Applying a bearing preload of machine tool spindle produces positive effects, including increased stiffness, rotation noise reduction, increase in shaft precision, position adjustment during operation, and prevention of rolling element resonance and rotating slip, along with a significant extension of the bearing lifespan. A variable preload technique is a method that improves the bearing performance by appropriately varying the preload applied to the bearing according to the spindle rotation speed and machining condition. In this study, a novel variable preload method utilizing a Terfenol-D actuator has greater power and more displacement and force than those of other transducer materials such as piezo elements or nickel alloys. Terfenol-D has greater power and more displacement and more force. A prototype of a spindle for the variable preload system using Terfenol-D was fabricated, and the axial force and displacement of the bearing were measured during a running experiment. In order to assess whether the proposed variable preload device can effectively apply preloading to the bearing, a comparative analysis was conducted between the theoretical and empirically obtained values of the bearing axial direction displacement. Through the comparative analysis, the real applicability of the proposed structure was confirmed.

中文翻译：

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超磁致伸缩材料Terfenol-D致动器机床主轴可变预紧力系统的研制

在机床主轴上施加轴承预紧力具有积极的效果，包括增加刚度、降低旋转噪音、提高轴精度、运行中的位置调整、防止滚动体共振和旋转滑动，同时显着延长轴承寿命。可变预紧力技术是一种根据主轴转速和加工条件适当改变施加在轴承上的预紧力来提高轴承性能的方法。在这项研究中，一种利用 Terfenol-D 致动器的新型可变预载方法比其他传感器材料（如压电元件或镍合金）具有更大的功率和更多的位移和力。Terfenol-D 具有更大的功率和更大的位移和更大的力。使用 Terfenol-D 制造了用于可变预紧系统的主轴原型，并在运行实验期间测量了轴承的轴向力和位移。为了评估所提出的可变预紧装置是否能有效地对轴承施加预紧力，对轴承轴向位移的理论值和经验值进行了比较分析。通过对比分析，证实了所提出结构的真正适用性。对轴承轴向位移的理论值和经验值进行了对比分析。通过对比分析，证实了所提出结构的真正适用性。对轴承轴向位移的理论值和经验值进行了对比分析。通过对比分析，证实了所提出结构的真正适用性。