Patent ID: 8381476

Claim:
A panel comprising: a working surface and four edges of which oppositely disposed pairs of edges have corresponding holding profiles so that similar panels are connectable at all four edges, wherein the holding profiles of a first pair of edges has, at an edge, a groove profile of undercut configuration and, at an opposite edge, a complementary tongue profile, such that the holding profiles of the first pair of edges are connectable by angular movement into interlocking relationship, wherein the holding profiles of a second pair of edges are complementary hook elements, each of the hook elements has at least one undercut surface, so that a similar adjacent panel is connectable at each of the hook elements substantially by means of a joining movement which occurs in a plane of movement perpendicularly to a plane of the panel, with a proviso that provided at least at one of the hook elements of the second pair of edges is a separate vertical locking element which at least partially projects into a path of joining movement of the hook elements, wherein during the joining movement of the hook elements of two panels, the vertical locking element is automatically movable out of the path of joining movement to clear same and in hooked condition of the hook elements is movable automatically into the path of joining movement again by a spring action, and wherein the undercut surface of each of the hook elements are arranged so that when the panels are in hooked condition, the undercut surface of each of the hook elements are arranged on a common unlocking curve and are in contact, and at least one panel is pivotable about an axis extending in a region of hooked edges in a direction in which an unlocking position is reachable, and that working surfaces of the panels in the unlocking position assume an angle relative to each other which is less than 180°.