Optimum Non-Offset Bending Die Design of Cold Roll-Formed Steel Sheet with Prepainted Hot-Dip Galvanized Layer

• Main Authors: MING-YI HUANG, 黃銘毅
• Other Authors: JINN-JONG SHEU
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/35984131745757265923

碩士 === 國立高雄應用科技大學 === 模具工程系碩士班 === 96 === This thesis focuses on the die design of non-offset punch profile for the cold-rolled zig-zag sheet blank bending in order to solve the wrinkling and fracturing problems occurred in the conventional offset punch profile design. The coated blank is cold roll-formed to create zig-zag edges to strengthen the plate in stead of plain sheet produced in rolling process. A special punch profile design called “golden finger” is proposed to cope with the roll-formed zig-zag edges on the blank and avoid the folding and wrinkling defects. The criterion of paint scratching has been established to evaluate the die design. The cutting profile designs are proposed to obtain a more uniform bent edge in the vertical wall of product. The design of experiments (DOE) method is adopted to study the effects of different die and process design factors. CAE analysis is adopted to predict the sheet material flow, stress, strain, and pressure induced after forming for different designs. The intuitive rules of non-offset punch profile design are proposed to create “golden fingers” on the punch to control material flow smoothly. The control point updating algorithm of a Bezier curve is proposed to design the profile of cutting edge effectively. The analysis results of the optimum design show a sound product was obtained without folding defect and less irregularity at the edge of vertical bent wall. The experimental results of bending are in good agreement with the edge profile prediction of simulations. The scratching of paint on the coated surface of blank is decreased using the optimum punch profile design.