As a key part of the whole machine, box casting has an important impact on the use of construction machinery, whether the product quality meets the technical requirements or not. Because the box parts have the characteristics of shell, groove, boss, diaphragm and so on, if the traditional sand casting is adopted, the box cavity needs to be assembled through the core. However, the process of core making, core lowering, mold taking and box closing is relatively complex, and the deviation is easy to occur during positioning, which will reduce the production efficiency and the dimensional accuracy can not be guaranteed, Increase the probability of waste products. Because the box body of lost foam casting has not only high geometric dimension accuracy, but also good quality of internal and external surfaces of the casting, consistent wall thickness and no leakage, most box parts will choose lost foam casting process. From the perspective of development prospect, because the large box of lost foam casting has small environmental pollution, rich resources and high profit margin, which is consistent with the industrial policy encouraged by the state, the prospect of box manufacturing by lost foam casting process is good.
However, due to the complexity of box casting itself, there are also bottlenecks restricting the production and development of box lost foam casting. In the process of lost foam casting, because the strength of the foam pattern is not large, the deformation is more serious. And because of the complexity of the mold design, the design cycle of the foaming mold is longer. Because the selection of process parameters is not very reasonable, it will cause defects such as insufficient casting, shrinkage, shrinkage, crack, blowhole, slag inclusion in filling and solidification process. Box collapse may also occur, resulting in a high scrap rate.
However, with the development of modern computer technology, modern system CAE software has emerged and plays an important role in guiding actual production. Therefore, the key to solve the bottleneck of box lost foam casting production is whether this CAE software tool can be used to guide lost foam casting production. The process of lost foam casting is the place where the metal liquid fills up the original foam shape, and the casting will be formed after solidification and cooling. Because molten metal is poured into the mold, molten metal rapidly softens, melds and decomposes the foam, and the mold will be discharged into the decomposition product.
However, due to the action of metal liquid and foam pattern, the filling front can not be predicted at the front of molten metal. Moreover, it also has an important impact on the internal quality of castings and the success of casting forming, because there are complex heat and mass transfer, physical and chemical reactions in this process, which makes the flow front of liquid metal more difficult to control. Therefore, it is difficult to predict the defects of castings. The main factor to reduce the scrap rate is how to use CAE software to simulate the internal mold filling and solidification process in the casting process, and summarize a more reasonable casting process according to the simulation results.