwardly and outwardly during locking such that they snap into a tongue groove.
All principles and embodiment described above could be used to lock floor panels horizontally with a horizontal displacement against each other. The tongue is located in a vertically extending fixation groove which could be formed in the groove panel with its opening towards the rear side or on the strip panel with its opening towards the front side. A tongue and groove could be used to lock the panels vertically. The rocker arms will in this embodiment turn or snap in a vertical plane. The fixation groove could be inclined and several rounded or beveled sliding surfaces could be used to facilitate the vertical rotation or snapping of the rocker arms.
All known materials that are described and used in fold down systems of the kind described in FIGS. 1-4 could be used to form tongues according to the invention. The rocker tongues could be adapted to fit into a displacement groove of the known bristle tongues and the same inserting equipment could be used.
The rocker arms could of course be formed with one or two legs and in a way that they could be bended inwardly and outwardly during locking. Such a tongue could be used to connect floor panels with snapping actions where the rocker arms are displace inwardly and are snapping outwardly during locking.

## Claims

1. A set of floor panels which are mechanically connectable to each other along one pair of adjacent edges by a vertical motion, so that upper joint edges of said floor panels in the connected state define a vertical plane, each of said floor panels comprising:
a tongue on a first edge of a panel having a length direction extending parallel with the first edge;
a tongue groove on a second opposite edge of the panel for receiving the tongue of an adjacent panel for mechanically locking together said adjacent edges in a vertical direction;
wherein the tongue has an inner part mounted in a sideward open fixation groove in the first edge and an outer part extending beyond the vertical plane, the inner part is fixed in the sideward open fixation groove,
wherein the tongue comprises at least one rocker arm extending in the length direction of the tongue, the rocker arm comprising a displaceable pressing protrusion that during locking is in contact with the second edge and a displaceable locking protrusion that in locked position cooperates with the tongue groove,
wherein the locking protrusion is displaced outwardly away from the main tongue body when the pressing protrusion is pressed and displaced inwardly towards the inner part of the tongue.

2. The set of floor panels as claimed in claim 1, wherein the inner part of the tongue comprises the main tongue body and the rocker arm comprises a fastening device that connects the rocker arm with the main tongue body.

3. The set of floor panels as claimed in claim 2, wherein the fastening device is flexible and located between the pressing protrusion and the locking protrusion.

4. The set of floor panels as claimed in claim 1, wherein the pressing protrusion protrudes from a pressing arm and the locking protrusion protrudes from a locking arm.

5. The set of floor panels as claimed in claim 4, wherein the locking protrusion is locked against the tongue groove with pre tension.

6. The set of floor panels as claimed in claim 1, wherein the tongue groove is formed in a core of the panel and is open towards the vertical plane.

7. The set of floor panels as claimed in claim 1, wherein the floor panels are provided with a horizontal mechanical connection locking the panels horizontally perpendicularly to the vertical plane.

8. The set of floor panels as claimed claim 7, wherein the horizontal mechanical connection comprises a locking element formed in one piece with the panel at the first edge and a locking groove at the opposite second edge, the locking groove being open towards a rear side of the panel that faces a subfloor.

9. The set of floor panels as claimed in claim 1, wherein said first and second opposite edges of the floor panels are mechanically connectable by vertical folding, a combined vertical and turning motion.

10. The set of floor panels as claimed in claim 1, wherein the tongue comprises resilient parts formed of a separate material than the core.

11. The set of floor panels as claimed in claim 10, wherein the resilient parts are formed of an injection moulded plastic material.

12. The set of floor panels as claimed in claim 1, wherein the sideward open fixation groove is open towards the vertical plane.

13. The set of floor panels as claimed in claim 1, wherein the pressing protrusion comprises the outer part of the tongue in an unconnected state and the locking protrusion comprises the outer part in a connected state.

14. The set of floor panels as claimed in claim 1, wherein the at least one rocker arm during locking is turning in a horizontal plane parallel to the panel surface and perpendicular to the vertical plane.

15. The set of floor panels as claimed in claim 1, comprising multiple rocker arms, wherein the rocker arms are spaced from each other in the length direction of the tongue.

16. The set of floor panels as claimed in claim 1, wherein the pressing protrusions and the locking protrusions are spaced from the main tongue body and wherein the tongue comprises cavities formed between the main tongue body and the rocker arm.

17. A tongue comprising a main tongue body having an elongated shape and a length direction and adapted to be connected into a groove formed in a building panel wherein the tongue comprises at least one rocker arm located along its length and extending in the length direction of the tongue and wherein the rocker arm is displaceable such that one part of the rocker arm is displaceable inwardly towards the main tongue body and another part of the rocker arm is displaceable outwardly away from the main tongue body,
wherein displacement of the one part of the rocker arm inwardly towards the main tongue body causes the another part of the rocker arm to be displaced outwardly away from the main tongue body.

18. The tongue as claimed in claimed in claim 17, wherein at least a part of the rocker arm is flexible.

19. The tongue as claimed in claim 17, wherein the rocker arm comprises a fastening device that connects the rocker arm to the main tongue body.

20. The tongue as claimed in claim 17, wherein the tongue constitutes a part of a tongue blank, the tongue blank comprising several tongues and wherein the blank is an injection moulded plastic component.

21. A tongue comprising a main tongue body having an elongated shape and a length direction and adapted to be connected into a groove formed in a building panel wherein the tongue comprises at least one rocker arm located along its length and extending in the length direction of the tongue and wherein the rocker arm is displaceable such that one part of the rocker arm is displaceable inwardly towards the main tongue body and another part of the rocker arm is displaceable outwardly away from the main tongue body,
wherein the another part of the rocker arm is displaced outwardly away from the main tongue body when the one part of the rocker arm is pressed and displaced inwardly towards the main tongue body; and
wherein the rocker arm comprises protrusions protruding outwardly from the main tongue body and spaced from each other in the length direction of the tongue.

22. The tongue as claimed in claim 21, wherein one of the protrusions is displaced outwardly away from the main tongue body when the other protrusion is pressed and displaced inwardly towards the main tongue body.

23. The tongue as claimed in claim 21, wherein the protrusions are spaced from the main tongue body and wherein the tongue comprises cavities formed between the main tongue body and the rocker arm.

24. The tongue as claimed in claim 21, comprising multiple rocker arms, wherein the protrusions located on one of the rocker arms are spaced in the length direction from the protrusions located on another one of the rocker arms.