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我厂生产的18型小四轮拖拉机制动鼓在制动器总成里是个重要零件,过去曾因工艺不合理产生缩松,造成大量废品,经过两次工艺改进,铸件质量大大提高,废品率从原来的48％下降为4％。一、18型小四轮制动鼓的零件图见图1。制动鼓形状不复杂,壁厚也较均匀,重量2.2kg。材质为QT42-10,化学成分为:C≥3.2％,Si2.4～3.0％,Mn≤0.5％,P≤0.1％,S≤0.03％,Re_残0.02～0.05％,Mg_残0.02～0.05％。浇注温度≥1340℃。要求铸件不存在气孔和缩松等缺陷。二、改进前的铸造工艺见图2。
I plant 18 small four-wheel tractor brake drum in the brake assembly is an important part of the past due to irrational process produce shrinkage, resulting in a large number of waste, after two process improvements, casting quality greatly improved, the rejection rate from The original 48% dropped to 4%. A small 18-wheel brake drum parts shown in Figure 1. Brake drum shape is not complicated, wall thickness is also more uniform, weight 2.2kg. The material is QT42-10, the chemical composition is as follows: C≥3.2%, Si2.4-3.0%, Mn≤0.5%, P≤0.1%, S≤0.03%, Re_residual 0.02 ~ 0.05%, Mg_0.02 ~ 0.05%. Pouring temperature ≥ 1340 ℃. Require casting does not exist pores and shrinkage and other defects. Second, to improve the casting process shown in Figure 2.