Study On The Computer Simulation Piston Forming Process Of In Situ Al₂O_3P/ZL109 Composites

In this paper,based on the characteristics of in-situ particle reinforced Al₂O_3P/ZL109 composites by the research group.The UG NX software was used to model the 3D piston.According to the casting manual and the actual situation,the main technology parameters were determined.The Pro CAST software was used to simulate the molding conditions of gravity diecasting process and indirect squeeze casting piston,including the crystal grain size.Based on FLUENT software's fluid mechanics simulation,the distribution of in-situ particle reinforced Al₂O_3P/ZL109 composites solid-liquid two-phase flow was investigated.Then,both of the mold designed by prophase process planning and simulation results.According to the simulation results and mold designed,the distribution of simulated particles of indirect squeeze casting was compared with the experimental results.According to the design size to determine the piston modeling size,and then 3D modeling it by UG NX software.The casting process of the gravity diecasting process and indirect squeeze engine piston was simulated by Pro CAST software under different conditions.The results indicated that the pouring temperature of 680? and above could ensure the good fluidity of the molten metal.Considering the energy saving,grain coarsening and cooling time reducing,the casting temperature should be controlled between 680⁷00?.To ensure smooth filling and sequence solidification,the suitable filling time of metal gravity casting was 10 s and the punch velocity of indirect squeeze casting was 32.5mm/s.Mold temperature was too high will hinder the product quality and reduce production efficiency.When the molten metal of piston thin wall was cooling too fast will not good for feeding the contraction,if the temperature was too low.So these two casting methods' mold temperature should be controlled between 250³00?,the preheating temperature of the punch was determined to be near 400? in indirect squeeze casting.The simulation of the indirect squeeze casting of in-situ particle reinforced Al₂O_3P/ZL109 composites piston microstructure was better than the tradition metal gravity casting by CAFé.The experimental results showed that the actual dispersion of the Al2O3 particles was similar to the simulation in the indirect squeeze casting.Al2O3 particles and ZL109 alloy are semi-coherent boundary,so the dispersed Al2O3 particles as effective nucleation core were refining the grain.Based on the addition of Al2O3 particles,the grain refinement could be determined in the case of heterogeneous nucleation core increased in the Pro CAST software simulation.Based on the fluid mechanics simulation of FLUENT software,the ICEM CFD software integrated in ANSYS was used to 2D modeling and meshed.The results indicated that the content of Al2O3 particles in the center section of the piston was slightly higher than the near surface section.The particle distribution was mainly affected by the collision of the particles and die wall,the migration of the particles during the filling process,and the effect of the solidified melt on the pushing and coating of Al2O3 particles during solidification.In general,the content of Al2O3 particles decreased with the increase of filling distance,and more concentrated in the anti-gravity parts,less concentrated in the flow gate.According to the preliminary simulation results,the piston mold structures of these two casting processes were designed respectively.To improve the indirect squeeze casting piston's top molding process,add water pipes or could be changed to copper and other cooling mode,and the gate angle of handle was modified to 120° to obtain high quality composite piston castings.The actual dispersion of the higher quality indirect squeeze casting piston was also studied,and the conclusion was in accordance with the simulation results.