QT400-15托盘铸件气孔和缩松的产生原因及防止措施

Analysis and Measures for Gas Hole and Shrinkage Defects in Large QT400-15 Tray Castings

介绍了托盘球墨铸铁件的结构及技术要求,阐述了原生产工艺及铸件出现气孔与缩松的位置和特征。分析了托盘产生气孔与缩松缺陷的原因,认为铸型水分过高导致了侵入性气孔缺陷的出现,冷铁使用不合理导致热节处产生了缩松缺陷。通过采取烘烤砂芯和砂型减少水分含量,提高砂型透气性和增加出气,优化冷铁摆放位置和形状以消除热节,增大冒口尺寸以提升液态补缩,提高铁液碳含量来增强自补缩能力等措施,消除了球墨铸铁托盘的气孔和缩松缺陷。验证试验生产的同型号托盘铸件均未产生气孔与缩松缺陷。

This article introduces the structure and technical requirements of ductile iron castings for pallets,elaborates on the original production process and the location as well as characteristics of porosity and shrinkage in castings.An analysis was conducted on the causes of porosity and shrinkage defects in the tray,and it was found that excessive moisture in the mold led to the appearance of invasive porosity defects,while improper use of cold iron resulted in shrinkage defects at the hot spot.By adopting measures such as baking sand cores and molds to reduce moisture content,improving sand mold permeability and increasing air output,optimizing the placement and shape of cold iron to eliminate hot spots,increasing riser size to enhance liquid shrinkage,and increasing the carbon content of molten iron to enhance self feeding ability,the porosity and shrinkage defects of ductile iron pallets have been eliminated.No porosity or shrinkage defects were found in the same type of tray castings produced in the verification test.