A floorboard assembly comprises first and second solid wood floor boards (10) and (12). The first floor board (10) has a tongue (14) extending longitudinally along a first side thereof. The second floor board (12) having a groove (16) extending longitudinally along a second side thereof. The groove (16) has a width defined between a top lip (22) and a bottom lip (24). The tongue (14) is insertable in a tight fit manner in the groove (16) to prevent translational separation of the boards (10, 12) in a common plane thereof. A clearance (26, 26′, 28, 32, 32′, 32″, 36 and 38) is provided between the tongue (14) and the groove (16) at one of a tip portion of the tongue (14) and an outermost portion of the top and bottom lips (22, 24) of the groove (16). The clearance (26, 26′, 28, 32, 32′, 32″, 36 and 38) is configured to allow angular withdrawal of the tongue (14) from the groove (16) by manually pivoting the first and second floor boards (10, 12) towards one another in one of an upward and a downward direction.

FIELD OF THE INVENTION

The application relates generally to hardwood floorboard assemblies and, more particularly, to a new hardwood flooring tongue and groove arrangement.

BACKGROUND ART

In the hardwood floor industry, two main types of hardwood floor are found on the market, 1) solid wood and 2) engineered wood composed of superposed layers of wood. Solid hardwood floorboards are manufactured pre-finished or unfinished. In the pre-finished hardwood floor, the sanding and varnishing process is done at the factory by opposition to the unfinished flooring where the sanding and varnishing are executed on-site after installation of the hardwood flooring.

The manufacturing process of pre-finished hardwood floor includes varnishing and/or staining steps on assembled floorboard sections of typically 4 feet wide. These sections allow effective use of sanding techniques prior to or concomitant with the varnishing and/or staining steps. There is a need for the manufacturers, to have a tight assembly of the tongue and groove joint between each adjoining floor hoards to prevent the same from becoming disassembled from one another during the sanding and varnishing process.

During the varnishing process, the floorboards can be assembled and disassembled 2 to 3 times prior to its final packaging. The manufacturers also traditionally packed the floorboards in 4 layers of 3 or 4 wide assembled floorboard panels. There is thus also a need for facilitating the separation of the floor boards into layers of 3 or 4 assembled floorboard panels without damaging the tongue and groove joint.

The requirement of having a tight assembly of the tongue and groove joint during the sanding operation is a major inconvenient for floorboards installers who need to disassemble the floorboard packages before the installation. If excessive force is used to separate the floorboards, especially those who were exposed to humidity, by applying excessive force, it may cause permanent damage to the tongue and groove joint and/or result in an increase of disassembling time and efforts for the installers.

None of the traditional floorboards are designed to provide a solid board assembly to prevent disengagement of the individual floor boards during the factory sanding process while still providing for easy disassembly of the pre-finished floorboards into floorboard sections of 3 or 4 floorboard panels prior to packaging and/or into individual floor boards prior the installation. If prior-art tongue and groove designs were made to ease detachment of floorboards, they could not insure a tight assembly during the manufacturing or installation.

There is thus a need to provide floorboards with tight assembly of the tongue and groove joint for the manufacturing process while remaining easy to detach at the time of installing the hardwood flooring.

SUMMARY

In view of the foregoing, it would be desirable to provide a tightly assembled tongue and groove joint to prevent individual floorboards from being disassembled during factory sanding and varnishing operations while providing for relatively easy manual separation of the boards by the contractor at the time of installation.

Those contradictory requirements can be met for a tongue-and-groove design that provides a firm grip and a tight assembly of floorboards to insure quality of processing at varnishing, while allowing ease of disassembling by a simple rotational or pivotal movement of the floorboards to ease the work of the installer without modifying the traditional way of installation.

According to a general aspect, there is thus provided a floorboard assembly comprising: at least first and second hardwood floor boards adapted to be mounted in a side-by-side coplanar relationship, the first floor board having a tongue extending longitudinally along a first side thereof, the second floor board having a groove extending longitudinally along a second side thereof, the groove having a width defined between a top lip and a bottom lip, the tongue being received in a tight fit manner in the groove to provide frictional resistance against translational separation of the first and second floor boards in a common plane thereof, a top surface of the tongue being in frictional engagement with an undersurface of the top lip of the groove from a top outermost contact point to a top innermost contact point, a bottom surface of the tongue being in frictional engagement with a top surface of the bottom lip of the groove from a bottom outermost contact point to a bottom innermost contact point, the top outermost contact point and the bottom innermost contact point defining a first diagonal, the top innermost contact point and the bottom outermost contact point defining a second diagonal, one of said first and second diagonals having a length sufficiently greater than the width of the groove to substantially lock the first and second floor boards against relative pivotal movement in one of an upward or a downward direction associated with said one of said first and second diagonals, and a clearance provided between the tongue and the groove, the clearance reducing the length of the other one of said first and second diagonals to approximate the width of the groove to permit an angular withdrawal of the tongue from the groove by manually pivoting the first and second boards toward each other in the other one of said upward and downward directions.

According to a further general aspect, there is provided a pre-finished floorboard assembly comprising at least first and second solid wood floor boards, the first floor board having a tongue extending longitudinally along a first side thereof, the second floor board having a groove extending longitudinally along a second side thereof, the groove having a width defined between a top lip and a bottom lip, the tongue being insertable in frictional engagement in the groove to counteract pull-apart forces exerted on the first and second floor boards during factory sanding and varnishing operations, and at least one play provided between the tongue and the groove at one of a tip portion of the tongue and an outermost portion of the top and bottom lips of the groove, the play being configured to allow the tongue to be angularly withdrawn from the groove by manually pivoting the first and second floor boards towards one another in only one of an upward and a downward direction.

The term “floor board” should not be strictly construed to the preliminary meaning of the word and is intended to broadly refer to any floor planks, floor strips and the like used in the fabrication of a hardwood flooring.

Floor boards can be made from different hardwood essence, such as pin, oak, maple, wild cherry, cherry, birch and walnut. It is understood that the present invention is not limited to only those commonly available wood species.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1shows a prior art tongue and groove joint of the type used to interconnect solid wood boards in a coplanar relationship to form hardwood flooring. More particularly,FIG. 1shows first and second adjoining floor boards10and12. Each floor board panel10,12has a tongue14extending axially along a first longitudinal side thereof and a groove16extending axially along an opposite longitudinal side thereof for receiving the tongue14of an adjacent floor board, as is well know in the art. As shown inFIG. 1, the tongue14of the first floor board10is frictionally engaged in the groove16of the second floor board12in order to maintain the first and second floor boards10and12in a coplanar side-by-side relationship. The tongue14has parallel top and bottom surfaces18and20which are respectively in frictional engagement with the top and bottom lips22and24of groove16. As can be appreciated fromFIG. 1, the top outermost contact point A, between the tongue top surface18and the groove top lip22, and the diagonally opposed bottom innermost contact point B, between the tongue bottom surface20and the groove bottom lip24, cooperate to lock the first and second floor boards10and12against relative upward pivotal movement, as depicted by arrows R1. The length of line AB is too great as compared to the width of the groove16(i.e. the distance between the top and bottom lips22and24) to permit any upward pivotal or tilting movement of the tongue14in the groove16. Likewise, the top innermost contact point C, between the tongue top surface18and the groove top lip22, and the diagonally opposed bottom outermost contact point D, between the tongue bottom surface20and the groove bottom lip24, cooperate to lock the first and second floor boards10and12against relative downward pivotal movement, as depicted by arrows R2. Again, the length of line CD is significantly greater than the width of the groove16, thereby preventing downward pivotal movement of the tongue14in the groove16and that even for soft wood species exhibiting relatively high level of compressibility. The difference between the length of lines AB and CD and the width of the groove16is simply too important to allow any upward or downward pivotal movement of the tongue14in the groove16. By analogy, it would be like trying to fit a 6 feet long vertical beam between 5 feet spaced-apart top and bottom beams.

Accordingly, the only way of disassembling the floor boards10and12without breaking the tongue14or the lips22,24of the groove16is to pull apart the boards10and12by applying withdrawal forces in the plane of the boards10and12in a direction opposite to a direction of insertion of the tongue14in the groove16, as depicted by arrows P1and P2. The top and bottom frictional surfaces respectively defined between: 1) top contact points A and C and 2) bottom contact points D and B, provide resistance against the linear withdrawal of the tongue14from the groove16. It can be appreciated that the distance between top contact points A and C is equal to the distance between bottom contact points D and B. The tighter the fit between the tongue14and the groove16, the greater the forces P1and P2must be to separate the floor boards10and12. A tight fit is particularly desirable where the floor boards are to be pre-finished (factory finished). If a loose fit is provided, the boards run the risk of becoming disengaged from one another during the sanding and varnishing procedures, thereby resulting in poor quality finish. However, once on-site, it is desirable for the boards to be easily separable to facilitate the installation thereof. The above tongue and groove joint arrangement with planar disengagement of the boards does not meet the above contradictory needs. Therefore, compromises had heretofore to be made between a good quality finish and easy installation.

Turning toFIG. 2, there is shown an embodiment of a new tongue and groove joint which still provides resistance against coplanar disengagement of the floor boards10and12while allowing easy separation of the floor boards10and12by a simple upward pivotal action. As will be seen hereinafter, the tongue and groove joint has been modified to permit an upward pivoting or tilting movement of the tongue14in the groove16, thereby allowing easy withdrawal of the tongue14from the groove16.

It can be appreciated fromFIG. 2, that the length of diagonal line AB can be shortened, for instance, by displacing the top outermost contact point A inwardly towards the bottom of the groove16(towards the right hand side onFIG. 2). By doing so, line AB is pivoted about the innermost bottom point B to a position closer to the vertical, thereby resulting in a shortening of the line AB to a dimension which is closer to the width of the groove B. When the length of line AB is sufficiently close to the width dimension of the groove16, it becomes possible to disengage the floor boards10and12by simply pivoting the boards10and12towards each other in an upward direction, as illustrated inFIGS. 5ato 5c. The angle θ between line AB and the vertical is herein referred to as a lip clearance angle. The lip clearance angle θ can be generally defined as the angle which permits pivotal disengagement of the floor boards10and12in one of the upward or downward direction, while still providing sufficient contact surfaces between the tongue14and the groove16to counteract planar pulling-apart of the floor boards during factory sanding/varnishing operations.

It has been found that pivotal separation of the floor boards10and12can be achieved without risking breaking the tongue14or the lips22and24of the groove16for lip clearance angles θ up to about 20 degrees. It is understood that this upper limit may vary depending on the level of compressibility of the wood species used to form the floor hoards. For instance, soft wood species, such as pine, may permit slightly greater lip clearance angle. It has also been noticed that the effort required to pivotally separate the floor boards10and12noticeably increases for clearance angles θ greater than 16 degrees. A 16 degrees lip clearance angle corresponds for instance to a 0.07 inch long top contact line AC for a 0.240 inch groove opening (i.e. distance between top and bottom lips22and24of the groove16) in the example illustrated inFIG. 2.

It has also been found that if the lip clearance angle θ becomes too small (i.e. the distance between the top outermost and innermost contact point A and C inFIG. 2), the planar retention benefit afforded by the frictional engagement of the tongue14in the groove16is lost. Such a planar retention lost should be avoided in order to prevent disengagement of the floor boards10and12during the sanding and varnishing operations. Tests have shown that the floor boards become subject to coplanar separation during factory sanding and varnishing operation for tip clearance angles smaller than about 12 degrees. This corresponds to a 0.05 inch long top contact line AC for a 0.240 inch groove opening. The best results (i.e. easy pivotal separation with good planar retention) have been obtained for a lip clearance angle of about 14 degrees. InFIG. 2, this can also be expressed in term of a ratio between the length of the top contact surface (length of line AC) and the width or opening of the groove16. A 14 degrees lip clearance angle corresponds to a 1/4 ratio. For instance, for a groove having a 0.240 inch width or opening, line AC would be 0.060 inch long.

In the embodiment illustrated inFIG. 2, the desired lip clearance angle θ is obtained by machining an undercut26in the outermost edge portion of the undersurface of the top lip22of the groove16. As will be seen hereinafter, the undercut26may have several configurations. The undercut26defines a play P to permit withdrawal of the tongue14from the groove16via a relative upward pivotal movement of the floor boards10and12. For instance, a 0.05 inch play P can be used for 0.240 inch groove opening and a 0.06 inch top contact line AC (i.e. 14 degrees lip clearance angle). With such a tongue and groove configuration, the tongue14can be tightly received in the groove16to provide strong planar retention of the floor boards10and12while allowing for easy pivotal separation of the floor boards10and12in the upward direction, as illustrated by arrows R1. However, any attempts at separating the floor boards10and12by means of downward pivotal movement, as represented by arrows R2, will be blocked by the contact points C and D. The line CD has not been altered by the modification made in the groove upper lip22. As can be appreciated inFIG. 2, line CD is significantly longer than line AB and way too long compared to the groove opening to permit any downward pivotal movement of the tongue14in the groove16.

Accordingly, the pivotal movement of the tongue14in the groove16has been unlocked in only one direction (i.e. the upward direction).

As shown inFIG. 3, the desired lip clearance angle θ can also be obtained by machining both the groove top lip22and the undersurface20of the tip portion of the tongue14. According to this embodiment, the position of both the top outermost contact point A and of the bottom innermost contact point B is modified in order to reduce the length of line AB. The embodiment shown inFIG. 3essentially differs from the embodiment ofFIG. 2by the addition of a second undercut28in the undersurface20of the tip of the tongue14. The second undercut28displaces the bottom innermost contact point B away from the bottom of the groove16that is to the left hand side onFIG. 3. By so displacing the bottom innermost contact point B in an outward direction relative to the groove16, the top outermost contact point A can be displaced to a lesser extend inwardly toward the bottom of the groove16. By comparingFIGS. 2 and 3, it can be seen that the undercut26′ (FIG. 3) is not as deep as undercut26(FIG. 2). In contrast to the embodiment ofFIG. 2where only the top contact line AC is shortened, the total length reduction of the contact surfaces between the tongue14and the groove16is shared by both the top and bottom contact lines AC and DB (in a proportion of for instance 70% on the top contact surface and 30% on the bottom contact surface). According to the embodiment ofFIG. 3, the resistance against planar separation of the floor boards10and12is more evenly shared by the top and bottom contact surfaces represented by lines AC and DB (inFIG. 2the top contact surface AC is significantly shorter than the bottom contact surface DB). As for the first embodiment, the floor boards10and12can be easily pivotally disengaged from one another in the upward direction, as indicated by arrows R1. Pivotal disengagement or separation is however once again prevented in the downward direction (arrows R2) by the contact points C and D which are not affected by undercuts26′ and28.

As shown inFIG. 3, a third undercut29can be defined in the undersurface of the bottom lip24along all the extent of the lip in a depth wise direction of the groove16(see L4inFIG. 4). The third undercut29provides added flexibility of the bottom lip24to facilitate the insertion and the withdrawal of the tongue14in the groove16. According to the illustrated embodiment, the third undercut29provides a bottom lip thickness reduction of about 0.020 inch to about 0.030. The play created by the third undercut29facilitates the insertion of the bottom lip24of the groove16underneath the tongue14after the board10has been nailed down to the sub floor structure. The third undercut can also compensate for expansion of the tongue14or of the groove lips due to environmental factors such as humidity. The third undercut29also contributes to minimise the risk of breaking the groove lips or the tongue when a board has to be removed.

FIG. 4shows some of the geometrical details of the embodiment ofFIG. 3. The length L1of the second undercut28can represent about 15% to about 30% of the length L2of the tongue14. The reduction in the tongue thickness T1can represent about 5% to about 20% of the total thickness T2of the tongue14. The transition angle δ defined by the undercut28can be about 10 to 50 degrees.

The length L3of the lip undercut26′ can represent 15% to 30% of the length or deepness L4of the groove16. The play P′ defined by the first undercut26′ can represent 5% to 20% of the width W of the groove16. A play P′ of at least 0.020 inch can be made in the undersurface of the upper lip of groove16for a 0.240 inch groove width W. The transition angle β defined by the undercut26′ can be about 10 to 50 degrees.

FIGS. 5aand 5cillustrate the procedure for pivotally separating the floor boards10and12shown inFIGS. 3 and 4. One has simply to grab the boards10and12by the sides thereof opposite to their adjoining edges and to exert an upward folding or pivoting action, as represented by arrows R1. The width of each floor boards10and12acts as a lever to facilitate the relative pivotal movement of the floor boards10and12about an initial point of pivot corresponding to a point of contact30between the top upper lip22of floor board12and the confronting side face of the other floor board10. The lip undercut26′ and the tongue undercut28provide the required clearance to permit the angular withdrawal movement of the tongue14from the groove16, thereby allowing for easy separation of the floor boards10and12, as shown inFIGS. 5band5c.

However, if downward pivotal efforts are applied on the floor boards10and12as represented by arrows R2inFIG. 6aor if manual pull-apart forces P1and P2are applied in the plane of the floor boards10and12as shown inFIG. 6b, the tight fit engagement of the tongue14in the groove16will restrain the board against becoming disengaged from one another, as explained hereinbefore.

FIGS. 7aand 7cillustrate various possible tongue and groove configurations that could be implemented to provide a desired lip clearance angle θ between the tongue and the groove of adjacent floor boards.FIGS. 7aand 7care not intended to constitute an exhaustive representation of all the possible alternatives. A person skilled in the art will understand that various permutations or combinations of the illustrated undercut arrangements can be provided to permit pivotal disengagement of the floor boards, in one of an upward or downward direction while still restraining linear removal of a board tongue from the associated groove of an adjacent board.

Now referring more particularly toFIGS. 7ato 7c, it can be seen that the upward pivotal movement can also be unlocked by solely adding one undercut32,32′ or32″ in the undersurface of the tip portion of the tongue14.

Irrespective of their emplacement (on the tongue or the lip of the groove) the undercut can have various profiles. For instance, the undercut can have a stepped profile (FIG. 7a), a slanted or bevel profile (FIG. 7b), or a rounded or arc profile (FIG. 7c). These profiles as well as other suitable profiles could also be applied to the undercut26defined in the undersurface of the groove upper lip22shown inFIG. 2. The person skilled in the art will understand that a wide variety of profiles could be adopted.

FIG. 8illustrates one example of a downwardly pivotable tongue and groove arrangement.

According to this embodiment, the diagonal AB remains unchanged as compared to line AB onFIG. 1. The length of line AB is significantly longer than the width of the groove16and thus upward pivotal movement, as represented by arrows R1, of the tongue14in the groove16is impossible without breaking the tongue14or the lips22and24of the groove16. However, relative downward pivotal movement of the floor boards10and12as represented by arrows R2is rendered possible by the shortening of the contact line CD. In the illustrated example, the shortening is accomplished by means of a slanted undercut36on the top of the tip portion of the tongue14and a two-step undercut38on the outmost portion of the top surface of the bottom lip24of the groove16. The lip clearance angle θ is defined between line CD and the vertical and like the lip clearance angle for unlocking the upward pivotal movement, it is comprised in range extending from about 12 degrees to about 20 degrees.

The above described tongue and groove arrangement is advantageous in that it can be “retrofitted” or adapted to any conventional tongue and groove arrangements. Also, it does not necessitate the purchase of any special tooling apart from new cutting knives having a cutting edge profile corresponding to the additional undercuts to be defined in the floorboards. It also facilitates the verification of the planarity between two adjoining boards since the tongue and groove engagement can be made very tight. The above described tongue and groove arrangement also reduces the likelihood that the floorboards being returned to the manufacturer by the installers because the boards are too difficult to separate from one another. It also contributes to improve the quality of the finish of factory finished floor boards by ensuring a greater integrity of the connection between the boards during the sanding and varnishing operations.

Still further embodiments and modifications of the present invention are available. The scope of the appended claims is not intended to be limited, therefore, only to the specific exemplary embodiments described above.