(1. 中南大學(xué) 數(shù)學(xué)與統(tǒng)計(jì)學(xué)院，長(zhǎng)沙 410083；
2. 北京科技大學(xué) 材料科學(xué)與工程學(xué)院，北京 100083)
摘 要: 分析齒輪零件粉末注射成形(PIM)實(shí)驗(yàn)成形坯密度分布以及成品容易出現(xiàn)飛邊和塌陷的位置特點(diǎn)。根據(jù)粉末注射成形技術(shù)工藝過程的特點(diǎn)給出PIM的雙流體模型及初邊界條件，基于計(jì)算流體力學(xué)軟件CFX對(duì)I型拉伸試樣和齒輪零件的PIM兩相流動(dòng)過程進(jìn)行三維數(shù)值模擬。根據(jù)數(shù)值模擬結(jié)果，對(duì)PIM充模流動(dòng)過程中粉末和粘結(jié)劑兩相速度的變化曲線進(jìn)行對(duì)比分析，證實(shí)I型拉伸試樣和齒輪零件的PIM充模過程中多個(gè)位置發(fā)生過不同程度的粉末與粘結(jié)劑兩相分離現(xiàn)象。對(duì)模腔中多個(gè)不同結(jié)點(diǎn)處發(fā)生粉末與粘結(jié)劑兩項(xiàng)分離的現(xiàn)象進(jìn)行分析比較。結(jié)果表明：PIM充模過程中位于遠(yuǎn)離澆口狹窄模腔內(nèi)的點(diǎn)容易產(chǎn)生兩相分離現(xiàn)象，粉末與粘結(jié)劑兩相分離現(xiàn)象只發(fā)生在相應(yīng)位置被充填初期的一段時(shí)間內(nèi)，且不同位置發(fā)生的兩相分離持續(xù)時(shí)間也不同。
關(guān)鍵字: 粉末注射成形；兩相流；數(shù)值模擬；速度分布
（1. School of Mathematics and Statistics, Central South University, Changsha 410083, China;
2. School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China）
Abstract:The density distribution and sink defects location characteristics of powder injection molding (PIM) green parts for a gear part were analyzed. According to characteristics of PIM process, mathematical models of two-phase flow with proper initial and boundary conditions were given for PIM filling process. Three-dimensional numerical simulations of two-phase flow in PIM filling process were carried out for a tensile test specimen and a gear part using the CFD software CFX. Based on the numerical simulation results, the velocity variation curves of powder and binder during the filling process were compared and analyzed. The powder-binder two-phase separation of different degrees was confirmed happening during PIM filling process for the tensile test specimen and gear part. The binder-powder separation phenomena observed at different locations of the cavity were compared and analyzed. The results show that powder-binder separation phenomenon is more possible to occur at those points far from the inlet and locates in the narrow regions of cavity. The powder-binder separation occurs only at the initial stage of the time when the corresponding position is filled and time duration of two-phase separation is different for different locations.
Key words: powder injection molding; two-phase flow; numerical simulation; velocity distribution
