Press working method

Abstract

The invention offers a pressed product (F) produced by press-forming a metal plate ( 1 ). The pressed product (F) has a peripheral surface that has a corner portion ( 12 ) connecting two surfaces in the peripheral surface. The corner portion ( 12 ) has an outside corner radius R that is equal to or smaller than the thickness “t” of the metal plate ( 1 ). That is, the pressed product (F) has the sharp corner portion ( 12 ).

1 - 9 . (canceled) 
     
     
         10 . A method for press working a metal plate, the method comprising:
 a first step of forming a pressed material having a side wall portion and an inside corner portion by pressing a first punch on the metal plate, the first punch including a shoulder portion having a corner radius Rp of 0.3 mm or less; and   a second step of forming a pressed product by pressing with a second punch, the inside corner portion and an end face of the side wall portion of the pressed material.   
     
     
         11 . The method according to  claim 10 , wherein the second step of forming the pressed product includes:
 forming a thickness of a top-plate portion of the pressed product and a thickness of the side-wall portion of the pressed product substantially uniform.   
     
     
         12 . The method according to  claim 10 , wherein the first and second steps are performed under temperature of 200° C. or more and 300° C. or less. 
     
     
         13 . The method according to  claim 10 , wherein the metal plate comprises:
 8.3 mass % or more and 9.5 mass % or less Al;
 0.5 mass % or more and 1.5 mass % or less Zn, and 
 the remainder that comprises Mg and impurities. 
   
     
     
         14 . The method according to  claim 10 , further comprising the step of:
 heat treating the pressed product at a temperature of 100° C. to 450° C.