Pressed work and manufacturing method thereof

Abstract

A rolled steel plate as a raw material is press-formed into a pressed work provided with a boss section, and the work is fitted to a shaft by press-fitting of the shaft into the boss section. Rolling flow of internal metallographic layers in the boss section is curved like a letter S. Moreover, a manufacturing method of such a pressed work comprises: a primary-boss forming process during which a primary boss having a hole section and a protruding section protruding from the periphery of the hole section at a position corresponding to the boss section on a plane-like raw material is formed; and a boss-section forming process during which the protruding section is pressed and deformed in the protruding length direction to form the boss section.

1 . A pressed work into which a rolled steel plate as a raw material is press-formed, and which is provided with a boss section, and is fitted to a shaft by press-fitting said shaft into said boss section, wherein 
 rolling flow of internal metallographic layers in said boss section is curved like a letter S.    
   
   
       2 . A manufacturing method of a pressed work into which a rolled steel plate as a raw material is press-formed, and which is provided with a boss section, and is fitted to a shaft by press-fitting said shaft into said boss section, said method comprising: 
 a primary-boss forming process during which a primary boss having a hole section and a protruding section protruding from the periphery of said hole section at a position corresponding to said boss section on a plane-like raw material is formed; and    a boss-section forming process during which said protruding section is pressed and deformed in the protruding length direction to form said boss section.    
   
   
       3 . The manufacturing method of a pressed work according to  claim 2 , comprising, as a preliminary process for said primary-boss forming process, 
 a swelled-section forming process during which a plane-like raw material is swelled to form a swelled section at a position corresponding to said boss section, wherein    during said primary-boss forming process, the central part of said swelled section is punched to form said primary boss provided with said hole section and said protruding section.