Frictional Characteristics of Plain Bearing Guideway in Minute and Transient Motion

研究了平面轴承导轨在滑动运动的微小和瞬态区域的位移-摩擦力特性。滑动轴承导轨上的滑块质量为150 kg，由力操作定位机构驱动，进给分辨率为1纳米，进给刚度为几牛顿/纳米。滑块在不同的两种运动模式下往复进料，最大行程范围为16妈妈。一种是连续运动，进料速度为50 ~ 5000nm /min。另一种是步长为1 ~ 1000nm的阶跃运动。设定了与连续运动时相同的平均进给速度和行程范围。结果如下：1。进给方向反转后的位移-摩擦力特性在已知稳态区域之前存在一个瞬态区域，该区域中摩擦力随位移的增加而恒定。瞬态区域在进给方向逆转到几百纳米位移后开始，具有几牛顿/纳米的等效刚度，随后是零等效刚度的稳态区域。提出了位移-摩擦力特性曲线的数学模型。在由自然阶进运动组成的数控运动中，与一般公认的值相比，摩擦力可以很小，甚至是负值。小值和负值是由微小的步进运动中的振荡运动引起的。瞬态区与稳态区在位移与摩擦力特性上的差异必然影响数控运动的可控性

Displacement-frictional force characteristics of a plan bearing guideway was investigated in minute and transient region of sliding motion. A slide on plain bearing guideways was 150 kg in mass and was driven by a force-operated positioning mechanism with feed resolution of one nanometer and feed stiffness of several Newton per nanometer. The slide was reciprocally fed for maximum travel range of 16 mum in different two motion modes. The one was continuous motion in feed rate of 50 to 5000 nm/min. The other was stepwise motion in step size of 1 to 1000 nm. The average feed rate and the travel range were set up as same as the one in the continuous motion. The results are as follows.1. A transient region exists in displacement-frictional force characteristics after reversing of feed direction before the known steady state region in which frictional force is constant for increase in displacement. The transient region starts just after reversing of feed direction to a few hundred nanometer displacement, has the equivalent stiffness of several Newton per nanometer and is followed by the steady state region with zero equivalent stiffness.2. A mathematical model of the displacement-frictional force characteristic curve was proposed.3. In numerically controlled motion composed of stepwise motion in nature frictional force can be very small and negative in comparison with generally recognized value.4. The small value and negative one are caused by oscillating motion in minute stepwise motion.5.The difference between the transient region and the steady state one in displacement to frictional force characteristics definitely affects controllability of numerically controlled motion