Study on sand mold casting without mold and composite mold

Traditional sand casting often has design limitations in process, especially for the forming of complex castings, the differences of casting structure, casting sand heat transfer coefficient and shrinkage are easy to lead to casting defects. Therefore, relevant scholars put forward the concept of multi-material composite mold to study the influence of composite molding sand material on temperature field, mechanical properties and dimensional accuracy of iron castings. At the same time, the proposal of adaptive mold process can also optimize the casting process to a certain extent. According to the casting structure, the mold CAD model is established, the mold model is pre divided and assembled, and the process parameters of the mold unit are reasonably changed to realize the adaptability of the mold to the cooling and solidification process of the casting. According to the assembly mode between mold units, the canker structures of four different molds are also conducive to the structural research of composite mold.

In addition, the composite mold process scheme based on compound forming of Dieless casting is proposed to obtain good overall mechanical properties of the casting and improve the tensile strength by 20.9%. A new mold coating device is designed and applied to the manufacture of multi-material composite mold. The design scheme of the mold unit is, on the one hand, from the perspective of mold forming, including investment casting, sand casting and differential pressure casting, which are used for the forming of composite mold at the same time. In the production of composite thin-walled shell castings, the tolerance level of complex mold surface shall be improved by at least 2 ~ 3 levels, and the surface roughness shall be improved α Reach 6.3 ~ 1.6 μ m。 A digital sand mold extrusion cutting integrated composite forming method is proposed, which opens up a new path for the forming of composite mold. At the same time, the dieless mold based on digital forming is applied to the machining of propeller mold. The forming of complex mold is realized by two parting methods and using 3D printing and NC machining technology.

The research on the technology of Moldless sand casting is still in the stage of theoretical exploration. The main purpose is to achieve good performance mold and casting forming, and gradually improve the research on mold structure, tool wear and material system, so as to adapt to the application scene and system of sand mold 3D printing and sand mold NC milling. It is undeniable that the application of the above material addition and material reduction manufacturing technology in the casting industry solves the problems of difficult forming of complex castings and low production efficiency, and has many advantages. The concept of composite mold strengthens the adaptability of the mold to the structural characteristics of castings, and improves the flexibility of mold production while retaining the advantages of additive and additive manufacturing technology. Therefore, low carbon design and Optimization Based on the composite mold of Moldless sand casting has certain practical significance for the sustainable development of traditional casting industry.