Floor panel provided with a core made of a derived timber product, a decorative layer and locking sections

The rectangular floor panel comprises a core of timber material, a decorative layer on the top and pairs of opposite side edges with complementary form-fitting hooked profiles. A receiving hook facing the lower side of the floor panel and a retaining hook located on the opposite side edge and facing the top side of the floor panel. The receiving and retaining hooks are provided with a distal side surface, one having at least one projecting interlocking element and another having an associated receiving pocket. The retaining hook is lockable with the receiving hook by vertical movement. The interlocking element and the top side of the floor panel are separated by at least one gap corresponding to one third the total thickness of the floor panel.

The invention relates to a rectangular floor panel, comprising a core made of a derived timber material and a decorative layer on the top side of the floor panel, with pairs of opposite side edges, where one pair of side edges displays complementary, form-fitting hooked profiles, namely a receiving hook facing the lower side of the floor panel and, on the opposite side edge, a retaining hook facing the top side of the floor panel, where both the receiving hook and the retaining hook display a distal side surface having at least one projecting interlocking element, which is associated with a receiving pocket in the complementary receiving hook, and the retaining hook is lockable with the receiving hook by a locking movement perpendicular to the plane of the floor panel.

Floor panels of this kind display the aforementioned hooked profiles on at least two opposite side edges. The remaining two side edges can display complementary profiles based on a groove and a tongue. These profiles can be connected to each other by contacting the side edge of a new floor panel obliquely with a side edge of a previously laid floor panel and subsequently swinging the new floor panel downwards into the plane of the previously laid floor panel. The latter profiles can be of form-fitting design. Profiles of this category are sufficiently known. They serve to connect floor panels in a first panel row to floor panels in a subsequent panel row.

In contrast, the hooked profiles mentioned in the opening paragraph serve to connect floor panels to each other that are located in the same row.

Both locking of a new floor panel on a previous row and interlocking with a floor panel of the same panel row are brought about by the swinging movement.

Interlocking is accomplished in that the retaining hook is swung down into the receiving hook. In this context, the retaining hook moves within a plane of rotation oriented perpendicularly to the top side of the floor panel. In this way, locking of the floor panel on the previous row takes place simultaneously with interlocking with a floor panel in the same panel row. The interlocking elements display an undercut that counteracts separation of connected hooked profiles.

An embodiment of a floor panel that can be categorised in the same class is known from WO 01/02670 A1. This is the embodiment whose form-fitting hooked profiles are shown in FIG. 5.1 of WO 01/02670 A1. The detail representation shows the complementary hooked profiles in connected state. Both hooked profiles display interlocking elements with a projecting curvature on distal side surfaces. The interlocking elements each engage receiving pockets in the hooked profile of the adjacent floor panel.

It has become apparent that the decorative layer on the top side of the floor panel is damaged during and after locking of the hooked elements. The decorative layer peels off and the top side of the floor panel warps, meaning that the decorative layer on the top side turns up at the side edges.

The object of the invention is to create a floor panel with hooked profiles of a kind that prevent damaging of the decorative layer.

According to the invention, the object is solved in that the interlocking element of the retaining hook and the top side of the floor panel are separated by a distance that, referred to the total thickness of the floor panel, corresponds to at least one-third of the total thickness of the floor panel.

The invention exploits a special property of the core made of a derived timber material. This special property consists in a decreasing density of the derived timber material with increasing material depth. A board made of a derived timber material consists of wood particles that have been mixed with binders and compacted in a press. The density of this kind of board made of a derived timber material is high near a surface, such as the top side or the lower side of the board. The density decreases as the distance from the surface increases. Both from the top side and from the lower side of the floor panel, the density initially decreases as the depth of the material increases. The density reaches a minimum in a central plane of the board made of a derived timber material.

It was found with the known floor panel that an interlocking element on a distal side surface of a hooked element causes damage on the decorative layer if it is located close to the top side of the floor panel. The core made of a derived timber material displays a high density close to the top side. If pressure is exerted by an interlocking element in this area, compression occurs in the material that splits the material. Internal cracks grow. Layers of the derived timber material peel off.

The invention envisages location of the interlocking element of the retaining hook at a greater material depth, i.e. at a greater distance from the top side of the floor panel.

The interlocking element is a greater distance from the top side of the floor panel and now lies in a soft area of the derived timber material, displaying a relatively low density in comparison with the density close to the surface. No splitting of the material close to the decorative layer occurs, since the softer material yields more. Moreover, the increased distance of the interlocking element from the top side of the floor panel has the effect that pressure and compression cannot reach up to the decorative layer.

The interlocking element preferably extends over the entire length of the side edge. Alternatively, several interlocking elements can be provided in series, one behind the other.

The distal side surface of the retaining hook preferably displays two interlocking elements. The two interlocking elements enlarge the degree of undercut and increase the retention force that counteracts separation of the hooked profiles.

Handling can be improved in that a first interlocking element of the retaining hook, located closer to the top side of the floor panel, projects farther from the distal side surface of the retaining hook than the second interlocking element. The effect of this is that the interlocking element projecting the shorter distance can pass the interlocking position for the interlocking element projecting the longer distance without inducing interlocking. Both interlocking elements subsequently interlock almost simultaneously in the receiving hook.

A further improvement is obtained if the side edges of the hooked profiles display plane contact surfaces facing towards the top side of the floor panel and such contact surfaces rest against each other in connected state of two floor panels. The contact surfaces are in contact in connected state of two floor panels. Seen from the top side of the floor panels, this results in a closed joint. A closed joint is desirable. This can be favoured by the form of the hooked profiles, e.g. in that the hooked profile is provided with an inclined plane and, as a result of interlocking, undergoes elastic deformation that forces the contact surfaces of two floor panels against each other.

It is useful if, during a locking movement, at least the second interlocking element can be moved past the contact surface of the receiving hook without making contact. The first interlocking element preferably does not project farther from the distal side surface than its contact surface. It is tolerable for the first interlocking element to make slight, grinding contact when passing the contact surface, in which context the grinding contact does not impair the function of the interlocking element.

The receiving hook favourably displays at least one interlocking hump, and the interlocking hump is located in front of the receiving pocket in the locking direction. The interlocking hump projects farther from the side edge than the contact surface of the receiving hook. As a result of elastic deformation of both the interlocking element and the interlocking hump, they engage each other in an undercut. Since the interlocking hump projects farther from the side edge of the receiving hook than its contact surface, the interlocking element of the retaining hook can be moved past the contact surface of the receiving hook without obstruction, until it strikes the interlocking hump and overcomes it by means of mutual elastic deformation.

Preferably, two interlocking humps and two receiving pockets are provided. These interact with two interlocking elements of the retaining hook and increase the retention force of the hooked profiles in interlocked state.

To facilitate interlocking of the two interlocking elements of the retaining hook with the two interlocking humps of the receiving hook, the first interlocking hump is a shorter distance from the top side of the floor panel than the second interlocking hump and projects a shorter distance from the distal side surface of the receiving hook than the second interlocking hump.

According to the drawing, floor panel1displays a rectangular, tabular core made of a derived timber material2. It is provided with a decorative layer4on a top side3and displays two parallel long side edges5and6, together with two parallel short side edges7and8. The side edges are intended for connecting several similar floor panels1. To this end, long side edges5and6display form-fitting interlocking profiles, namely an undercut tongue5aon side edge5and an undercut groove6aon opposite side edge6.

Several floor panels1are laid in rows. The interlocking profiles of long side edges5and6serve to connect the individual rows of floor panels1. A long side edge5of a new floor panel1is first contacted with a complementary interlocking profile of a previous panel row. The new floor panel1is initially positioned at an angle. This means that, at the start of the connecting procedure, the new floor panel1is held in a plane that is inclined relative to the plane assumed by floor panels1in their working position. In the spirit of the invention, the working position of floor panels1is also referred to as the working plane of floor panels1.

By swinging down new floor panel1into the working plane, the interlocking profiles of long side edges5and6are connected in form-fitting fashion. The form fit prevents separation of the two floor panels1in the working plane transversely to long side edges5and6. Perpendicularly to the working plane, the form fit moreover prevents vertical offset between interlocked long side edges5and6.

Within a row, floor panels1are connected to each other at their short side edges7and8, which are also referred to as face edges7and8.

Hooked profiles are provided on face edges7and8of the illustrated floor panel1. In reference to a horizontal working position of floor panel1, complementary hooked profiles are connected to each other by a vertical joining movement.

A hooked profile of a face edge7of floor panel1can be seen in the foreground inFIG. 1. The hooked profile projects from face edge7and is located close to the lower side of floor panel1. It is open towards top side3of floor panel1and is referred to as receiving hook9in the spirit of the invention. Opposite face edge8displays a complementary hooked profile, the cross-sectional shape of which is shown in enlarged form inFIG. 2. In the spirit of the invention, this hooked profile is referred to as retaining hook10.FIG. 3shows the cross-sectional shape of receiving hook9fromFIG. 1in enlarged form.

Both inFIG. 2and inFIG. 3, the density of the derived timber material of the core made of a derived timber material2is represented symbolically by dotting of the cross-section. The core made of a derived timber material2displays a high density near to top side3and near to the lower side. From top side3, the density decreases with increasing material depth, reaching a minimum roughly in a central plane or central layer of the core made of a derived timber material2.

According toFIG. 2, retaining hook10displays a distal side surface11, which is provided with a contact surface12facing towards the top side and with two projecting interlocking elements13and14. The distance from top side3to first interlocking element13is more than one-third of the total thickness of floor panel1. Second interlocking element14is located behind first interlocking element13at a greater distance from top side3of floor panel1. Both interlocking elements,13and14, are located in material areas of the derived timber material that display a relatively low density compared to the density close to top side3of floor panel1.

Apart from distal side surface11, retaining hook10displays an undercut surface15that interacts with receiving hook9in connected state. A recess16, facing towards the lower side, is provided on retaining hook10on proximal side surface11′.

Receiving hook9, illustrated inFIG. 3, displays a single interlocking element18on a distal side surface17. Distal side surface17of receiving hook9has a smaller height than distal side surface11of retaining hook10. Receiving hook9is provided with an undercut surface19that interacts with undercut surface15of retaining hook10in interlocked state of two floor panels1. Undercut surface19of receiving hook9is located a distance behind distal side surface17.

Undercut surfaces15and19of interlocked floor panels1prevent separation of floor panels1in their working plane and perpendicularly to face edges7and8.

Provided at roughly the same distance behind undercut surface19of receiving hook9is a receiving surface20with receiving pockets21and22for the two interlocking elements13and14of retaining hook10. Towards top side3of floor panel1, receiving surface20transitions into a contact surface23. In connected state of floor panels1, contact surfaces12and23of the retaining hook and the receiving hook form a joint24, visible from top side3.

Receiving surface20displays two projecting interlocking humps25and26. Each receiving pocket21and22is preceded by one of interlocking humps25and26. An interlocking hump25or26is located n front of each receiving pocket21and22in the direction in which retaining hook10is moved for the purpose of interlocking. Interlocking elements13and14of retaining hook10must be moved, by elastic deformation of the derived timber material, behind interlocking humps25and26, together with which they form an undercut in this way. The hooked profiles undercut in this way secure the floor panels to prevent separation in a direction perpendicular to the working plane of floor panels1.

First interlocking hump25projects farther from side edge7than contact surface23of receiving hook9. Because first interlocking hump25projects farther from side edge7of receiving hook9than its contact surface23, interlocking element13of retaining hook10is designed in such a way that it can be moved past contact surface23of receiving hook9without obstruction, until it strikes interlocking hump25and overcomes it by mutual elastic deformation. Second interlocking element14of retaining hook10projects a shorter distance from distal side surface11. As a result, it can be moved past first interlocking hump25of receiving hook9. As soon as second interlocking element14of retaining hook10reaches second interlocking hump26, contact is made because second interlocking hump26projects farther than first interlocking hump25.

The derived timber material has to be elastically deformed in order to move second interlocking element14into receiving pocket22behind second interlocking hump26.

In the present design, interlocking of the two interlocking elements13and14, past interlocking humps25and26, takes place almost simultaneously.

The elastic deformation and material compression take place at a great distance from top side3of floor panels1. The density of the core made of a derived timber material2is low in this area. This avoids cracking close to decorative layer4of floor panels1.

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