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根据球墨铸铁件收缩缺陷形成的本质 ,对铸件凝固过程中形成的孤立区进行了体积变化计算 ,并以孤立区的净体积变化量与此孤立区刚形成时的体积之比作为判别收缩缺陷严重程度的依据 .在呋喃树脂砂型条件下 ,针对不同模数、不同冒口颈尺寸的圆柱试样进行了模拟计算和浇注试验 .通过比较计算和试样解剖结果 ,确定了各模数试样恰好不产生收缩缺陷时孤立区净体积变化率的临界值 ,以此作为球铁件宏观缩孔、缩松收缩缺陷的判据 ,并对该判据进行了试验验证
According to the nature of the formation of shrinkage defects in ductile iron castings, the volumetric changes of the isolated areas formed during the solidification of castings were calculated and the ratio of the net volume change of the isolated areas to the volume at the time of the formation of this isolated area was taken as the criterion for judging the serious defects Degree basis.Under the condition of furan resin sand, the cylindrical specimens with different modulus and different riser neck sizes were simulated and the pouring tests were carried out.According to the calculation and the anatomical results of the specimens, The critical value of the rate of change of the net volume of the isolated area without shrinkage defects is used as a criterion for the macro-shrinkage and shrinkage defects of the ductile iron piece, and the criterion is verified by experiments