Effect of Rolled Surface Texture on the Earing of Micro Deep Drawing

• Main Authors: Jian-Jun Wang, 王建鈞
• Other Authors: Heng-Sheng Lin
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/76296220780834190374

碩士 === 國立高雄應用科技大學 === 模具工程系 === 103 === Most studies on microforming focus on the effect of grains on the formability. There have been rare publications emphasizing the influence of surface textures. Surface texture becomes influential on the sheet outline geometry when the thickness gauge decreases to the range of grains. This work investigates the influence of surface textures on the micro drawing of spherical bottom. The metal sheets were imprinted with textured rolls. Both simulation and experiment were conducted. Copper sheets with three thickness gauges 0.2, 0.1 and 0.05 mm were used in this study. Longitudinal, transverse and isotropic surface lays were obtained through a pair of printing rolls. The textured sheets were drawn to diameters of 8, 4 and 2 mm of spherical bottom, which correspond to macro, meso and micro forming conditions, respectively. DYNAFORM software was used to obtain the reasonable drawing ratios of the respective forming conditions. The effect of friction condition on the thinning of drawing was also evaluated. DEFORM software was used to analyze the effect of longitudinal or transverse surface lays on the drawing performance. The result of simulation was verified with experiment. Both simulation and experiment show that the earing will change in the drawing of different surface textures. The macro forming condition with 0.2 mm thick sheets does not change with the variation of surface textures. The meso forming condition with 0.1 mm thick sheets exhibits concave geometry in the accumulation zone. The micro forming condition with 0.05 mm thick sheets is significantly affected by the surface texture. Wrinkling appears in the accumulation zone. Moreover, the variation of thickness becomes substantial in the thin sheets, and the thinning during drawing cause tearing on the workpiece. Therefore, surface texture becomes an influential factor in micro forming of thin sheets. Drawing load is minimal with the isotropic lays for the three macro, meso and micro forming conditions. This is attributed to the lubricant pockets provide sound lubrication and cause lower forming load. There are problems with leakage in the longitudinal or transverse lays. The lubrication deteriorates and the forming load increases.