连杆加工工艺过程对其残余应力及变形影响研究

Research on the Residual Stress and Deformation of Connecting Rod Caused by Machining Process

为了深入研究加工工艺对连杆变形的影响,首先采用"生死单元"方法,基于不同工艺阶段连杆的几何形状建立相应的有限元模型。其次,针对不同工序顺序、回火温度、以及约束方式下的平行度和基本尺寸的影响进行分析,获得加工变形最小的加工工艺方案。最后,基于最优方案对连杆的残余应力与变形分布进行研究。结果表明:当加工工序为铣两平面、钻小头孔、锯开连杆、装配和车大头孔,回火温度为640℃,约束方式为小头孔时,平行度误差最小;回火温度对连杆的基本尺寸影响较大,而约束方式和工序顺序影响较小;加工完成后,连杆内部为拉应力,表面为压应力且最大变形出现在大头孔处。

To investigate the machining process effect on the deformation of connecting rod, the finite element model is established based on the geometry of the connecting rod with the birth-death element method firstly. Secondly, the parallelism and the basic size of the connecting rod under different procedure sequence, tempering temperature and constraint are investigated to obtain the machining processes with minimum deformation. Eventually, the residual stress and the deformation distribution of the connecting rod are studied based on the optimal machining processes. The results show that, the minimum parallelism error is obtained when the process order is plane milling, hole drilling, sawing, assembling and turning, the tempering temperature is 640℃ and the little hole is constrained. The tempering temperature has a great influence on the basic size of the connecting rod, while the procedure sequence and the constraint have little influence. After processing, the inner and surface residual stress of the connecting rod are tensile stress and compressive stress respectively, and the maximum deformation occurs in the big hole.