Test And Simulation Of Residual Stress In The Casting Of Cylinder Body

Casting is the liquid forming method of casting billet or parts after pouring molten alloy into casting mould and cooling solidification.In the solidification process,the casting residual stress is introduced in the casting due to the difference of solidification sequence,the difference of solid phase change and casting resistance.The release of the stress in the process of placing,processing,transporting and using after forming can cause casting deformation and even cracking,resulting in the scrap of the casting and even the whole equipment.For engine cylinder body skeleton,should not only inherit the components of gravity,on cylinder head bolt fastening force,but the outbreak of the pressure in the cylinder and the piston connecting rod mechanism motion of inertial force.When the residual stress of the cylinder is interacted with these forces,the light will change the force of the cylinder body,which will cause the cylinder body to deform and crack.Therefore,it is very important to explore the residual stress distribution law of the cylinder body and formulate the residual stress control measures to ensure the normal and stable operation of the engine.The paper takes H15 series automobile engine cylinder body as the research object,first adopts xstress-3000 stress analyzer,and the casting residual stress on the surface of the cylinder block is measured by the side inclination method.The test results show that the residual stress of casting in the direction of length and width of cylinder body surface is generally lower than 50 MPa,and most measuring points of cylinder head and bottom surface are in the state of tensile stress.After pretreatment of the model by Magics software,MAGMA and ProCAST were used to analyze the residual stress of casting,and the measured value and simulation value were compared and analyzed.The results show that:(1)The residual stress distribution of the top and bottom of the cylinder body is basically uniform in the casting far away from the cylinder sleeve area,and the equivalent stress is below 50 MPa.The residual stress in the area around the cylinder liner is large,and the equivalent stress is over 200 MPa.(2)The stress distribution trend of simulation and measurement results is basically the same at the measuring point of the top surface of circulating cylinder body,and there are some differences between the stress properties and the numerical value,with a maximum difference of 24 MPa..(3)At the measuring point of bottom surface of the cylinder body,the difference between the simulation results and the measured results in length and direction is small,within 10 MPa.The stress distribution trend is the same in the width direction,and there is a certain difference in the value.According to the author,the difference between the above simulation and the measured casting residual stress should be derived from the solidification physical model,boundary condition,material high temperature performance and actual difference or absence.The influence of casting process parameters on residual stress of stress frame casting is also simulated.The results show that:(1)Pouring temperature increased by 20?,the casting residual stress value decrease about 7MPa;Die preheating temperature increased by 20?,the casting residual stress value rise about 5MPa;Cooling water temperature increased by 20?,the casting residual stress value rise about 6MPa;The injection ratio increased by 30 MPa,and the residual stress of casting decreased about 5MPa.(2)The interaction between casting temperature and mold preheating temperature has significant influence on the residual stress.