Patent ID: 7444791

Claim:
A locking system for mechanical joining of floorboards, said locking system comprising a tongue-and-groove joint, the groove and tongue of which have cooperating upper abutment surfaces and cooperating lower abutment surfaces for vertical locking of two joint edges of two adjacent floorboards, said upper abutment surfaces extending in a first plane essentially parallel to a principal plane of the floorboards and said lower abutment surfaces extending in a second plane essentially parallel to the principal plane of the floorboards, and said locking system comprising, for horizontal mechanical joining of the joint edges in a direction perpendicular to the joint edges, a locking groove formed in an underside of a first one of the floorboards and extended in parallel therewith and spaced from the joint edge, and a portion projecting from a second one of the floorboards, said portion supporting, at a distance from the joint edge, a locking element cooperating with the locking groove, wherein said tongue is anglable into the groove, and wherein the locking element is insertable into the locking groove by mutual angular motion of the floorboards about upper portions of the joint edges, wherein in a joined state, the cooperating upper abutment surfaces are in contact with each other and are limited horizontally inwards from the joint edge and horizontally outwards to the joint edge by an inner vertical plane and an outer vertical plane, respectively, the tongue-and-groove joint is so designed that there is in the groove between the inner vertical plane and the outer vertical plane and below the tongue, a space which extends horizontally from the inner vertical plane and at least halfway to the outer vertical plane, an uppermost surface of the locking element is below the first plane, and at least a portion of the lower abutment surfaces are positioned outside the outer vertical plane, wherein in an angling state, the tongue-and-groove joint is further so designed that the floorboards, during a final phase of an inwards angling when the locking element is inserted into the locking groove, can take a position where there is space in the groove between the inner and the outer vertical plane and below the tongue, and wherein the projecting portion is at least partially made in one piece with a body of the floorboard.