球墨铸铁件补缩冒口的新进展

News about Risering/Feeding of Ductile Iron Castings

对于铸件使用者来说,最主要的要求之一就是要保证铸件品质,无缩孔或缩松等铸造缺陷,因为这些缺陷的存在容易导致零部件的突然失效。所有铸造材料在冷却过程中均存在液态收缩,因此通常都要设计补缩冒口。在铸铁(如球墨铸铁)凝固过程中,因为石墨膨胀是有利于补缩的,如果模型设计师懂得凝固机理的话,他就会利用这一特点设计较小的冒口。综述了球墨铸铁冒口设计的基本原理。运用该原理可以减小冒口尺寸同时保证生产的球铁铸件无收缩缺陷,从而进一步提高工艺出品率,提高球铁件生产的经济效益。

One of the main requests from castings uers is the guaranty that the part is sound and free of shrinkage or porosity defects that could result in catastrophic failure. Since all materials liquid contraction during cooling, the use of risers/feeders is a common practice. However, because graphitic irons, such as Ductile Iron, can benefit from the expansion of graphite during solidification, the pattern plate designers can take advantage of this characteristic and use smaller risers if he understands the solidification mechanisms. In this paper, the principles of risering Ductile Iron are reviewed. In order to further improve pattern yield and, as a consequence, the economics of Ductile Iron castings production, these principles are applied in order to reduce the size of the risers, while maintaining the objective of producing shrinkage free Ductile Iron castings.