高浮雕银章热压材料本构模型及成形特性研究  

Research on Constitutive Model and Forming Characteristics of Hot-Pressed Materials for High-Relief Silver Medals

作　　者：张杰[1] 朱恒飞 汪旭超 孔宁[1] 李钢 杨玉 Zhang Jie;Zhu Hengfei;Wang Xuchao;Kong Ning;Li Gang;Yang Yu(School of Mechanical Engineering,University of Science and Technology Beijing,Beijing 100083,China;China Gold Coin Group Co.,Ltd.,Beijing 100045,China;Shenzhen Guobao Mint Co.,Ltd.,Shenzhen 518118,China)

机构地区：[1]北京科技大学机械工程学院,北京100083 [2]中国金币集团有限公司,北京100045 [3]深圳国宝造币有限公司,深圳518118

出　　处：《天津大学学报（自然科学与工程技术版）》2023年第10期1021-1030,共10页Journal of Tianjin University：Science and Technology

基　　金：国家自然科学基金资助项目(51605026)。

摘　　要：随着纪念币成形向高浮雕、大变形方向的发展,传统的通过冷加工方法的纪念币挤压成形已无法满足大变形的成形要求,为了解决高浮雕银章成形困难的问题,研究了热加工条件下的银章成形特性.通过Gleeble3500单向压缩试验对25~600℃的银材料热流动行为进行研究,结合有限元仿真软件研究材料的成形性能与热压工艺,随后开展了高浮雕银章热压试验.通过Gleeble3500试验确定了银材料的热压金属流动行为,在25℃时存在明显的加工硬化现象,而高温时回复再结晶软化机制占据主导地位.利用Johnson-Cook本构方程实现了对应力-应变曲线的分温度区间描述.依据拟合的Johnson-Cook本构模型开展25~600℃纯银板坯杯突有限元仿真,研究温度、摩擦系数和冲压速度对板坯成形的影响.采用杯突值(IE)来衡量材料的变形能力,结果表明高温、低摩擦、低冲压速度时,材料拥有更大的IE值.当温度从25℃增大到600℃时,IE值随之增大了94.7%.在同一温度下,当冲压速度从3 mm/min增大到12 mm/min、摩擦系数从0增大到0.100时,IE值均减小,减小幅度在10.9%以内.开展的高浮雕银章热压试验也验证了热压成形特性,在温度高时浮雕的填充效果更好.600℃时银章的浮雕填充饱满,而25℃和300℃分别出现了饼坯开裂和压印不足的缺陷.高浮雕银章的热压结果表明了热加工条件下银章的成形特性优于冷加工成形,本研究工作可为高浮雕银章的热压成形理论及应用技术的发展奠定基础.The stamping of commemorative coins is developing toward high relief and large deformation.Traditional cold working methods cannot achieve forming requirements with large deformation.To solve the difficulty of forming high-relief silver medals,the forming characteristics of silver medals under hot working conditions were studied.The thermal flow behavior of silver materials at 25—600℃was studied by the Gleeble3500 unidirectional compression test.The forming properties and hot pressing process of the material were studied using the finite element simulation software.Subsequently,the high-relief silver medal hot pressing test was performed using finite element simulation software.At 25℃,there was an obvious work hardening phenomenon,and at high temperatures,the recovery recrystallization softening mechanism dominated.Using the Johnson-Cook constitutive equation,the stress-strain curve was described in different temperature ranges.Based on the fitted Johnson-Cook constitutive model,the finite element simulation of cupping of 25—600℃pure silver plates was performed.The effects of temperature,friction coefficient,and stamping speed on the formability of the plates were studied.The cupping value(IE)was used to measure the deformation ability of the material.The results showed that the material has higher IE value at high temperature,low friction and low stamping speed.When the temperature increased from 25℃to 600℃,the IE value increased by 94.7%.At the same temperature,when the stamping speed increased from 3 mm/min to 12 mm/min or the friction coefficient increased from 0 to 0.100,the IE value decreased within a range of 10.9%.The implementation of the high-relief silver medal hot pressing test verified the hot-press forming properties.The relief-filling effect was better when the temperature was high.The relief filling of the silver medal was full at 600℃,while the cracking of the cake and the insufficient imprinting defects appeared at 25℃and 300℃,respectively.The hot pressing results of the high

关 键 词：高浮雕银章 银章压印 本构模型 热压试验 

分 类 号：TG376.2[金属学及工艺—金属压力加工]