Automatic design system for welding margin sub-assembly part and method of thereof and record media recorded program for realizing the same

PURPOSE: An automatic welding margin design system of a small member and a recording medium for storing a program which realizes the method are provided to previously predict bending transformation of a production process before executing a welding work, thereby improving productivity. CONSTITUTION: A reverse design target file and a material property information file are inputted(S10). Through the reverse design target file, an outline is generated. An element network is generated within the outline(S30). Through the material property information file, a welding transformation amount of a small member is calculated(S50). The welding amount of deformation and a temperature value are inputted to the element network. A reverse shape including a welding margin is generated(S70). A reverse shape-reflected reverse design shape file is generated(S90).