Helix Type Vertical Axis Turbine Blades and Method for Continuously Making Same

Abstract

A sheet metal blank is formed into a helical turbine blade by stretching an outer portion of the blank by creating indents and detents thereon. Then the stretched side is flattened and the stretched structure is formed into a helical shape.

I claim: 
     
         1 . A sheet turbine blade for use in a vertical axis turbine, the sheet turbine blade comprising:
 an inner edge, an upper edge, an outer edge and a bottom edge;   said upper edge and bottom edge contacting said inner edge, said upper edge extending outward from the top of the inner edge in a substantially straight line for a predetermined length from said inner edge, and thereafter said upper edge is curved into a semicircular shape;   said outer edge contacting said upper edge, said outer edge extending downwardly and forming a helical shaped curvature of said outer edge.   
     
     
         2 . The sheet turbine blade of  claim 1 , wherein:
 said sheet turbine blade is made of metal.   
     
     
         3 . A method for making a helically shaped turbine blade from a sheet metal blank, the method comprising the steps of:
 calculating the amount of stretch needed per unit length thereof for forming a helical outer edge on said sheet metal blank;   feeding the sheet metal blank over a first metal form to produce detents and indents on said blank in a first metal form for providing the needed stretch to said sheet metal blank;   bending said sheet metal blank over a second metal form to flatten the stretched indents and detents; and   cutting the sheet metal blank to a predetermined length.   
     
     
         4 . The method of  claim 3 , further including the step of:
 providing an inner edge of said metal form with clamping members assuring that said sheet metal blank stays stationary when said press is in operation.   
     
     
         5 . The method of  claim 3 , further including the step of:
 sizing and shaping said indents and detents follow the digital length of indexing of said sheet metal blank as it passes over said first metal form.   
     
     
         6 . The method of  claim 3 , further including the step of:
 forming said blank into a helical shape before feeding said sheet metal blank over said first metal form.   
     
     
         7 . The method of  claim 3 , further including the step of:
 forming said blank into a helical shape after bending said sheet metal blank over the second metal form;   the method of  claim 3  further including the step of flattening said stretched indents and detents.   
     
     
         8 . The method of  claim 3  wherein:
 the steps for calculating the amount of stretch needed per unit length for forming an helical outer edge include:
 a. calculating the length of a swept line s created by said outer edge when each of said turbine blade rotates around a center of rotation; 
 b. measuring the vertical distance l, of the helically shaped turbine blade from said bottom edge; 
 c. finding the length l of the hypotenuse applying the equation:
     l =√{square root over ( h   2   +v   2 )}
 
 
 d. finding the amount of stretch x needed to form the outer edge of the helix by subtracting v from l
     x−l−v.    
 
 
 
     
     
         9 . The method of  claim 8 , wherein:
 the steps for calculating the length of a swept line s created by the outer edge when each said turbine blade rotates around a center of rotation include:
 a. measuring the included angle of rotation of the turbine blade by dividing the number of turbine blades used in the system into 360°; 
 b. determining the radius r by measuring the perpendicular distance from the turbine blade center of rotation to any specific point on the part profile; 
 c. determining the swept line s applying the equation: 
   
       
         
           
             
               s 
               - 
               
                 2 
                  
                 n 
                  
                 
                     
                 
                  
                 τ 
                 × 
                 
                   
                     ( 
                     
                       
                         included 
                          
                         
                             
                         
                          
                         angle 
                       
                       360 
                     
                     ) 
                   
                   .