运用均衡凝固技术解决压缩机缸体缩孔缩松

利用均衡凝固技术，将大型活塞式压缩机气缸体的原底注工艺改为项注雨淋工艺，并采用冷铁等措施，使项注雨淋方式的下低上高的温度场分布趋势得到明显的加强，改变了先中间后两头的凝固顺序，缸体从总体上形成了从下往上的有利于补缩的凝固顺序，从而有效解决了压缩机缸体缩孔缩松缺陷。数值模拟结果和实际生产结果验证了工艺改进的正确性，而且废品率由原来的10％降低为5％，工艺出品率由原来的75％提高到85％～90％，效果显著。

Solution of the Shrinkage Cavity and Porosity in the Cylinder of Compressor Adopting the Proportional Solidification Technology

The original bottom gating system of the cylinder of large piston compressor is changed into top shower gating system using the proportional solidification technology and the distribution of temperature gradient from the bottom to the top changes significantly in the top-shower gating system adopting chill, thus improves the distribution of liquid phase, changes the original solidification sequence from middle to two ends of cylinder and forms a new solidification sequence from the bottom to the top, which is beneficial to the feeding of casting, therefore solve the shrinkage cavity and porosity in the cylinder efficiently. The numerical simulation and production verify the modified technology. The reject ratio decreases from 10% to 5%, and the yielding rate increases from 75% to 85~90%.