Abstract
KEYWORDS – Flange, Hemming, Pre-hemming, Main-hemming, Height Difference
ABSTRACT – External panel of an automobile is completed by a series of processes such as drawing, flanging, hemming, etc. Although a degree of precision of a car panel is determined during drawing process, the actual quality of exterior of a finished automobile is determined during a following process—hemming process. Hemming is the last step of a forming process, composed of pre hemming and main hemming, and is a process of connecting the formed outer panel and inner panel or folding of the end section of the outer panel. This process increases part’s strength and secures the quality of the outer panel. Therefore, this process determines the marketability of a product, and because it protects the passengers’ safety from burr or sharp sections caused from cut sections, it is typically applied to moving parts, such as door, hood and trunk lid. However, during hemming, tensile and compression occur simultaneously in the thickness direction on a plate, and tensile and a compressive force causes recovery of elasticity after bending, and these phenomena is the cause for lowering of precision of size of a product and occurrence of minute curves. This study conducted a finite-element analysis of continuous process of hemming using 3-D model, and evaluated and confirmed degree of hemming analysis by comparing height difference’s, one of flaws of hemming, analysis value and try-out result value.