Patent ID: 7068268

Claim:
A system for designing a product having at least a computer, a display connected to the computer for displaying result of processing of the computer, an input device connected to the computer for allowing an engineer to enter data and an interactive program, stored in the computer, for aiding the engineer to design the product through the display and the input device, the program having a shape modelling function and including at least: product design process for allowing the engineer to design a product model by modelling the product by a geometric model comprising a combination of basic elements through the shape modelling function; and mold design process for allowing the engineer to design a mold for producing the product based on the designed product model; wherein the program of the product design process comprising; virtual boundary line determining means for determining a virtual boundary line between a portion of surface and rest of the geometric model, when a shape of the portion of surface of the geometric model is to be changed; area determining means for determining an area extending to the virtual boundary line as the portion of surface whose shape is to be changed; and shape changing means for changing the shape of the portion using a definition of shape of the portion, wherein, in a case that the portion of surface and the rest of the geometric model comprises curves, the virtual boundary line determining means prolongs each curve with a same curvature as that of each curve, determines positions on the prolonged curves such that a distance connecting the positions is minimum or maximum in absolute value, and determines the virtual boundary line at each of the positions.