TECHNICAL FIELD

The invention generally relates to the field of mechanical locking systems for floor panels and building panels.

FIELD OF APPLICATION OF THE INVENTION

The present invention is particularly suitable for use in floating floors, which are formed of floor panels which are joined mechanically with a locking system integrated with the floor panel, i.e., mounted at the factory, are made up of one or more upper layers of veneer, decorative laminate or decorative plastic material, an intermediate core of wood-fiber-based material or plastic material and preferably a lower balancing layer on the rear side of the core. The following description of known techniques, problems of known systems and objects and features of the invention will therefore, as a non-restrictive example, be aimed above all at this field of application and in particular laminate flooring formed as rectangular floor panels with long and short sides intended to be mechanically joined on both long and short sides. The long and short sides are mainly used to simplify the description of the invention. The panels could be square. It should be emphasized that the invention can be used in any panel and it could be combined with all types of known locking systems, where the floor panels are intended to be joined using a mechanical locking system connecting the panels in the horizontal and vertical directions on at least two adjacent sides. The invention can thus also be applicable to, for instance, solid wooden floors, parquet floors with a core of wood or wood-fibre-based material and a surface of wood or wood veneer and the like, floors with a printed and preferably also varnished surface, floors with a surface layer of plastic or cork, linoleum, rubber. Even floors with hard surfaces such as stone, tile and similar are included and floorings with soft wear layer, for instance needle felt glued to a board. The invention can also be used for joining building panels which preferably contain a board material for instance wall panels, ceilings, furniture components and similar.

BACKGROUND OF THE INVENTION

Laminate flooring usually comprises a core of a 6-12 mm fibre board, a 0.2-0.8 mm thick upper decorative surface layer of laminate and a 0.1-0.6 mm thick lower balancing layer of laminate, plastic, paper or like material. A laminate surface comprises melamine impregnated paper. The most common core material is fibreboard with high density and good stability usually called HDF—High Density Fibreboard. Sometimes also MDF—Medium Density Fibreboard—is used as core.

Traditional laminate floor panels of this type have been joined by means of glued tongue-and-groove joints.

In addition to such traditional floors, floor panels have been developed which do not require the use of glue and instead are joined mechanically by means of so-called mechanical locking systems. These systems comprise locking systems, which lock the panels horizontally and vertically. The mechanical locking systems are usually formed by machining of the core of the panel. Alternatively, parts of the locking system can be formed of a separate material, for instance aluminium or HDF, which is integrated with the floor panel, i.e., joined with the floor panel in connection with the manufacture thereof.

The main advantages of floating floors with mechanical locking systems are that they are easy to install. They can also easily be taken up again and used once more at a different location.

Definition of Some Terms

In the following text, the visible surface of the installed floor panel is called “front side”, while the opposite side of the floor panel, facing the sub floor, is called “rear side”. The edge between the front and rear side is called “joint edge”. By “horizontal plane” is meant a plane, which extends parallel to the outer part of the surface layer. Immediately juxtaposed upper parts of two adjacent joint edges of two joined floor panels together define a “vertical plane” perpendicular to the horizontal plane.

By “locking systems” are meant co-acting connectors which connect the floor panels vertically and/or horizontally. By “mechanical locking system” is meant that joining can take place without glue. Mechanical locking systems can in many cases also be joined by gluing. By “integrated with” means formed in one piece with the panel or a separate material factory connected to the panel.

Known Techniques and Problems Thereof

For mechanical joining of long sides as well as short sides in the vertical and horizontal direction (direction D1, D2) several methods could be used. One of the most used methods is the angle-snap method. The long sides are installed by angling. The panel is than displaced in locked position along the long side. The short sides are locked by horizontal snapping as shown inFIGS. 1a-1c. The vertical connection is a tongue10and a groove9during the horizontal displacement, a strip6with a locking element8is bent and when the edges are in contact, the strip springs back and a locking element8enters a locking groove14and locks the panels horizontally. The vertical displacement of the locking element during the snapping action is caused by the bending of the strip. Such a snap connection is complicated since a hammer and a tapping block is frequently used to overcome the friction between the long edges and to bend the strip during the snapping action. The friction on the long side could be reduced and the panels could be displaced without tools. The snapping resistance is however considerable, especially in locking systems made in one piece with the core. Wood based materials are generally difficult to bend. Cracks in the panel may occur during snapping and the locking element must be rather small in the vertical direction in order to allow snapping.

It is known that a snap system could have a separate plastic strip6′, integrated with the panel and with a resilient part as shown inFIGS. 1d-1f. Such a locking system could be locked with less resistance than the traditional one-piece snap system. This locking system has however several disadvantages. The plastic strip is used to replace both the tongue and the strip with a locking element. The material cost is therefore high and the locking system is generally not compatible with the locking system used in old panels. The groove9is difficult to produce since it must have a locking element8′. In fact4locking elements, two flexible locking elements on the strip and two (8,8′) in the panel, must be used to lock in the horizontal direction. It is difficult to fix the plastic strip over the whole length of the short side. This means that corner portions will not have any tongue and this could cause problems in some applications.

SUMMARY AND OBJECTS

A first overall objective of the present invention is to provide a locking system, which could be locked by horizontal snapping and with less snapping resistance than the known systems. The costs and functions should be favourable compared to known technology. An aspect of the overall objective is to improve the function and costs of those parts of the locking system that locks in the horizontal direction when panels are pushed against each other.

More specifically an object is to provide a snap locking system where one or several of the following advantages are obtained.

The floor panel should preferably be possible to displace and lock with such a low force that no tools will be needed.

The locking function should be reliable and the vertical and horizontal locking should be strong and prevent that two locked panels will move when humidity is changing or when people walk on a floor.

The locking system should be able to lock floor panels vertically with high precision so that the surfaces are essentially in the same plane.

The locking system should be designed in such a way that the material and production costs could be low.

Another objective is to provide a snap locking system which could be compatible with traditional locking systems.

According to a first embodiment, a flooring system is provided, comprising a plurality of rectangular floor panels with long and short edges, which are mechanically connectable to each other along one pair of adjacent edges. The floor panels are provided with tongue and groove formed in one piece with the panels for mechanically locking together said one pair of adjacent edges at right angles to the principal plane of the panels, thereby forming a vertical mechanical connection between the panels. The panels are provided with a first locking element at one first edge formed in one piece with the panel and a locking groove at an opposite adjacent second edge, the locking groove being open towards a rear side or a front side of the panel. Each panel is provided with a second locking element, formed of a separate material and connected to the locking groove. The first and second locking elements form a mechanical connection locking the panels to each other horizontally parallel to the principal plane and at right angles to the joint edges. The second locking element is flexible and resilient such that two panels, can be mechanically joined by displacement of said two panels horizontally towards each other, while at least a part of the second locking element at said second edges is resiliently displaced vertically, until said adjacent edges of the two panels are brought into engagement with each other horizontally and the second locking element at said second edge is displaced towards its initial position against the first locking element at the first edge.

Although it is an advantage to integrate the flexible locking element with the panel at the factory, the invention does not exclude an embodiment in which flexible locking elements are delivered as separate components to be connected to the panel by the installer prior to installation.

The embodiment allows horizontal and vertical locking of all sides of floor panels with for instance an angling of the long sides, a simple horizontal displacement along the long sides and snapping of the short sides. In this preferred embodiment the flexible locking element is on the short sides. It could be on the long side or on the long and short sides.

The invention is especially suited for use in floor panels, which are difficult to snap for example because they have a core, which is not flexible, or strong enough to form a strong snap locking system. The invention is also suitable for wide floor panels, for example with a width larger than 20 cm, where the high snapping resistance is a major disadvantage during installation, in panels where parts of the locking system is made of a material with high friction, such as wood and in locking systems which are produced with tight fit or without play or even with pretension. Especially panels with such pretension where the locking strip is bent in locked position and presses the panels together are very difficult to displace and snap. A locking system that reduces the snapping resistance will decrease the installation time of such panels considerably.

