Research On Anti-fatigue Machining Of Silicon Aluminum Alloy For Piston

Compared with traditional steel and other materials,silicon aluminum alloy has the advantages of light weight,high strength,good wear resistance,etc.,and the raw material cost is low,which is widely used in the manufacture of engine pistons.When the piston is working,it is impacted by high-temperature and high-pressure gas and continuously receives the effect of alternating load,which has high requirements for mechanical properties and fatigue performance.At present,the fatigue life of pistons is mainly improved by optimizing the proportion of raw materials and structural design,and there is less research on the impact of machining surface integrity on the fatigue life of pistons.In this paper,through the combination of experiments and finite element simulation,the effect of cutting parameters on the cutting surface integrity and low cycle fatigue life of the piston silicon aluminum alloy ZL109 is explored,and then the cutting parameters are optimized to improve the machining surface integrity to achieve anti-fatigue processing.The cutting mechanism of silicon aluminum alloy ZL109 was studied in detail by using single-factor cutting experiment combined with finite element numerical simulation technology.A simulation model of turning and residual stress was established in ABAQUS software,and the cutting force and temperature during the turning of silicon aluminum alloy ZL109 and the surface residual stress after turning were successfully simulated.Comparing the simulation results with the experimental results,the cutting force in the simulation is slightly smaller than the cutting force in the actual turning experiment,the cutting temperature in the simulation is higher than the actual cutting temperature,and the simulated residual stress is relatively close to the experimental result.The simulation results of cutting force,cutting temperature and residual stress with cutting parameters are consistent with the experimental results,which proves the reliability of the simulation model.According to the final finishing design,three factors and four levels of orthogonal turning experiments were designed,and the influence of different cutting parameters on the surface roughness,residual stress and work hardening of ZL109 turning was studied.Range analysis and analysis of variance were performed on the experimental results.The results showed that the feed amount f was the main factor affecting the roughness,and the increase in the feed amount f significantly increased the roughness Ra.The turning surface of ZL109 is easy to form residual tensile stress.The main impact on the surface residual stress is the cutting speed v and feed amount f.The residual tensile stress increases significantly with the increase of the feed rate f and the cutting speed v.The turning surface of ZL109 will produce a certain degree of machining hardening,and the feed rate f has the greatest effect on the degree of hardening.However,the overall range of machining hardening degree of turning ZL109 with cutting parameters is relatively small,about 40%to 50%.Through the low cycle fatigue test at room temperature,the fatigue life curve of ZL109 is obtained as N=-85992*?+103484.The fatigue life of ZL109 is negatively correlated with the strain amplitude.The low cycle fatigue fracture morphology of ZL109 is dominated by fatigue striation at room temperature,while a large number of dimples appear on the fracture surface at high temperature.Samples with different surface integrity were obtained by changing the cutting parameters and low cycle fatigue tests were performed under the same conditions.At the same time,based on the actual size,a finite element model of the ZL109 fatigue specimen was established in ABAQUS.After the static load was applied,the stress analysis results were imported into the FE-safe software for fatigue life calculation.The results show that when using a smaller cutting speed v and feed amount f(at this time,the surface roughness and residual tensile stress of the sample are at a lower level),the silicon aluminum alloy ZL109 has a higher low-cycle fatigue life and fatigue life.The calculated results are close to the experimental results,which provides a feasible idea for predicting the fatigue life of the piston and improving the efficiency of research and development.Finally,the response surface method was used to optimize the cutting parameters of silicon aluminum alloy ZL109.The results showed that the highest fatigue life was obtained when the cutting speed v=40m/min and the feed rate f=-0.05mm/r.