(1. 浙江大学 流体动力与机电系统国家重点实验室，杭州 310027；
2. 浙江大学 机械工程学系，杭州 310027)
摘 要: 为改善微凸台阵列结构的半固态触变成形充型效果，采用Deform−2D软件，模拟研究半固态A356铝合金在微凸台阵列触变成形过程中的流动特性和充型行为。在有限元分析中，将微凸台简化为二维平面上深度固定，宽度和位置逐渐变化的凹槽，模拟分析触变成形工艺参数(坯料温度、冲头速度、模具温度)和模具结构参数(凹槽深宽比、模具占空比、凹槽位置)对微凸台阵列充型效果的影响。数值模拟结果表明：坯料在触变成形过程中，液相率应保持在40%~50%；随着冲头速度的降低，边缘微凸台的径向充型增加；模具温度的提高有助于增加坯料在触变成形过程中温度的均匀性，从而减少微凸台的弯曲或折叠；凹槽深宽比越小，微凸台充型越好；微凸台径向充型随着模具占空比的增加而增加，随着微凸台与坯料轴线距离的增加而越来越不均匀。
关键字: A356铝合金；半固态；触变成形；微凸台阵列；有限元法
（1. The State Key Lab of Fluid Power Transmission and Control, Zhejiang University, Hangzhou 310027, China;
2. Department of Mechanical Engineering, Zhejiang University, Hangzhou 310027, China）
Abstract:To improve the cavity-filling performance of micro-pin-fin arrays, the flow characteristics and filling cavity behaviors of semi-solid A356 aluminium alloy during the micro-pin-fin array thixoforming were numerically investigated based on Deform−2D software. In the finite element analysis, micro-pin-fins were simplified as two-dimensional grooves with a constant depth, various widths and various locations. The influences of the process parameters, such as billet temperature, punch velocity and die temperature, and the punch structure parameters, such as groove aspect ratio, die duty ratio and groove location, on the cavity-filling performance of micro-pin-fin arrays were analyzed. The simulation results show that the liquid fraction of billets should be 40%−50% during thixoforming. With the decrease of the punch velocity, the radial cavity-filling of the edge micro-pin-fins increases. The increase of the die temperature can improve the uniformity of the billet temperature, leading to the lessening of micro-pin-fin bending or folding. The decrease of the groove aspect ratio results in a better cavity-filling. The radial cavity-filling of micro-pin-fins improves with the die duty ratio increasing, and becomes increasingly non-uniform with the distance between the micro-pin-fin and the billet axis increasing.
Key words: A356 aluminum alloy; semi-solid; thixoforming; micro-pin-fin arrays; finite element method
