Dynamiac Analysis Of Rolling Contact Of Steel Ball Unwinding Process

The bearing is the heart of the machinery industry,the steel ball is rolling body in bearings,and its surface quality directly determines the performance of bearing.But the traditional method of detection has been difficult to meet the market demand,development of high efficiency and high precision testing equipment has become an urgent problem.The important prerequisite for spherical nondestructive testing is to obtain complete information of the spherical surface.On the issues of completely expand surface of steel ball,based on motion analysis,friction analysis and contact analysis,this paper analyzes dynamics and simulation of steel ball unwinding.In order to establish dynamic model of steel ball unwinding process,firstly,analyzes motion of the steel unwinding mechanism,According to the geometry and contact constraint relationship of unwinding wheel,establishes a contact model of wheel and steel ball,uses Newton iterative method to solve the model and gets the trajectory curves of center of a sphere and unwinding wheel in unwinding process of steel ball,position expression of center of sphere is pretended by fitting the trajectory curve for contact point.Then,based on Hertz theory,analyzes contact conditions of steel ball to expanding wheel and driving wheel,the relationship expression of contact force and contact deformation is established;Finally,combining motion analysis and contact analysis,based on Coulomb friction law,establishes modified model of Coulomb friction to determine the expression of friction.Based on theoretical analysis,analyze dynamic characteristic of steel ball unwinding process.Through analyzing the interaction of components of the steel ball unfolding mechanism,establishes dynamic model of steel ball unwinding process based on Euler method,uses the fourth-order R-K method to do numerical analysis of dynamics model,gets displacement curve of center of a sphere and unwinding wheel and determines contact state of the steel ball.Analyzes friction force curve further,determines whether existing sliding friction in the process of steel ball unwinding,and then confirm the unwinding situation of steel ball.In order to verify the accuracy and reliability of dynamic model,uses the data post-processing function of simulation software to verify dynamic characteristic of steel ball unwinding process by virtual simulation.Combining results of numerical analysis,analyzes the measurement result of load and speed,displacement of steel ball and unwinding wheel to verify the accuracy of the dynamic model analysis results.At the same time,analyzes the unwinding situation of steel ball under the condition of different load and speed,determines the factors of influencing steel ball unwinding,and verifies the reliability of the dynamic model further.Through the analysis of the dynamic properties of the unwinding process of steel ball,this paper provides a theoretical basis for the development of detection prototype.