US Patent 7398625 Locking system for floorboards

The invention relates to a locking system for mechanical joining of floorboards (1, 1′), a floorboard having such a locking system and a flooring made of such floorboards. The locking system has mechanical cooperating means (36, 38; 6, 8, 14) for vertical and horizontal joining of adjoining floorboards. The means for horizontal joining about a vertical plane (F) comprise a locking groove (14) and a locking strip (16) which is located at opposite joint edge portions (4a, 4b) of the floorboard (4). The locking strip (6) projects from the joint plane (F) and has an upwards projecting locking element (8) at its free end. The locking groove (14) is formed in the opposite joint edge portion (4a) of the floorboard at a distance from the joint plane (F). The locking groove (14) and the locking element (8) have operative locking surfaces (10, 11). The locking surfaces are essentially plane and spaced from the upper side of the projecting strip and inside the locking groove and make a locking angle (A) of at least 50° to the upper side of the board. Moreover the locking groove has a guiding part (12) for cooperation with a corresponding guiding part (6) on the locking element (8).