Method for bending a rigid pipe

Abstract

A method for bending a rigid pipe to accomplish a centerline radius less than or equal to the outside diameter of the pipe. Moreover, the method accomplishes such a bend whereby the wall thickness of the pipe on the outermost portion of the wall of the pipe is substantially maintained, as is the inside diameter throughout the bend of the pipe. The pipe bend is accomplished by first determining the desired angle of bend and the desired centerline radius. The arc length of the outermost portion of the pipe is then determined. The height and width of each corrugation is then selected in order to determine the length of the outer surface of each corrugation. The arc length is then divided by the corrugation length to determine the number of corrugations required to accomplish the desired bend. The pipe is then deformed to define the required number of corrugations having the determined height and width. After forming the corrugations, the pipe is bent through the selected degree of the bend.

Having thus described the aforementioned invention, I claim:  
     
         1 . A method for bending a rigid pipe, said method comprising the steps of: 
 a) determining a degree of bend;    b) determining a centerline radius;    c) determining an arc length of an outermost portion of said pipe;    d) selecting a corrugation height and width;    e) determining a length of said corrugation;    f) determining a required number of corrugations;    g) deforming said pipe to define said required number of corrugations having said height and width;    h) bending said pipe through said degree of bend, whereby a ratio f said centerline radius and an outside diameter of said pipe is no greater than 1:1, whereby a thickness of the wall of said pipe remains substantially unreduced, and whereby an inside diameter of said pipe remains substantially unreduced.    
     
     
         2 . The method of  claim 1  wherein said arc length is determined as:  
       
         
           
             
               
                 
                   I 
                   o 
                 
                 = 
                 
                   2 
                    
                   
                     
                       Π 
                        
                       
                         [ 
                         
                           
                             r 
                             CL 
                           
                           + 
                           
                             ( 
                             
                               
                                 d 
                                 o 
                               
                               2 
                             
                             ) 
                           
                         
                         ] 
                       
                     
                     · 
                     
                       
                         Θ 
                         bend 
                       
                       360 
                     
                   
                 
               
               , 
             
           
           
           
               
           
         
       
       where l o  is said arc length, r CL  is said centerline radius, and wherein Θ bend  is said degree of bend.  
     
     
         3 . A method for bending a rigid pipe, said method comprising the steps of: 
 a) determining a degree of bend;    b) determining a centerline radius;    c) determining an arc length of an outermost portion of said pipe;    d) selecting a number of corrugations to be formed in said pipe;    e) determining a length of said corrugation;    f) determining a corrugation height and width;    g) deforming said pipe to define said required number of corrugations having said height and width;    h) bending said pipe through said degree of bend, whereby a ratio f said centerline radius and an outside diameter of said pipe is no greater than 1:1, whereby a thickness of the wall of said pipe remains substantially unreduced, and whereby an inside diameter of said pipe remains substantially unreduced.    
     
     
         4 . The method of  claim 3  wherein said arc length is determined as:  
       
         
           
             
               
                 
                   I 
                   o 
                 
                 = 
                 
                   2 
                    
                   
                     
                       Π 
                        
                       
                         [ 
                         
                           
                             r 
                             CL 
                           
                           + 
                           
                             ( 
                             
                               
                                 d 
                                 o 
                               
                               2 
                             
                             ) 
                           
                         
                         ] 
                       
                     
                     · 
                     
                       
                         Θ 
                         bend 
                       
                       360 
                     
                   
                 
               
               , 
             
           
           
           
               
           
         
       
       where l o  is said arc length, r CL  is said centerline radius, and wherein Θ bend  is said degree of bend.