Precision Ball Screw Strong Overload Under Bearer Failure Mechanism

The paper study on precision ball screw, taking into account the special conditions of Aeronautics and Astronautics, analyzed the bearing failure and failure mechanism of the ball screw. This paper studied form following aspects:The Hertz contact theory can only be used in the elastic range, Because of this limitations, we use the theory of elastic-perfectly plastic model to establish the Plastic contact model of the ball screw. Then calculated the plastic contact of the ball screw using the model. While simulated the ball screw plastic contact by Finite element method, know the stress and strain distribution. Compared the two methods calculating results, the results shows that the elastic-plastic contact model is feasible to the actual calculation. It provides the basis theory for the calculating the rolling resistance.According to the elastic-plastic deformation of the ball and the raceway surface, established a new model of the working ball under the strong overload condition. Application of the Plastic contact model derived contact stress of contact place between the ball and raceway, then using surface integral calculated the rolling resistance. According to elastic-plastic deformation and failure analysis of the ball screw under the strong overload condition proposed five failure modes of ball screw:the rolling pavement cracks, ball stuck, raceway chatter, ball rupture, screw fracture. Derived the criteria of failure destruction, reveals ball screw's destruction mechanism under the strong overload. With examples, quantitative analysis of the failure mode of ball screw with MATLAB.Analysis the failure modes of ball screw bearings return system to the failure under the special condition, shows that continuity Curvature play a Decisive role in Failure damage of the ball screw bearings return system. Derived the design process of the Sinusoidal spiral curve, proving its curvature continuously change. So the Sinusoidal spiral curve has its unique advantages under the special conditions. Considering the machining errors, this paper improve the Sinusoidal spiral curve, then using MATLAB calculated each feature points of the return curve.