Structure design and characteristics analysis of a cylindrical giant magnetostrictive actuator for ball screw preload

Abstract

In order to achieve automatic adjustment of the double-nut ball screw preload, a magnetostrictive ball screw preload system is proposed. A new cylindrical giant magnetostrictive actuator (CGMA), which is the core component of the preload system, is developed using giant magnetostrictive material (GMM) with a hole. The pretightening force of the CGMA is determined by testing. And the magnetic circuit analysis method is introduced to calculate magnetic field intensity of the actuator with a ball screw shaft. To suppress the thermal effects on the magnetostrictive outputs, an oil cooling method which can directly cool the heat source is adopted. A CGMA test platform is established and the static and dynamic output characteristics are respectively studied. The experimental results indicate that the CGMA has good linearity and no double-frequency effect under the bias magnetic field and the output accuracy of the CGMA is significantly improved with cooling measures. Although the output decreased with screw shaft through the actuator, the performance of CGMA meets the design requirements for ball screw preload with output displacement more than 26 μm and force up to 6200 N. The development of a CGMA will provide a new approach for automatic adjustment of double-nut ball screw preload.

摘要

为实现双螺母滚珠丝杠副预紧力的自动调整, 提出一种磁致伸缩滚珠丝杠副预紧系统。以中空 的超磁致伸缩材料(GMM)为核心, 完成了新型环状超磁致伸缩致动器(CGMA)的结构设计; 通 过测试数据确定了CGMA 的预压力; 利用磁路分析法对穿入丝杠后致动器内部磁场进行了分析计算; 为抑制发热对磁致伸缩输出的影响, 提出了直接冷却发热源的油冷散热方法。对自行研制的预紧用致 动器输出的位移和力进行了实验研究, 结果表明, 偏置磁场可以消除CGMA 的倍频效应, 改善线性 度; 油冷散热可有效减小热变形影响, 使CGMA 磁致伸缩输出特性稳定; 穿入滚珠丝杠后致动器的 输出减小, 但在工作区间内输出位移可达26 μm、输出力超过6200 N, 满足所选滚珠丝杠副预紧系统 设计要求。新型CGMA 的研制为双螺母滚珠丝杠副预紧力的自动调整提供一种新的方法。