Zinc Ingot Mold Thermal Properties And Structural Improvements

Thermal fatigue is the most common failure mode of mould, especially for large ingot mold. At present, failure hot work moulds because of thermal fatigue crack account of 70% in total failure molds in our country. Thermal fatigue not only shortened the mold life, but also reduced production efficiency because the metal liquid entered thermal crack which lead to difficult mold unloading. Thermal fatigue also reduced the surface quality of casting. Therefore, to study the changes of temperature and stress of the mold in the working process will have an important value for design on long life large ingot mold. According to the thermal crack located at die radius in ZHUZHOU SMELTER GROUP CO.LTD., this paper using the finite element method studied thermodynamics behavior of mold in working process, and analyzed the failure reasons of mold because of hot cracking. On the base of this analysis, this pager found rules of multiple factors of mold life and designed the structure of large ingot mold with long life.1 .Three-dimensional solids of the mold and zinc ingots by Pro/Engineer respectively were built. Based on ProCAST-finite element software for casting process, temperature field and stress field of the casting mold were simulated. Freezing curve of zinc ingots and stress variations trend were obtained. The reasons of thermal fatigue crack of mold were analyzed based on the mechanical performance of its material and the structure and casting process of large ingot mold; this study laid a foundation to improve the structure of the mold and the casting process.2.In different thickness, materials, structures of the outer wall of the mold and casting processes conditions of the ingot, clotting time of the ingot, temperature field and stress-strain field of the mold were simulated in numerical way. The rules were obtained which explained the impact of above-mentioned factors on the solidification rate of the ingot and stress and strain of the mold. Therefore, the structure design program of the mold and application technology were presented that could improve the efficiency and prolong mold life.3.Study on casting experiment of molds with different structures. The temperature and stress-strain of the molds in the casting process were tested. Compared with the numerical simulation and the experiment, the effect law of the temperature and stress of different structure mold in casting process were verified, and accuracy in anterior study was also verified.Through thermal-stress behavior analysis of Zinc ingot mold and study on the laws of multiple factors of mold life, it was considered that the mold failure was caused by thermal fatigue; the crack of mold surface was thermal fatigue crack, and the cycle alternative stress of the mold was the main reason of hot fatigue crack. On the basis of study on the laws of multiple factors of mold life, improvement of structure and casting process of mold was studied, which could obviously prolong the life of large ingot mold.