| Due to the special structure and strict technical requirements of the front shock absorber sleeve of motorcycle, which leads to casting defects, such as shrinkage porosity, surface blowhole, are very easy to occur in production. Owing to long period and high cost of technological design, difficult to guarantee the casting quality by traditional trial-and-error approach, numerical simulation technology is applied during the process design of casting. Through numerical simulation technology, not only the status of filling and solidification of the liquid metal from which the causes for formation of defects can be obtained in permanent mold is directly demonstrated on the screen, but also the position and the size of defects can be predicted by criterion of defects. Through numerical simulation technology, the purpose of reducing trial production period, assuring the casting quality, increasing casting yield, decreasing cost of product can be achieved.Taking shock absorber sleeve of motorcycle of Suzuki GS125 which material is ZL107 aluminum alloy as research object, this paper discusses the permanent mold casting technology of it. Based on the deep research of present production situation of shock absorber sleeve, basic theory of numerical simulation and functional characteristics of casting simulation software ProCAST, two different technology schemes have been designed, which is respectively none core-pulling casting technology and core-pulling casting technology. Then, the filling process of tilting pouring with four different degrees of two schemes have been simulated and analyzed, and the solidification process and shrinkage cavity and porosity defects prediction with the optimum status of filling process in each group angle have been simulated and analyzed. Finally, a comparative analysis is conducted between two schemes, and practical validation of the simulation results is carried out.The simulation results show that: a).using "Multiple Meshes" model in ProCAST software can effectively avoid the common problems, such as intersection, bad elements, in the mesh partition and significantly improve the grid partition efficiency of complex casting. b).when using none core-pulling casting technology, the inclination angle increases, filling status become better and better. Tilting pouring with 60°has a minimum flow velocity of the sprue, none significant eddy current of terminal of the runner and the best status of inlet of ingate, and solidification analysis and defect prediction show that a spot of shrinkage porosity which doesn't affect the casting quality occurs in blind-hole of cylinder. c). when using core-pulling casting technology, due to the influence of intersection of liquid metal, tilting pouring with 50°has the best status of intersection and effectiveness of step-to-step filling, an excellent flow velocity of the sprue, but the solidification process doesn't meet casting requirement, shrinkage porosity occurs in oblate circle, lateral lug and neck. d). owing to technical requirements forbidding using riser feeding with Residual Root, improvement measures of core-pulling casting technology include that setting spillway trough and dredging channel. After the process improvement, none shrinkage porosity occur in casting. e). Comparing none core-pulling casting with core-pulling casting technology from aspects of the amount of liquid metal, working procedure, time and production equipment, and we can draw a conclusion that none core-pulling casting is suitable for small-batch producing, while core-pulling casting fit to mass production by company with high professional level.Trial production results prove that both two schemes can significantly improve technological yield, reject rate of casting reduce to 5%.By the research of this project show that: if deeply researching numerical simulation, it will effectively improve the competitiveness of enterprise, and promote production mode of foundry industry in our country. |
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