Multi-scale Accuracies Prediction And Control Of Engine Cylinder Bore Honing

The cylinder bore is the most important part of engine as it performs as the combustor and the platform for converting chemical energy to mechanical energy.Its accuracies make great influence on the dynamics performance,friction power loss and the lifespan of engines.The multi-scale accuracies including roundness,cylindricity,roughness Ra,Rz,Rpk,Rvk,Rk,Mr1,Mr2 of cylinder bores are usually tested after honing.And they are influenced by multiple factors such as honing stone geometry,abrasive concentration,abrasive particle size,abrasive material;honing speed,feed rate,honing pressure,etc.The relations between factors and process accuracy results are quite complex.Meanwhile,the accuracy tolerances of cylinder bore honing process are extremely hard like the tolerance of roughness Rpk is within 2 μm.Therefore,it is of great significance to study the effects of honing stone properties and processing parameters on accuracies by honing for better control of cylinder bore qualities,and furtherly making contribution to stabilizing engine manufacturing process,improving the processing efficiency.The present researches on predicting and controlling accuracies of cylinder bore honing only analyzed the effects of limited process parameters.The combined effects of honing stone properties,process parameters and accuracy errors by previous machining process were not taking into account.Models were constructed to simulation the honing cylinder bore honing process.However,these models only considered the single-stage honing process and were unable to predict the macro and micro accuracies of cylinder bore by honing simultaneously.This paper aims to study the most commonly applied sequential honing process including the rough,finish,and plateau honing in engine cylinder bore manufacturing.The kinematic simulation model is built by simulating the surface topography and trajectory of honing stones.It makes the synchronous prediction of macro and micro scale accuracies possible.The multiple relations between process parameters,honing stone properties with honing accuracies are obtained based on the model simulation and experiment analysis.A strategy for controlling cylinder bore multi-scale accuracies by multi-stage honing process are proposed then.The main effects and contributions made by this paper are included as the following:1)Proposed a new method to model honing stone surface topography based on the simulation of sifting and mixing process in honing stone manufacturing.MATLAB simulation and discrete element method are applied to model the sifting and mixing process in honing stone manufacturing to obtain the abrasive particle size and position distribution.Particle posture and wear condition are also considered in the honing stone surface topography simulation.The modelling results are validated by comparing with the observed topography of honing stone.2)Structured the model of sequential honing process in macro and micro scale.Based on the considering of multiple effects including process errors previous honing,honing stone surface topography properties and process parameters in each stage,the model of sequential honing process is built by kinematic simulation method.It is able to predict the macro and micro accuracies by cylinder bore honing synchronously.Verification tests are conducted,and predicting errors of Rz,Rk,Mr1,Mr2 are shown to be lower than10%.3)Proposed the method of controlling cylinder bore honing accuracies in the view of sequential process.Experiments of cylinder bore honing process are performed with uniform design to study the influence of process parameters on honing accuracies.By incorporating with simulation results,the principle parameters to influence roundness and cylindricity are found to be shape errors previous honing,material removal and honing speed.The principle parameters to influence roughness are found to be abrasive particle shape,abrasive concentration,wear condition of honing stone and feed rate.The method for controlling the multi-scale accuracies in the sequential honing process of cylinder bore is proposed based on the obtained effects of each parameter.The presented effects have made the mechanism of engine cylinder bore honing process clearer and provided theoretical foundation for the accuracies control in the process.