Optimization Research On Machining Process For Aluminum Alloy Piston Pin Hole

Piston is the heart of the engine. Piston pin hole is the dangerous area of piston failure, and the accuracy and reliability of the piston pin hole affect the performance of the engine. In this thesis, the pistons condition and surface stress concentration factor of the pin hole were simulated. A preferably integrated method for choosing the optimum cutting tool material to machine piston pin hole was proposed. The simulation model of Si-Al alloy cutting was established and validated, and the changing trends of cutting force and cutting temperature under different cutting parameters and geometric parameters were analyzed by boring simulation. Using response surface methodology, the parameters of boring process were optimized.The simulation of the piston under working conditions reveal that, the upper inside edge of the pin hole was found that it was the most dangerous areas of stress destroy. The model of surface roughness of the pin hole was established and the stress concentration formula was modified. When the surface roughness Ra of the pin hole was decreased from 0.4μm to 0.3μm, the stress concentration could be reduced by 13.8%.Combining the subjective method called AHP and objective method called Entropy Law, a preferably integrated method for choosing the cutting tool material to machine piston pin hole was proposed. And PCD tool was found to be the most suitable material for machining Si-Al alloy piston pin hole.The three-dimensional simulation model of cutting Si-Al alloy with PCD was established and the effectiveness of the model was verified by cylindrical turning. Furthermore, the chip morphology of cylindrical turning was analyzed and the changing trends of surface hardness and surface roughness with cutting parameters were obtained. Using boring simulation, the changing trends of cutting force and cutting temperature under different geometric parameters (rake angle, clearance angle and corner radius) and cutting parameters (cutting speed, depth of cut and feed rate) were analyzed. The changing trend of the residual stress of the pin hole was also studied.Tool wear and chip morphology in boring Si-Al alloy using PCD tool were analyzed, as well as the effect of cutting parameters on surface roughness. And the parameters of boring process was optimized using response surface methodology.According to the response surface, when the cutting speed was within a certain range (200m/min-250m/min), the impact of depth of cut and feed rate on the surface roughness was more significant. When feed rate was higher than 0.13mm/r, the surface roughness increased significantly. Using the optimized cutting parameters, lower surface roughness was obtained, indicating that the optimization effect was good.