用挤压铸造方法生产深桶形薄壁铸件时，由于铸件的收缩，凸型的脱型困难，往往造成铸件裂纹或凸型损坏，采用高退让凸型是解决问题的有效途径之一。利用覆砂金属型做凸型，由于覆砂层的高温溃散性较好，即使铸件的锥度为０°时，也能顺利脱型。本文对覆砂机的结构、覆砂工艺及挤压铸造工艺做了阐述。 When using the squeeze casting method to produce deep bucket thin-walled castings, it is difficult to remove the convexity due to shrinkage of the castings, which often leads to cracks or convex damage to the castings. Using high concession convexity is an effective way to solve the problem. The use of sand-coated metal-based convex type, due to the high temperature collapse of the sand layer is better, even if the casting taper is 0 °, but also smooth off. In this paper, the structure of sand mill, sand-covered technology and squeeze casting process are described.