Panel unit for use as floor board for floor covering, has groove whose lower contact surface is concave, and whose upper contact surface is transversely formed in one direction, such that groove narrows to groove base in another direction

摘要

The unit has a projection whose lower contact surface rests against a lower contact surface of a groove (3) and whose upper contact surface rests against a upper contact surface of the groove. The lower contact surface of the groove is concave, and the upper contact surface of the groove is transversely formed in a direction, such that the groove wedge-shapely narrows to a groove base in another direction, which is normal to a groove side (11).