摘要
制备了多特征尺寸微弯曲模具,并利用激光动态柔性成形技术实现了单次脉冲下箔板的等压弯曲成形。为了研究工件尺寸(厚度)、晶粒尺寸对高应变率下箔板变形行为的影响,使用超景深显微系统观测成形件三维形貌及轮廓形状,采用纳米压痕仪测量其厚度方向上的微硬度分布,并借助冷镶嵌技术测量成形件厚度减薄率。实验结果表明:铜箔厚度由50μm减小到30μm时,材料流动应力减小,成形件轮廓形状由圆顶状转变为槽状,表面硬度由于模具底部的碰撞滑移得到显著强化;相比于细晶成形件,粗晶件的微塑性成形能力较差;工件底部回弹形变及厚度方向应变硬化不均匀;圆角处易于破裂,最大减薄率比细晶件增大约10%。
After the preparation of the multi-feature micro-bending mold, the isobaric micro-bending of foil plate can be achieved by laser dynamic flexible microforming under single pulse. In order to investigate the workpiece size （thickness） and grain size effects on high strain rate deformation behavior of foil plate, the digital microscopic is used to observe the surface topography of formed parts. Besides, Triboindenter nanomechanical test instrument is employed to obtain the micro-hardness distribution along thickness direction. With the aid of cold mosaic technique, the thinning rate of thickness is measured. Experimental results show that the contour of formed parts change from dome shape to groove shape when the thickness decreases from 50 ~m to 30 p.m due to the reduced flow stress of copper foil. After the strong impact with the bottom of micro-mold, the groove-like parts rebound and the micro-hardness of parts is improved significantly. Compared with the fine-grained formed parts, the forming ability is rather poor with the uneven rebound deformation and strain hardening across thickness direction. The maximum thinning rate of coarse-grained parts has an increase of approximately 10% than the fine-grained ones, which means the fillet region is easier to rupture.
出处
《中国激光》
EI
CAS
CSCD
北大核心
2015年第5期116-123,共8页
Chinese Journal of Lasers
基金
国家自然科学基金(51175235)
江苏省自然科学基金(BK 2012712)
江苏省高校自然科学研究面上项目(13KJB460003)
关键词
激光光学
激光技术
尺寸效应
动态微成形
铜箔
软膜
laser optics
laser technology
size effects
dynamic microforming
copper foil
flexible rubber
