Abstract:
Poles for supporting electric transmission lines and a method for forming such poles are provided. An exemplary embodiment pole includes multiple interlocking inner panels forming an inner wall of the pole and multiple interlocking outer panels forming an outer wall of the pole. In inner wall interlocks with the outer wall. The method includes simultaneously forming two inner panels and simultaneously forming two outer panels. The method also includes interconnecting each inner panel to an inner panel and an outer panel, and interconnecting each outer panel to an outer panel and an inner panel.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S)  
       [0001]     This application is based upon and claims priority on U.S. Provisional Application No. 60/705,522 filed on Aug. 3, 2005, the contents of which are fully incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention relates generally to the field of power poles for the support and travel of electrical conductor cables designed to transmit electrical power.  
       BACKGROUND OF THE INVENTION  
       [0003]     Electric transmission lines are the life-lines of a country&#39;s economy. Transmission lines interconnecting giant load centers with distant generation sources are vital to redistribute electrical power as required.  
         [0004]     It is known to use treated wood poles to form transmission poles. However, chemicals used to treat wood poles have been found to contain carcinogens. Environmental and economic concerns stemming from the special disposal of treated wood poles have led to the search for alternatives to wood.  
         [0005]     Concrete and steel are also used to form power poles. However, weight of these materials makes cost of transport and installation excessive. Moreover, steel is highly conductive, while concrete structures expand and contract with temperature causing vertical cracking.  
         [0006]     Resistance to corrosion is an additional common concern when using power poles. The ground in which the pole is placed, as well as the surrounding environment, can cause the pole to corrode, decreasing pole strength and pole life.  
         [0007]     Cost of power pole manufacture is an additional concern. This cost results from materials used, scrap, waste, time of manufacture, and labor. It is therefore desirable to provide a power pole that can be inexpensively manufactured and transported and that is environmentally safe while being resistant to corrosion and environmental factors such as wind, moisture, heat, cold, etc.  
       SUMMARY OF THE INVENTION  
       [0008]     In an exemplary embodiment, a composite pole for supporting an electric transmission line is provided. The composite pole includes a plurality of interlocking outer panels forming an outer wall of the pole, and a plurality of interlocking inner panels forming an inner wall of the pole surrounded by the outer wall. The inner wall is interconnected with the outer wall forming the pole for supporting the electric transmission line. In one exemplary embodiment, the outer panels are formed from a first composite material and the inner panels are formed from a second composite material. The first and second composite materials may be the same materials and they may be non-conductive composite materials. In an exemplary embodiment, the composite materials include E-glass and a vinyl ester resin.  
         [0009]     In another exemplary embodiment, the plurality of inner panels are identical. In a further exemplary embodiment, the plurality of outer panels are identical.  
         [0010]     In yet another exemplary embodiment, the inner wall has a cross-section selected from the group of polygonal and circular cross-sections and the outer wall has a cross-section selected from the group of polygonal and circular cross-sections. In another exemplary embodiment, at least one of the inner and outer walls is tapered along its length.  
         [0011]     In yet another exemplary embodiment, each inner wall panel interconnects with two other of the plurality of inner wall panels and with one of the plurality of outer wall panels. In yet a further exemplary embodiment, each outer wall panel interconnects with two other outer wall panels and with one inner wall panel. In one exemplary embodiment, the inner wall is interconnected with the outer wall by a plurality of ribs extending radially outward from the inner wall to the outer wall. In a further exemplary embodiment, each of the plurality of inner panels includes such a rib. In yet a further exemplary embodiment, each of the plurality of outer panels is interconnected with another of the plurality of outer panels via a first interconnection and with one of the plurality of inner panels via a second interconnection, such that the one of the plurality of inner panels is interconnected with another of the plurality of inner panels via a third interconnection, such that each interconnection is formed by one of the plurality of inner and outer panels being received in a slot formed in another of the plurality of inner and outer panels.  
         [0012]     In another exemplary embodiment, a composite pole for supporting an electric transmission line is provided. The pole includes a plurality of identical interlocking outer panels forming an outer wall, and a plurality of identical interlocking inner panels forming an inner wall surrounded by the outer wall, such that each of the outer panels is interconnected with another outer panel and an inner panel and such that each of the inner panels is interconnected with an outer panel and another inner panel, and such that a rib extends from either each of the inner panels or each of the outer panels such that the ribs interconnect the inner wall to the outer wall forming the pole for supporting the electric transmission line. In an exemplary embodiment, the inner and outer panels are tapered such that the pole tapers from a base to a top, such that the pole base is wider than the pole top.  
         [0013]     In yet another exemplary embodiment a method is provided for forming a composite pole for supporting an electric transmission line. The method includes extruding a first composite material through a first die forming a first extruded composite panel, cutting the first extruded composite panel as it is being extruded forming two identical outer panels, extruding a second composite material including a resin through a second die forming a second extruded composite panel, cutting the second composite panel as it is being extruded forming two identical inner panels, interconnecting the inner panels forming an inner pole wall, interconnecting the outer panels forming an outer pole wall, and interconnecting each of the inner panels to an outer panel. In an exemplary embodiment, cutting the extruded first composite panel includes placing a first blade proximate an exit of the first die such that as the first composite material is being extruded forming the first composite panel it is also cut by the first blade. Cutting the extruded second composite panel includes placing a second blade proximate an exit of the first die such that as the second composite material is being extruded forming the second composite panel it is also cut by the second blade.  
         [0014]     In a further exemplary embodiment, the first composite panel exits the first die along a first path and the second composite panel exits the second die along a second path. The first blade travels along a third path generally perpendicular to the first path as the first composite panel is extruded cutting the first composite panel along a path oblique to the first path forming the two identical outer panels each having a tapered edge. The second blade travels along a fourth path generally perpendicular to the second path as the second composite panel is extruded cutting the second composite panel along a path oblique to the second path forming the two identical inner panels each having a tapered edge. In yet another exemplary embodiment, the method further includes routing the tapered edge of each of the outer panels as the outer panels are being extruded and routing the tapered edge of each of the inner panels as the inner panels are being extruded. In one exemplary embodiment, routing the tapered edges of the outer panels includes placing a first routing blade downstream of the first cutting blade such that the first routing blade simultaneously routes the tapered edges of both outer panels. In another exemplary embodiment, routing the tapered edges of the inner panels includes placing a second routing blade downstream of the second cutting blade such the second routing blade simultaneously routes the tapered edges of both inner panels. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]      FIG. 1  is a perspective view of an exemplary embodiment power pole assembly with a partially cut away view;  
         [0016]      FIG. 2  is a cross sectional view of the exemplary embodiment power pole shown in  FIG. 1 ; and  
         [0017]      FIG. 3  is a perspective view of an exemplary embodiment power pole 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0018]      FIG. 1  shows a cut away view of a power pole assembly  10  according to an exemplary embodiment of the invention. As shown, the power pole assembly  10  includes a plurality of side wall panels, or outer panels,  12  and a plurality of center panels, or inner panels,  14 . In the shown exemplary embodiment, the center panels  14  have a portion that extends radially inward. As described below, in one embodiment, the side wall panels  12  and the center panels  14  are connected by interlocking such as snap fit connections. In the embodiment of  FIG. 1 , the power pole assembly  10  is tapered downwardly to form an enlarged base  16 . In another embodiment, the power pole assembly  10  is not tapered and maintains a constant size along a length thereof.  
         [0019]     Although not limited to a specific range, the height of the exemplary power pole assembly  10  is generally 45 to 120 feet. In one embodiment, the power pole assembly is composed of a non-conducting composite material, such as a composite of E-glass and a vinyl ester resin or other fiber reinforced resin composite materials. Such compositions are resistant to corrosion both from the environment and from the earth. As such, a portion of the base  16  of the power pole assembly  10  may be buried without risk of corrosion or rot.  
         [0020]      FIG. 2  shows a cross-section of the power pole assembly  10  shown in  FIG. 1 . As shown, each center panel  14  includes a first arm  21 , a second arm  22  and a third arm  23 . Each first arm  21  includes two fingers having a gap therebetween for receiving the second arm  22  of an adjacent center panel  14  to form an interlocking connection therewith. When each of the plurality of center panels  14  are connected, the plurality of first and second arms  21  and  22  form an inner support ring  24  to the power pole assembly  10 , and the plurality of third arms  23  form a plurality of spokes or ribs extending from the inner support ring  24 . In an alternative exemplary embodiment, the inner support ring  24  can have a polygonal structure wherein the second arm  22  of each center panel  14  is substantially straight.  
         [0021]     The inner support ring  24  adds mechanical strength and assists in preventing local buckling of the power pole assembly  10 . The inner support ring  24  defines a central opening into which additional hardware can be inserted and through which electrical and fiber optic cables can pass.  
         [0022]     Each side wall panel  12  includes a side wall arm  25 , a center panel connector  26  and a side wall connector  27  (see also detail A.) Each center panel connector  26  extends inwardly toward the inner support ring  24  of the power pole assembly  10 , and includes two fingers having a gap therebetween for receiving the third arm  23  of one of the center panels  14  to form an interlocking connection therewith. In an exemplary embodiment, each side wall connector  27  includes two fingers having a gap therebetween and at least one ramp  28   a  on an inner surface thereof. Each ramp  28   a  receives a corresponding ramp  28   b  on an end of an adjacent side wall arm  25  to form a snap fit connection therewith. The snap fit connection is formed as the corresponding ramp  28   b  of the adjacent side wall arm  25  pushes outwardly on the fingers of the side wall connector  27 . Once the corresponding ramp  28   b  of the adjacent side wall arm  25  advances into the gap a predetermined distance, i.e. when aligned with ramp  28   a , the fingers of the side wall connector  27  have nothing pressing them outwardly. The fingers then snap inwardly and the ramp  28   a  on the inner surface of the side wall connector snaps over and mates with the corresponding ramp  28   b  of the adjacent side wall arm  25 . In the exemplary embodiment of  FIG. 1 , the connection can be formed with more than one ramp  28   a  and corresponding ramp  28   b  as shown in  FIG. 2 . Alternatively or in addition, the connection can be effected using an adhesive bond such as polyurethane adhesive.  
         [0023]     When each of the plurality of side wall panels  12  is connected, the plurality of side wall arms  25  form an outer support polygon  29  of the power pole assembly  10 . The side wall panels  12  are disposed in surrounding relation to the center panels  14 . Such an arrangement allows for snap fit connections between the side wall panels  12  and/or the center panels  14 . In an alternative exemplary embodiment, the outer support polygon  29  can have a circular structure wherein the side wall arm  25  of each side panel  12  is substantially curved. A top plate can be snapped onto a top surface of the power pole assembly  10  to prevent moisture from entering.  
         [0024]     The structure of the power pole assembly  10  is relatively lightweight. Shipping weight of the power pole assembly  10  is 30 percent of that of traditional wood poles, and much less than steel or concrete poles. The inner support ring  24  increases the moment of inertia of the power pole assembly, which stiffens the pole and allows for better (less) deflection properties. In the shown exemplary embodiment, the outer support polygon  29  is formed of six side wall panels  12  and has six sides. In an alternative exemplary embodiment, the power pole assembly  10  may be formed of eight side wall panels  12  to form an outer support polygon  29  having eight sides. In other exemplary embodiments, the power pole assembly may be formed with more or less than six sides.  
         [0025]     In an exemplary embodiment, the side wall panels  12  and the center panels  14  are manufactured via a pultrusion process, where the panels are extruded through a die assembly. With reference to  FIG. 3 , in an exemplary embodiment where the power pole assembly  10  is tapered, two side wall panels  12  are pultruded at the same time and then cut apart at an angle to form a tapered edge  30 . The cut is made as the two side wall panels  12  leave the pultrusion die, saving time and labor. This is accomplished by placing a cutting blade adjacent to the pultrusion machine. In an exemplary embodiment, the cutting blade is diamond-formed and sits 4 feet from the pultrusion die. The cutting blade travels on a track substantially perpendicular to the direction of movement of the panels exiting the pultrusion die assembly.  
         [0026]     The cured panels exit the pultrusion machine at a speed which is measured by a wheel traveling with the pultruded panels. The cutting blade operates in conjunction with the traveling wheel, either mechanically or by computer program, to travel along the track to cut laterally across the moving pultruded member at a speed proportional to that of the pultruded member. Changes in pultrusion speed are detected directly or indirectly by the traveling wheel, and corresponding changes are made to the speed at which the cutting blade travels across the track to ensure a straight line cut.  
         [0027]     The shape of the end of the side wall arm  25  can be formed on the tapered edge  30  by a high speed router, such that the two pieces formed from the cut can be assembled into one another as the tapered edge  30  of one of the cut side wall panels  25  fits into the side wall connector  27  of the other cut side wall panel  25 . A routing blade, as for example a double sided routing blade, is placed in line with the cutting blade such that the two pultruded, cut members are routed by the routing blade along the tapered edge  30  to form the shape of the end of the side wall arm  25 . In an exemplary embodiment, the routing blade sits six inches from the cutting blade, and is coupled to the cutting blade. The routing blade travels with the cutting blade laterally across the moving pultruded member(s).  
         [0028]     In an alternative exemplary embodiment, the two side wall panels  12  are not cut at an angle from one another, and when assembled with other similarly shaped panels, form a power pole assembly that is substantially straight.  
         [0029]     To form the tapered exemplary embodiment shown in  FIG. 3 , two center panels  14  are similarly pultruded at the same time and then cut apart at an angle to form a tapered edge  32 . The tapered edge  32  defines a portion of the third arm  23  which engages the center panel connector  26 . Changes in the diagonal cutting make possible a range of taper in the power pole assembly  10 .  
         [0030]     In an alternative exemplary embodiment, the two center panels are not cut at an angle to one another, and fit to form the inner support ring having a substantially straight shape. Any cutting and routing of the center panels  14  can be performed according to the exemplary embodiment outlined above.  
         [0031]     The modular shape of the side wall panels  12  and the center panels  14  allow the panels to be stacked for ease of storage and transport.  
         [0032]     In an alternative exemplary embodiment, at least one of the arms  21 ,  22 ,  23  of the center panel  14  can be formed as a separate member and assembled into the center panel  14 . The connection can be achieved by the snap fit connection outlined above, or may also include an adhesive bond. In another alternative exemplary embodiment, the third arm  23  of the center panel  14  can be formed integral with the side panel  12 , and may snap into the center panel  14 , according to the snap fit connection outlined above, or may also include an adhesive bond.  
         [0033]     In still another exemplary embodiment, a center panel  14  can be formed having two first arms  21 , one being in place of the second arm  22 . Center panels can be also be formed having two second arms  22 , one being in place of the first arm  21 . A center panel having two first arms can be connected to a center panel having two second arms, and the inner support ring can be formed by alternating the center panels having two first arms and the center panels having two second arms, the connections between the first and second arms being the same as described herein.  
         [0034]     Although specific embodiments of the invention have been described above, the invention may have other variations as well. The present invention has only been described by way of exemplary embodiments. Specific descriptions are not intended as limitations of the invention. The current invention also covers other embodiments within the scope of the invention but not specifically described herein.