Mechanical locking system for floor panels

1. A flooring system, comprising a plurality of rectangular floor panels adapted to be installed on a sub floor, said panels having long and short edges which are connectable to each other along one pair of adjacent edges of adjacent panels having a mechanical locking system comprising a tongue formed in one piece with the panels and a groove for mechanically locking together said adjacent edges at right angles to the horizontal plane of the panels, thereby forming a vertical mechanical connection between the panels, and a locking element at one first edge and a locking groove at an opposite second edge thereby forming a first horizontal mechanical connection locking the panels to each other in a direction parallel to the horizontal plane and at right angles to the joint edges, wherein:

each panel is made up of one or more upper layers of decorative plastic material and an intermediate core plastic material,

each panel at said adjacent edges being provided with a second horizontal mechanical connection locking the panels to each other along the joint edges, in a direction parallel to the horizontal plane and parallel to the joint edges, when the panels are laying flat on the sub floor,

said second horizontal mechanical connection comprises a plurality of protrusions in said mechanical locking system which reduces displacement of the panels along the joint edges when the panels are laying flat on the sub floor and are locked with the vertical mechanical connection and the first horizontal mechanical connection, the protrusions extending in a direction that traverses a line along the joint edges.

2. The flooring system as claimed in claim 1 , wherein the locking groove is open towards the rear side.

3. The flooring system as claimed in claim 1 , wherein the protrusions are formed on both the first edge and the second edge.

4. The flooring system as claimed in claim 1 , wherein the first horizontal mechanical connection comprises a strip which is an extension of the lower part of the groove and the locking element is formed on the strip.

5. The flooring system as claimed in claim 1 , wherein the mechanical locking system comprises a separate material, other than the material of the core of the panels, which is connected to the panels.

6. The flooring system as claimed in claim 5 , wherein the protrusions are formed in each panel such that the protrusions cooperate with the separate material when two panels are locked in the same plane.

7. The flooring system as claimed in claim 5 , wherein the protrusions are formed in the separate material.

8. The flooring system as claimed in claim 5 , wherein the protrusions are formed in the separate material and in the panels.

9. The flooring system as claimed in claim 5 , wherein the separate material is aluminum.

10. The flooring system as claimed in claim 1 , wherein essentially the whole length of an adjacent edge comprises protrusions.

11. The flooring system as claimed in claim 1 , wherein there is a space between the protrusions and the adjacent edge of the adjacent panel when the adjacent panels are in an angled position relative each other.

12. The flooring system as claimed in claim 11 , wherein the adjacent panels are displaceable along the joint edges when an upper part of the joint edges are in contact and when said adjacent panels are in an angled position relative each other.

13. The flooring system as claimed in claim 12 , wherein the panels are displaceable at an angle of less than 45 degrees when top edges of the panels are in contact with each other.

14. The flooring system as claimed in claim 1 , wherein the locking system is integrated with the panel.

15. The flooring system as claimed in claim 1 , wherein the plurality of protrusions in said mechanical locking system prevents displacement along the joint edges when the panels are laying flat on the sub floor and are locked with the vertical mechanical connection and the first horizontal mechanical connection.

16. The flooring system as claimed in claim 1 , wherein the protrusions are arranged in a pattern that repeats in a direction along the joint edges.

17. A flooring system, comprising a plurality of rectangular floor panels adapted to be installed on a sub floor, said panels having long and short edges which are connectable to each other along one pair of adjacent edges of adjacent panels having a mechanical locking system comprising a tongue formed in one piece with the panels and a groove for mechanically locking together said adjacent edges at right angles to the horizontal plane of the panels, thereby forming a vertical mechanical connection between the panels, and a locking element at one first edge and a locking groove at an opposite second edge thereby forming a first horizontal mechanical connection locking the panels to each other in a direction parallel to the horizontal plane and at right angles to the joint edges, wherein:

each panel is made up of one or more upper layers of decorative plastic material and an intermediate core plastic material,

each panel at said adjacent edges being provided with a second horizontal mechanical connection locking the panels to each other along the joint edges, in a direction parallel to the horizontal plane and parallel to the joint edges, when the panels are laying flat on the sub floor,

said second horizontal mechanical connection comprises a plurality of protrusions in said mechanical locking system which reduces displacement of the panels along the joint edges when the panels are laying flat on the sub floor and are locked with the vertical mechanical connection and the first horizontal mechanical connection,

wherein the protrusions are formed in one piece with each panel.

18. A flooring system, comprising a plurality of rectangular floor panels adapted to be installed on a sub floor, said panels having long and short edges which are connectable to each other along one pair of adjacent edges of adjacent panels having a mechanical locking system comprising a tongue formed in one piece with the panels and a groove for mechanically locking together said adjacent edges at right angles to the horizontal plane of the panels, thereby forming a vertical mechanical connection between the panels, and a locking element at one first edge and a locking groove at an opposite second edge thereby forming a first horizontal mechanical connection locking the panels to each other in a direction parallel to the horizontal plane and at right angles to the joint edges, wherein:

each panel is made up of one or more upper layers of decorative plastic material and an intermediate core plastic material,

each panel at said adjacent edges being provided with a second horizontal mechanical connection locking the panels to each other along the joint edges, in a direction parallel to the horizontal plane and parallel to the joint edges, when the panels are laying flat on the sub floor,

said second horizontal mechanical connection comprises a plurality of protrusions in said mechanical locking system which reduces displacement of the panels along the joint edges when the panels are laying flat on the sub floor and are locked with the vertical mechanical connection and the first horizontal mechanical connection,

wherein sliding strength of the second horizontal mechanical connection exceeds horizontal locking strength of the first horizontal mechanical connection.