制动盘铸件N2气孔缺陷的防止措施

Preventive Measures for Brake Disc Casting N2 Blowhole Defects

介绍了灰铸铁制动盘制动面出现的“孔洞”缺陷特征,通过对缺陷部位进行金相组织和扫描电镜分析,确定该缺陷为N2气孔。利用鱼骨图分析认为:铸件浇注过程中型腔的排气不畅和砂芯粘结剂发气量大是形成N2气孔的主要原因。采取了以下措施:(1)在原工艺的基础上,增加了排气冒口和排气道,提高型腔中的排气速度;(2)将砂芯1中Fe2O3加入量从0.2%提高至0.4%~0.8%,在保证砂芯强度的条件下,尽量降低树脂的加入量,树脂加入量由1.3%降低至1.0%。生产结果显示:经过多次验证,铸件制动面气孔基本消除。

The hole defect characteristics of the brake surface of gray iron brake disc were introduced. The metallographic structure and scanning electron microscopy analysis of the defect part were used to determine the defect was N2 blowhole. The fishbone diagram analysis showed that the poor exhaust of the cavity during casting and the large amount of gas generated by the sand core binder were the main reasons for the formation of N2 blowhole. The following measures were taken:(1)On the basis of the original process,the exhaust riser and exhaust passage were increased to increase the exhaust velocity in the cavity.(2)The Fe2O3 addition amount in the sand core 1 was increased from 0.2% to 0.4%~0.8%,under the condition of ensuring the strength of the sand core,the amount of resin added was reduced as much as possible,and the amount of resin added was reduced from 1.3% to 1.0%. The production results showed that after repeated verification,the pores of the casting brake surface were basically eliminated.