Analysis And Prediction Of Machining Deformation Of Connecting Rod Based On Key Process Stress Superposition Effect

With the strengthening of global marine economic development and China's maritime rights and interests protection,ship and marine equipment performance requirements,the reliability of the power system is more and more high,especially large power marine diesel engine crankshaft,connecting rod,lead,camshaft,roller motion and heavy work intensity increasing,increased risk failure,restricting the marine diesel engine performance improvement,development and influence of the shipbuilding industry national defense force of the ocean.In marine diesel engine,connecting rod as the key component is one of the most serious parts that bear the load,so it must have enough fatigue strength and structural strength.The key parameters of the diesel engine connecting rod head including the size of hole diameter and cylindricity and parallel to the axis and the head end flatness,parallelism and flatness and overall link dimension and shape precision,directly affect the working performance of the diesel engine and the service life,in the process of production and quality of products are mainly checks to maximum production efficiency.In this dissertation,the deformation of the connecting rod of marine high power diesel engine during machining and after processing is analyzed,and the residual stress is the main factor that affects the deformation of the connecting rod.Heat treatment and machining directly affect the distribution of residual stress of the connecting rod.Therefore,the deformation mechanism of the connecting rod is analyzed by combining finite element method with experiment,and the prediction of the deformation process of different links of the connecting rod is carried out,so as to lay the foundation for improving the quality of the connecting rod.The main contents are as follows:(1)Establish three-dimensional models and finite element models for key processes of connecting rods.Based on mathematical models for the temperature field and stress field of the connecting rods of diesel engines,an indirect coupling method is used to establish a finite element model for the heat treatment of connecting rods using CAE,and the heat treatment process for the connecting rods The temperature field and the stress field are analyzed and calculated,and the residual stress field distribution results of the connecting rod are obtained,which lays the foundation for the next research.Based on the orthogonal experiment,the relationship between the various factors in the connecting rod machining process and the deformation of the connecting rod was established,and the deformation of the connecting rod and the stress distribution of the connecting rod were analyzed.(2)According to the simulation results,the experimental scheme was designed and the residual stress in the connecting rod was measured by X-ray diffractometry.The actual residual stress distribution of the connecting rod was determined.The simulation results and the test results are taken into consideration,and the distribution trend of the stress field of the connecting rod is consistent,which provides the reference basis for the simulation of the connecting rod deformation.(3)Based on the Generalized Regression Neural Network(GRNN),combined with the orthogonal test connecting rod machining process,the relationship between the factors and the connecting rod deformation in the key process of the connecting rod is established,including process sequence,quenching temperature,tempering temperature and cooling rate.The deformation of connecting rod is predicted by the range value given by four factors.The selection of technical parameters of rod processing provides guidance.