消除灰铁凸轮轴内浇口附近粗大石墨的措施

Measures to Eliminate Coarse Graphite in Ingate Area of Gray Iron Camshaft

化学成分分析发现：凸轮轴w（Ti）量较低时,内浇口附近不但石墨较粗大,而且局部区域还有缩松,硬度为177~198 HB;而w（Ti）量较高时,内浇口附近的石墨不但较细小而且局部还出现D、E型石墨,硬度提高到205~210 HB。讨论了国内文献介绍的几种细化石墨的方法,包括提高铸件凝固冷却速度、降低灰铸铁的CE、合金化、熔体处理等。结合工厂实际生产条件,采用在炉料中增Ti（加四川V-Ti生铁或加Ti铁）的方法,使凸轮轴的石墨得到细化并使其硬度提高。

It was revealed by analyzing chemical compositions that when the titanium content of the camshaft was relatively low,the graphite in the ingate area was relatively coarse,and there was also shrinkage porosities found in local zones,the hardness of camshafts was of 177~198 HB;however,when the titanium content of the camshaft was relatively higher,the graphite in the ingate area was relatively fine,and there was also D type graphite and E type graphite found in local zones,the hardness of camshafts was increased to 205~210 HB.Some graphite refining methods reported in both the Chinese and overseas references was discussed including increasing cooling rate during casting solidification,lowering CE of gray irons,alloying,melt treatment,etc.Based on the practical productive conditions of the foundry and by adopting the method of adding Sichuan-produced V-Ti containing pig iron or adding ferrotitanium to increase titanium content of the melting charge,it was realized that the graphite of the camshafts was refined,and the hardness was also raised.