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本文以离心铸造280型柴油机汽缸套为对象进行了数值模拟及实验研究。计算采用了全隐格式的直接差分法,用热焓法处理潜热;在边界处理中考虑了模套外表面的对流换热及铸件内表面的辐射换热。同时,设计制造了一套柔性传动的刷一环测温装置,获得了实测温度场。数值计算结果与实测温度场基本吻合。由计算结果和对铸件本体的解剖可见:离心铸造汽缸套的凝固过程主要取决于传热的综合效应,在不同部位表现出不同程度的双向凝固,不存在明显的同时凝固区域;缩孔产生于临界固相率曲线封闭位置深入断面中心的情况下;缩松产生于固相率梯度很小的场所,特别是遍布于固相率梯度为负值的区域。改变与传热有关的工艺条件可以改变缸套的凝固方式,有可能控制或避免缩孔、缩松缺陷。
In this paper, centrifugal casting 280 diesel cylinder liner for numerical simulation and experimental research. The direct implicit difference method is adopted in the calculation, and the latent heat is treated by the enthalpy method. The convection heat transfer on the outer surface of the die sleeve and the radiation heat transfer on the inner surface of the casting are taken into account in the boundary treatment. At the same time, we design and manufacture a set of flexible transmission brush ring temperature measuring device, obtained the measured temperature field. The numerical results are in good agreement with the measured temperature field. From the calculation results and the anatomy of the casting body, it can be seen that the solidification process of the centrifugal casting cylinder liner mainly depends on the comprehensive effect of heat transfer, showing different degrees of bidirectional solidification in different parts and no obvious simultaneous solidification zone; The critical solid fraction curve is closed at the center of the cross-section; shrinkage occurs at sites where the gradient of the solid fraction is very small, especially throughout the areas where the solid fraction gradient is negative. Changing the process conditions associated with heat transfer can change the way in which the liner is solidified, possibly controlling or avoiding shrinkage cavities and shrinkage defects.