Search Results

Surface distortions are frequently introduced into the Class “A” surfaces during various sheet metal forming operations such as drawing, trimming and flanging. The origins of those surface distortions have not been well understood. The scope of this research is to investigate the distortion that occurs in draw operation and to find effective and practical corrective methods. Five geometric parameters are first identified to represent a typical depression feature in automobile outer panels. Experimental dies are then designed to reflect various combinations of these five geometric parameters with the assistance of numerical simulations to ensure that the dies can make parts free of major defects like splits and wrinkles. Surface distortions are observed in our stamping experiments and various techniques are used to measure and record the distortions for further mathematical analysis.

Draw beads are commonly used in stamping operations to control sheet metal flow. The amount of sheet metal flow, or called draw-in amount, is an important index that controls the formability and quality of sheet metal parts. Numerical simulation of sheet metal forming processes is widely adopted. The draw-in map obtained through simulation serves as a guideline for successful die tryout and robust stamping. This study addresses some issues of using draw bead in simulations such as the calculation of draw bead holding and pulling forces, the thinning effect of real draw bead on draw-in amount, the adjustment of math based draw-in amount, the feasibility of using draw bead geometry in simulation, and the effect of draw bead location and configuration on sidewall curl.