Patent Application
20110041994
The present invention relates to structural members for docks, seawalls, walkways, decks and the like constructed in wetlands or adjacent a body of water where decay or deterioration of structures erected in such areas is accelerated by the prevalent moisture. More particularly, the present invention relates to wooden structural members for such environments wherein the wooden structural members are encased in a resin, vinyl, or plastic based coating.
Plastic encasement of wooden or steel members is known as shown in U.S. Pat. Nos. 7,393,482 and 5,226,751 and 4,713,129, however, the known methods have not provided a reliable, economical, and durable structural member for use in the above environments. The present invention provides an economical reproducible structural member for use in the high moisture environment.
The product forming the basis for this invention is a wooden structural member such as a beam, upright, piling or the like which has been encased in a waterproof plastic or vinyl outer layer. In accordance with the invention the structural member has been wrapped with an extruded sheet of plastic or FRP while the sheet is still hot from the extrusion process such that as the sheet spirals about the structural member it bonds to the structural member and itself at instances of overlap including along a spiral seam and at the ends of the structural member where excess sheet material is folded on itself to seal the ends.
To manufacture the product, we have designed an apparatus for applying a vinyl cover to an elongated wooden member such as a beam or post, comprising: a sheet extruder providing a sheet of pliable vinyl or fiber reinforced polymer of predetermined width, a feed conveyor capable of supporting and rotating a wooden member adjacent the sheet extruder such that a still hot and pliable sheet may be applied to the wooden member beginning at an end proximal the sheet extruder as the wooden member rotates. The feed conveyor includes a linear drive urging the wooden member supported thereby transversely of the sheet extruder to position the wooden member for continuous application of the sheet substantially along the length of the wooden member, an out feed conveyor engaging the wooden member at the proximal end and capable of rotating the wooden member to continuously apply the sheet over an opposite end of the wooden member such that the wooden member is completely encased by vinyl, and a magazine for supplying wooden members to the feed conveyor.
Using the above apparatus the invention provides a process for applying a vinyl cover to an elongated wooden member comprising the steps of: extruding a continuous sheet of vinyl having a predetermined width and thickness; rotatably supporting a wooden member in position to receive a leading end of the hot, pliable continuous sheet about a proximal end of the wooden member with a portion of the sheet extending beyond the proximal end; compressing the portion of the continuous sheet against a face of the wooden member on the proximal end thereof to cause the sheet to bond to itself; urging the wooden member transversely of the continuous sheet at a rate sufficient to wrap the sheet about the wooden member with the sheet overlapping itself along the length of the member and bonding to itself; severing the sheet member as a second end of the wooden member is wrapped within the sheet with a trailing portion extending beyond the second end; and, compressing the trailing portion against a second face of the wooden member on its second end thereof such that the sheet bonds to itself providing watertight encasement of the wooden member.
The product, its method of manufacture and the apparatus for manufacturing the product are illustrated in the accompanying drawings which form a portion of this disclosure and wherein:
Referring to the figures for a clearer understanding of the invention it should be understood that
Referring to
Carriages 16a-16d are moved along rail or track 33 which runs adjacent extruder 11 by a mover 35 which allows wooden member to be advanced a controlled even rate, thus a fluid driven motor, an electric motor, a linear actuator with appropriate limit switches and controls, or any conventional controllable drive may be used to urge the carriages and wooden member along track 33. Preferably, the drive is be reversible such that carriages 16a-d can be returned to their starting location.
In operation wooden member 13 is secured between spindles 18 and 27 in any suitable manner and supported on rollers 31. It will be appreciated that the surface of the wooden member may need to be prepared such as by sanding or shaving to remove any severe discontinuities which might penetrate the vinyl coating during the encasement process. Motor 25 is engaged to rotate wooden member 13 and extruder 11 is engaged to extrude a sheet of vinyl. The leading edge of the extruded vinyl sheet 12 is carried over the leading end of wooden member 13 by an operator or by a puller mechanism, such as a gripper mounted for outward and downward movement relative to extruder 11, such that the lateral 36 margin of sheet 12 extends beyond the leading end. As sheet 12 is extruded wooden member 13 is rotated by motor 25 until the leading end of wooden member 13 is completely encircled by sheet 12 with a portion of sheet 13 extending beyond the end. Mover 35 is then actuated to urge wooden member 13 along track 33 such that sheet 12 wraps about wooden member 13 as an overlapping spiral, thereby adhering to wooden member 13 and to itself to form a substantially water tight elongated casing about wooden member 13. Sheet 12 is wrapped about the trailing end of wooden member 13 as carriage 14 moves the member past the extruder and then severed such that the free end of sheet 12 may be folded over the trailing end of member 13. Spindles 18 and 27 may then be disengaged and an end sheet of vinyl may be applied to the ends of the wooden member to complete the sealing of the casing about the wooden member. The application may be made by manually heating a circular sheet of vinyl until it softens sufficiently to adhere to the portion of sheet 12 already applied to the ends and to the end of the wooden member. Alternatively the end covers may be applied with heated mechanical paddles in an automated manner.
It is to be understood that the term wooden members means any elongated wooden member, whether made from solid wood or some other composite such as pressed wood or laminate. Further, it is contemplated that the present invention may be utilized to encase other structural members made from core material other than wood, such as metal, foam or other composites. It is also contemplated that the vinyl sheet may comprise any suitable vinyl polymer or fiber reinforced polymer having suitable physical characteristics to prevent corrosion or rotting of the core material when the spiral encasement is completed. It is further to be understood that the specific embodiments described herein are not intended as limitations on the invention which is entitled to the full scope of the appended claims.
