激光烧结新型复合蜡粉的z向精度研究

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In order to study the z-direction dimensional accuracy of laser sintering wax models for investment casting, both the shrinkage rate and the incrassation of bottom which affected the accuracy were separated by building calculation model. The wax models with high accuracy were sintered by filtering powder bed temperature of sintering process. The results indicate that, the sensitivity of the shrinkage near setting powder bed temperature to the change of temperature and prototyping system heater output temperature error are two important factors which affect the wax model dimensional accuracy. The wax model shrinkage rate is very sensitive to the change of temperature, when powder bed temperature is between 60 ℃ and 66 ℃. Powder bed temperature of sintering process should be lower than agglomeration temperature of composite wax powder, which result in dimensional instability.为了研究激光烧结熔模铸造蜡模的z向尺寸精度，建立计算模型使影响精度的收缩率和底部增厚分离。通过对烧结过程中粉床温度的筛选，烧结出尺寸精度较高的蜡模。研究结果表明：设定粉床温度附近收缩率对温度变化的敏感程度和成型系统加热器的输出温度误差是影响蜡模尺寸精度的两个重要因素。当粉床温度处于60～66℃时，蜡模的收缩率对温度的变化十分敏感。为了使蜡模获得稳定的尺寸，烧结过程中的粉床温度应尽量低于蜡粉材料的板结温度。