康明斯武当缸盖排气管面气孔成因及解决措施

Reasons Causing Blowholes Formation on the Exhaust Side of Cummins (Wudang) Engine Cylinder Head and Solving Measures

介绍了康明斯武当缸盖的铸造工艺,对其外表面暴露气孔和内部隐蔽气孔分别进行解剖,发现气孔具有以下特点:气孔尺寸较大,为椭圆形或梨形,气孔孔壁有被氧化的现象。根据铸造工艺气孔分类,将这种气孔类型判定为侵入型气孔。分析气孔形成的原因,主要为:覆膜砂发气量大,排气通道排气不畅。改进措施如下:(1)更换覆膜砂;(2)上型增加封火泥;(3)垫封火垫片;(4)优化分型面排气通道;(5)保证砂芯上排气通道连通。生产结果显示,武当缸盖铸件的废品率由原来的3.2%降低到0.3%,产品质量得到显著提高。

The casting method of cummins（Wudang）cylinder head was introduced. The outer exposed blowhole and internal hidden blowhole of the head were dissected and found that the blowhole had following characteristics：the blowholes had quite big dimensions,oval shape or pear shape,the wall of the blowholes had the appearance of being oxidized. According to the classification of casting technological blowholes,this type of blowhole was determined as the intruding blowhole. The main reasons causing blowhole formation were analyzed as：gas evolution of the resin-coated sand was too big,venting passageway was not enough unobstructed. The improving measures were as followings：（1）Changing resin-coated sand.（2）Adding sealing clay on the cope mold.（3）Setting sealing pad.（4）Optimizing venting canals on the mold parting face.（5）Ensuring the venting holes of the sand cores to be connected each others. The production result showed,the rejection rate of Wudang cylinder head was reduced from original 3.2% to 0.3%,the casting quality had been obviously improved.