Intelligent design method and system of trimming block for stamping dies of complex automotive panels

Trimming block is the most important working component of trimming die for automotive panels. Its structure and form are various and complex, resulting in its design quite tedious and time-consuming, which affected the efficiency and quality of die design. Aiming at the three problems of curve offset, surface construction, and flange uncertainty, an intelligent design method based on parameters and sketch driven is proposed to realize the rapid and intelligent design of trimming block. According to the curve offset criterion of trimming block, a 3D curve offset method based on the feature inflection point is proposed, which considers the characteristics of curve from offset direction, curvature, and perturbation, and meets the requirement of minimum offset distance, to maintain the shape following of initial curve. The offset spline curve ensures the minimum offset distance and its trend with the original curve. Combined with the group concept, it introduces a segmented surface construction method for trimming block surfaces based on non-uniform rational B-spline mesh surface and supplemented by filling surface, which can well track the tendency of trimming curve and meet the G1 continuity conditions between adjacent surfaces. It presents an interactive sketch to solve the diversity and uncertainty of flange, which can free to draw the 2D outline of any flange. Finally, the whole design process of trimming block is serialized by parameters and sketch driving to achieve the fully automated intelligent design method, which is integrated into the NX software, and an intelligent design system of trimming block is developed as a submodule in the modular design of the trimming die. The design example of the fender trimming block shows that the system can control the error well and guarantee the success of the onetime design. The designed trimming block has a smooth blade surface, a smooth transition, and excellent structural strength, which can significantly improve design quality and efficiency.