A Study on Ultra-precise Positioning over A One-millimeter Stroke Using Differential Ball Screw

本研究的目的是利用差动滚珠丝杠实现一毫米行程的纳米级分辨率的简单定位机构。采用滑动式螺杆的差动螺杆机构，定位精度高。但目前还没有利用滚珠丝杠实现差动机构超精密定位的尝试，因此还没有对其在纳米级范围内的定位性能进行讨论。螺旋轴上有A、B两部分滚珠丝杠，其公称导程分别为P_A=2.00 mm和P_B=1.95 mm，差动导程(d=P_A-P_B)为0.05 mm。对加工出的滚珠丝杠的导程误差进行了精确测量，并对差动滚珠丝杠的定位性能进行了评估。明确了滚珠丝杠A和B的导程误差相位不同，但估计…通过调整两个螺母之间的相位，可以减小更多的差动导联误差。为探讨滚珠丝杠的定位性能，设计并制造了滚珠丝杠定位机构样机，并对其进给特性和定位特性进行了详细的测量。在实验结果的基础上，明确了丝杠的跳动误差和直线导轨的摩擦力是影响差动性能的关键因素，并对定位机构进行了改进，避免了上述干扰，构建了1 mm行程的超精密定位系统。为了消除螺旋轴跳动误差的影响，设计了柔性元件。设计了V形平槽滚动导轨，以减小导轨元件的摩擦力。修正后的工作台行程误差完全消除了跳动误差的影响。确定了其典型行程误差为0.9μm，波动小于0.5μm，在微观范围内获得了转台位移与转角成正比的线性特性，比例系数与设计值相符。在上述实验结果的基础上，建立了差动滚珠丝杠的定位机构结构，以展示差动滚珠丝杠的能力。较少

This study aims at realizing a simple positioning mechanism with nanometer level resolution over a one-millimeter stroke using a differential ball screw. Differential screw mechanism using a sliding type screw has been used for positioning with fine resolution. However, there has never been any trial to realize ultra-precise positioning by differential mechanism using ball screw, so that its positioning performance in nanometer range has not been discussed.A differential ball screw with outer diameter of 12 mm was manufactured on trial. The screw shaft has two part of ball screw, part A and B, in the same axis, whose nominal leads are P_A=2.00 mm and P_B=1.95 mm, so that the differential lead (d=P_A-P_B) is 0.05 mm. The lead error of the manufactured ball screw was measured precisely, and the positioning performance of the differential ball screw was estimated. It is clarified that the phase of lead error is not identical between the ball screw A and B. However, it is estimated that th … More e differential lead error can be decreased by adjusting the phase between the two nuts. To discuss the positioning performance of the ball screw, a prototype of positioning mechanism was designed and constructed, and the feed or positioning characteristics were measured in detail. On the basis of the experimental results, it is clarified that the run out error of the screw shaft and the friction of the linear guide ways become critical disturbances for the differential performance.The positioning mechanism was revised to improve the performance avoiding the above disturbances, and an ultra-precise positioning system over a one-millimeter stroke was constructed. Flexible elements are devised to eliminate the effect of run out error of the screw shaft. Rolling guide ways using V-flat shaped groove are designed to decrease the friction of the guide way elements. After the revisal, the effect of run out error is completely eliminated from the travel error of the stage. It is confirmed that the representative travel error is 0.9 μm with the fluctuation less than 0.5 μm. Linear characteristics are obtained in microscopic range that the table displacement is proportional to the rotational angle, and the proportional coefficient agrees with the designed value. On the basis of the above experimental results, a construction of positioning mechanism is established to exhibit the ability of the differential ball screw. Less