摘要
腰鼓形是圆柱体常规镦粗过程中常见的一种变形不均匀现象。为提高镦粗成形均匀性,以Φ4.08 mm×4.8 mm的6061铝合金圆柱体为实验对象,采用超声辅助分段镦粗工艺,即先进行超声辅助镦粗,然后继续进行无超声常规镦粗,分别得到细腰形中间体和最终的Φ5.4 mm×2.8 mm近圆柱体。实验和有限元仿真研究表明:超声辅助镦粗作用下形成的细腰形中间体可表现出近似椭圆形曲线或双曲线轮廓,同时细腰形轮廓的形成促进了圆柱形试样的端面径向变形。此外,超声辅助的分段镦粗可促进试样内等效塑性应变近似均匀地分布,从而改善腰鼓形不均匀变形。细腰形试样内部产生的切应变可与后段无超声常规镦粗形成的切应变产生抵消性矢量叠加,该切应变抵消机制促进了圆柱形试件整体的均匀变形。
Barrel-shape is a common phenomenon of non-uniform deformation generated in the conventional upsetting process of cylinder.In order to improve the uniformity of upsetting,taking a 6061 aluminum alloy cylinder of Φ4.08 mm×4.8 mm as the experimental object,the ultrasonic-assisted multi-step upsetting process was adopted,namely,ultrasonic-assisted upsetting was performed first,and then conventional non-ultrasonic upsetting was continued to obtain the anti-barrel-shape intermediate and the final near-cylindrical body of Φ5.4 mm×2.8 mm respectively.The experiments and the FEM simulation research indicate that the anti-barrel-shape intermediate formed by ultrasonic-assisted upsetting can show an approximately elliptical curve or hyperbola profile,and at the same time,the formation of anti-barrel-shape profile promotes the radial deformation of the end face for cylindrical specimen.In addition,ultrasonic-assisted multi-step upsetting can promote an approximately uniform distribution of equivalent plastic strain in the specimen,thereby improving the uneven deformation of barrel-shape.The shear strain generated in the anti-barrel-shape specimen can be superposed with the shear strain caused by conventional non-ultrasonic upsetting in the subsequent section to create a counteracting vector.The shear strain offset mechanism promotes the uniform deformation of the entire cylindrical specimen.
作者
朱宁远
陈俊郎
陈世豪
左寿彬
廖羽昊
Zhu Ningyuan;Chen Junlang;Chen Shihao;Zuo Shoubin;Liao Yuhao(School of Mechanical and Electrical Engineering,Jiangxi University of Science and Technology,Ganzhou 341000,Chi)
出处
《锻压技术》
CAS
CSCD
北大核心
2024年第1期1-11,共11页
Forging & Stamping Technology
基金
江西省自然科学基金资助项目(20224BAB204044)。
关键词
超声辅助
镦粗
成形均匀性
成形轮廓
等效塑性应变
ultrasonic assistance
upsetting
forming uniformity
forming profile
equivalent plastic strain