1. Field of the Invention
This invention relates to tongue and groove joints. These joints are particularly useful for joining pieces of laminate flooring. Glue in these joints resists penetration of moisture.
2. Description of the Related Art
Commercially available laminate flooring generally includes a wear surface glued to a substrate. The wear surface generally is high-wear resistant decorative laminate. The substrate generally is fiber board or particle board. Each piece of laminate flooring generally has a groove along one end and one side suitable for joining with a tongue along one side or end of an adjacent piece of laminate flooring.
While such laminate flooring has found wide acceptance in Europe as flooring, it is not substantially used in the United States. In part the reason may be due to installation difficulties and the lack of moisture resistance in the joint areas.
Laminate flooring is assembled by placing glue in the groove and inserting the tongue of one piece into the groove of an adjacent piece. A substantially complementary fit of a tongue and groove results in difficulty in aligning the tongue and groove. Additionally, as the glue is absorbed into substrate, the substrate swells, causing the groove to tightly squeeze the tongue. This can make full insertion of the tongue into the groove extremely difficult. Furthermore, as the tongue and groove are moved together, glue can be compressed in the groove by the tongue in a piston fashion. This can increase the difficulty in abutting the wear surfaces of adjacent laminate flooring pieces.
To overcome this assembly problem, laminate flooring manufactures offer special tools for assembling pieces of laminate flooring.
One such special tool is a hammering aid that has a flat surface and complementary tongue and groove engaging surfaces. When difficulty is encountered in abutting the wear surfaces of adjacent pieces, the hammering aid is placed along the edge of the laminate. The flat surface of the hammering aid is then struck with a hammer repeatedly to apply a force to the joint and force the tongue and groove together.
However, even with the use of a hammering aid, a gap can remain between adjacent pieces. The gap is unsightly and allows for damaging penetration of moisture to the substrate. The problem with moisture penetration into the joint is that it can cause the substrate to swell. Excess swelling damages laminate flooring.
Laminate flooring with tongue and groove joints are difficult to manufacture. The tight complementary fit between the tongue and groove requires attention be paid to cutting tolerances for the widths of the tongue and groove. An interesting yet problematic phenomenon occurs during the process of cutting the tongues and grooves. The cutting process itself progressively dulls and wears the cutting blades. As the blades progressively wear, grooves of later cut articles are progressively narrower than grooves of earlier cut articles. Likewise, tongues of later cut articles are progressively wider than tongues of earlier cut articles. Unfortunately, at some point, the widths of the tongues and grooves are not within acceptable tolerances.
Thus there is a need in the art for an improved tongue and grooved joint. There is a need for a tongue and groove joint that does not require special tools for installation. There is a need for a moisture resistant tongue and groove joint. These and other needs will become apparent to those of skill in the art upon review of this specification, including its claims and drawings.