Investigation On Constitutive Relationship For Springback Of High Compacted Molding Sand

With the continuous development of the high compacted molding methods and technique, the quality of casting especially their surface quality and size accuracy have been increased significantly, and the rate of waste product was reduced greatly. The degree of ramming of sand mold was improved highly, but the sizes of cavity were changed by the springback of sand mold at the same time, and then it causes the variety of the sizes of casting. So the springback of sand mold has been one of the important factors that affect the quality and accuracy of casting. Therefore it is necessary to research the mechanism of greensand used for high compacted molding methods thoroughly.This subject is one section of the National Natural Science Foundation subject "Ivestigation on Predicting Method and Mechanism of Springback for High Compacted Sand Molds", followed of the other completed one named "Research on Microdeformation of Molding Sand". A serious of experiments has been done on the reequipped three axial machine under certain technological conditions, and the mechanics, material science, rheologic science. It is systematically studied that the influences on the springback of sand mold were caused by the main influence factors: pressure, compacted rate and the content of soil. Through the analyzed experiments' data, the experienced stress-strain relationship concerning the main influence factors were obtained;under different technical parameter, the springback and spingback's potential energy are compared, the differences and indifferences between them are found out, and the springback's mechanism is discussed;according to the tests' data of YangGuoping coming from Tinghua University, experienced formula of molding sand's springback displacement is induced, the displacement and springback are compared, the margin of error's reasons are analyzed, and they are tested and verified mutually.On one hand the subject has strongly academic value. The experienced stress-strain relationship of molding sand provides basis for the cast of high compacted sand molding and precise casting's stimulation. On the other hand, the subject has significant meaning. The research of springback and its mechanism is value for controlling the quality of high compacted sand molding and promoting cast's precise. It is also the demand for advanced manufacture technology that is developing net shaping, accurate casting and so on.