柴油机耐压球铁件的铸造工艺优化

柴油机的上壳体铸件用QT600—3球铁铸造，工作压力高达35MPa。不允许有缩松缺陷。为此对两种工艺进行了对比：(1)内孔不铸出，厚大端朝上，顶部设大尺寸冷冒口，结果中心部位生产缩松和晶粒粗大。(2)大端朝下，内孔设内冷铁，顶部冒口有内浇道与直浇道连接，缩松和晶粒粗大问题得到解决。

Foundry Method Optimizing of a Hi-Pressure Resistant Ductile Iron Casting for Diesel Engine

A case casting of marine diesel engine is to be cast with QT600-3 grade ductile iron. Its working pressure is up to 35 MPa. It is not permitted that the casting has shrinkage. Therefore, two foundry methods were compared: (a) The inner hole was solid-cast, thick end was put upwards and a large cold riser was set on the top end. As a result, there was shrinkage porosity and open structure in the central area of the casting. (b) The thick end was put downwards, and inner densener was set in the inner hole, and the top feeder was connected with the sprue through a slope ingate. As a result, the shrinkage porosity and open structure was eliminated.