Abstract: A tool and process utilizing the tool for forming a compressed-radius hem on a sheet metal assembly is provided. A concave portion on the tool is formed by at least two surfaces that together define a cavity. A flange on the perimeter of an outer panel is initially formed to an approximate perpendicular angle and is then formed to about 45°. In a final forming step, an intermediate portion of the flange is engaged by the cavity and is formed into a compressed-radius hem.

Abstract: A method of developing a stamping die for a workpiece is provided, which includes the steps of stamping a workpiece in a current die. A measurement is made of the stamped workpiece to determine its profile. The profile is compared with the design intent workpiece to determine dimensional variance. If the variance is within predetermined limits, the development is complete. If the variance is beyond limits, a conceptual determination is made of the residual forces in the current die stamped workpiece when the current die stamped workpiece is restamped by a design intent die. This conceptual determination is carried out on a computer. From the determination of residual forces, a new current die is developed. The new current die then stamps the workpiece. The steps are repeated until the stamped workpiece profile is within predetermined limits.

Abstract: A tool and process utilizing the tool for forming a compressed-radius hem on a sheet metal assembly is provided. A concave portion on the tool is formed by at least two surfaces that together define a cavity. A flange on the perimeter of an outer panel is initially formed to an approximate perpendicular angle and is then formed to about 45°. In a final forming step, an intermediate portion of the flange is engaged by the cavity and is formed into a compressed-radius hem.

Abstract: A method (100) for predicting distortion of a sheet metal during a sheet forming process to form the sheet metal into a part. The method (100) of the present invention is for use with a computer including memory and sheet forming tools. The method (100) comprises applying (104-116) the radial return method to compute the total stress for the anisotropic hardening rule of Mroz. The method (100) of the present invention does not divide a given strain increment into hundreds of subintervals as long as the movement of the center of the active yield surface is along a fixed path. If a break occurs, the given strain increment is divided into a few segments (110).