铝合金压铸过程铸件/铸型界面换热行为的研究 Ⅰ．实验研究和界面换热系数求解

STUDY ON HEAT TRANSFER BEHAVIOR AT METAL/DIE INTERFACE IN ALUMINUM ALLOY DIE CASTING PROCESS Ⅰ.Experimental Study and Determination of the Interracial Heat Transfer Coefficient

采用"阶梯"铸件,设计了压铸过程模具温度测量的实验方案并进行了压铸实验.以实验中测得的铸型内部不同位置的温度为基础,采用热传导反算法求解了压铸过程中铸件/铸型界面热流以及换热系数;分析了铸件的厚度对于界面热流以及换热系数的影响,结果表明:压铸过程铸件/铸型界面热流或是换热系数随着压射过程的进行迅速升高直至最大值,然后随着凝固过程的进行而减小;同时,铸件的不同厚度部位与铸型之间的界面热流和换热系数的变化规律也不同,随着铸件厚度的增大,铸件铸型之间的界面热流和换热系数峰值均减小,但是界面热流和换热系数较大值保持的时间则逐渐增大.

By using a step-shape casting, die casting experiments were designed and performed. Based on the temperature profiles obtained at different locations inside the die, heat flow density （HFD） and interfacial heat transfer coefficient （IHTC） were determined using the nonlinear estimation method The influences of the casting thickness on HFD and IHTC were examined. Results show that the HFD or IHTC increases sharply right after the fast phase injection until approaching its maximum value after which the IHTC falls as the solidification proceeds. Besides, different change tendencies are found in the HFD and IHTC between the die and the casting of different thicknesses. As the thickness of the casting step, the maximum value of HFD and IHTC decrease, but the duration during which the HFD or IHTC can maintain its value at a higher level increases.