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1.条件 0273整流叶片精铸特点是形状较简单,尺寸不大。最长不到90mm,壁厚不小于3mm。所用合金为Crl7Ni2,中频熔炼。每炉浇注合格率为40％～60％。型壳材料采用硅酸乙酯,刚玉砂涂料。刚玉砂不仅价格较贵,而且来源紧张,型壳强度稍低。 为提高型壳强度,降低成本,我们曾设想全部型壳采用铝矾土砂取代刚玉砂。经使用效果不太理想,浇注后的零件表面常存在下列问题:(1)表面出现大量的蚁点;(2)表面和R转接处常有大量的龟裂和细小裂纹。 2.蚁点 叶片在浇注脱壳后,表面出现不规则的一薄层颜色较深的氧化皮,似白蚁爬过一般。较严重的蚁点发白带银灰色,经吹砂后,常显出0.2～0.5mm深的缺陷,萤光检验多数不能通过。凡带蚁点的零件80％～90％报废。 3.龟裂
1. Conditions 0273 Rectifier blade casting is characterized by simple shape, size is not large. The longest less than 90mm, wall thickness of not less than 3mm. The alloy used is Crl7Ni2, medium frequency melting. Per furnace casting pass rate of 40% to 60%. Shell material using ethyl silicate, corundum sand paint. Corundum is not only more expensive, but also the source of tension, slightly lower shell strength. In order to improve the strength of the shell and reduce the cost, we have assumed that all the shells use bauxite instead of corundum. The use of the effect is not ideal, casting the surface of the parts often the following problems: (1) the surface of a large number of ants point; (2) the surface and the R junction often have a large number of cracks and small cracks. 2. Ants after the leaves in the casting shelled, the surface of the irregular appearance of a thin layer of dark color scale, like termites climb over the general. More serious ant spot fat band silver gray, after blowing through the sand, often showing 0.2 ~ 0.5mm deep defects, the majority of fluorescent test can not pass. All parts with ants 80% ~ 90% scrapped. 3. Cracked