Mechanical locking system for panels and method of installing same

1. A set of floor panels which are mechanically connectable to each other along one pair of adjacent edges, each of said floor panels comprising:

a flexible tongue on a first edge of the panel;

a tongue groove on a second opposite edge of the panel for receiving the flexible tongue of an adjacent panel for mechanically locking together said adjacent edges at right angles to a principal plane of the panels thereby forming a vertical mechanical connection between the panels;

the tongue groove is formed in a core of the panel;

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;

the locking element and the locking groove form a horizontal mechanical connection, the locking element having a substantially vertical locking surface that is adapted to directly contact a substantially vertical locking surface of the locking groove for locking the panels to each other horizontally parallel to the principal plane and at right angles to the joined first and second edges;

the flexible tongue being resilient and formed of a separate material than the core, and cooperates with the tongue groove;

wherein two of the panels can be mechanically joined together by displacement of said two panels vertically towards each other, while at least a part of the flexible tongue is resiliently displaced horizontally until said adjacent edges of the two panels are brought into engagement with each other vertically and the tongue is then displaced towards its initial position against the tongue groove;

wherein the flexible tongue has an inner part mounted in a sideward open groove in the first edge and a protruding part, and wherein said inner part is glued in said sideward open groove.

2. The set of floor panels as claimed in claim 1 , wherein the part of the tongue which is resiliently displaced is the protruding part.

3. The set of floor panels as claimed in claim 1 , wherein during the resilient displacement of the flexible tongue the inner part is resiliently displaced.

4. The set of floor panels as claimed in claim 2 , wherein the protruding part is bendable around a center point located at an upper part of the protruding part.

5. A set of floor panels which are mechanically connectable to each other along one pair of adjacent edges, each of said floor panels comprising:

a flexible tongue on a first edge of the panel;

a tongue groove on a second opposite edge of the panel for receiving the flexible tongue of an adjacent panel for mechanically locking together said adjacent edges at right angles to a principal plane of the panels thereby forming a vertical mechanical connection between the panels;

the tongue groove is formed in a core of the panel;

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;

the locking element and the locking groove form a horizontal mechanical connection, the locking element having a substantially vertical locking surface that is adapted to directly contact a substantially vertical locking surface of the locking groove for locking the panels to each other horizontally parallel to the principal plane and at right angles to the joined first and second edges;

the flexible tongue being resilient and formed of a separate material than the core, and cooperates with the tongue groove;

wherein two of the panels can be mechanically joined together by displacement of said two panels vertically towards each other, while at least a part of the flexible tongue is resiliently displaced horizontally until said adjacent edges of the two panels are brought into engagement with each other vertically and the tongue is then displaced towards its initial position against the tongue groove;

wherein the flexible tongue has an inner part mounted in a sideward open groove in the first edge and a protruding part, and wherein said inner part is glued in said sideward open groove;

wherein the part of the tongue which is resiliently displaced is the protruding part; and

wherein the protruding part comprises a first locking surface at a lower point of the protruding part and the tongue groove in the second edge comprises a second locking surface at its lower outer part and the first and the second locking surfaces are configured to cooperate to obtain the vertical locking.

6. The set of floor panels as claimed in claim 2 , wherein the protruding part has a sliding surface which extends downwards.

7. The set of floor panels as claimed in claim 1 , wherein the flexible tongue is made of polymer material.

8. The set of floor panels as claimed in claim 1 , wherein the flexible tongue is of a moulded or extruded polymer material reinforced with glass fibre.

9. The set of floor panels as claimed in claim 7 , wherein the polymer material is a thermoplastic material.

10. The set of floor panels as claimed in claim 8 , wherein the polymer material is a thermoplastic material.

11. The set of floor panels as claimed in claim 2 , wherein the inner part of the flexible tongue is provided with a protrusion on a surface of the inner part, and the protrusion engages an inner surface of the sideward open groove to facilitate a mechanical connection between the flexible tongue and the sideward open groove.

12. The set of floor panels as claimed in claim 1 , wherein each of the floor panels further comprises a balancing layer on the rear side of the panel and a decorative layer on an opposite front side of the panel, the balancing layer facing a sub floor over which the floor panels are adapted to be provided.

13. A flooring system as claimed in claim 1 , wherein the tongue has at least two sections along a length direction of the tongue and the displacement of one of the sections is larger than the displacement of the other one of the sections.

14. The flooring system as claimed in claim 1 , wherein the size of said protruding part and/or said inner part varies along the length of the tongue.

15. The flooring system as claimed in claim 1 , wherein the tongue is spaced from a corner portion.