Embeddable breakaway utility pole

Abstract

An embeddable breakaway utility pole comprises separate upper and lower aluminum pole pieces, wherein the lower pole piece is to be embedded below ground surface. The upper and lower pole pieces are interconnected by a weld which defines a breakaway zone enabling the upper pole piece to break off the lower pole piece in response to vehicular impact. The weld can be connected to a backer ring which provides a guide surface that axially aligns the pole pieces. Alternatively, the pole can be formed of a single pole piece which is welded between its ends to form a weakened region that defines the breakaway zone.

1 . An embeddable breakaway utility pole comprising a metallic lower pole piece and a separate metallic upper pole piece disposed on the lower pole piece, the upper and lower pole pieces being of circular cross section; a top end of the lower pole piece having a thicker wall than a bottom end of the upper pole piece; a circumferential recess formed at the top end of an exterior face of the lower pole piece for defining therein an axial guide surface and a radial support surface; the bottom end of the upper pole piece being seated in the recess and axially guided by the axial guide surface, wherein exterior faces of the upper and lower pole pieces are substantially flush with one another; a weld extending circumferentially around the exterior faces of the upper and lower pole pieces to form a breakaway joint between the upper and lower pole pieces. 
     
     
         2 . The utility pole according to  claim 1 , wherein the upper and lower pole pieces comprise aluminum. 
     
     
         3 . The utility pole according to  claim 1 , wherein the bottom end of the upper pole piece is spaced above the radial support surface to define an axial gap therebetween, and the weld comprises a groove weld projecting radially through the gap to connect with the guide surface of the recess. 
     
     
         4 . An embeddable breakaway utility pole comprising a metallic lower pole piece and a separate metallic upper pole piece disposed on the lower pole piece; the upper and lower pole pieces being of circular cross section; a circular backer ring located within the pole such that a top end of the lower pole piece and a bottom end of the upper pole piece are situated axially between upper and lower ends of the backer ring; the backer ring including a cylindrical outer surface with a diameter substantially corresponding to an inner diameter of a top end of the lower pole piece and to an inner diameter of a bottom end of the upper pole piece to define an axial guide which brings exterior faces of the upper and lower pole pieces into substantially flush relationship; and a weld extending circumferentially around the exterior faces of the upper and lower pole pieces to form a breakaway joint between the upper and lower pole pieces; wherein the bottom end of the upper pole piece is spaced above the top end of the lower pole piece to form an axial gap therebetween through which the weld extends to join to the backer ring. 
     
     
         5 . The utility pole according to  claim 4 , wherein the upper and lower pole pieces and the backer ring comprise aluminum. 
     
     
         6 . The utility pole according to  claim 4 , wherein the weld comprises a groove weld. 
     
     
         7 . The embeddable utility pole according to  claim 4  wherein the backer ring comprises aluminum. 
     
     
         8 . The utility pole according to  claim 4 , wherein the backer ring includes an annular projection extending radially from the cylindrical outer surface of the backer ring at a location axially between top and bottom ends of the backer ring the projection projecting radially through the axial gap;
 the projection including upper and lower ends spaced from the bottom end of the upper pole piece and the top end of the lower pole piece, respectively; the weld comprising upper and lower weld portions, the upper weld portion extending radially through the axial gap between the upper end of the projection and the bottom end of the upper pole piece; the lower weld portion extending radially through the axial gap.   
     
     
         9 . An embeddable breakaway utility pole formed of a single pole piece comprised of aluminum and having a circumferential weld extending around an exterior surface thereof between top and bottom ends of the pole piece to define a weakened breakaway zone in the pole piece; the breakaway zone located nearer to a bottom end of the pole piece than to a top end of the pole piece. 
     
     
         10 . The utility pole according to  claim 9 , wherein the weld includes a circumferential reinforcing bead projecting radially beyond an exterior surface of the pole piece. 
     
     
         11 . An embeddable breakaway utility pole comprising a metallic lower pole piece and a separate metallic upper pole piece disposed on the lower pole piece; the upper and lower pole pieces being of circular cross section; a metallic circular plate having inner and outer diameters being situated axially between the upper and lower pole pieces and welded thereto to form a breakaway joint. 
     
     
         12 . The utility pole according to  claim 11  wherein the outer diameter of the plate is greater than respective outer diameters of the upper and lower pole pieces; the inner diameter of the plate is less than respective inner diameters of the upper and lower pole pieces; the weld comprising upper and lower weld portions, the upper weld portion extending between an upper end of the plate and an exterior face of the upper pole piece; the lower weld portion extending between a lower end of the plate and an exterior face of the lower pole piece. 
     
     
         13 . The utility pole according to  claim 12  wherein the upper and lower pole pieces and the plate are formed of aluminum. 
     
     
         14 . A method of making an embeddable breakaway utility pole comprising forming a circumferential weld around an aluminum pole piece between top and bottom ends thereof at a first temper, and then heating the pole piece at a second temper which is harder than the first temper, wherein the weld weakens the pole piece to define a circumferential breakaway zone therein.