汽车发动机缸体缸筒壁厚不均匀的成因分析

Analysis of Reasons Causing Uneven Cylinder Wall Thickness of the Automotive Engine Block

介绍了汽车发动机干式缸套缸体的生产情况,对立浇工艺生产的铸铁缸体缸筒壁厚不均匀问题进行了大量的分析,认为产生缸筒壁厚不均匀的原因主要为:单薄的水套芯热膨胀受力变形,水套芯高度的影响,浇注呛火,浇注时间过长以及水套芯组装偏移失控。采取了以下措施,解决了缸筒壁厚不均匀问题:(1)选用含一定比例宝珠砂的低膨胀高强度覆膜砂制作水套芯;(2)将覆膜砂灼减量控制在2%以内,并设置好水套芯的排气通道和做好烘干、浇注引火工作;(3)合理设计浇注系统,实现平稳快速充型;(4)保证水套芯与缸筒芯组合正确,没有偏移,最好采用组芯胎具工装。

The produetion situation of cylinder block of automotive engine with dry cylinder liners was introduced. A great deal of analysis works was conducted on the problem that the cylinder wall thickness of the vertically-east gray iron hloek had been uneven,and it was considered that the main reasons causing uneven wall thickness of the cylinder holes were as follows：the thin and weak water jacket core was distorted due to the thermal expansion fi）rce;influenee of the height of water jacket core;boiling during pouring process;pouring time was too hmg and displacement of water cores assembling lost control. The problem of uneven cylinder wall thickness was solved by adopting following measures：（ 1 ）Using proportional pearl sand- eonlaining low expansion and high streugth resin-coated sand to make water jacket core.（ 2 ）Controlling the LOI of the resin- coated sand less than 2%,properly setting the venting canal and thoroughly drying the water jacket core,as well as conduct- ing instantly gas-ignition during pouring. （3）Designing proper gating system to realize stable t？tst mohl filling.（ 4 ）Assuring the water jacket core and cylinder hole cores to be correctly assembled without deviation and it was suggested to nse the die equipment for assembling.