Patent Publication Number: US-2002000542-A1

Title: Insulating fencing

Description:
FIELD OF THE INVENTION  
       [0001] The present invention relates to post adapters that support and electrically insulate fencing wires from a fence post to which they are attached.  
       BACKGROUND OF THE INVENTION  
       [0002] Modern fencing for farms and ranches often makes use of fence posts that are made of metal, the posts being generally T shaped in cross-section. The outer surface of the cross bar of the T is a forwardly facing, generally vertical, substantially planar surface, and from this surface arises a series of forwardly extending bumps or nibs. The metal posts commonly are painted to reduce corrosion. However, continued exposure to the weather and the abrasive movement of fencing wires upon the post, as may be due to cattle rubbing or leaning against the fencing wire, may lead to a wearing away of the paint, enabling the bare metal of the post to contact the metal wire fencing to which it is attached, resulting in rusting. In the case of an electric fence, of course, metal-to-metal contact between the fencing wire and the metal post short-circuits the system and renders it inoperable.  
       [0003] Various attempts have been made to provide insulation between fencing wire and metal or wooden posts, but such insulators in general are characterized by substantial bulk and highly convoluted shapes, often formed of molded plastic, resulting in substantial expense both in the manufacture of such insulators and installation of the insulators on fence posts. Reference is made to U.S. Pat. Nos. 5,063,274 (Johnson), 5,032,693 (Langlie et al.), 4,883,923 (Langlie et al.), 4,905,968 (Eby et al.), 4,866,218 (Wilson), 4,771,137 (Thompson), 4,680,428 (Wilson), 4,623,756 (Wilson), 4,580,767 (Zimmerman), and 4,263,477 (Wilson).  
       SUMMARY OF THE INVENTION  
       [0004] The present invention provides a fence post adapter for separating and insulating fencing wire from a metal post of the type having a generally planar, forwardly facing vertical surface with vertically spaced nibs protruding forwardly from that surface. The adapter works well in providing an insulating barrier between metal fencing wire and the metal post, and is particularly useful with electric fencing. The adapter comprises a body of electrically insulating material having a rearward facing surface for confronting and engaging the forward facing surface of the metal post, and an oppositely facing forward surface. A recess is formed in the rearward surface of the body to receive one of the protruding nibs of the fence post when the adapter is mounted to the post, and the forward surface of the body includes a pair of vertically spaced, forwardly protruding portions defining between them a forwardly open groove for receiving and supporting fencing wire.  
       [0005] In a preferred embodiment, the invention provides, in combination, a metal fence post as described above, together with an attached post adapter for insulating fencing wire from a fence post. The adapter comprises a body of electrically insulating material having a rearwardly facing surface confronting the forwardly facing surface of the post, and an oppositely facing forward surface. The body has a recess formed in its rearward surface within which is received one of the protruding nibs of the post in a manner restraining sliding movement between the confronting surfaces of the post and body. The forward surface of the body has a pair of vertically spaced, forwardly protruding portions defining between them an open groove for receiving and supporting fencing wire.  
       [0006] Preferably, one of the forwardly extending protrusions of the body is formed by a portion of the forward surface of the body on the opposite side from the nib-receiving recess. Further, the adapter body desirably contains rearwardly extending side flanges which confront side edges of the post and shield the side edges of the post from contact with the fencing wire. 
     
    
    
     DESCRIPTION OF THE DRAWINGS  
     [0007]FIG. 1 is a broken-away, perspective view showing an adapter of the invention mounted to a metal fence post and supporting metal wire fencing;  
     [0008]FIG. 2 is a front view of the adapter shown in FIG. 1;  
     [0009]FIG. 3 is an end view of the adapter of FIGS. 1 and 2;  
     [0010]FIG. 4 is a cross-sectional view taken along Line  4 - 4  of FIG. 1;  
     [0011]FIG. 5 is a cross-sectional view taken along Line  5 - 5  of FIG. 2; and  
     [0012]FIG. 6 is a broken-away view of an adapter showing a modification thereof. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
     [0013] Referring first to FIG. 1, a metal fence post is shown generally as  10 , the post having a generally “T” shaped cross-section providing a generally planar, forwardly facing vertical surface  12 . Protruding forwardly from the surface  12  are a plurality of vertically spaced nibs  14 . The surface  12  is bounded by vertically extending side edges  16 ,  18 . Leg  20  of the “T”-shaped post configuration extends rearwardly, generally normal to the surface  12 , and  20  terminates in a vertical edge  22 . The nibs  14 , as will be seen from FIG. 1, are positioned intermediate the edges  16 ,  18 . The nibs  14  generally are each formed with generally parallel, spaced sidewalls  24 , and forwardly converging top and bottom walls  26  that terminate forwardly in a generally flat surface  28  that is approximately parallel to the surface  12 . Metal posts of the type thus described have been used for many years, and commonly are provided with a coat of protective paint.  
     [0014] Shown also in FIG. 1 is fencing wire  30  which is held to the post  10  by means of an insulating adapter shown generally as  32  and a wire tie  34 . The wire tie, shown better in FIG. 4, is made of a length of malleable metal wire  36  such as copper, steel or aluminum, the wire bearing an insulating polymeric coating  38 . The wire tie passes behind the post in contact with the edge  22  of the leg of the metal T post, and then extends forwardly tautly on each side of the post and is wrapped around the fencing wire to urge the fencing wire rearwardly into contact with the adapter. Because of its insulating covering  38 , the wire tie does not make metal-to-metal contact with the post  10  or with the fencing wire  30 . The core wire is of a diameter to provide it with sufficient malleability so that it can be bent around the post leg and wrapped around the fencing wire by hand, but also with sufficient stiffness so that once it is conformed to the post and fencing wire, it stays in place. The metal core wire preferably is 11 gauge or heavier, and the insulating sheath is preferably of plastic of a type and thickness that resists damage caused by abrasion of the plastic by the metal post or fencing wire and damage caused by continuous exposure to the weather.  
     [0015] If desired, the wire tie  34  may instead be formed and supplied as a relatively rigid insulated wire length having the general configuration shown in FIG. 4, that is, the wire tie having ends that are bent back upon themselves to form a bight within which the fencing wire may be received. Here, the wire tie is sufficiently springy to enable the doubled-back ends  40  of the tie to be snapped about the fencing wire  30 . If desired, the wire tie  34  could be made of other, preferably polymeric materials, and shaped to pass behind the wire post and to snap over the fencing wire  30 . Also, although the wire tie in FIG. 4 is shown as having an insulating sheath extending continuously from end to end, it is only necessary that insulation be provided at the points where the tie comes into contact with the metal post or fencing wire  30 . Although FIG. 4 depicts the wire tie wrapped about the fencing wire only once, in practice it may be desirable to wrap the wire tie several times around the fencing wire to secure it in place.  
     [0016] The adapter  32  is shown best in FIGS. 2, 3 and  5 . The adapter preferably is made of one piece out of a polymeric material, preferably a thermoplastic material such as nylon or polypropylene. It preferably is made by injection molding techniques. The adapter comprises an electrically insulating body  42  having a rearwardly facing, preferably generally planar surface  44  that confronts and engages the forward surface  12  of the metal post. As shown best in FIG. 4, the forward surface  12  of the metal post commonly is not precisely flat, but rather has a slightly serpentine configuration. The confronting surface  44  of the adapter, if desired, may be configured so as to more closely fit against the post surface  12 . A rearwardly open recess  46  is formed in the surface  44 , the recess being configured so as to closely receive within it one of the post nibs  14 . In this manner, when the adapter is placed against the forward face  12  of the post as shown in FIG. 1, the nib  14  within the recess  46  prevents the confronting surfaces  12 ,  44  of the post and adapter, respectively, from sliding with respect to one another.  
     [0017] Protruding forwardly from the forward surface  48  of the adapter are a pair of vertically spaced portions  50 ,  52  forming between them a forwardly open, lateral groove  54  within which the fencing wire  30  may be received, as shown in FIG. 1. It will be understood that in the preferred embodiment thus described, the wall  56  bounding the recess  46  in the adapter has a forward outer surface that forms the forwardly extending protrusion  50 , as shown best in FIG. 5. Similarly, the surface  44  of the adapter may be provided with a second recess  58  (FIG. 5), and the wall  60  bounding the recess  58  may have an outer surface forming the smaller, forwardly extending projection  52 .  
     [0018] To protect the fencing wire from contact with the metal fence post, the body  48  is made suitably thick, preferably on the order of about 2 mm, at least in the area of the adapter that comes into contact with the fencing wire. To avoid warping during molding, the wall thickness of the flat portion of the body desirably is essentially uniform. The side edges of the adapter body are provided with rearwardly extending, vertical flanges  64 , the flanges extending rearwardly a sufficient distance as to shield the edges  16 ,  18  of the post from contact with the wire tie  34 . Although the flanges preferably extend at right angles from the rear surface  44  of the body, the flanges may converge rearwardly slightly to enable the adapter to “snap” over the edges  16 ,  18  of the post to hold the adapter to the post as wire fencing is attached to the adapter. To reduce stress concentration, a rounded configuration is employed at the intersection of the inner surfaces  70  of the flanges and the rear surface  44  of the body, the included angle between these intersecting surfaces desirably being approximately a right angle or slightly less than a right angle.  
     [0019] The adapter preferably is dimensioned so that it snugly receives within its recess  46  a respective nib of a metal fence, and also so that it receives snugly between its side flanges  64  the edges  16 ,  18  of the metal post. The dimensions of the metal posts, however, may vary throughout their lengths, and also from post to post, for that matter. As a result it is desired that the recess  46  and distance between the side flanges  64  be made sufficiently large as to accommodate variations in the dimensions of the metal fence posts. If desired, small, elongated, deformable internal ribs or webs, such as those shown at  66  in FIGS. 5 and 6, may be provided within the recess  46 , preferably extending from the surface  44  inwardly of the recess to enable the part to be made by injection molding. The purpose of the ribs  66 , which are somewhat flexible and deformable, is to engage the surfaces of the nib to hold the nib more closely in place and, desirably, to hold the adapter to the post as wire fencing is attached to the adapter. In a less preferred embodiment, similar elongated ribs may be formed on the mutually confronting surfaces  70  of the flanges, these ribs also being deformable and being provided for the purpose of more closely encountering the fence post edges.  
     [0020] In practice, a plastic adapter  32  of the invention is placed against the forward surface of the fence post, as shown in FIG. 1, and fencing wire  30  is positioned in the groove  54  between the protrusions  50 ,  52 . One end  40  of the wire tie may first be wound about the fencing wire  30 , the tie wire being passed rearwardly and bent around the leg  20  of the fence post and the other end of the tie wire being pulled snug and wound around the fencing wire on the opposite side of the adapter. Preferably, if the fencing wire is going to be subjected to forces tending to urge it downwardly along a particular post (as, for example, where the fencing wire connections to neighboring posts are at elevations below the elevation of the connection to the particular post), then the adapter of the invention preferably is placed on the fence post in the configuration shown in FIG. 1 so that the fencing wire may press downwardly against the larger protrusion  50 . Similarly, if the fencing wire is expected to be urged upwardly in use, (as may occur, for example, if the fencing wire connections to neighboring posts are at elevation above the elevation of the connection to the particular post), then the adapter may be turned upside down to place the larger protrusion  50  above the fencing wire so that the fencing wire may press upwardly against the larger protrusion  50 .  
     [0021] The fencing system as described positions the fencing wire closely adjacent the forward surface of the post, and the resulting connection is physically strong in comparison to prior art connections utilizing long, cantilevered insulating rods that protrude from a fence post. Such strength is important when, for example, cattle are to be fenced into or out of a particular area. Moreover, the fencing wire is positively insulated from contact with the metal post, and this is particularly important in the case of electric fencing. The adapters of the invention are easy to mold, utilize only small amounts of material, and hence are inexpensive to manufacture.  
     [0022] While a preferred embodiment of the present invention has been described, it should be understood that various changes, adaptations and modifications may be made therein without departing from the spirit of the invention and the scope of the appended claims.