Fences – Miscellaneous
Reexamination Certificate
2002-02-22
2003-05-06
Browne, Lynne H. (Department: 3679)
Fences
Miscellaneous
C256S019000
Reexamination Certificate
active
06557829
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates in general to fence structures and in particular to a picket fence structures.
BACKGROUND OF THE INVENTION
A wide variety of fencing structures have long been used to separate or enclose areas of industrial, commercial, residential and other properties. Common examples include stockade, chain link, wire, split rail and picket fencing. Fencing products may be fabricated from many different type of materials such as metal, wood, plastics and combinations or composites thereof. Among these, plastic and plastic-based fencing products are becoming increasingly popular. This is because they are relatively easy and inexpensive to manufacture and because consumers appreciate their attractiveness, low-maintenance, durability and competitive cost.
Plastic picket fencing represents a significant segment of the fencing industry. The pickets of a typical plastic picket fence are designed to resemble wooden pickets but are usually made from two pieces, the picket member and an upwardly pointed cap member that may be adhesively attached or mechanically fastened to the picket member. A disadvantage of using glue to attach the cap to the picket is that it can be messy and unsightly if applied improperly. Moreover, adhesives tend to become brittle and lose their bonding strength when exposed to the elements for extended periods of time. As such, after the passage of time it is not unusual for an adhesively attached cap to become relatively easily detachable from its picket. Such loosened caps can then become separated from their pickets by vandals or by something as benign as a strong wind, thereby leaving the fence in an incomplete, unsightly condition.
Mechanical fixation is an alternative to adhesive attachment of a plastic cap member to a plastic picket fence member. Mechanical fixation involves the creation of a friction or interference fit between the cap and picket members. Examples of picket fence cap assemblies that utilize such a friction fit principle are marketed by LMT Products Corporation (“LMT”) of Lawrenceville, N.J. These assemblies comprise the cap member itself as well as a pair of stainless steel metal clips. The molded plastic cap member includes a plurality of downwardly depending legs that are adapted for insertion into the open top of a plastic picket. The picket is a typically a predetermined length of hollow extruded rigid polyvinyl chloride (PVC), polycarbonate, acrylic ester-modified styrene acrylonitrile terpolymer (ASA) or other plastic material having a rectangular cross sectional configuration designed to impart to the picket the shape of a wooden board or plank. Each of the metal clips includes a barb that functions to securely attach the clips to the cap member when the clips are press fitted onto the bottoms of legs disposed at opposite ends of the cap member. The clips include outwardly and upwardly inclined flat tabs or fingers that, when the cap member is inserted into the picket member, frictionally engage the inner surfaces of opposite end walls of the picket member. It is this frictional engagement of the clips with the picket member which serves to retain the cap member on the picket member.
As presently constructed, the LMT clip-on picket fence cap assemblies cap members can be extracted from their pickets by the exertion of about 8-15 lbs. tensile or pulling force. While this level of resistance is sufficient to prevent detachment of the cap member as a result of a strong wind, it would not be enough to deter a determined vandal.
An advantage exists, therefore, for a clip-on picket fence cap assembly that can resist detachment of a plastic picket cap member from a plastic picket member when significant pulling force is applied to the cap member.
SUMMARY OF THE INVENTION
The present invention provides a clip-on picket fence cap assembly that can resist detachment of a plastic picket cap member from a plastic picket member when significant pulling force is applied to the cap member. The assembly overcomes the deficiencies of existing products in several ways. First, the legs of the cap member upon which the clips are installed are very stiff by virtue of being reinforced by gussets that resist deflection of the legs when inserted in a picket. This is contrasted with conventional cap members whose unreinforced legs flex inwardly upon insertion into a picket, thereby inhibiting the metal tabs of the clips from “hooking” or “biting” into the inner walls of the extruded picket. Second, the metal clips that are fastened to the legs are substantially thicker and less easily deformed than presently available clips. Preferably, at least the outer surfaces of the clips are convex curvilinear in shape in order to enhance the strength of the clips and their resistance to deformation. In addition, the outer surface of each clip is preferably provided with at least one outwardly projecting retention means adapted for secure embedment into the inner wall surfaces of a picket member when the cap assembly is inserted therein. Preferably, the retention means is constructed as at least one convex curvilinear barb. Just as the convex arch or bow shape of the clip stiffens the clip, the convex curvilinear shape of the retention means acts to resist deformation of the retention means. The resultant assembly is substantially stiffer and stronger than presently available clip-on picket fence cap assemblies. Because of this, its clips very firmly embed themselves into a picket and make it very difficult to extract the cap from the picket by simply pulling on the cap.
Other details, objects and advantages of the present invention will become apparent as the following description of the presently preferred embodiments and presently preferred methods of practicing the invention proceeds.
REFERENCES:
patent: 4602765 (1986-07-01), Loper et al.
patent: 5556079 (1996-09-01), West
patent: 5645270 (1997-07-01), Lawrence
Picket Fence Caps and Clips Product Literature, 2001 LMT-Mercer Group, Lawrenceville, New Jersey.
Picket Fence Caps and Clips Product Literature, TopCaps, Pompano Beach, Florida.
Browne Lynne H.
Certain-Teed Corporation
Cottingham John R.
Klehr Harrison Harvey Branzburg & Ellers LLP
Letchford John F.
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