Edge adjacent crown trick5/8/2023 ![]() ![]() If the process/method planning engineer were to utilize a conventional springback compensation technique, they would likely create, in the initial forming tool, shape in the opposite direction of the observed springback-forming the surface an equal amount downward as compensation for the springback distortion. Tensile forming conditions lead to a shrinking in the flange edge adjacent surface springs upward This shrinking pulls the ends of the flange toward one another and in doing so makes the adjacent surface “overcrown.” Springback in flange distorts the adjacent surfaceīecause of the radial stretching mode in the forming of the flange, the springback behavior is a radial shrinking of the material. When the forming is complete and the tool opens, elastic strains spring back toward the sheet’s initial shape. As with all conventionally stamped sheet metals, the stretching deformation during the forming process is a combination of plastic and elastic strain. The material in the flange edge will stretch as it is being formed. The stretching in the free edge is caused by the difference in the developed trim line stretching to form the larger radius of the finished flange. Stretch Flangesįlanges where the curvature of the flange line creates a need to stretch material in the free edge of the flange are often called stretch flanges. Springback of this outer hood shows significant overcrown at the windshield-cowl line. In fact, some springback phenomena cannot be compensated. While this is sensible for some modes of springback, it is not universal. If you observe a sheet metal part with springback, merely deform it an equivalent amount in the opposite direction of the springback and voila, compensation. The most common method of springback compensation is the overbend/overcrown method. Everybody wants a springback “silver bullet” or easy solution for Springback Compensation-alternative geometry in the tooling, which allows the stamped part to have the desired shape after elastic deformation recovery. ![]() In previous posts, we discussed the industry challenge of springback. ![]()
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