( 1. 華南理工大學(xué) 機(jī)械工程學(xué)院，廣州 510640;
2. 大阪大學(xué) 智能工學(xué)系， 大阪 5650871)
摘 要: 對(duì)于直接有限差分法， 提出了單元表面無(wú)量綱距離、 表面充填比率和體積充填比率， 以描述鑄件充型過(guò)程中自由表面的形狀，建立了相應(yīng)的充型過(guò)程數(shù)學(xué)模型， 考慮了自由表面形狀對(duì)動(dòng)量、 質(zhì)量和能量傳輸?shù)挠绊懀?提出了充型過(guò)程自由表面碰撞中表面氧化膜破碎， 及其后破碎氧化膜流動(dòng)的計(jì)算模型。對(duì)實(shí)驗(yàn)鋁合金鑄件進(jìn)行了模擬應(yīng)用， 通過(guò)實(shí)際鑄件充型過(guò)程的特殊X射線實(shí)時(shí)觀察和記錄， 及實(shí)際鑄件的氣孔、 收縮缺陷分布的檢測(cè)，對(duì)模擬結(jié)果進(jìn)行了驗(yàn)證分析。 結(jié)果表明： 充型過(guò)程模擬結(jié)果與X射線實(shí)時(shí)觀察結(jié)果吻合較好， 尤其是自由表面的變化；氧化膜卷入模擬結(jié)果與實(shí)際鑄件氣孔、 收縮缺陷的分布存在一定的對(duì)應(yīng)關(guān)系。
關(guān)鍵字: 鋁合金鑄件； 充型過(guò)程； 自由表面； 氧化膜卷入； X射線實(shí)時(shí)觀察；數(shù)值模擬
mold filling process of Al casting
（ 1. College of Mechanical Engineering,
South China University of Technology, Guangzhou 510640, China;
2. Department of Adaptive Machine Systems,
Osaka University, Osaka 5650871, Japan）
Abstract: Surface dimensionless distance, surface filled ratio and volume filled ratio for the direct finite difference method(DFDM) elements were proposed to describe the shape and position of free surface in simulation of mold filling process. The model of the process, taking into account the effect of free surface on transfer of momentum, mass and energy, was established. The method of estimating the breakup of oxide films on free surfaces during collision of the surfaces as well as judging movement of the entrapped broken oxide films was proposed. The model and method were applied to an experimental Al casting. By in-situ observation and recording actual mold filling process of the casting with special X-ray apparatus, and measuring porosities of the casting, the simulation results were further verified and analyzed. The simulation results indicate that mold filling are in good agreement with in-situ X-ray observation, especially in the evolution of free surface, and that the simulation results of entrapped oxides has some relationships with the distribution of porosities in the actual casting.
Key words: Al casting; mold filling; free surface; oxide entrapment; in-situ X-ray observation; numberical simulation
