浇注系统截面比与大孔出流规律的研究

根据水力学基本原理在铸造生产中应用的实际情况,通过水力模拟试验,指出在浇口杯、直浇道和内浇道组成的浇注系统中,由于直浇道和内浇道的截面比值很少超过5,根据连续流动定律,直浇道和内浇道的流速同属一个数量级。直浇道流速对降低内浇道实际出流压头的影响不可以忽略不计。内浇道实际出流压头小于按托里拆利小孔出流定律确定的“从浇口杯液面到内浇道中心的垂直距离的静压头”。本文称直浇道与内浇道截面积比值小于5时的内浇口出流为大孔出流。大孔出流时,内浇口实际出流压头可以根据“浇口杯液面到内浇道中心的静压头”和浇注系统截面比值进行理论计算。把截面比纳入浇注系统流速、流量的定量计算公式,不仅可以提高计算精度、使浇注系统截面积理论计算值偏小的问题得到解决,而且对水力学孔口与管道出流的分析及铸造中型腔充填的平稳性控制也有实用价值。

Investigation on the Cross-sectional Area Ratios of Gating System Based on the Large Orifice Discharge Theory

According to basic hydraulic principles applied to practical foundry production, the velocities of metal flow down sprue and along ingate arc in same order due to the crosssectional area ratios of sprue to ingate seldom exceed 5. The actual head on ingate is smaller than the static total head. In the paper, a gating system is called Large Orifice Discharge (LOD) when its cross-sectional area ratios of sprue to ingate are less than 5. In Large Orifice Discharge theory, the actual head on ingate can be theoretically calculated by the static total head and the cross-sectional area ratio of sprue to ingate. The problem that theoretically calculated values of cross-sectional areas of gating system were often smaller than practically required ones is solved.