离心铸造柴油机缸套内孔加工余量的控制

Internal Machining Allowance Control of Centrifugally Cast Cylinder Liner

离心铸造柴油机缸套内孔分层组织过厚，导致加工余量不足，缸套内孔表面加工后有“云斑”状缺陷存在。为解决上述缺陷问题，分析了合金元素、孕育处理、浇注温度、浇注速度、砂衬厚度、铸型转速、冷却速度等因素对此缺陷的影响；根据分析结果，采用了提高熔炼温度、孕育温度和浇注温度，减薄铸型砂衬厚度，提高铸型转速，延长冷却时间等措施，结果小型缸套内孔加工余量已经控制在15～18mm、大型缸套加工余量控制在20～25mm，满足了缸套的技术要求和使用性能要求。

It had been found in the internal surface layer of the centrifugally cast diesel engine cylinder liners that there was too thick stratified structure in the internal surface layer and caused shortage of machining allowance and ＂cloud-like spot ＂ defect existing on the internal surfaee after machining. In order to solve above problem, the influenee of alloying elements, inoculation treatment, pouring temperature, poming rate, thickness of sand liner,rotation speed of the mould,cooling rate etc. on the defects was analyzed. Based on the analysis result, appropriate improving measures were adopted including： enhancing pouring temperature, enhancing inoculation temperature and enhancing pouring temperature, reducing thickness of sand liner, increasing rotation speed of the mould ,lengthening casting cooling time and so on. As the result, the internal machining allowance of small cylinder liners has been controlled in the range of 15-18 ram,and the internal machining allowance of big cylinder liners has been controlled in the range of 20-25 ram,that met the technical requirement and application property requirement.