Patent Publication Number: US-6712330-B1

Title: Support pole

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a support pole comprising a hollow shaft extending upwardly from a base which is secured to a footing and more particularly to a means for providing a mechanical connection of the shaft to the base. 
     2. Description of the Related Art 
     Support poles for supporting lights, etc., thereon are commonly constructed of a metal material such as aluminum or steel. In most instances, the support pole comprises a pole member or shaft which is secured to a base which in turn is secured to a concrete footing. The base is normally comprised of a substantially flat baseplate or plate portion having a generally cylindrical portion extending upwardly therefrom. The base is sometimes comprised of a flat baseplate portion only without a cylindrical portion. When the shaft is comprised of aluminum or steel, the shaft is normally welded to the metal baseplate. If the shaft is constructed of aluminum, the welding operation may weaken the shaft in the area of the weldment which is commonly referred to as a heat affected zone (HAZ). 
     A typical prior art support pole construction is illustrated in FIG. 2 wherein the numeral  10  refers to a base  10  including a plate portion  12  having a generally cylindrical portion  14  extending upwardly therefrom with the cylindrical portion  14  including a central opening  15  defined by surface  16 . The hollow metal shaft  18  is positioned in the central opening  15  of the base  10  so that the lower end  20  of the shaft  18  is spaced above the bottom surface  22  of the plate portion  12  of base  10 . The lower end  20  of the shaft  18  is welded to the base  10  at  22 . In some cases, the outer surface of the shaft  18  is welded to the upper end of the base  10  by weldment  24 . Normally, central opening  15  has a slight taper or draft to facilitate the removal of the base  10  from the mold if the base  10  is a casting. Such draft or taper results in a small gap  23  which makes welding more difficult at quality levels. 
     Although the prior art method of securing the shaft to the base in FIG. 2 is extensively used in the industry, the same has certain disadvantages. First, two heat affected zones (HAZ) are created due to the weldments  22  and  24 . Second, the use of two weldments increases the cost of fabricating the assembly. Third, since the lower end of the shaft  18  is spaced above the bottom surface  22  of the base  10 , a taller base  10  is required as a way of transferring the loads away from the weldments. 
     SUMMARY OF THE INVENTION 
     A support pole is described which includes a horizontally disposed base for attachment to a footing with the base including a plate portion, having a bottom surface, and a generally cylindrical portion extending upwardly therefrom. The base has a central opening formed therein which extends between the upper and lower ends thereof. The plate portion has an annular cut-away portion formed in its bottom surface which communicates with the lower end of the central opening. A hollow metal shaft is inserted into the central opening of the base so that its lower end is substantially flush with the bottom surface of the plate portion. A weldment is provided in the annular cutaway portion which welds the outer surface of the lower end of the shaft to the base. The shaft has an enlarged diameter portion immediately above the upper end of the base. The single weldment and the enlarged diameter portion on the shaft securely attach the shaft to the base. In another embodiment, the cylindrical portion is omitted from the base. Further, the cylindrical portion may be replaced with a square portion to accommodate square shafts. 
     In some cases, the base will be comprised of a flat baseplate portion without a cylindrical portion. 
     It is therefore a principal object of the invention to provide an improved support pole. 
     Still another object of the invention is to provide a mechanical connection for the shaft of the pole to a base which requires only a single weldment. 
     These and other objects will be apparent to those skilled in the art. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a partial perspective view of the support pole of this invention; 
     FIG. 2 is a partial vertical sectional view of a prior art support pole; 
     FIG. 3 is a sectional view as seen along lines  3 — 3  of FIG. 1; and 
     FIG. 4 is a sectional view of a modified form of the base. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The support pole of this invention (FIGS. 1 and 3) is referred to generally by the reference numeral  26  and includes a hollow shaft or pole member  28  which is received by and which is secured to a base or base plate  30 . Although the pole member  28  may be cylindrical, square or multi-sided, the invention will be described as being used with a cylindrical pole Shaft  28  will normally be comprised of an aluminum material but may be comprised of a steel material or the like. The base  30  may either be an aluminum casting or it may be formed by milling. The base  30  may also be comprised of a steel material. 
     Base  30  includes a plate portion  32  having a bottom surface  34 . Base  30  also includes a generally cylindrical portion  36  (square if a square pole is being used) which extends upwardly from plate portion  32  and which has an upper end  38 . Base  30  will normally be provided with webs or reinforcing members  40  extending between the plate portion  32  and a cylindrical portion  36 . Base  30  has a central opening  41  extending therethrough which is defined by surface  42 . Opening  41  will be square if a square pole is being used. A generally arcuate cut-away portion  44  is formed in base  30  which extends upwardly thereinto from bottom surface  36  of plate portion  32 , as illustrated in FIG.  3 . As illustrated in FIG. 3, the cut-away portion  44  communicates with the central opening  41 . For purposes of description, shaft  28  will be including a lower end  43 . In many instances, the base will include a plate portion without a cylindrical portion such as seen in FIG.  4 . 
     Shaft  28  is extended downwardly into the central opening  41  so that its lower end  43  is substantially flush with bottom surface  34 , as seen in FIG.  3 . The outer surface  46  of the lower end of shaft  28  is welded to base  30  by a weldment  48  in cut-away portion  44 . The welding operation may be either manual or robotic. The shape of the cut-away portion  44  lends itself to robotic welding since the welding tip of the robotic welder may be easily inserted into the cut-away portion  44  from the bottom of the support pole. 
     In some cases, there may be a small clearance between the outer surface  46  of shaft  28  and the surface  42  due to manufacturing tolerances. It is preferred that the lower end of shaft  28  be expanded outwardly into mechanical engagement with surface  42  and such is achieved by hydraulic expansion equipment to force shaft  28  outwardly into mechanical engagement with the base  30 . It is also preferred that hydraulic expansion equipment or the like be used to expand the shaft  28  outwardly immediately above the upper end  38  of base  30  to create an enlarged diameter portion or protrusion  49 . The protrusion  49  and the weldment  48  cooperate to securely lock or attach the shaft  28  to the base  30 . The protrusion  49  is relatively small and therefore is not very noticeable. Hence, the visual appearance of the shaft is not adversely affected. 
     It can therefore be seen that a novel support pole has been provided which includes a shaft  28  secured to a base  30  by a single weldment  48  thereby reducing fabrication costs and which also results in a single HAZ. The method of attaching the shaft to the base of this invention also eliminates the need for a tall cylindrical portion on the base. 
     FIG. 4 illustrates a modified form of the base or baseplate. In FIG. 4, the base  50  does not have a cylindrical portion extending upwardly therefrom. Base  50  includes an upper surface  52  and a bottom surface  54 . Base  50  has a central opening  56  formed therein which receives shaft  28  therein. Base  50  has an arcuate cut-away portion  58  formed therein which is identical to cut-away potion  48  on base  30 . The lower outer end of shaft  28  is welded to base  50  by means of a weldment  60  in cut-away portion  58 . Preferably, the shaft  28  has a protrusion or enlarged diameter portion  49  formed therein immediately above the upper surface  52  of base  50  for the same purpose as that in FIG.  3 . 
     As in the embodiment of FIG. 3, it is preferred that the shaft  28  be secured to the base  50  by both the weldment  60  and the protrusion  49 . However, the protrusion  49  may be omitted in some cases. 
     The use of the invention described herein makes it possible to eliminate all but a thick base plate since the invention allows for better load transfer (i.e., higher load transfer to weld) and hence a shorter casting height is needed. 
     Thus it can be seen that the invention accomplishes at least all of its stated objectives.