(1. 浙江大學 流體動力與機電系統(tǒng)國家重點實驗室，杭州 310027；
2. 浙江大學 機械工程學系，杭州 310027)
摘 要: 為改善微凸臺陣列結構的半固態(tài)觸變成形充型效果，采用Deform−2D軟件，模擬研究半固態(tài)A356鋁合金在微凸臺陣列觸變成形過程中的流動特性和充型行為。在有限元分析中，將微凸臺簡化為二維平面上深度固定，寬度和位置逐漸變化的凹槽，模擬分析觸變成形工藝參數(坯料溫度、沖頭速度、模具溫度)和模具結構參數(凹槽深寬比、模具占空比、凹槽位置)對微凸臺陣列充型效果的影響。數值模擬結果表明：坯料在觸變成形過程中，液相率應保持在40%~50%；隨著沖頭速度的降低，邊緣微凸臺的徑向充型增加；模具溫度的提高有助于增加坯料在觸變成形過程中溫度的均勻性，從而減少微凸臺的彎曲或折疊；凹槽深寬比越小，微凸臺充型越好；微凸臺徑向充型隨著模具占空比的增加而增加，隨著微凸臺與坯料軸線距離的增加而越來越不均勻。
關鍵字: A356鋁合金；半固態(tài)；觸變成形；微凸臺陣列；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
