Method for designing material to be subjected to cylinder forming and product formed by performing cylinder forming

Abstract

An object of the present invention is to provide a method for designing a metal material having mechanical properties with which a specified spring back angle can be achieved after any one of metal materials having a wide variety of mechanical properties and thicknesses has been formed by performing cylinder forming and a product formed by using the method. A method for designing a material to be subjected to cylinder forming, the method including, in the design of a metal material to be subjected to cylinder forming in which the metal material is formed by performing bending forming, calculating the yield strength YP, the Young's modulus E and the thickness t of the metal material so that a spring back angle Δθ becomes a specified value when cylinder forming is performed under conditions of a radius of curvature of bending r of 5 mm or more and a bending angle θ of 90 degrees or more and 180 degrees or less and designing the metal material so that the metal material has the calculated yield strength YP and Young's modulus E.

1 . A method for designing a material to be subjected to cylinder forming, the method comprising, in the design of a metal material to be subjected to cylinder forming in which the metal material is formed by performing bending forming, calculating the yield strength YP, the Young's modulus E and the thickness t of the metal material on the basis of equation (1) below so that a spring back angle Δθ becomes a specified value when cylinder forming is performed under conditions of a radius of curvature of bending r of 5 mm or more and a bending angle θ of 90 degrees or more and 180 degrees or less and designing the metal material so that the metal material has the calculated yield strength YP and Young's modulus E:
   Δθ/θ=−5.52[( YP·r )/( E·t )] 2 +4.13( YP·r )/( E·t )  (1),
 
 where, Δθ: spring back angle (degrees), θ: bending angle (degrees), YP: yield strength (MPa), E: Young's modulus (MPa), t: thickness (mm), r: radius of curvature of bending (mm). 
 
     
     
         2 . A product formed by performing cylinder forming, the product being manufactured by performing cylinder forming in which the metal material designed by using the method according to  claim 1  is subjected to bending forming.