Sheet Metal Construction Truss and its Method of Continuous Automated Manufacture

Abstract

A linear construction truss comprising a hollow shell with a square cross section and a core composed of linked tetrahedra, and a method of manufacturing of said linear construction truss.

1 . A linear construction truss, comprising:
 a hollow shell with a square cross-section;   a core located inside the hollow shell, comprising a plurality of tetrahedra rigidly connected together at their edges, the edge length of each tetrahedron being approximately equal to the inside diagonal of the cross-section of the hollow shell.   
     
     
         2 . The linear construction truss of  claim 1 , where the core is rigidly connected to the hollow shell. 
     
     
         3 . The linear construction truss of  claim 1 , where the tetrahedra are hollow. 
     
     
         4 . The linear construction truss of  claim 1 , where the tetrahedra are chamfered in such a way that the chamfered surfaces can be rigidly connected to the sides of the hollow shell. 
     
     
         5 . The linear construction truss of  claim 3 , where at least one face of at least one tetrahedron has at least one perforation. 
     
     
         6 . The linear construction truss of  claim 1 , where the hollow shell and the core are made of sheet metal. 
     
     
         7 . A method of manufacturing a linear construction truss, comprising:
 bending a first sheet metal strip in such a way as to result in a plurality of equilateral triangular faces where the altitude of each triangular face approximately equals the width of the sheet metal strip, such that:
 the angle between a first triangular face and a second triangular face is approximately 109.4667 degrees; 
 the angle between the second triangular face and a third triangular face is approximately 289.4667 degrees; 
 the angle between the third triangular face and a fourth triangular face is approximately 109.4667 degrees; 
 the angles between neighboring faces continue to alternate between approximately 109.4667 degrees and approximately 289.4667 degrees throughout the length of the first sheet metal strip; 
   bending a second sheet metal strip identically to the first sheet metal strip;   rigidly connecting the first sheet metal strip and the second sheet metal strip in such a way as to result in a core of linked tetrahedra;   forming a hollow shell with a square cross-section such that the length of the inner diagonal of the cross-section is approximately equal to the edge length of the tetrahedra;   rigidly connecting the core to the hollow shell.   
     
     
         8 . The method of  claim 7 , where the bending step comprises chamfering the area between the triangular faces in such a way that the chamfer surfaces can be rigidly connected to one of the sides of the hollow shell. 
     
     
         9 . The method of  claim 7 , where the forming step comprises winding a strip of sheet metal around the core in a spiral pattern in order to form the hollow shell. 
     
     
         10 . The method of  claim 7 , where the forming step comprises winding a plurality of strips of sheet metal around the core in a spiral pattern in order to form the hollow shell. 
     
     
         11 . The method of  claim 7 , where the forming step comprises rigidly connecting four sheet metal sides on the outside of the tetrahedral core in order to form the sides of the hollow shell. 
     
     
         12 . The method of  claim 7 , where prior to the bending step, one or both of the first sheet metal strip and the second sheet metal strip are cut in such a way that the perforations do not impinge on the edges of the tetrahedra.