Research On HPDC Technology And Mechanical Performance Analysis Of Automobile Aluminum Alloy Shock Tower

New energy vehicles and buses have become the main transportation means in major cities due to their advantages such as no pollution,low energy consumption and low noise.Because of the current restrictions on the development of battery technology,the power batteries equipped on the cars have low specific energy,short endurance and large volume density,which seriously affects the application and development of new energy vehicles.Therefore,if we can proceed from the body and components,through structural design and the use of lightweight materials,we can reduce the quality of each component and thus reduce the weight of the vehicle.It is important to reduce energy consumption,reduce pollutant emissions,save costs,and promote the development of the new energy vehicle industry.As an important load-bearing component,the shock tower not only plays the role in fixing the spring and determining the bearing capacity,its performance will also directly affect the comfort,operability and safety of passengers and drivers when riding.Traditional automobile shock towers are made of high-strength steel and have a large weight,which has been difficult to meet the current situation and demand of the automotive lightweight market.Therefore,this article uses the lightweight material “AlSi10MnMg aluminum alloy” and advanced manufacturing technology “High Pressure Die Casting” to propose a HPDC forming process for an automobile aluminum alloy shock tower.Besides,the finite element analysis of the static and dynamic characteristics of the castings based on the actual service process was performed.Under the condition of achieving safe performance,the weight of the shock tower is minimized by replacing the steel with aluminum,which provides valuable guidance for the research on the lightweight of body and parts of small and medium-sized cars.The main research contents and conclusions of this article are as follows:(1)Research on HPDC technology of AlSi10 MnMg aluminum alloy automobile shock tower.First,according to the relevant technical standards,ProCAST software is used to simulate the HPDC process of the shock tower.The main research is the influence of typical process parameters such as injection speed(pressure),pouring temperature,mold preheating temperature and time on the casting quality.The results show that the most obvious factor is the injection speed.In the range of 2.5 m/s to 3.5 m/s,the filling capacity of the alloy gradually increases with the increase of speed,and the optimal injection speed is 3.0 m/s.At 2.5 m/s,the filling capacity of the alloy is low,resulting insufficient filling of the cavity.At 3.5 m/s,although the filling capacity of the alloy is improved,it is not much different from that when the injection speed is 3.0 m/s.However,the excessive velocity of the alloy liquid has a strong erosion effect on the die,which greatly reduces the life of the mold.The second influential factor is the pouring temperature.In the range of 680 °C ~ 720 °C,the alloy’s fluidity increases with the increase of temperature.At the same time,the higher the temperature,the longer the filling distance of the alloy is,and the best pouring temperature is 700 °C.If the pouring temperature is too low,it will inhibit the alloy’s fluidity,affect the filling ability,and form a cold shut mark.If the temperature is too high,it will cause a gas hole,flocculation,and formation of a shrinkage cavity and porosity.The influence of the mold preheating temperature is the smallest.According to the relevant data,the optimal temperature is selected as 200 °C.In this paper,the optimal parameters for HPDC process of shock towers are: injection speed 3.0 m/s,pouring temperature 700 °C,mold preheating temperature 200 °C.(2)Experimental research on HPDC process of the shock tower.Based on the above simulation results,production experiments were performed under the optimal parameters to further verify the feasibility and reliability of HPDC forming of aluminum alloy shock towers.The microstructure observation,tensile properties measurement and fracture morphology analysis on the castings show that the casting quality is good and the relevant properties meet the requirements.(3)Static and dynamic characteristics analysis of the actual service process of the shock tower castings.Combined with relevant technical standards,the static/dynamic analysis of the shock tower obtained in the die casting process under typical dangerous conditions is performed to determine whether it meets the mechanical performance requirements.The results show that the static/dynamic strength and stiffness of the shock tower meet the design requirements under four typical dangerous working conditions.The maximum deformation of the shock tower occurs under the working condition 4,and the displacements in the three directions x,y and z are 0.390 mm,0.441 mm,and 0.487 mm,which are all less than the critical deformation value of 0.5 mm.In addition,modal analysis is performed on the shock tower,and the results show that the low-order natural frequency is 62.292 Hz,which avoids the frequency range of external excitation and does not cause resonance.The purpose of this article is to study the HPDC process of aluminum alloy shock towers and analyze the mechanical properties of castings from the perspectives of die-casting process simulation,die-casting experimental scheme,process design,and static/dynamic structural performance analysis.This paper provides a reference for the lightweight design of automobile shock absorption towers.