抽真空对消失模铸造液态金属填充时的导流撇渣影响

运用基础理论揭示出砂箱内真空管路的分布对液态金属的填充及渣孔、气孔、碳缺陷分布的影响规律并通过实践加以证明。为减少砂箱内的真空压降,应采用单一大颗粒干砂、减少白模密度、砂箱应专用且不可有过大吃砂量、吸真空管路分布面积应较大、直浇道横截面积不可过大、浇注温度不可过高。根据这一原理为提高铸件质量,使渣孔、气孔、碳缺陷集中并上浮应采用单一顶抽式砂箱为宜。

Effect of Vacuumize on Diversion and Skimming of Expendable Pattern Casting During Mold Filling

The effect rule of vacuum pipes' distribution in the flask on filling of liquid metal, and distribution of slag blowhole, blow hole and C defects was put forward using the basic theory and approved with practice. In order to decrease the vacuum pressure drop many aspects should be paid attention to, such as using the big grain size dry sand, decreasing the density of lost foam pattern, using the specialized flask with proper mold thickness, and the vacuumize pipes should be distributed in a big area, the cross-sectional area of sprue cannot be too big, the pouring temperature cannot be too high. On the basis of the principle above, the top-vacuumize flask should be applied to made the slag blowhole, blow hole and C defects centralized and floated up, so as to improve the castings quality.