# Patent

## Title
Mechanical lockings of floor panels and a tongue blank

## Abstract

Floor panels are provided with a mechanical locking system including tongue and grooves provided with protrusions and cavities which are displaceable in relation to each other.

## Background
CROSS-REFERENCE TO RELATED APPLICATIONS
The present application is a divisional of U.S. application Ser. No. 13/146,731, filed on Jul. 28, 2011, which is a national stage application of International Application No. PCT/SE2009/051238, filed on Nov. 2, 2009, which claims priority to International Application No. PCT/SE2009/050103, filed on Jan. 30, 2009, and to Swedish Application No. 0900580-2, filed on Apr. 29, 2009. The entire contents of U.S. application Ser. No. 13/146,731, International Application No. PCT/SE2009/051238, International Application No. PCT/SE2009/050103, and Swedish Application No. 0900580-2 are hereby incorporated herein by reference in their entirety.


AREA OF INVENTION
The invention generally relates to the field of floor panels with mechanical locking systems comprising a separate displaceable tongue allowing easy installation. The invention provides new improved locking systems and methods to install and disconnect building panels, especially floor panels and methods to produce the locking system.
BACKGROUND OF THE INVENTION
In particular, yet not restrictive manner, the invention concerns a mechanical locking system for rectangular floor panels with long and short edges, which could be installed with vertical folding. It should be emphasized that long and short edges are only used to simplify the description. The panels could also be square, they could have more than 4 edges and the adjacent edges could have angles other than 90 degrees. However, the invention is as well applicable to building panels in general. More particularly the invention relates mainly to the type of mechanically locking systems, which allow that angling of long edges and vertical movement of short edges could lock all four edges of a panel to other panels with a single action method generally referred to as vertical folding.
Floor panel of this type are presented in WO 2008/004960 (Applicant Välinge Innovation AB) and WO 2008/017301 (Schulte). The main principles are shown in FIG. 1a-1d. 
FIG. 1a shows that two adjacent short edges in a first row could be locked with a displaceable tongue (30) which is displaced, as shown in FIG. 1b, by a side push at one edge section (32) when the adjacent short edges 1b, 1c have been folded down and positioned in the same plane. This vertical “side push” folding, which generally is activated by a pressure P from a long side of a third panel 1d in a second row, displaces the separate and displaceable tongue 30 along the short edge joint 1b but also perpendicular to the joint direction D2 such that a part of the tongue is displaced into a tongue groove 20 of the adjacent short edge 1c. FIG. 1c show that the displaceable tongue 30 is located in a displacement groove 40, which has a cavity 41. This cavity cooperates with a protrusion 31 on the displaceable tongue such that the displaceable tongue 30, when pushed along the edge and the displacement groove, is also displaced perpendicularly to the edge in D2 and into a tongue groove 20 of an adjacent panel. FIGS. 2a-2d show a known method to form a cavity 41. A rotating tool 71, similar to a thin saw blade, rotates in a horizontal plane HP parallel with the panel surface and forms a cavity 41. The main disadvantage is that the tool will form a cavity 41 with a considerable depth as shown in FIG. 2d. 
A side push locking system according to known technology that requires that a displacement groove is formed which is not parallel to the edge is very difficult to produce and deep grooves will have a negative effect on the stability and strength of the panel edge. As an alternative wedge shape tongues consisting generally of two parts, which are not parallel with the edge could be used. Such tongues are expensive and complicated to produce and insert into an edge.
The main disadvantage of side push systems of this kind compared to other mechanical locking systems is that it is difficult to form cavities that cooperates with protrusion on a displaceable tongue in a precise and cost effective way and to avoid negative effects on the stability and the strength of the panel edge.
DEFINITION OF SOME TERMS
In the following text, the visible surface of the installed floor panel is called “front face”, while the opposite side of the floor panel, facing the sub floor, is called “rear face”. The edge between the front and rear face is called “joint edge”. If not defined otherwise upper and lower means towards the front face and towards the rear face. Inner and outer means towards or away from the center of the panel. By “horizontal 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” perpendicular to the horizontal plane. By “horizontally” is meant parallel with the horizontal plane and by “Vertically” parallel to the vertical plane.
By “joint” or “locking system” are meant co acting connecting means, which connect the floor panels vertically and/or horizontally. By “Strip panel” is meant a panel edge that comprises a strip and a locking element and by “groove panel” is meant a panel edges that comprises a locking groove, which cooperates with the locking element in the horizontal locking.
By “vertical push folding” is meant an installation method where the short edges of two panels are locked when they are laying flat on a sub floor after the angling. The vertical locking is obtained by a side push that displaces a separate tongue in the length direction of the short edges. The horizontal locking is in conventional fold down systems obtained in the same way as for the angling systems with a locking element in one edge of a strip panel that cooperates with a locking groove on another edge of a groove panel. By “side push locking system” is meant a locking system, which could be locked with the vertical push folding method.
By “tongue width” is meant the maximum distance between two parallel lines along the length of a tongue that are in contact with the most outer and inner part of the tongue.
SUMMARY OF THE INVENTION
The general objective of the present invention is to improve the function and strength of a side push locking system and particularly of those parts that cause a displaceable tongue to move perpendicularly to an edge from one groove and into an adjacent groove when the displaceable tongue is displaced along the edge.
According to a first aspect of the invention a floor panels is provided with a locking system comprising a displaceable tongue in a displacement groove in a first edge and a tongue groove in adjacent second edges for vertical locking. A locking strip with a locking element in the first edge cooperates with a locking groove in the second edge for horizontal locking. The displaceable tongue comprises a protrusion and the displacement groove a cavity such that the protrusion is sliding against a cavity wall and in a first direction perpendicular to the edge when the displaceable tongue is displaced in a second direction along the edge. The displacement in the first direction causes the displaceable tongue to enter into the tongue groove whereby the edges are locked vertically. The cavity extends vertically downwards to the rear side of the panel.
The advantage is that a simple machining could be used to form the cavities and such forming will not have an adverse effect on the strength and stability of the edge.
The cavity is according to a preferred embodiment a blind hole surrounded by an essentially vertical wall.
Such cavity provide an extremely stable edge and a minimum of material must be removed.
According to a second aspect of the invention a floor panels is provided with a locking system comprising a displaceable tongue in a displacement groove in a first edge and a tongue groove in adjacent second edges for vertical locking. A locking strip with a locking element in the first edge cooperates with a locking groove in the second edge for horizontal locking. The displaceable tongue comprises a protrusion and the displacement groove a cavity such that the protrusion is sliding against a cavity wall and in a first direction perpendicular to the edge when the displaceable tongue is displaced in a second direction along the edge. The displacement in the first direction causes the displaceable tongue to enter into the tongue groove whereby the edges are locked vertically. The protrusion is flexible and configured to exert a horizontal pre tension against the tongue groove.
This second aspect offers the advantages that the negative effects of production tolerances could be reduced and an improved locking quality could be reached.
According to a third aspect of the invention a floor panels is provided with a locking system comprising a displaceable tongue in a displacement groove in a first edge and a tongue groove in adjacent second edges for vertical locking. A locking strip with a locking element in the first edge cooperates with a locking groove in the second edge for horizontal locking. The displaceable tongue comprises a protrusion and the displacement groove a cavity such that the protrusion is sliding against a cavity wall and in a first direction perpendicular to the edge when the displaceable tongue is displaced in a second direction along the edge. The displacement in the first direction causes the displaceable tongue to enter into the tongue groove whereby the edges are locked vertically. The protrusion is located on the lower and/or upper part of the displaceable tongue.
The third aspect offers the advantage that it possible to form a displacement groove with small depth and improved stability and strength could be reached.
According to a fourth aspect of the invention a set of floor panels are provided with a locking system comprising a displaceable tongue having a main tongue body and at least two wedge parts located in a displacement groove in a first edge of a first floor panel, cooperating for vertical locking of the edges with a tongue groove in adjacent second edge of a second floor panel. The locking system further comprises a locking strip with a locking element in one edge, which cooperates, for horizontal locking of the edges, with a locking groove in an adjacent edge. The main tongue body comprises at least two flexible protrusions and two recesses. The wedge parts are located at least partly in the recesses. The flexible protrusions are slideable against the wedge parts to obtain a displacement of the main tongue body perpendicular to the edges and thereby causing the vertical locking of the edges. The flexible protrusions are in unlocked position essentially displaced along the displaceable tongue in relation to the wedges and configured to exert a pre-tension against the wedge parts and the tongue groove. The main tongue body comprises a friction connection that allows displacement along the displacement groove and prevents the main tongue body to fall out from the displacement groove. The wedge parts comprise friction connection that prevents the wedge parts to be displaced in the displacement groove when the main tongue body is displaced along the edge. The wedge parts and the main tongue body comprise releasable wedge part connections adapted to be released during the insertion of the displaceable tongue into the displacement groove.
The fourth aspect offers the advantages that the edge could be formed with only a simple machining parallel to the edges in the same way as conventional mechanical locking systems. The displaceable tongue could be formed in a cost efficient way as a one-piece component and converted to a two-piece component during a controlled insertion of the tongue into a groove.
According to a fifth aspect of the invention a tongue blank is provided comprising at least two tongues having a tongue length and being connected to each other. The tongues are adapted to be separated from each other and inserted into an edge groove of a floor panel. Each tongue comprises a main tongue body comprising at least two protrusions extending essentially in the tongue length direction and two recesses. The tongue comprises two wedge parts located at least partly in or adjacent to the recesses. The main tongue body and the wedge parts comprise releasable wedge part connections adapted to be released from the main tongue body during the insertion of the tongue into the groove.
The fifth aspect offers the advantages that the tongues could be produced, handled and inserted into a groove in a simple and cost efficient way.
All embodiments of the first, second, third, fourth and fifth aspects could be combined and the flexible protrusion could for example be used together with a cavity extending to the rear side and being located on an upper and/or lower side of the displaceable tongue.
The invention provides for new embodiments of locking systems preferably at short edges but also at long edges or in square panels. Useful areas for the invention are wall panels, ceilings, exterior applications and floor panels of any shape and material e.g. laminate; especially panels with surface materials contain thermosetting resins, wood, HDF, veneer or stone.
Almost all embodiments of the locking system are described with a displacement groove and a displaceable tongue on the strip panel, mainly in order to simplify the description. It is obvious that the main principle or the invention could also be used on the locking groove side. A tongue is inserted into a displacement groove in one edge, which is located adjacent, and preferably above the locking groove and a tongue groove is formed in another edge adjacent to the locking strip and preferably essentially above the strip.



BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1a-1d illustrate prior art locking system.
FIGS. 2a-2d show a prior art production method to for a cavity in an edge of a panel.
FIGS. 3a-3f show a production method to form cavities in an edge of a panel.
FIGS. 4a-4d show an alternative production method to form cavities in an edge of a panel.
FIGS. 5a-5d show a production method using a screw cutter to form cavities in an edge of a panel.
FIGS. 6a-6b show how cavities could be formed in a core of a panel prior to applying a surface layer on the core.
FIGS. 7a-7d show a locking system with cavities formed by saw blades.
FIGS. 8a-8f show a locking system with a cavity formed by cutters as a drilled blind hole.
FIGS. 9a-9d show a locking systems with horizontally open cavities formed by cutters.
FIGS. 10a-10e show a locking system with a displaceable tongue comprising flexible protrusions.
FIGS. 11a-11d show a locking system with a displaceable tongue comprising protrusions at the lower part of the tongue.
FIGS. 12a-12f show a locking system with a displaceable tongue comprising protrusions on upper and/or lower parts of the tongue.
FIGS. 13a-13d show flexible protrusions on the lower part of a displaceable tongue and production methods to form a stable and strong edge.
FIGS. 14a-14d show a locking system with cavities formed by a vertically rotating saw blade.
FIGS. 15a-15b show a locking system with cavities formed by a horizontally rotating saw blade.
FIGS. 16a-16c show a locking system utilizing cavities, which are formed in connection to the forming of the long edge locking system.
FIGS. 17a-17b show a locking system with spikes that cooperates with protrusions.
FIGS. 18a-18e show a locking system with spikes cooperating with recess and an embodiment comprising a displaceable tongue on the groove panel.
FIGS. 19a-19e show a locking system with an one piece displaceable tongue that after insertion is separated into several unconnected parts.
FIGS. 20a-20d show insertion of a tongue into a groove and locking of a locking system according to the invention.
FIGS. 21a-21c show a method to position a tongue in a groove.
FIGS. 22a-22d show a tongue blank and an edge of a floor panel during locking.
FIGS. 23a-23f show tongue blanks and locking system at an edge of a floor panel during locking.
FIGS. 24a-24i show embodiments according to the main principles of the invention.



DESCRIPTION OF EMBODIMENTS OF THE INVENTION
FIG. 3a-3e shows a production method to form cavities 41a-d according to a cutter principle. Several cutters 70a-d could be used, one for each cavity. The forming could take place before or after forming of the profile.
FIG. 3a shows that the cuter principle could form a cavity, which is smaller than the diameter of the cutter.
FIG. 3e shows a cavity, which is larger than the diameter, if the panel and the tool are displaced in relation to each other. FIG. 3f shows a cavity, which is formed, as a blind hole comprising a solid upper part and an opening.
FIG. 4a-4d show that the above mentioned forming could also be made with a saw blade principle where preferably several saw blades 71a-d preferably on the same axes, forms cavities 41a-d. The cavities are in this embodiment smaller than the diameter of the saw blades. They could of course be equal or larger.
FIG. 5a-5d show a method to form the above mentioned cavities 41a-f with a screw cutter principle. Such forming could be produced in a very cost efficient way in a continuous production line and with high accuracy especially if the panel position and speed is synchronized accurately with the tool position and the tool rotation speed. The screw cutter 72 could be used as separate equipment or more preferably as an integrated tool position in a double-end tenoner. The panel edge is displaced essentially parallel to the axis of rotation AR of the screw cutter tool 72. It is possible to produce any shape, with round or sharp cavities. The cutting could take place before, after or in connection with the profile cutting.
The position in the length direction of a cavity formed on a panel edge depends on the position of the first entrance tool tooth 56a that comes into contact with the panel edge as shown in FIG. 5c. This means that the rotation of the tool must be adjusted to the panel edge that is moved towards the tool. The position between cavities could be very accurate if the tool rotation is adjusted and synchronized with the speed that the panel is displaced in relation to the screw cutter. Such an adjustment of the position of the first entrance tool and the tool rotation could be made by measuring the position of a panel edge and the speed of a transportation chain or a belt or the driving device that moves the chain or the belt. It is possible to obtain very accurate machining of the cavities and to position the first cavity at a pre-determined position from the edge with a tolerance of about ±0.2 mm or even lower. The diameter 53 of the shown screw cutter tool 72 should preferably be smaller on the entrance side ES than on the opposite exit side. The screw cutter tool could however have the same diameter 53 over the whole length 54. The increased cutting depth could in such a tool configuration be reached with an axis of rotation that is slightly angled in relation to the feeding direction of the panel edge.
The pitch 55 of the tool configuration defines the intermediate distance of the cavities. It is therefore very easy to form a lot of cavities and protrusions with very precise intermediate distances over a considerable length of a joint. The teeth 56 of a screw cutter are preferably made of industrial diamonds.
Cavities could also be formed with a large rotating tool similar to a saw blade, which comprise cutting teeth on only a portion of the tool body. This is a simple variant of the screw cutter principle and each rotation forms one cavity. The advantage is that the intermediate distance between the cavities could be changed by an adjustment of the tool rotation speed or the feeding speed of the panel.
A planned or unplanned production stops where the displacement of a panel is stopped is a problem if the screw cutter is integrated with the profiling equipment since the screw cutter will destroy all cavities of a panel that are in contact with the tool teeth. This problem could be solved with production methods comprising the following steps where some or all steps could be used independently or in combinations.
a) The panel is always stopped when is has passed the crew cutter tool and after a full production of all cavities located on a panel edge. This method is used for all planned stops. The screw cutter is displaced away from the panel edge when a panel is stopped at a position, which does not allow a full production of all cavities on an edge. Such panels with partly produced cavities are detected and rejected from normal production.
b) The screw cutter is displaced away from the panel edge when the panel stops. The transportation device is than reversed. The screw cutter is moved back to its original position and the panel is produced in the normal way.
c) The screw cutter comprises a moving device that allows that it could be displaced parallel to the panel edge and against the feeding direction of the panels when a panel stops. The screw cutter is displaced such that its teeth pass the panel edge of a stopped panel. All cavities will always be fully machined even when an emergency break occurs. The screw cutter returns to its original position when the transportation device starts and a new panel is produced in the normal way.
The displaceable screw cutter method as described in c) above offers the advantages that conventional profiling equipment could be used without any modification of the transportation device or the control systems.
The above described production methods to form cavities with a crew cutter could be used in all type of panel machining and especially in such machining where cavities are formed which comprises parts of a mechanical locking system for floor panels.
FIG. 6a-6b show that forming of cavities could be made before the profile cut. A separate material 62 or a panel core with protrusions cavities 41a could be connected to an edge of the floorboard and preferably glued between a surface layer 60 and a balancing layer 61 in a wood or laminate floor.
FIGS. 7a-7d show that the describe methods to form cavities in an edge could be used to displace a displaceable tongue 30 from one displacement groove 40 into an adjacent tongue groove 20 as described in FIGS. 1a-1d. One or several cavities 41a-c with horizontally extending inclined or parallel walls could be formed by cutting through the strip 6 and such an embodiment and production method is more cost efficient than the known methods where thin horizontally cutting saw blades are used to make a cavity. The cavities could preferably be formed with jumping tool heads 71a-71c, mounted on the same tool shaft, and which are displaced towards the rear side when the panel is displaced in relation to the jumping tool heads. The panel could of course also be displaced towards the saw blades vertically or horizontally. The jumping heads could be mounted in the same machine that forms the long edges and the forming of the cavities could be made in a cost efficient way in line with the forming of the locking system. The jumping heads could also be displaced along the feeding direction and the relative speed between the displacement of the jumping heads and the displacement of a panel edge could also be used to obtain cavities with an opening, which is larger than the width of the rotating tools. Jumping non-rotating scraping tools could also be used to form cavities or protrusions. FIG. 7c shows a displaceable tongue in an unlocked position with its protrusions 31a-c located in the cavities 41a-c. FIG. 7d shows the locked position when the tongue 30 has been displaced along the edge with a side pressure P applied at an edge section 32 of the displaceable tongue 30. The protrusion will during this displacement slide along the walls of the cavities and force the tongue to move perpendicularly PD to the edge and lock into the adjacent tongue groove 20.
FIGS. 8a-8f show an embodiment with a cavity 41a formed as a blind hole. A cutter 80a with a diameter of for example 5-15 mm could be used and one or several cavities 41a-41c shaped as blind holes could be formed from the rear side as shown in FIGS. 8a-8d. The panel and/or the cutter 80a are displaced vertically towards each other during machining. The cavities could be positioned such that they cooperate during locking with protrusions 31a-31d located on the inner part of the tongue 30 as shown in FIGS. 8d-8f. Such an embodiment will make it possible to form a very strong and stable edge since the cutters 80a will remove very small amounts of material.
FIGS. 9a-9d show an embodiment with cavities 41a-d formed with a cutter and where the cutter and/or the panel are displaced horizontally during machining. It could be an advantage to use such a production method in some application. The cutters could for example be stationary or fixed to a jumping tool head that also could be displaceable along the feeding direction of the panel.
FIGS. 10a-10e show that protrusions 31a-c could be made flexible and this could be used to compensate for production tolerances and to create a horizontal pre tension between the tongue 30 and the tongue groove 20 such that a vertical pressure force VF could be created between the upper part of the strip 6 and the adjacent panel as shown in FIG. 10d. The vertical pressure force VF is preferably caused by contact surface between the tongue 30 and the tongue groove 20 which are slightly inclined in relation to the horizontal plane HP.
FIGS. 11a-11d show that protrusions 31a-31c which during locking cooperate with cavities 41a-41c could be formed on for example the lower part of the displaceable tongue 30. The depth of the displacement groove 40 could be decreased considerably and this will increase the moisture stability and the strength of the joint.
FIGS. 12a-12f show that protrusion 31a-c, 31a′-c′ could be formed on the upper and/or lower part of the displaceable tongue 30. Such protrusions could during locking cooperate with cavities 41a located above and/or below the main body of the displaceable tongue 30.
FIGS. 13a, 13b show that flexible protrusions 31a could be formed which protrudes downwardly and/or upwardly from the main body of the displaceable tongue 30. Such protrusion could create a pre-tension in the same way as described above in connection to FIGS. 10a-10d. FIGS. 13c and 13d show that a protrusion 31a on the lower part of the displaceable tongue 30 give the advantages that the cavity 41a could be made considerable smaller, as shown in FIG. 13d and this could be used to improve the strength of the edge. Cavities formed by a vertically rotating tool 71 comprise preferably a lower part 81, which is positioned vertically inwardly to an upper part 82 of the cavity. This gives sufficient strength and stability to the edge and allows a cost efficient production.
FIGS. 14a and 14b show a displaceable tongue 30 with protrusions 31a, b on the lower part and with cavities 41a, b formed by rotating saw blades. FIG. 14c, 14d show that all embodiments of the cavities and protrusions could be used to create a counter pressure P′ and to bend a flexible tongue 30′. The protrusion 31a cooperates with the cavity 41a and prevents the tongue to be displaced when a side pressure P is applied. The tongue 30 bends and locks into a tongue groove. This could be used to lock panels in a first row where a counter pressure from a long side in an adjacent row is not possible to obtain in order to bend a tongue.
FIG. 15a, 15b show that horizontally rotating saw blades 71a-c could be used to form cavities 41a-c which extend above and/or below the main body of the displaceable tongue 30 and which cooperates with protrusions 31a, b located above and/or below the main body of the tongue. One saw blade 71a could be vertically offset in relation to another saw blade 71c. Such production methods and embodiments could be used to form displacement grooves 40 with limited depth or to increase the angle Al of the perpendicular displacement.
FIG. 16a-16c show that it is possible to displace the displaceable tongue 30 perpendicularly to the joint without any additional machining than what is required to form the locking system on long and short edges. Protrusions 31a, 31b at each edge section of the tongue 30 could be formed that cooperate with the long edge tongue groove 9 and locking groove 14. The protrusion 31b, which cooperates with the locking groove 14, is in this embodiment flexible and located on the lower side of the main tongue body. This principle could also be used to bend the flexible tongue described in FIG. 14c. The protrusion could be rigid and could for example be formed as a simple wedge part protruding downwards. The vertical extension of the protrusion 31b should be such that it allows a locking element 8 of an adjacent long edge to be located in the locking groove 14 and under the protrusion 31b as shown in FIGS. 16a-16c. 
FIG. 17a, 17b show that spikes 42a, 42b could be used to form a vertical wall in a displacement groove 40 and to displace the displaceable tongue 30 perpendicular PD to the joint. The displacement is in the shown embodiment caused by one or several cooperating pairs of spikes 42a, b and protrusions 31a, b. The spikes 42a, b could be made of metal, for example soft steal or aluminium, or plastic or even hard wood. Such embodiments could also be used to bend a flexible tongue. Spikes could of course also be connected horizontally or in an angle into the displacement groove 40.
FIG. 18a, 18b show that a displacement could also be accomplished by the use of one or several spikes 42a, b that cooperate with one or several recesses 42a, b. formed preferably at the inner part of the displaceable tongue 30. The displaceable tongue comprises in this embodiment one of several friction connections 44a, b that are preferably flexible in the vertical direction and that prevent that the tongue falls out from the displacement groove 40. Other type of friction connections could be used.
FIGS. 18c-18e show an embodiment comprising a displaceable tongue 30 located on the groove panel 1c, which is intended to be folded on the strip panel 1b. FIGS. 18c and 18 d show the displaceable tongue 30 in an unlocked position and FIG. 18e shows the locked position when the displaceable tongue 30 has entered into the tongue groove 40. The perpendicular displacement is in this embodiment caused by a cooperation between one or several protrusions 31a-c located on the lower side of the displaceable tongue and one or several cavities 41a-c which in this embodiment are located under the main tongue body. The cavities (41a-c) could preferably be formed by a screw cutter. Such an embodiment offers several advantages. A limited amount of material has to be removed from the panel edge in order to form the cavity. The cavities are also easy to form since there is no strip protruding from the edge. The displaceable tongue 30 is also easy to insert into the displacement groove which could be formed with a limited depth due to the fact that the protrusion 31a and the cavity 41a extends downwards from the lower part of the main tongue body.
FIGS. 19a-19e show a displaceable tongue 30 according to one embodiment of the invention. The displaceable tongue 30 is made in one piece, preferably by injection mounding of a preferably thermoplastic material. FIG. 19a show a displaceable tongue 30 comprising a main tongue body 30a and one or several wedge parts 45a-e, which are fixed to the main tongue body with wedge part connections 46a-e, located preferably partly in or adjacent to tongue recesses 43a-e formed in the main tongue body (30a). The wedge parts comprise wedge friction connections 47a, b. The main tongue body 30a comprises preferably one or several tongue friction connections 44 and preferably one or several flexible protrusions 31a-e preferably extending essentially in the length direction of the displaceable tongue body 30a. 
FIGS. 19b-19e are enlargements of a tongue section according to FIG. 19a. 
The tongue friction connection 44 is preferably flexible. Such tongue friction connections, which could be used to create a controlled pre tension against an upper and/or lower wall of the displacement groove 40, keep the tongue in the displacement groove in a controlled way and prevent that the tongue falls out from the displacement groove. The flexible tongue friction connection 44 allows a smooth and easy displacement along the joint and eliminates the need for tight production tolerances when the displacement groove is formed. The wedge parts 45 comprise one or several wedge friction connections 47 that could be formed as vertically extending small protrusions. Such protrusions could also be flexible.
The wedge friction connections 47 should preferably be designed to create a friction, which is larger than the friction created, by the tongue friction connections 44. The wedge friction connections 47 should create a firm connection between the wedge parts 45 and the displacement groove 40 and prevent that the wedge part 45 is displaced when the main tongue body 30a is displaced along and perpendicular to the joint during locking. Such a firm friction connection could be accomplished for example with a displacement groove which is formed with a smaller vertically extending opening in an inner part than in an outer part of the groove. The inner part of a wedge friction connection could be pressed against the upper and lower parts of the displacement groove during locking when the main tongue body 30a creates an inwardly directed pressure against the wedge part 45.
FIG. 19b shows that the wedge part 45 forms the outer part of the displaceable tongue when the displaceable tongue is produced and not connected to an edge of a panel. The outer part of the wedge part 45 protrudes partly beyond the main tongue body 30a. The width of the displaceable tongue TW 1 is larger than the width of the main tongue body TW 2. The wedge part comprises an inclined or rounded wedge ramp surface 48a and a connection surface 49, which in this embodiment is preferably essentially vertical. The flexible tongue protrusion 31 comprises an inclined or rounded tongue ramp surface 48b, which is designed to cooperate with the wedge ramp surface 48a and to displace the displaceable tongue perpendicularly to the panel edge when a side pressure P is applied on an edge section of the displaceable tongue. It is preferred that the flexible tongue protrusion 31 and the wedge part 45 is formed with overlapping parts in the width direction as indicated by the line L1. The wedge ramp surface is in the shown embodiment inclined 45 degrees against the length direction of the displaceable tongue 30. Other angles could be used. Preferred angles are about 25-60 degrees.
FIG. 19c shows that the wedge part 45 is preferably separated from the main tongue body 30a when the displaceable tongue 30 is inserted into the displacement groove 40 and pressed towards the inner part 40′ of the displacement groove 40. The wedge part connection 46 should preferably be designed such that it breaks when the wedge part 45 is pressed into the recess 43 formed in the main tongue body. The wedge part 45 could alternatively be separated partly or completely before insertion of the displaceable tongue 31 or when a side pressure P is applied during locking. It is preferred that the ramp surfaces 48a, 48b are in contact or at least overlapping in the width direction of the displaceable tongue when the displaceable tongue is in its inner unlocked position. Such an embodiment will limit the displacement distance DD that is required to accomplish a pre-determined locking distance LD.
FIG. 19d shows the position of the main tongue body 30a and the wedge part 45 when a side pressure P is applied on an edge of the main tongue body 30a and when the main tongue body has been displace along the displacement groove 40 and into its final locking distance LD where it has obtained its largest tongue width TW 3 and when it is locked to an inner part of a tongue groove 20 of an adjacent panel edge. It is preferred that the displaceable tongue is designed such that the main tongue body could be displaced further in order to enable final angling and locking of another panel 1d in another row as shown in FIG. 1b. FIG. 19e show that such further displacement along the edge will cause the flexible protrusion 31 to bend outwardly towards the outer parts of the main tongue body and the displaceable tongue could be locked with pre tension. The flexible protrusion is an essential part of this embodiment and could be used to eliminate negative effects of production tolerances related to the forming of the grooves and the insertion of the tongue into a groove. Such an embodiment, which allows that the displacement distance DD could be increased while the locking distance LD remains essentially unchanged will increase locking quality and reduce production costs.
The protrusion 31 could be formed such that the pre tension increases when the main tongue body is displaced during the final locking as shown in FIG. 19e. The pre tension could also be constant as shown in FIG. 24a. 
The protrusion 31 could according to one embodiment shown in FIG. 19e be formed such that it could flex horizontally inwardly and outwardly during locking but also vertically against an upper or lower part of the displacement groove. Such vertical flexibility could be used to create a friction connection 44′ that prevents the main tongue body to fall out from the displacement groove 40. The advantage is that a more rigid tongue body could be formed without any additional flexible friction connections on the main tongue body than the protrusions (31).
The displaceable tongue comprises in this embodiment three tongue widths. A maximum width TW 3 when it is in a locked position, a minimum width TW 2 when it is in an unlocked position and an intermediate width TW 1 between the maximum and minimum width when it is produced and not connected to an edge of a panel.
The minimum tongue width TW 2 is preferably about 4-6 mm, the maxim tongue width TW 3 is preferably 5-8 mm and the intermediate tongue width TW 1 is preferably 5-7 mm. The locking distance is preferably 1-3 mm and the displacement distance preferably DD about 2-5 mm.
FIG. 20a-20b shows how a displaceable tongue 30 could be inserted into a displacement groove 40 with a pusher 67. The displacement groove 40 comprises an inner 40a, 40a′ and outer 40b, 40b′ pair of opposite and essentially parallel groove surfaces. The vertical distance between the inner groove surfaces 40a, 40a′ is smaller than between the outer 40b, 40b′. Such a groove could be used to separate the wedge part 45 in a controlled way during insertion since the wedge part will be released when the main tongue body 30a has entered the groove and it will prevent the wedge part to turn or twist during insertion. FIG. 20c shows a cross section of a locking system in unlocked position and FIG. 20d in locked position.
It is essential that the tongue is fixed to the displacement groove in a rather precise manner. This could be accomplished with inserting equipment that inserts a tongue into a groove and a positioning device 90 that positions a tongue at a pre-determined and precise distance from a panel corner after insertion as shown in FIGS. 21a-21c. The positioning device 90 comprises a panel contact surface 91 and a tongue edge contact surface 92. These surfaces could be aligned or offset in the feeding direction with a pre-determined tongue distance TD. The displaceable tongue is preferably always connected in a position that requires a displacement in one direction, preferably against the feeding direction, FD as shown in FIG. 21a. The displaceable tongue 30 obtains automatically its pre-determined tongue distance TD (which could be zero) when the panel contact surface 91 is in contact with a panel edge preferably extending perpendicular to the feeding direction FD as shown in FIG. 21b. FIG. 21c show that a pressure wheel 93 could be used to finally fix the tongue in the correct position. Essentially vertical wedge connection surfaces 49, as shown in FIG. 19c, facilitate a controlled push back of the displaceable tongue.
A displacement and positioning in both directions could be obtained by for example a chain or belt comprising several pushers with panel contact surfaces 91 and tongue edge contact surfaces 92. The speed of the chain/belt could be increased and decreased in a controlled way in relation to the displacement speed of the panel such that a contact between the pushers and two opposite edge parts extending perpendicular to the feeding direction is established and the tongue is pushed along or against the feeding direction to its pre-determined position.
The above described production methods could be used to position any type of tongues in any locking system.
The production methods comprising inserting and positioning as described above require however that the tongue body and the wedge parts are displaced in a groove and this could create locking problems due to for example loose wedge parts that could slide during locking. The tongue is therefore most preferably connected and positioned in a pre-determined position during connection and no further adjustments should be required. Such a precise insertion of a tongue in a groove could be obtained if the speed of a pusher or hammer 67 that inserts the tongue is synchronized with the speed of the chain or belt that displaces the panel edge relative to the inserting equipment. Such a precise and controlled insertion could be used to insert any type of tongue or separate parts into a groove.
One tongue cavity and one wedge part could be sufficient to accomplish a locking especially if a flexible protrusion is used in one edge section that cooperates with a corner section of a panel. It is preferred however to use at least two tongue cavities and wedge parts. Such an embodiment provides easier and more controlled displacement and a stronger vertical locking.
FIG. 22a shows a tongue blank 80 comprising several displaceable tongues 30 according to the embodiments of the invention.
FIG. 22b shows a displaceable tongue 30 that has been separated from the tongue blank 80. FIG. 22c shows the displaceable tongue in a connected state when the wedge parts 45 have been separated from the main tongue body 30a. FIG. 22d shows the displaceable tongue 30 in an outer and locked position when a side pressure P is applied on a tongue edge.
FIG. 23a show that recesses 43′ could be formed in the main tongue body in order to save material. FIG. 23b shows that the wedge parts 45 could be connected to a fixed wedge connection 63. FIG. 23c-23f show that wedges could be position automatically and that no friction connections are needed. The fixed wedge connection 63 is displaced by the main tongue body 30a until an edge of the fixed wedge connection 63 is in contact with a perpendicular edge 64, generally the long edge, of an adjacent panel in an adjacent row as shown in FIG. 23d. The wedges are prevented to move further and the main tongue body 30a will be displaced perpendicularly to the edge as shown in FIG. 23e. 
FIG. 23g show that the fixed wedge connection could have a wedge hook 69 that is connected to a groove formed on an edge extending perpendicular to the main tongue body 30a. The groove that generally is used to receive a tongue of a long edge has in this embodiment an increased depth 66 that preferably is formed by a tool with a jumping head. The advantage is that the wedge connection does not have to be adapted to the panel width.
FIG. 24a shows that the protrusion 31 and/or the wedge part 45 could be flexible and create a pre-tension against the tongue groove.
FIG. 24b-24g show that protrusions 31a, 31b could be formed on each side of a wedge and that displacement of a main tongue body 30a could be made in both directions along the edge. The wedge part connection 46 is in this embodiment formed on the outer part of the wedge part 45.
FIGS. 24h and 24i show a simple way to obtain a friction connection that prevents a displaceable tongue of any kind to fall out from the displacement groove 40. A displaceable tongue 30 is formed such that it is slightly bended vertically along its length. Such bending could extend over the whole tongue or over limited sections and could be used to create a pre-tension against the upper and lower part of the displacement groove 40. The tongue is preferably after separation from a tongue blank pressed together by the inserting equipment, such that the bending is eliminated, and inserted into a groove. The bending could be obtained in many ways. A simple bending of a tongue formed of HDF material could for example be accomplished by a local compression 68 on upper and/or lower side of the main body. Different densities could also be used and this could be accomplished for example by machining a HDF board on essentially one side only. HDF could also be reinforced and bended in a controlled way if for example a layer, preferably a paper impregnated with a thermosetting resin, is applied on one side only. Such layer could be laminated and formed with a surface structure, which facilitates sliding and creates a predetermined friction against the groove. The above described friction connection could be used independently to connect any type of tongue, preferably a displaceable tongue, into a groove or in combinations with other friction connections or tongues according to the described embodiments.
All embodiments of the tongues could be formed in a material comprising wood fibers. Such materials could for example be wood fibers mixed with thermoplastic or wood comprising thermosetting resins. Extruded, injection molded or sheet shaped materials could be used. A preferred material is HDF and preferably HDF with a density exceeding 700 kg/cm2. Combinations of machining and/or punching and/or material compression could be used to form tongues or tongue blanks with rather complex three-dimensional forms and which could be used in any application where a separate and/or displaceable tongue is used to lock adjacent panel edges, preferably floor panels. This production method is very cost efficient end environmental friendly.

## Claims

1. A set of floor panels comprising a locking system, the locking system comprising a displaceable tongue in a displacement groove in a first edge of a first floor panel of the set of floor panels, cooperating with a tongue groove in an adjacent second edge of a second floor panel of the set of floor panels for vertical locking of the first and second edges,
the locking system further comprises a locking strip including a locking element in one of the first and second edges which cooperates, for horizontal locking of the first and second edges, with a locking groove in the other of the first and second edges,
the displaceable tongue comprises a protrusion and the displacement groove comprises a cavity, and the protrusion is slideable against a wall of the cavity to obtain a displacement of the displaceable tongue in a first direction perpendicular to the first and second edges and thereby obtain the vertical locking of the first and second edges,
wherein the cavity extends vertically downwards to a rear face of the first floor panel.

2. The set of floor panels as claimed in claim 1, wherein the cavity is formed as a blind hole.

3. The set of floor panels as claimed in claim 1, wherein the cavity is formed on one of the first and second edges comprising the locking groove.

4. The set of floor panels as claimed in claim 1, wherein the protrusion is flexible and configured to exert a horizontal pre-tension against the tongue groove.

5. The set of floor panels as claimed in claim 1, wherein the cavity comprises a lower part which is positioned vertically inwardly to an upper part of the cavity.

6. The set of floor panels as claimed in claim 1, wherein a displacement of the displaceable tongue in a second direction along the first and second edges causes the displacement of the tongue in the first direction such that the displaceable tongue enters into the tongue groove.

7. The set of floor panels as claimed in claim 1, wherein a final displacement of the displaceable tongue in a second direction along the first and second edges causes a displacement of the displaceable tongue essentially parallel to the first edge of the first panel.

8. The set of floor panels as claimed in claim 1, wherein the floor panels comprise a surface layer.

9. The set of floor panels as claimed in claim 1, wherein the cavity is circular as seen from a front face of the first floor panel.

10. The set of floor panels as claimed in claim 1, wherein the displacement groove comprises multiple cavities.

11. The set of floor panels as claimed in claim 10, wherein the displaceable tongue comprises multiple protrusions, each of which is slideable against a wall of one of the cavities.

12. The set of floor panels as claimed in claim 1, wherein the protrusion is exposed to a subfloor through the cavity.

13. The set of floor panels as claimed in claim 1, wherein the protrusion is slideable against the wall of the cavity during locking from a first location along the first and second edges to a second location along the first and second edges.

14. A set of floor panels comprising a locking system, the locking system comprising a displaceable tongue in a displacement groove in a first edge of a first floor panel of the set of floor panels, cooperating with a tongue groove in an adjacent second edge of a second floor panel of the set of floor panels for vertical locking of the first and second edges,
the locking system further comprises a locking strip including a locking element in one of the first and second edges which cooperates, for horizontal locking of the first and second edges, with a locking groove in the other of the first and second edges,
the displaceable tongue comprises a protrusion and the displacement groove comprises a cavity, and the protrusion is slideable against a wall of the cavity during locking from a first location along the first and second edges to a second location along the first and second edges to obtain a displacement of the displaceable tongue in a first direction perpendicular to the first and second edges and thereby obtain the vertical locking of the first and second edges,
wherein the protrusion is located on a lower and/or upper part of the displaceable tongue.

15. The set of floor panels as claimed in claim 14, wherein the cavity extends to a rear face of the first floor panel.

16. The set of floor panels as claimed in claim 15, wherein the cavity comprises a lower part which is positioned vertically inwardly to an upper part of the cavity.

17. The set of floor panels as claimed in claim 14, wherein the protrusion is flexible.

18. The set of floor panels as claimed in claim 14, wherein a displacement of the displaceable tongue in a second direction along the first and second edges causes the displacement of the tongue in the first direction such that the displaceable tongue enters into the tongue groove.

19. The set of floor panels as claimed in claim 14, wherein a final displacement of the displaceable tongue in a second direction along the first and second edges causes a displacement of the displaceable tongue essentially parallel to the first edge of the first panel.

20. The set of floor panels as claimed in claim 14, wherein the floor panels comprise a surface layer.