织机GA615-0204齿轮坯,材质HT200,在试制生产的几个月中,曾因其结构较复杂,厚薄悬殊大的原因,在其侧壁轮缘、轮筋交界处出现裂纹而报废的达40％～50％。 GA615-0204齿轮外坯,因其六条轮筋只有轮缘厚度的三分之一,故在浇注后首先凝固,形成固相骨架,并产生线收缩,而此时厚的轮缘尚处在逐层凝固之中,又因为轮缘和筋交接处型砂散热条件差,热量集中,凝固层薄,当轮板产生线收缩时,因轮缘和轮毂间型砂的强烈阻 Loom GA615-0204 gear blanks, material HT200, in the trial production of a few months, had because of its complex structure, the thickness of the great reasons, in its sidewall rims, tendons at the junction of the cracks and scrapped up 40% ~ 50%. GA615-0204 gear blank, because of its six rims only one-third of the rim thickness, so after the first solidification pouring to form a solid skeleton, and produce line contraction, while the thick rim is still in the Layer solidification, but also because the rim and tendons junction sand cooling conditions are poor, heat concentration, thin layer of solidification, when the wheel line contraction occurs due to the strong friction between the rim and the hub sand