Creep Properties Of Ball Bowl And Torque Attenuation Law Of Automobile Ball Joint

The ball joint is an important connecting part of the car.An important performance indicator of the ball joint is the torque,but the ball bowl interference and the residual stress of the assembly process make the ball joint torque generally too large,so a thermal finishing process is required to reduce the torque and ensure the consistency of the product torque parameters.Aiming at the problem that the ball joint heat finishing condition can not be determined,this paper studies the torque attenuation law of the ball joint in the hot finishing process based on the creep effect of the ball bowl and the creep simulation to determine the hot finishing condition.The main contents of this article are:The room temperature creep effect of the polyoxymethylene(POM)which is a ball bowl material was studied by conducting a normal temperature compression creep experiment and establishing a creep model.The strain-time curves under different stresses were measured,and the creeping creep law of POM at room temperature was obtained.The creep data model was used to fit the experimental data under different stresses,and the creep model parameters and steady creep rate were obtained.The strain-time curves of POM at different temperatures and stresses were measured by high temperature compression creep experiments under different temperatures and stresses.The high temperature creep law of POM was obtained.The experimental data of different creep models were analyzed.The fitting accuracy and applicability determine the creep model of the material and provide a creep model for subsequent creep simulation.The hot finishing process of the ball joint was simulated by the combination of creep model and CAE creep simulation.The three-dimensional finite element mesh model and creep model of the ball joint are established.The creep simulation of the ball joint is carried out.The distribution of the contact stress and the displacement distribution of the ball before and after creep are analyzed.The ball joint torque model is established,and the ball joint torque value of each time period of creep is calculated.The theoretical torque decay curve is drawn,and the torque attenuation law of the ball joint heat finishing process is obtained.The ball joint heat finishing experiment was designed to verify and perfect the theoretical torque attenuation curve.According to the torque attenuation curve established in the paper,the ball joint heat finishing condition is finally determined,which ensures the stability of the ball joint torque parameter.