Condition based preload adjustment at ball-screw-drives by hydraulic expansion actuators

滚珠丝杠传动是机床中最重要的直线传动系统，它决定了机床的生产率、精度和动态性能。正如在每个机械传递元件中一样，其行为受到磨损的影响，这对系统行为（例如动态刚度，控制行为和精度）有负面影响。机械预紧力的变化导致动态系统行为的改善，但也导致更高的压力、摩擦、温度和磨损的发展。已知用于控制滚珠丝杠螺母或推力轴承处的预载荷的不同方法。本课题提出了一种基于液压膨胀作动器的新型作动控制原理。因此，一般来说，必须开发驱动原理。液压膨胀致动器具有易于集成在滚珠丝杠元件中的优点，并且应该具有非常长的使用寿命。在这个项目中，该系统的集成到滚珠丝杠螺母和推力轴承和不同的控制策略进行了评估。

Ball-Screw-Drives are the most significant linear drive system of machine tools, they define produc-tivity, accuracy and dynamics. As in every mechanical transfer element, its behavior is influenced by wear, which has a negative influence to the systems behavior (e.g. dynamic Stiffness, control-behavior and accuracy). Changes of the mechanic preload leads to improvement of the dynamic system behavior, but also leads to higher pressure, friction, temperature and developing wear. Dif-ferent approaches for control of preload at ball-screw-nut or thrust bearing are known. A new actu-ation control principle, based on hydraulic expansion actuators should be realized in this project. Therefore, the actuation principle has to be developed in general. Hydraulic expansion actuators have the benefit of a easy integration in the ball screw elements and should have a verry long life-time. The integration of the system into the ball-screw-nut and the thrust bearing and different control-strategies are evaluated in this project.