Abstract: To decrease the quantity and the depth of the concave regions for facilitating the addendum-design, a smoothing method for automotive panels based on Offset technique of polyline is proposed. Project the outer boundary of the part in stamping direction, Offset the contour with the distance R and construct arcs to close the offset curve, based on the principle of roll cylinder method. The self-intersection points of the closed Offset curve are the judgment to recognize the smoothing regions, with the resulting smoothing endpoints of the contour a mapping of the ones in outer boundary. Generate the smoothing curves and surfaces by using NURBS and covering method with the geometry data of the outer boundary. Offset technique is robust to accurately find all smoothing regions with no errors and adjustments. Integrate the algorithm into the independently developed KMAS forming analysis system. A comparison with Dynaform die face engineering is made and the result shows that our method has great applicability and reliability.

Key words: Automobile panel, Contour smooth, Die-face design, Offset curve, Polyline curve