WO2013151494A1

WO2013151494A1 - Building panel with a mechanical locking system

Info

Publication number: WO2013151494A1
Application number: PCT/SE2013/050367
Authority: WO
Inventors: Christian Boo
Original assignee: Välinge Innovation AB
Priority date: 2012-04-04
Filing date: 2013-04-03
Publication date: 2013-10-10
Also published as: PL3235971T3; RU2622945C2; RU2014142450A; LT2852722T; PL2852722T3; PT2852722T; CN104204379B; EP3460143A1; EP2852722B1; KR102149414B1; CA2867324C; ES2639512T3; KR20140144710A; EP2852722A4; CN104204379A; CA2867324A1; EP3235971B1; EP3235971A1; EP3460143B1; EP2852722A1

Abstract

The present invention relates to building panels 1, 1' provided with a mechanical locking system including a tongue 30, at an edge of a first panel 1, cooperating with a tongue groove 20, at an edge of an adjacent second panel 1', for vertical locking of the building panels. The edge of the first panel is provided with a displacement groove 60, which is downwardly open, and includes an inner wall 61, an outer wall 62, and an upper wall 67. The tongue 30 is formed out of the edge of the first panel. A resilient and displaceable and part 66 of the tongue 30 is displaceable into the displacement groove 60.

Description

BUILDING PANEL WITH A MECHANICAL LOCKING SYSTEM

Field of the invention

The present invention relates to a building panel such as a floor panel, a wall panel, a ceiling panel, a furniture component or the like, which is provided with a mechanical locking system, and a method for producing said building panel with said locking system.

Technical background

Building panels provided with a mechanical locking system comprising a displaceable and resilient tongue cooperating with a tongue groove for vertical locking is known and disclosed in, e.g., WO2006/043893. The tongue is a separate part and is made of e.g. plastic and inserted in a displacement groove at an edge of a panel. The tongue is pushed into the displacement groove during a vertical assembling of the panels and springs back into the tongue groove of an adjacent panel when the panels have reached a locked position.

Also known is a locking system for panels comprising a tongue, which is displaceable along the edge of a panel, see, e.g., WO2009/1 16926, and cooperates with a tongue groove for vertical locking. The tongue is a separate part and is provided with several protrusions, which initially match recesses of the tongue groove. The panels may be assembled by a vertical movement and the tongue is displaced to a position in which the protrusions no longer match the recesses in order to obtain the vertical locking.

Although the description relates to floor panel, the description of techniques and problems thereof is applicable also for other applications, such as panels for other purposes, for example wall panels, ceiling panels, furniture etc.

A drawback with the known system is that a separate tongue must be produced and special inserting machines are required to position the tongue in the displacement groove with high precision.

The above description of various known aspects is the applicant's characterization of such, and is not an admission that any of the above description is considered as prior art. Summary of the invention

It is an object of certain embodiments of the present invention to provide an improvement over the above described techniques and known art.

A further object is to provide a locking system with a flexible and displaceable tongue that may be formed out of the edge of the building panel. Such a system may simplify the production since no loose and additional part is necessary to produce and position at the correct position in the locking system.

Another object is to provide a more efficient production method and which requires less complicated production equipment.

At least some of these and other objects and advantages that will be apparent from the description have been achieved by building panels provided with a mechanical locking system comprising a tongue, at an edge of a first panel, cooperating with a tongue groove, at an edge of an adjacent second panel, for vertical locking of the building panels. The edge of the first panel may be provided with a displacement groove, which is downwardly open, and comprises an inner wall, an outer wall, and an upper wall. The tongue may be formed out of the edge of the first panel. A displaceable part of the tongue may be displaceable into the displacement groove and the upper wall may be vertically positioned at an upper surface of the displaceable part of the tongue.

The length of the displacement groove, along the edge of the first panel, is preferably smaller than the length of the edge of the first panel. The length of the displacement groove is preferably in the range of about 10% to about 90% of the length of the edge of the first panel

The resilient and displaceable part of the tongue makes it possible to assemble the first and the second panel by displacing the edges vertically in relation to each other. A part of the edge of the second panel may push the displaceable part of the tongue into the displacement groove. The resilient and displaceable part of the tongue is preferably configured to be displaced into the displacement groove by a lower lip of the tongue groove during assembling of the first and the second panel. The displaceable part of the tongue may spring at least partly back, when the first and the second panel are positioned in a locked position, and into the tongue groove of the second panel. The part of the edge and the displaceable tongue part are preferably configured such that the displaceable part is pushed in an essentially horizontal direction. An essentially horizontal displacement may decrease the risk that the displaceable part of the tongue gets stuck in the displacement groove. The upper wall may cooperate, for guiding the displaceable part of the tongue and/or for the vertical locking, with the upper surface.

The upper wall may be positioned somewhat above the upper surface of the displaceable part, but a position at an essential equal level, may make the locking system more stable and stronger.

The displacement groove may be arranged in relation to the edge of the first panel so that a thin wall or sidewardly open groove is created, at the outer wall of the displacement groove, above and/or below the displaceable part of the tongue.

The thickness of the outer wall of the displacement groove at a first and upper part of the displacement groove, at the upper surface of the tongue, is preferably configured such that the outer wall at the first and upper part breaks during said assembling of the building panels when the displaceable part of the tongue is pushed into the displacement groove.

The thickness of the outer wall of the displacement groove at a second part of the displacement groove, below the displaceable part of the tongue, is preferably configured such that such that the outer wall at second part breaks during said assembling of the building panels when the displaceable part of the tongue is pushed into the displacement groove.

The outer wall at the first and upper part of the displacement groove and/or the outer wall of the displacement groove at the second part of the displacement groove may also be broken by a tool, preferably a rotating wheel, before assembling. An alternative for breaking is to make a cut by a tool, e.g., a knife or preferably a rotating knife.

The displacement groove may also be sidewardly open at the first and/or second part of the displacement groove.

A wall that breaks may provide overlapping surfaces between the displacement groove and the displaceable part when the displaceable part is not pushed into the displacement groove. The overlapping surfaces make the locking system more stable and stronger.

A sidewardly open displacement groove makes it easier to push the displaceable part of the tongue into the displacement groove.

The broken outer wall of the displacement groove may cooperate, for guiding the displaceable part of the tongue and/or for the vertical locking, with the displaceable part of the tongue. The tongue may comprise a fixed part at each side of the displaceable part of the tongue.

The tongue groove may comprise recesses, which match the fixed part of the tongue.

The recesses may be in a lower lip of the tongue groove. The length, along the edge of the second panel, of the lower lip between the recesses is preferably smaller than the length displacement groove.

A contact surface of the lower lip of the tongue groove may cooperate, for the vertical locking, with a lower surface of the displaceable part of the tongue.

The contact surface may be positioned such that when the displaceable part of the tongue springs back, during assembling of the building panels, the displaceable part is prevented to reach its original position. The lower surface of the displaceable part tongue may assert a force against the contact surface of lower lip in order to avoid a play between the panels.

The tongue may have several displaceable parts and the edge of the first panel may be provided with several displacement grooves.

The locking system may comprise a locking element, preferably arranged on a locking strip, at the edge of the first or the second panel, which cooperates with a locking groove at the edge of the other of the first or the second panel, for locking the panels horizontally.

The first and the second panel are preferably essential equal, thus an edge opposite said edge of the first panel is provided with the same parts of the locking system as said edge of the second panel.

The panels may be square-shaped and the edges between the said edge and said opposite edge are preferably provided with a locking system which enables assembling to an adjacent panel by an angling movement.

The displacement groove may be filled with a resilient material, such as plastic or rubber, to improve the resilient properties of the displaceable part and/or to make the locking system stronger.

The building panel may be a floor panel, a wall panel, a ceiling panel, a furniture component or the like.

The core of the building panels may be a wood-based core, preferably made of MDF, HDF, OSB, WPC, or particleboard or of plastic e.g. vinyl or PVC. The edge of the panels, of which the locking system may be made, may comprise the core material.

A second aspect of the invention are building panels provided with a mechanical locking system comprising a tongue, at an edge of a first panel, cooperating with a tongue groove, at an edge of an adjacent second panel, for vertical locking of the building panels. The edge of the first panel may be provided with a displacement groove to obtain a resilient and displaceable tongue part. Said displacement groove may be downwardly open, and comprises an inner wall, an outer wall and an upper wall. The tongue may be formed out of the edge of the first panel. The resilient and displaceable part of the tongue may be configured to be displaced partly into the displacement groove by a lower lip of the tongue groove during assembling of the first and the second panel by a vertical displacement of the second panel toward the first panel.

The thickness of the outer wall of the displacement groove at a first and upper part of the displacement groove, above the upper surface of the tongue, is configured such that the resilient and displaceable tongue part is obtained. Also the thickness of the outer wall of the displacement groove at a second part of the displacement groove, below the resilient and displaceable part of the tongue, is configured such that the resilient and displaceable tongue part is obtained. The outer wall at the first and upper part and at the second part is not, according to certain embodiments of the second aspect, intended to break. The purpose of the displacement groove and the outer wall at the first and upper part and at the second part is to make the resilient and displaceable tongue part more resilient and to provide an improved locking strength.

The tongue may comprise fixed parts at the side of the resilient and displaceable part of the tongue.

A contact surface of a lower lip of the tongue groove may cooperate, for the vertical locking, with a lower surface of the resilient and displaceable part of the tongue.

The contact surface may be arranged such that when the displaceable part of the tongue springs back, during the assembling of the building panels, the displaceable part is prevented from reaching its original position.

The tongue may have several displaceable parts and the edge of the first panel may be provided with several displacement grooves. Also parts of the lower lip of the tongue groove may be made flexible and resilient. This may be achieved by providing a displacement groove also at the edge of the second panel.

The core of the building panels may be a wood-based core, preferably made of MDF, HDF, OSB, WPC, or particleboard or of plastic e.g. vinyl or PVC.

The edge of the panels, of which the locking system may be made, may comprise the core material.

A third aspect of the invention is a method to produce a building panel according to embodiments of the first or second aspect. The method may comprise the steps of:

• forming the tongue at the edge of the first panel.

• forming the displacement groove at the underside of the first panel, preferably by milling, sawing and/or drilling.

• milling the tongue groove at the opposite edge of said edge of the first panel.

• forming the recesses in the lower lip of the tongue groove, preferably by milling, sawing and/or drilling.

Brief description of the drawings

The present invention will by way of example be described in more detail with reference to the appended schematic drawings, which shows embodiments of the present invention.

FIG. 1 shows a known locking system with a separate and resilient tongue.

FIGS. 2A-C shows a cross section of a known locking system with a separate and displaceable tongue.

FIG. 3 shows a known locking system with a separate and displaceable tongue.

FIG. 4 shows a 3D view of building panels according to an embodiment of the invention.

FIG. 5 shows a 3D view of building panels according to an embodiment of the invention. FIGS. 6A-B show cross sections of building panels according to an embodiment of the invention.

FIG. 6C shows a side view of building panels according to an embodiment of the invention.

FIGS. 7A-D shows an embodiment of assembling according to an embodiment of the invention.

FIGS. 8A-B show top views of the building panels according to embodiments of the invention.

FIGS. 9A-B show a cross of the building panels according to embodiments of the invention.

FIGS. 10A-B show a top view and a side view of the building panels according to an embodiment of the invention.

FIGS. 1 1A-D show a top view, a side view and two cross sections of building panels according to an embodiment of the invention.

FIGS. 12A-C show a side view and two cross-sections of building panels according to an embodiments of the invention.

Detailed description

A known locking system for building panels, which comprises a displaceable and resilient tongue 30 cooperating with a tongue groove 20 for vertical locking of the short edges is shown in FIG. 1 . The tongue 30 is a separate part and is made of, e.g., plastic, and inserted in a displacement groove at a first short edge of a panel. The tongue is pushed into a displacement groove during a vertical assembling of the short edges of the panels and springs back into a tongue groove at a second short edge of an adjacent panel when the panels have reached a locked position. The long edges of the panels are provided with a locking system, which enables assembling to an adjacent panel by an angling movement, to obtain a simultaneous assembling of adjacent long and short edges.

FIGS. 2A-B show cross sections of different embodiments of the known displaceable and resilient tongue 30 during assembling of two adjacent short edges. The panel with the tongue groove is lowered in relation to the panel with tongue 30, which is pushed into the displacement groove by the lowered panel. The tongue springs back, and into the tongue groove, when the panels has reached an assembled position, and locks the panels vertically. A known locking system for panels comprising a tongue 30, which is displaceable along the short edge 4a of a panel 1 in a displacement groove 40 and cooperates with a tongue groove 20 for vertical locking of adjacent short edges 4a, 4b is disclosed in FIG. 3. The tongue is a separate part and is provided with several protrusions 31 a, which initially match recesses 33b of the tongue groove 20. The panels 1 , 1 ' may be assembled by a vertical movement and the tongue is displaced, by applying a force at a part 32 of the tongue 30, to a position in which the protrusions no longer match the recesses in order to obtain the vertical locking. The long edges 5a, 5b of the panels are provided with a locking system, which enables assembling to an adjacent panel 1 " by an angling movement, to obtain a simultaneous assembling of adjacent long 5a, 5b and short edges 4a, 4b.

Embodiments of the invention is shown in FIGS. 4, 5, 6A-C, 7A-D, 8A-B and 9A-B. A locking system is formed at adjacent edges of an adjacent first and second panel 1 , 1 ' for locking the adjacent edges in a vertical and/or horizontal direction. An embodiment of the locking system enables assembling of panels at the adjacent edges by a vertical movement, see FIGS. 7A-D. The locking system is preferably formed by mechanical cutting, such as milling, drilling and/or sawing, of the edges of the panels.

A tongue 30 is formed at an edge of the first panel 1 . The tongue 30 cooperates with a tongue groove 20, which is formed at an edge of an adjacent panel 1 ', for vertical locking of the panel 1 , 1 '. A locking strip 8 with a vertically protruding locking element is formed in the edge of the first panel. The locking element 6 cooperates with a locking groove 14, formed at the edge of the second panel 1 ', for horizontal locking of the panels 1 , 1 '.

A displacement groove 60 is formed in the edge of the first panel behind the tongue 30. The displacement groove 60 makes a part 66 of the tongue 30 displaceable. During assembling of the first and the second panel 1 , 1 ' the displaceable part 66 is pushed into the displacement groove 60 by a lower lip 31 of the tongue groove 20. When the panels are in a locked position the displaceable part 66 springs back and into the tongue groove 20.

Other parts 68 of the tongue 30, beside the displacement groove 60 and the displaceable part 66 of the tongue 30, is fixed. To enable the panels 1 , 1 ' to be assembled by a vertical movement, recesses 69 are formed in a lower lip 31 of the tongue groove 20. The recesses 69 match the fixed parts 68 of the tongue. FIGS 4, 5, 6A-C, 7A-D and 8B show a first embodiment comprising a tongue 30 with two displaceable parts 66 and three fixed parts 68, two displacement grooves 60, and a lower lip 31 of a tongue groove 20 with three recesses 69. The cross section in FIG. 6A is at the D-D line indicated in FIG. 8A and the cross section in FIG. 6B is at the C-C line indicated in FIG. 8A.

FIG. 8A shows a second embodiment comprising a tongue 30 with one displaceable part 66 and two fixed parts 68, one displacement groove 60, and a lower lip of the tongue groove 20 with two recesses 69.

The first embodiment is shown in a 3D view in FIG. 4 and 5.

The cross sections in FIGS. 6A and B and the side view in FIG. 6C, show that a lower surface of the displaceable part 66 cooperates, for vertical locking of adjacent edges of the panels 1 , 1 ', with a contact surface 70 of the lower lip 31 of the tongue groove 20. A vertical movement of the displaceable part is restrained, since the displaceable part of the tongue is continuous with the fixed part 68 of the tongue 30a.

The displacement groove 60 is formed from the underside of the first panel V and comprises an inner wall 61 , an outer wall 62, and an upper wall 67. The displacement groove 60 may be positioned, in relation to the edge of the first panel, such that the thickness of the outer wall at a first 64 and upper part of the displacement groove 60, at the upper surface 65 of the tongue 30, is configured such that the outer wall breaks during assembling of the building panels when the displaceable part 66 of the tongue is pushed into the displacement groove 60.

The displacement groove 60 may also be positioned, in relation to the edge of the first panel, such that the thickness of the outer wall of the displacement groove 60 at a second part 63 of the displacement groove 60, below the displaceable part 66 of the tongue 30, is configured such that outer wall breaks during assembling of the building panels when the displaceable part 66 of the tongue is pushed into the displacement groove 60.

The walls at the at the first 64 and upper part of the displacement groove

60 and/or the second part 63 of the displacement groove 60 may also be broken before assembling of the building panels by pushing the displaceable part 66 of the tongue 30 into the displacement groove by a tool, such as a rotating wheel. An alternative is to use a cutting tool, such as a rotating wheel to separate the displaceable part 66 from the walls. The broken outer wall of the displacement groove may cooperate with the displaceable part of the tongue and thereby improve the guiding of the displaceable part 66 of the tongue 30 and/or improve the vertical locking.

If the displacement groove 60 is positioned, relation to the edge of the first panel, such that a sidewardly open groove is formed at the first and/or second part 64, 63 of the displacement groove, the force required to push the displaceable part 66 of the tongue 30 into the displacement groove 60 is lowered.

The contact surface 70 of the lower lip 31 may be positioned such that the displaceable part 66 of the tongue 30 is prevented to spring back to its initial position before assembling and thereby remains, in an assembled and locked position of the panels 1 , 1 ', partly in the displacement groove 66. This position of the contact surface 70 result in that the lower surface of the displaceable part of the tongue asserts a force against the contact surface of lower lip in the locked position of the panels 1 , 1 ', which is shown in FIGS. 9A and 9B. The asserted force improves the locking and a play between the panels may be possibly avoided or reduced.

To decrease the force applied on the tongue when a load is applied on the building panels and to further improve the strength and tolerances of the locking system, the edges of the adjacent panels may be provided with upper overlapping surfaces 90, which are shown in FIG. 9B. The upper overlapping surfaces are preferably essentially horizontal.

If the tongue remains in the displacement groove 60 the upper wall 67 of the displacement groove 60 may cooperate, for an improved vertical locking of the adjacent edges of the first and second panels 1 , 1 ', with an upper surface 65 of the displaceable part 66 of the tongue 30.

In order to improve the spring properties of the displaceable part 66 of the tongue 30, the displacement groove 60 may be filled or provided with an elastic material such as plastic or rubber. The improved spring properties may result in an improved locking.

An embodiment comprising a displacement groove 60 with an outer wall, which is not intended to break during assembling, is shown in FIG. 10A. The side view in FIG. 10A shows that the distance from the edge of the first panel 1 is increased. The displacement groove has the result that a resilient and displaceable tongue part 66 is obtained. The top view in FIG. 10B shows an embodiment with an edge of a first panel 1 comprising two displacement grooves 60 and a tongue 30 with two resilient and displaceable parts 66 and three fixed parts 68 and an adjacent edge of a second panel V comprising a tongue groove with a lower lip provided with three recesses 69 that matches the fixed parts 68 of the tongue. The tongue comprises an upper essentially horizontal surface 90, which preferably extends along the whole edge. The upper essentially horizontal surface increases the strength of the locking system. FIG. 12A shows in a side view that the size of the tongue may be increased for building panels comprising favourably resilient material.

FIGS. 1 1A-C show an embodiment in which also parts of the lower lip of the tongue groove is made flexible and resilient. This is achieved by providing a displacement groove also at the edge of the second panel. The side view in FIG. 1 1A and the cross section in FIG. 1 1 C show an embodiment comprising a displacement groove 71 which downwardly open at a distance from the tongue groove. The cross section in FIG.1 1 C is indicated in the top view in FIG.1 1 B by the A-A line. The cross section in FIG.1 1 D is indicated in the top view in FIG.1 1 B by the B-B line. The top view in FIG. 1 1 B shows an embodiment with an edge of a first panel 1 comprising two displacement grooves 60 and a tongue with two resilient and displaceable parts 66 and three fixed parts 68 at an edge of a first panel 1 , and an adjacent edge of a second panel V comprising a tongue groove with a lower lip provided with three recesses 69 that correspond to fixed parts 68 of the tongue, and two displacement grooves 71 , to obtain two flexible parts at the lower lip of the tongue groove.

Alternative shapes of displacement grooves 60, 71 at the edge of the first and second panel 1 , V are shown in FIGS. 12B-C. The upper wall of the displacement groove is of a rounded shape in order to increase the strength of the displacement groove.

Claims

1 . Building panels (1 , 1 ') provided with a mechanical locking system comprising a tongue (30), at an edge of a first panel (1 ), cooperating with a tongue groove (20), at an edge of an adjacent second panel (1 '), for vertical locking of the building panels characterized in

that the edge of the first panel is provided with a displacement groove (60) to obtain a resilient an displaceable tongue part (66), said displacement groove is downwardly open, and comprises an inner wall (61 ), an outer wall (62) and an upper wall (67),

that the tongue (30) is formed out of the edge of the first panel,

that the resilient and displaceable part (66) of the tongue (30) is configured to be displaced into the displacement groove (60) by a lower lip of the tongue groove during assembling of the first and the second panel (1 , 1 ') by a vertical displacement of the second panel toward the first panel,

that the thickness of the outer wall of the displacement groove (60) at a first and upper part (64) of the displacement groove (60), at the upper surface of the tongue (30), is configured such that the outer wall at the first and upper part (64) breaks during said assembling, and

that the thickness of the outer wall of the displacement groove (60) at a second part (63) of the displacement groove (60), below the resilient and displaceable part (66) of the tongue (30), is configured such that the outer wall at the second part (63) breaks during said assembling.

2. Building panels as claimed in claim 1 , wherein the upper wall (67) is vertically positioned at an upper surface (65) of the resilient and displaceable part (66) of the tongue (30).

3. Building panels as claimed in claim 2, wherein the upper wall (67) is configured to guide the resilient and displaceable part (66) of the tongue (30).

4. Building panels as claimed in claim 2 or 3, wherein the upper wall (67) is configured to cooperate with the upper surface (65) of the resilient and displaceable part (66) for the vertical locking.

5. Building panels as claimed in claim 1 , wherein the broken outer wall at the first and upper part (64) and/or at the second part is (are) configured to guide the resilient and displaceable part (66) of the tongue (30) during the assembling.

6. Building panels as claimed in claim 1 , wherein the broken outer wall at the first and upper part (64) and/or at the second part cooperate(s) with the resilient and displaceable part (66) of the tongue (30) for the vertical locking.

7. Building panels as claimed in any one of the preceding claims, wherein the tongue (30) comprises fixed parts (68) at the side of the resilient and displaceable part (66) of the tongue (30).

8. Building panels as claimed in claim 7, wherein the tongue groove comprises recesses, which correspond to the fixed part (68) of the tongue (30).

9. Building panels as claimed in any one of the preceding claims, wherein a contact surface (70) of a lower lip (31 ) of the tongue groove (20) cooperates, for the vertical locking, with a lower surface of the displaceable part (66) of the tongue (30).

10. Building panels as claimed in claim 9, wherein the contact surface is arranged such that when the resilient and displaceable part (66) of the tongue springs back, during the assembling of the building panels, the displaceable part (66) is prevented from reaching its original position.

1 1 . Building panels as claimed in any one of the preceding claims, wherein the tongue (30) has several displaceable parts (66) and that the edge of the first panel is provided with several displacement grooves (60).

12. Building panels (1 , 1 ') provided with a mechanical locking system comprising a tongue (30), at an edge of a first panel (1 ), cooperating with a tongue groove (20), at an edge of an adjacent second panel (1 '), for vertical locking of the building panels characterized in

that the tongue (30) is formed out of the edge of the first panel,

that the resilient and displaceable part (66) of the tongue (30) is configured to be displaced partly into the displacement groove (60) by a lower lip of the tongue groove during assembling of the first and the second panel (1 , 1 ') by a vertical displacement of the second panel toward the first panel,

that the thickness of the outer wall of the displacement groove (60) at a first and upper part (64) of the displacement groove (60), above the upper surface of the tongue (30), is configured such that the resilient an displaceable tongue part (66) is obtained, and

that the thickness of the outer wall of the displacement groove (60) at a second part (63) of the displacement groove (60), below the resilient and displaceable part (66) of the tongue (30), is configured such that the resilient an displaceable tongue part (66) is obtained.

13. Building panels as claimed in claim 12, wherein the tongue (30) comprises fixed parts (68) at the side of the resilient and displaceable part (66) of the tongue (30).

14. Building panels as claimed in claim 13, wherein the tongue groove (20) comprises recesses (69), which corresponds to the fixed part (68) of the tongue (30).

15. Building panels as claimed in any one of the claims 12-14, wherein a contact surface (70) of a lower lip (31 ) of the tongue groove (20) cooperates, for the vertical locking, with a lower surface of the resilient and displaceable part (66) of the tongue (30).

16. Building panels as claimed in claim 15, wherein the contact surface is arranged such that when the displaceable part (66) of the tongue springs back, during the assembling of the building panels, the displaceable part (66) is prevented from reaching its original position.

17. Building panels as claimed in any one of the claims 12-16, wherein the tongue (30) has several displaceable parts (66) and that the edge of the first panel is provided with several displacement grooves (60).