Method of producing polygonal ring-shaped machine parts having complex cross-section

Abstract

Disclosed is a method of producing a polygonal, ring-shaped machine part having a complex cross-section starting from a metal rod with improved productivity and remarkably increased material yield. The method comprises the steps of: forging a rod to prepare a notched blank 1 having large diameter parts 11 and the remaining small diameter parts 12; bending the large diameter parts 11 to form a first intermediate 3 of polygonal, open ring-shape and a complex cross-section with confronting ends; butting and welding the confronting ends of the first intermediate 3 to form a second intermediate 5; die-forging the second intermediate 5 to form a ring-shaped product 7; and subjecting the product 7 to necessary finishing step such as machining to obtain the final product.

We claim:  
     
         1 . A method of producing a polygonal, ring-shaped machine part having a complex cross-section from a metal rod, comprising the steps of: 
 A 1 ) forging the rod material to prepare a long notched blank  1  having large diameter parts  11 , the number of which corresponds to the number of the parts to be bent, and the remaining small diameter parts  12 ;    B 1 ) bending the large diameter parts  11  of the above long blank  1  to form a first intermediate  3  of polygonal, open ring-shape with confronting ends;    C 1 ) butting and welding the confronting ends of the above ring-shaped first intermediate  3  to form a polygonal, closed ring-shaped second intermediate  5 ;    D 1 ) die-forging the above closed ring-shaped second intermediate  5  to form a polygonal, ring-shaped product  7  having a complex cross-section; and    E 1 ) subjecting the above polygonal, ring-shaped product  7  to necessary finishing step such as machining to obtain a polygonal, ring-shaped machine part  8  having a complex cross-section.    
     
     
         2 . A method of producing a polygonal, ring-shaped machine part having a complex cross-section from a metal rod, comprising the steps of: 
 A 2 ) forging the rod material to prepare two short notched blanks  2  having large diameter parts  21 , the number of which corresponds to half of the parts to be bent, and the remaining small diameter parts  22 ;    B 2 ) bending the large diameter parts  21  of the above short blanks  2  to form an intermediate  4  of square U-shape, which is a half of the final product;    C 2 ) butting the ends of the above two square U-shaped intermediates  4  and welding the confronting ends to form a polygonal, closed ring-shaped second intermediate  6 ;    D 2 ) die-forging the above closed ring-shaped second intermediate  6  to form a polygonal, ring-shaped product  7  having a complex cross-section; and    E 2 ) subjecting the above polygonal, ring-shaped product  7  to necessary finishing step or steps such as machining to obtain a polygonal, ring-shaped part  8  having a complex cross-section.    
     
     
         3 . The method of producing according to  claim 1  or  claim 2 , wherein the long notched blank  1  or the short notched blank  2  is prepared by using a rotary forging machine.  
     
     
         4 . The method of producing according to  claim 1  or  claim 2 , wherein the welding is carried out by flash butt welding.  
     
     
         5 . A polygonal, ring-shaped machine part having a complex cross-section, which is a frame for transition piece of a gas turbine produced by the method according to  claim 1  or  claim 2.