Research On Squeeze Casting Forming Technology Of Thin-walled And High Strength-toughness Aluminium Alloy Piston

Piston is one of the important parts of power machinery.The property of the piston has directly effect on series of important performance of power machinery.The lightweight of piston is an important way to improve its performance,which can reduce body vibration and improve the fuel consumption of power machinery.In order to achieve its lightweight and high performance manufacturing,this paper references squeeze casting technology and focuses on materials improvement,optimization design of technological scheme and die structure design.A systematic study was carried out and the main contents are as follows:First,in the view of the limitations of existing aluminum alloy material,a new material was obtained by modifying the content of alloy composition and comprehensive treatment.After comprehensive treatment,the experimental results show that the tensile strength of the material increased by 37.6%,elongation increased from 2.47%to 3.2%and air content controled in 0.18 ml/100g,which can meet the production requirements of thin-walled and high-tough aluminum alloy piston.Secondly,as for improved materials,squeeze casting flow and filling experiments mold was designed to study its liquidity and filling ability.The results show that the material could fill cavity completely with thickness of 1.65mm and 1.25mm.When the thickness is 0.88mm,filling length is more than 60%of cavity length.It indicates that it has good thin filling capacity after comprehensive treatment.On the basis of these research,two squeeze casting scheme has been designed.Then pros and cons of the two forming scheme was analyzed,and the squeeze casting parameters ranges had been confirmed.Three critical parameters,which have a very important effect on casting quality,has been chose.By means of orthogonal experiment and filling-solidification numerical simulation,we can conclude that direct squeeze casting has superiority over indirect squeeze casting.Finally,the optimized squeeze casting process parameters of piston are confirmed as follows:punch moving speed 0.6m/s,pouring temperature 810?,die preheating temperature 200 ?.Finally,the main forming mold components were designed.The piston was trial-produced by optimized process parameters and designed mold.The specimen which was sampled respectively from the different position of piston was studied through mechanical property test and OM experiment.The test results show that tensile strength,yield strength,elongation and hardness of the casting are up to 300MPa,268MPa,7%,and 95HB,respectively.The microstructure grain is compact,and there is no shrinkage defects on castings,which can meet the application requirements.