1. Field of the Invention
The present invention is broadly concerned with a novel planking system utilizing an inventive groove design, combinations of planks having an inventive tongue-and-groove configuration, and methods of assembling planks to accommodate the expansion and contraction of the assembled planks.
2. Description of the Prior Art
Wood panels and planks are commonly used for various structures, including decks, porches, walls, and the like. Composite materials offer many benefits over natural wood products for these uses, including improved durability and enhanced moisture resistance. However, wood composites still expand and contract with changes in temperature and moisture like natural wood, which can cause unwanted buckling when these products are used in tongue-and-groove arrangements. In particular, tongue-and-groove arrangements are commonly used in the construction of covered porches, where a small uniform space between each plank is desirable, and where wood composite materials have become increasingly popular. There are two main concerns that arise during the assembly and installation of porch planks when wood or wood composites are used. The first problem is efficiently creating a small space between the planks that is uniform and that can be maintained throughout the installation process. The second problem is accommodating the expansion and contraction of the planks after installation is complete.
Previous attempts to relieve the pressure between planks upon the expansion of the interconnected boards have utilized a “crush bead” located on the tip of the tongue of the plank in anticipation of it being crushed during expansion. Although these crush beads do create the desired space during installation, they do not always crush wider the compressive forces of the adjacent planks, resulting in buckling of the interconnected boards. This especially common in composite tongue-and-groove configurations due to the high compressive strength of the wood composite materials from which the planks and crush beads are formed. It is therefore desirable to have planks or panels with a tongue-and-groove configuration that create the desired space, while at the same time accommodating the expansion and contraction of the interconnected boards.
The present invention solves these problems by providing planks with a tongue-and-groove configuration providing generally opposed tongue-engaging projections on the side walls of the groove, which create the desired space that is maintained during installation.
In more detail, the present invention provides a plank configured to be assembled with an adjacent plank having a first edge surface and a tongue extending from the first edge surface. The tongue of the adjacent plank is defined by a tongue end wall and a pair of tongue side walls extending between the tongue end wall and first edge. The plank comprises a body presenting a second edge surface and a groove projecting inwardly from the second edge surface along a groove axis, with the groove being configured to receive the tongue of the adjacent plank. The groove is defined by a groove end wall and a pair of groove side walls that extend between the groove end wall and the second edge surface. The groove side walls present generally opposed tongue-engaging projections that are spaced from the groove end wall in alignment substantially perpendicular to the groove axis.
In another embodiment, there is provided a combination of planks comprising a first plank and a second plank utilizing a tongue-and-groove arrangement. The first plank presents a first edge surface, and a tongue extending from the first edge surface. The tongue comprises a tongue end wall and a pair of tongue side walls extending between the tongue end wall and the first edge surface. The second plank presents a second edge surface, and a groove projecting inwardly from the second edge surface along a groove axis and receiving the tongue of the first plank. The groove comprises a groove end wall and a pair of groove side walls extending between the groove end wall and the second edge surface. The groove side walls present generally opposed tongue-engaging projections that are spaced from the groove end wall in alignment substantially perpendicular to the groove axis.
In a further embodiment, a method of assembling porch planks to accommodate expansion and contraction of the assembled planks is provided. The method comprises securing a first plank to a support and positioning a second plank adjacent to the first plank. The first plank presents a first edge surface and a tongue extending from the first edge surface. The tongue comprises a tongue end wall and a pair of tongue side walls extending between the tongue end wall and the first edge surface. The second plank presents a second edge surface and a groove projecting inwardly from the second edge surface along a groove axis to receive the tongue. The groove comprises a groove end wall and a pair of groove side walls extending between the groove end wall and the second edge surface. The groove side walls present generally opposed tongue-engaging projections that are spaced from the groove end wall in alignment substantially perpendicular to the groove axis. The planks are assembled by inserting the tongue into the groove so that the tongue is received in the groove and the tongue end wall is engaged by the tongue-engaging projections, thereby providing an interior space between the tongue end wall and groove end wall, and first and second spaces between the first edge surface of the first plank and the second edge surface of the second plank.
Expansion of the planks after installation pushes the projections off edge-wise, exercising the projections in shear, instead of in compression. In this sense, the tongue-engaging projections are “shearable.” Thus, when a given force is applied to the projections, they break away, relieving the pressure and preventing the buckling of the assembled planks.
Additional advantages of the novel tongue-and-groove configuration and method will be appreciated based upon the drawings and detailed description of the preferred embodiments below.
a depicts an enlarged profile view of a preferred groove;
b depicts an enlarged profile view of a preferred tongue, and illustrates preferred tongue dimensions;
The following sets forth preferred embodiments in accordance with the present invention. It is to be understood, however, that these preferred embodiments are provided by way of illustration and nothing therein should be taken as a limitation upon the overall scope of the invention that is claimed.
Referring to
a-2b illustrate an enlarged view of a preferred groove 16 and a preferred tongue 22 in accordance with the present invention. In more detail, as shown in
The dimensions of a preferred groove are shown in more detail in
The tongue-engaging projections 38, 40 also preferably have a height “h.” The height h is measured from the highest point of the projections 38, 40 to their respective groove side walls 26, 28 on the respective sides of tongue-engaging projections 38, 40 that are adjacent the groove end wall 24. The tongue-engaging projections 38, 40 also preferably have a width “w,” as measured from the widest portion of the tongue-engaging projections 38, 40. In a particularly preferred embodiment, the tongue-engaging projections 38, 40 have a height h of at least about 0.50 mm, preferably from about 0.70 mm to about 0.90 mm, and more preferably about 0.812 mm, and a width w of at least about 0.01 mm, preferably from about 0.02 mm to about 0.05 mm, and more preferably about 0.030 mm. It is also preferred that the height h be greater than the width w, more preferably at least about 2% greater, and even more preferably from about 2% to about 6% greater.
As shown in
The first and seconds spaces 46, 48, and the interior space 52 are determined by the placement of the tongue-engaging projections 38, 40 along the groove side walls 26, 28 in relation to the second edge surface 15. Referring again to
The planks can be made from any suitable material including sized lumber, synthetic materials, and wood composites. When formed from natural woods, the novel tongue-and-groove configuration can be formed for example, by conventional routering methods. A preferred method for forming wood composites with the novel tongue-and-groove configuration is by extrusion so that the tongue-and-groove configuration, including the tongue-engaging projections, are integrally formed with the material forming the planks.
In particular, a preferred method for making wood composites can be found in U.S. Pat. No. 6,737,006, incorporated by reference herein. In more detail, the products are formed by introducing ingredients including respective quantities of a fibrous or cellulosic material and polypropylene into the inlet of an extruder (preferably a twin screw extruder). Preferably, the weigh blender is positioned immediately above the extruder, at the extruder inlet, so that the blend of ingredients is formed immediately prior to entering the extruder, thus minimizing or preventing separation of the ingredients.
The screw(s) is then rotated at a rate of from about 10-50 rpm, and preferably from about 15-34 rpm to advance the ingredients through the extruder barrel and out the extrusion die to form the composite product. The die is configured to present an orifice configured to correspond to the desired plank or board profile, including the tongue-engaging projections 38, 40. Preferably, the screw(s) has a compression ratio of from about 2:1 to about 4:1, and more preferably from about 2.8:1 to about 3.6:1.
The temperature of the ingredients in the extruder barrel is preferably from about 150-260° C., and more preferably from about 175-230° C. The retention time of the ingredients in the barrel should be from about 20-120 seconds, and more preferably from about 40-80 seconds. Finally, the ingredients should be advanced through the barrel at a rate of from about 500-2,000 lbs/hr., and more preferably from about 1,000-1,500 lbs/hr.
The fibrous material is preferably present in the ingredients at a level of from about 20-80% by weight, more preferably from about 30-70% by weight, and even more preferably from about 50-70% by weight, based upon the total weight of the ingredients taken as 100% by weight. The polypropylene is preferably present in the ingredients at a level of from about 20-80% by weight, more preferably from about 30-70% by weight, and even more preferably from about 30-50% by weight, based upon the total weight of the ingredients taken as 100% by weight.
Preferred fibrous materials include those selected from the group consisting of sawdust, newspaper, alfalfa, wheat pulp, wood scraps (e.g., ground wood, wood flour, wood flakes, wood chips, wood fibers, wood particles), wood veneers, wood laminates, cardboard, straw, cotton, rice hulls, paper, coconut shells, peanut shells, bagasse, plant fibers, bamboo fiber, palm fiber, kenaf, and mixtures thereof. Furthermore, the average particle size of the fibrous material should be less than about ½ inch, and more preferably from about 1/16-¼ inch. Finally, the particles of the fibrous material should have an average aspect ratio (i.e., the ratio of the length to the widest thickness) of at least about 10:1, preferably at least about 20:1, and more preferably from about 30:1 to about 50:1. The use of such long particles increases the flexural modulus of the product as compared to products with lower aspect ratios by at least about 25%, and preferably at least about 40%, thus causing the final composite product to have a stiffness comparable to natural wood.
The preferred polypropylene for use in the invention is reactor flake polypropylene (i.e., the polymer flakes as they are produced in the reactor), preferably without any further treatment (e.g., without the addition of chemical additives or modifiers) to the polypropylene. The preferred polypropylene has a melt index at 230° C. of from about 0-10 g/10 min., preferably from about 0.1-4 g/10 min., and more preferably from about 0.1-1 g/10 min. Furthermore, it is preferred that the polypropylene has a bulk density of from about 20-40 lbs/ft3, and more preferably from about 28-32 lbs/ft3. The average fiber length or particle size of the polypropylene flakes utilized should be from about 350-1,000 μm, and preferably from about 500-700 μm.
The resulting composite product is in the form of a self-sustaining body and has an ASTM D-6109 flexural modulus of from about 600-1,100 psi, and preferably from about 800-1,100 psi. The product should have an actual density of from about 40-60 lbs/ft3, and preferably from about 50-58 lbs/ft3.
A number of optional ingredients can also be added to modify or adjust the properties of the final composite product. Examples of such ingredients include acrylic process aids (e.g., Rohm and Haas K175, Kaneka Kane-AcePA-101), UV stabilizers (e.g., CYTEC 38535, CYTEC 3346), and coloring agents. If a process aid is utilized, it is preferably present in the ingredients at a level of from about 0.5-5% by weight, and more preferably from about 1-2% by weight, based upon the total weight of the ingredients taken as 100% by weight. Unexpectedly, these acrylic process aids are particularly useful in the present invention in spite of the fact that they are intended to be used in PVC products rather than polypropylene products.
In use, the planks can be assembled and secured using traditional methods, including by securing through the face of the board, or through the tongue and/or groove, depending upon the final desired use. With reference to the plank system illustrated in
With reference to
It will be appreciated by those skilled in the art that although the foregoing description has been given with reference to planks having a length and respective end portions, the novel tongue-and-groove configuration and spacing system can be adapted to a wide number of areas, in addition to porch planking. In particular, the novel tongue-and-groove arrangement can be adapted to accommodate any application where wood and/or wood composites are commonly used, such as in wood and simulated wood flooring, decking, wall paneling, and roof paneling, door sills and jambs, fascia board, window edging, window sills, decorative architectural trim (e.g., deck or patio railing), and landscaping products (e.g., raised bed edging, flowerbed edging, driveway edging). It will also be appreciated that the inventive tongue-and-groove configuration can extend along the length of the planks, panels, or boards. However, the tongue-and-groove configuration can also be segmented along the length of the planks, panels, or boards, without going beyond the scope of this invention.