Research On Flow Behavior Of 357 Semi-solid Slurry In Rheological Die Casting Process

Semi-solid rheocasting die casting technology is an important method for the preparation of aluminum alloy parts for high-performance automobiles.which provides a new way for the lightweight of automobiles.However,there is a lack of systematic research on the flow behavior of semisolid slurry in the process of die casting,especially the flow filling capacity,flow stability and welding quality of slurry.Based on semi-solid rheocasting and forming technology,this paper independently designs and manufactures special molds f-or studying the flow behavior of slurry flow filling capacity,flow stability and rewelding quality in rheological die casting process.The influence of parameters,slurry state and other factors on these three flow behaviors,and the research results are used to guide the adjustment and optimization of process parameters in actual productionThe increase of the ingate velocity,the increase of the mold temperature and the decrease of the solid fraction all increase the flow filling ability of the slurry;the increase of the number of dendrites in the microstructure of the slurry causes the solid-liquid separation of the slurry during the flow.Based on those rules,the process parameters in the actual product development are adjusted and optimized.By increasing the ingate speed,increasing the mold temperature and lowering the solid fraction.the defect of filling defects in the mobile phone frame was successfully eliminatedThe initial solid fraction of the slurry increases and its flow stability increases first and then decreases;the decrease of the percentage of filling and the increase of the mold temperature will improve the flow stability of the slurry:in this experiment,the inflow velocity is less than 6m/s,which has little effect on the flow stability of the slurry.According to the experimental results.the flow instability index is defined as the product of the degree of disturbance of the slurry front and the degree of the wall of the cavity.The greater the instability index.the worse the stability.The ProCAST software was used to simulate the solid fraction distribution of the slurry flow front during the filling process.and the variation of flow stability was explained.Based on the above rules.the process parameters in the actual product development are adjusted and optimized.By improving the solid fraction and increasing the mold temperature.the instability problem in the automobile shock absorber products is successfully solved.Adding slag pack exhaust,raising the mold temperature,increasing the die casting pressure,and reducing the ingate speed can effectively improve the rewelding quality of the slurry.The ProCAST software was used to simulate the temperature distribution of the slurry flow front during the filling process,and the variation of the rewelding quality was explained.Based on the above rules,the process parameters in the actual product development are adjusted and optimized.By improving the mold temperature and increasing the die-casting pressure,the defects of rewelding defects in the automobile bracket products are successfully eliminated.