微型金属杯形件的三维超声波振动辅助拉深机理及缺陷控制

Micro electromechanical system (MEMS) is developing fast in recent years, leading to a frequent upgrade. Beside more powerful functions, portability is another factor to win in market competition. Higher demand of micro metal parts promotes application of micro deep drawing in mass production. However, due to downscaling of product characteristic size, the plastic property varies from that in macro scale, in addition, higher influence of material inhomogeneity and worse lubricant effect decrease size accuracy and quality of micro parts seriously. To solve the problems mentioned above, a new process is proposed in this research to improve performance of micro deep drawing with 3D ultrasonic vibration. By applying 3D ultrasonic vibration to die in micro deep drawing, the deformability of material is increased, disadvantageous friction of deep drawing is reduced, as a result, the limit drawing coefficient is increased, and the deep drawing defects could be avoided due to control of tension stress and shear stress. By building material and friction model with consideration of size effect and ultrasonic softening effect and applying in simulation, the simulation accuracy is improved. Though analysis of micro deep drawing process and defects at different conditions, combining numerical simulation and micro deep drawing experiment, optimized settings of micro deep drawing process and ultrasonic vibration are determined and high dimension accuracy and high quality micro metal cups are formed without lubricant.

近年来，微机电行业发展迅速，产品更新换代频繁，除功能不断强化外，便携性也成为提高市场竞争力的重要因素。对微型金属件需求的提高，促进了板材微拉深技术在微型金属零件大批量制造中的应用。然而由于零件特征尺寸减小而产生的材料塑性变形行为改变、材料微观不均匀性影响增大、润滑困难等问题严重影响了微型零件的尺寸精度和质量。针对以上问题，本课题提出利用三维超声波振动改善板材微拉深工艺。通过对微拉深工艺中凹模施加三维超声波振动，提高材料成形性能，降低拉深工艺中不利摩擦的影响，从而提高极限拉深系数，抑制因材料所受轴向拉应力和周向切应力过大造成的缺陷；通过构建考虑材料尺寸效应和超声波软化效应的的材料和摩擦模型并完成在有限元仿真中的调用，提高模拟精度。根据对不同振动条件下微拉深工艺及缺陷的研究，结合有限元分析和微拉深实验，优化微拉深工艺及振动参数设置，最终实现无润滑剂条件下，高精度、高质量的微型金属杯形件的成形。

近年来，微机电行业发展迅速，产品更新换代频繁，除功能不断强化外，便携性也成为提高市场竞争力的重要因素。对微型金属件需求的提高，促进了板材微拉深技术在微型金属零件大批量制造中的应用。然而由于零件特征尺寸减小而产生的材料塑性变形行为改变、材料微观不均匀性影响增大、润滑困难等问题严重影响了微型零件的尺寸精度和质量。针对以上问题，本课题提出利用三维超声波振动改善板材微拉深工艺。通过对微拉深工艺中凹模施加三维超声波振动，提高材料成形性能，降低拉深工艺中不利摩擦的影响，从而提高极限拉深系数，抑制因材料所受轴向拉应力和周向切应力过大造成的缺陷；通过构建考虑材料尺寸效应和超声波软化效应的的材料和摩擦模型并完成在有限元仿真中的调用，提高模拟精度。根据对不同振动条件下微拉深工艺及缺陷的研究，结合有限元分析和微拉深实验，优化微拉深工艺及振动参数设置，最终实现无润滑剂条件下，高精度、高质量的微型金属杯形件的成形。