柴油机剖分式轴承孔接合面错位变形分析

Analysis of Misalignment on the Interface of Split Bearing Bore in Diesel Engine

柴油机剖分式轴承孔的加工通常采用螺栓预紧后组合加工的方式,其加工精度会对滑动轴承服役过程中的受力状态产生显著影响,进而影响使用寿命。针对实际工艺过程中,剖分式轴承孔出现的轴承孔变形、接合面错位等问题,建立了预紧过程中柴油机轴承孔变形的有限元分析模型,对剖分式轴承孔的变形特性进行了定量分析,对接合面摩擦系数、预紧力矩等影响因素进行了研究。通过实验验证了建模过程的正确性和仿真结果的有效性。结果表明:预紧力作用下,轴承孔内缩变扁,曲轴箱刚度低于气缸体,接合面两侧发生错位变形。随着接合面摩擦系数增大,预紧过程错位变形减小,宏观平面度不变的情况下增大接合面粗糙度可增大接合面摩擦系数,减小错位变形。随着螺栓预紧力矩增大,预紧过程错位变形增大,接合面接触变形导致边界非线性问题,但预紧力矩和错位变形仍保持线性关系。

The split bearing bore of diesel engine is generally assembled and processed after pre-tightening bolts.The machining accuracy significantly affect the stress state during the working process of the sliding bearing,and then affect the working life of bearing.The finite element analysis model of bearing bore and interface was established to quantitatively analyze the deformation characteristics and influencing factors such as the friction coefficient of interface and pre-tightening torque.The correctness of the modeling process and the validity of the simulation results are verified by experiments.The result shows that bearing bore shrinks flattened under the preload force.The stiffness of the crankcase is lower than that of cylinder block,and the two sides of the interface are deformed and misaligned.As the friction coefficient of the interface increases,the degree of misalignment deformation decreases during the preloading process.Increasing the roughness of interface can increase the friction coefficient and reduce the misalignment deformation.As the pre-tightening torque increases,the degree of misalignment deformation increases during the pre-tightening process.The contact deformation of the joint surface causes the boundary nonlinear problem,but the preload torque and the dislocation deformation still maintain a linear relationship.