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建立了Ti6Al4V合金铸件/铸型界面换热系数(h)的一维反算模型,从数学及数值模拟的角度研究了型壳热物性参数和热电偶定位等参数对h计算的影响,分析了不同参数影响的不同特点,据此对型壳热物性参数和热电偶定位位置等进行了修正,提高了h反算精度.修正计算参数后的反算结果表明,Ti6Al4V合金熔模铸造条件下,h的变化可分为4个阶段:(1)铸件为液态,h维持约440 W/(m2·K);(2)铸件表面生成完整凝固层,此阶段h下降近60%;(3)凝固层不断增厚至铸件凝固,此阶段h下降接近峰值的20%;(4)铸件凝固后,h随温度缓慢下降.在三维模型中对反算得到的h进行了验证,得到的模拟温度与实测温度基本吻合,表明反算得到的h较为准确,可以应用于Ti6Al4V合金熔模铸造过程的数值模拟中.
The one-dimensional inverse model of the interface heat transfer coefficient (h) of Ti6Al4V alloy castings / molds was established. The influence of parameters such as thermophysical properties and thermocouple orientation of housings on h calculation was studied from the point of mathematical and numerical simulation. Different parameters affect the different characteristics, based on the thermophysical properties of the shell and thermocouple location and so on were amended to improve the accuracy of h inversion.After the correction of the calculated parameters of the inverse calculation results show that, Ti6Al4V alloy investment casting conditions, The change of h can be divided into four stages: (1) the casting is in liquid state and h maintains about 440 W / (m2 · K); (2) the complete solidified layer is formed on the surface of the casting, The solidified layer continuously thickens to the solidification of the casting, and the value of h drops nearly 20% of the peak during this period; (4) h decreases slowly with the temperature after the solidification of the casting, and the inversely calculated h is verified in the three- And the measured temperature is basically consistent, indicating that h obtained by the inverse is more accurate and can be applied to numerical simulation Ti6Al4V alloy investment casting process.