Patent Application
20070218243
1. Technical Field
This invention generally relates to railing systems. More particularly, the invention relates to an engineered handrail. Specifically, the invention relates to a handrail which includes an outer layer surrounding an inner core that is made from a plurality of horizontally oriented layers and includes a relatively thick bottom layer made from the same material as the outer layer.
2. Background Information
Handrails have been made from solid pieces of wood for many centuries. However, with the rising cost of wood, it has become customary to manufacture handrails with an inner core of an inexpensive or inferior wood and to cover this core with a veneer of a more expensive and superior wood. This gives the handrail the external appearance of being manufactured entirely of the superior wood, but reduces the production costs of the rail.
This type of process has been disclosed in the prior art in U.S. Pat. Nos. 6,367,878 and 6,582,021; both issued to Chung for an arm rail with an oak veneer layer. In these patents, Chung discloses a substantially solid inner core formed of an inferior wood that is surrounded by a very thin, shaped veneer layer in the U.S. Pat. No. 6,367,878 and by a thicker, three piece veneer layer in the U.S. Pat. No. 6,582,021. The construction disclosed by Chung in these patents works well for an arm rail because of its short length, the fact that it is almost never seen from below and that other components are typically not connected to the underside of the arm rail. This type of construction does not work as well if used to manufacture handrails. The first reason for this is that handrails are much longer than armrests. Over time a relatively thin, elongated piece of wood will tend to warp along its length giving the piece of wood a bowed appearance. This tendency is fairly minimal when high quality woods are used, but is more likely in inexpensive, lower grades of woods. Consequently, manufacturing a relatively thin, elongated handrail using an inexpensive, lower grade wood core would increase the likelihood that the handrail will become bowed over time. Furthermore, lower grade woods tend to have more knots and holes and the fibers of the wood are less dense. These woods also crack more easily. Consequently a lower grade wood core would not provide a stable solid base into which other components, such as balusters, can be securely fixed. The underside of a handrail is also important because they are frequently seen from below, either from lower floors in a building or when climbing up a staircase. Using a dissimilar, inexpensive wood as the inner core to a handrail would therefore result in an unsightly underside to the handrail and would highlight the fact that the handrail is not made from a single piece of wood. Chung addressed this to a certain degree in U.S. Pat. No. 6,582,021, in FIG. 6, where he shows a thin veneer layer disposed over the interior core. While the veneer layer would hide the lower grade core, it would not prevent the tendency of the core to crack when components are connected to the underside of the handrail.
There is therefore a need in the art for an improved engineered handrail that will not warp and bow over time that aesthetically has the appearance of a solid piece of wood, but is stable and strong enough to securely affix components to the underside of the handrail.
The device of the present invention comprises an elongated wood member comprising an elongated first layer of a high grade wood product and an elongated second layer of a lower grade wood product that are disposed horizontally relative to each other are secured together to form an inner core. An outer layer of a high grade wood product is disposed substantially around all of said inner core, except for a bottom surface of the first layer. The first layer and outer layer are manufactured from substantially the same wood product, that product preferably being solid timber strips or boards. The second layer is manufactured from a lower grade wood product, preferably of the same wood species, so that the entire handrail is made from the same type of wood. The first layer preferably is between ¼ inch and 1 inch thick so as to provide a solid stable surface for the attachment of components such as balusters or posts. The elongated wood member may further include a third layer of a lower grade wood product adhesively connected to the first and second layers and again disposed in a horizontal orientation. The horizontal orientation of the first, second and third layers helps the elongated wood member resist the tendency to warp along the longitudinal axis thereof over time.
The preferred embodiments of the invention, illustrative of the best mode in which applicant has contemplated applying the principles, are set forth in the following description and are shown in the drawings and are particularly and distinctly pointed out and set forth in the appended claims.
Referring to
In accordance with one of the specific features of the present invention, inner core 12 comprises a plurality of layers of wood bonded together. As shown in
As may be seen from
In accordance with another specific feature of the present invention, layers 16, 18, 20 preferably are disposed horizontally one above another and an adhesive is applied between layers 16 and 18. An adhesive is also applied between layers 18 and 20. This results in an inner core 12 where upper surfaces 21, 23 and 25 of layers 16, 18 and 20 are disposed substantially parallel to the upper surface 36 of handrail 10. It will be understood that it would be possible to orient layers 16 and 18 vertically, i.e., so that they will ultimately lay substantially at right angles to the upper surface 36 of handrail. Layers 16 and 18 would be glued to each other and then the combined unit would be glued to a horizontally oriented layer 20. Utilizing horizontally oriented layers of wood results in a handrail that is both strong and has a reduced tendency to warp along the rail's length “L”. It would be undesirable to all three layers 16, 18 and 20 oriented vertically as the inferior materials and the joint lines would be visible on the underside of the handrail, the rail would have a greater tendency to warp along length “L” and the joints between layers 16, 18 and 18, 20 would form lines of weakness that would potentially cause problems when installing balusters and the like.
The outer region 14 of handrail 10 preferably is comprised of three separate and shaped pieces of wood being an upper section 28 and two lateral sections 30 and 32. All three pieces 28, 30 and 32 are manufactured from aesthetically appealing solid timber strips or boards of the same type of wood such as oak, maple etc. In order to have timber of a sufficient length to create pieces 28, 30 and 32, solid strips or boards may be butt-joined to one another.
Upper section 28 of outer region 14 has an upper surface 36 a lower surface 37 and arcuate side walls 38. Lower surface 37 of upper section 28 is adhesively bonded to the horizontally oriented upper surface 21 of layer 16. Lateral sections 30 and 32 are oriented generally vertically with respect to lower surface 37 of upper section 28. Each lateral section 30, 32 has a first end 30a, 32a, a second end 30b, 32b, an interior surface 30c, 32c and an exterior surface 30d, 32d. Lateral sections 30, 32 are oriented so that first ends 30a, 32a abut a portion of the bottom surface 37 of upper section 28 and are adhesively secured thereto. Interior surfaces 30c, 32c of lateral sections 30, 32 abut the sides 16a, 18a, 20a and 16b, 18b, 20b, of layers 16, 18 and 20 respectively, and are adhesively bonded thereto. Upper section 28 and lateral sections 30, 32 are shaped to give handrail 10 a gently rounded appearance that is both aesthetically pleasing and easy to grip.
Lateral sections 30, 32 are shown to be formed with a decorative molding 40 thereon. Molding 40 runs from the first end 10a to the second end 10b of rail. While molding 40 is shown to be formed as part of lateral sections 30, 32, it may be formed in any other suitable manner such as by the insertion of a rib as shown in U.S. Pat. No. 6,367,878.
Handrail 10 is installed by securing first end 10a thereof to a suitable support, such as a post or mounting bracket extending outwardly from a wall (not shown) and securing second end 10b to a second suitable support. Balusters (not shown) may also be inserted between handrail 10 and a bottom rail or stair treads. Preferably, the posts, mounting brackets or balusters are connected to layer 20 of handrail 10. The orientation and substantial thickness of layer 20 makes for a more stable base for the installation of balusters and the like and reduces the tendency of the handrail to crack during installation of the same. Furthermore, because layer 20 is manufactured from more expensive and better quality woods and preferably is a substantially unitary piece of material that is color-matched to outer region 14, once installed, the entire handrail 10 has the appearance of being manufactured from a single solid piece of wood.
While the preferred embodiment of the handrail of the present invention has been disclosed as being manufactured entirely from wood from the same species, with the outer region comprising higher grades of that wood and the inner core comprising lower grades of the same species, it will be understood by those skilled in the art that the inner core may alternatively be manufactured from different, less expensive, lower grade woods including manufactured wood products such as chip board or particle board.
In the foregoing description, certain terms have been used for brevity, clearness, and understanding. No unnecessary limitations are to be implied therefrom beyond the requirement of the prior art because such terms are used for descriptive purposes and are intended to be broadly construed.
Moreover, the description and illustration of the invention is an example and the invention is not limited to the exact details shown or described.
