Process Simulation And Process Optimization Of ZL205A Large Metal Mold Casting

With the vigorous development of the manufacturing industry,equipment industry to develop in the direction of motors,lightweight,ZL205 A alloy with good mechanical properties and the characteristics of low density to be instead of steel of casting lightweight materials,but because of doping elements,leads to the alloy solidification paste form in large temperature range,easy to produce the flaws such as crack,shrinkage.At present,abundant experience has been accumulated in the development and production of small thin-walled parts in China.However,with the increase of casting volume and wall thickness,the distribution area of metal liquid increases,and the defect of poor casting performance of ZL205 A alloy is amplified at the same time.At present,the development process of this ZL205 A alloy large parts is not mature.This topic will take a large projectile body transmission part as the research object,as a typical part in the weapons and equipment industry,it has the characteristics of large volume and large wall thickness.Aiming at the problem of high cost in the early research,the casting process simulation technology is used to optimize the casting scheme and casting process.The main research contents are as follows:Taking ZL205 A alloy large transmission parts as the research object,the casting process scheme was designed.According to its structural characteristics,the combination mode of external metal casting and internal sand core is proposed.According to the location of gate introduction,two sets of gating system structures of bottom injection type and middle injection type are preliminarily designed.The size parameters of each gate are calculated by using section proportion method,and the parameters are preliminarily determined by calculation and consulting data.Then detailed introduced the filling of large ZL205 A casting solidification process involves the theory model,analyzed the mechanism of thermal coupling simulation,lists the common reasons for the formation of casting defects,chose the shrinkage cavity defects prediction criterion,summarized the process of casting simulation experiments further theoretical basis for the optimization of metal mold casting process.The casting scheme of the large transmission parts was simulated and analyzed,and the casting system structure and casting process parameters were optimized.Pro CAST software was used to simulate and analyze the casting process.On the basis of the bottom injection gating system,four inner gates were added and the size of the inner gate was adjusted to obtain the side-injection and stepped gating system.Then in view of the pouring process parameters simulation orthogonal experiment design,the simulation result is analyzed by response surface method,and optimizing the best craft: pouring speed 2 kg/s,pouring temperature of 260 ℃ to710 ℃,mould preheating temperature,the process parameters under the combination of the simulation results of the total shrinkage porosity is only 2.2%,quality defects only distributed in the gating system and riser.Production experiments were carried out to verify the reliability of the process optimization by analyzing the microstructure and mechanical properties of the castings under different processes.According to the principle of control variables,a single factor casting production experiment was conducted to obtain ZL205 A alloy castings with different process parameters.The density and mechanical properties of each casting sample were tested,and the microstructure and morphology of tensile fracture surface were analyzed.It was found that the castings with casting speed of 2kg/s,casting temperature of 710℃ and casting preheating temperature of 260℃ had the best properties: density 99.92%,vickers hardness 167.8HV,tensile strength 486.2MPa and elongation 8.6%.The results show that the numerical simulation results can accurately display the flow of liquid metal filling and the change of solid rate during solidification,and predict the defect area.Using the casting simulation results to assist the preliminary optimization design,the development cycle can be shortened by nearly 60%,and the material cost caused by repeated adjustment of the casting can be saved.Using the optimized process to guide the casting production,the yield of the casting is obviously improved.This study provides technical optimization for the production and application of ZL205 A large projectile transmission parts,and provides reference for its subsequent production practice.