用覆砂铁型铸造线生产奥贝球铁齿轮铸件

Production of ADI Gear Castings on Resin Sand-Coated Iron Mold Casting Line

介绍了用覆砂铁型线生产奥贝球铁齿轮铸件的铸造工艺。通过增加补贴,促使铸件同时凝固,消除了铸件的内部缩松;通过采用含钡SiFe瞬时孕育,降低了铸件硬度,改善了加工性能。对比了铸态和退火态齿轮半精加工后等淬处理前后的金相组织、力学性能和尺寸变化,结果表明:与铸态等淬齿轮相比,退火态等淬齿轮的伸长率提高、硬度降低、奥铁体中残余奥氏体量增加,但两种齿轮都能满足QT950-7对材料性能的要求;0.15mm的精磨余量对铸态和退火态齿轮都足够了。

The casting method and process of ADI gear castings produced on resin sand-coated iron mold casting line was introduced. The internal shrinkage was eliminated by adopting supplemental machining allowance to promote all parts of the casting to solidify simultaneously; the hardness of the castings was decreased and their machinability was improved by adopting stream inoculation with Ba-containing SiFe as instant inoeulant. The microstructures and mechanical properties of both the as-cast gears and the as-annealed gears before and after isothermal quenching treatment was inspected, and the results showed that, compared with the gears obtained by isothermally quenching the as-cast castings, the gears obtained by isothermally quenching the pre-annealed castings have higher elongation, lower hardness and higher content of residual austenite in the ausferrite, however properties of both kinds of gears met the requirement of ADI 950-7 grade. The fine grinding allowance of 0.15 mm is sufficient for both kinds of gears.