The Analysis of Interfacial Heat Transfer Between Mold and Casting

• Main Authors: Meng-Jie Zheng, 鄭盟傑
• Other Authors: Long-Sun Chao
• Format: Others
• Language: zh-TW
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/cb9d2y

碩士 === 國立成功大學 === 工程科學系碩博士班 === 92 === 　　In the heat-transfer analysis of a casting process, how to deal with the heat-transfer condition at the mold/metal interface is a key problem. If the problem is not handled properly, it will directly affect the analysis result. Since the contact between mold and metal is not perfect, the heat-transfer analyzer needs a heat-transfer coefficient h to balance the heat flux q at the interface. 　　In this paper, the experiment method of green-sand-mold casting is used and the casting materials are pure aluminum, A356 alloy and Sn-20Wt%Pb alloy. The casting geometry is cylindrical. Thermocouples are utilized to measure the temperatures near the mold/metal interface. The Beck inverse, a lump capacitance and copper-assisted measurement methods are used to calculate interfacial heat flux and heat-transfer coefficient. 　　During the solidification of liquid metal, the cooling curves of different locations are similar. The cooling curve of pure aluminum would stay at the solidification temperature for a while. The curves of A356 and tin-lead alloys show two solidification stages of: one is the primary phase (or pro-eutectic) solidification, and the other is the eutectic one. The time-varying trends of interfacial heat flux and heat transfer coefficient are similar. In the curves of q (or h) versus time of A356 and tin-lead alloys have two peaks, corresponding with two solidification stages. However, the curve of pure aluminum only has one peak. The curves of q or h predicted by the Beck inverse method are similar to those of the lump capacitance method, but they are quite different from those of the copper-assisted measurement method. From the point of computing method, the copper-assisted method is the simplest way and the Beck inverse method is the most difficult one.