常规驱动进给系统（Conventional drive feed system，CDFS）的低速运行动态性能对机床的跟踪及定位精度、零件表面加工质量等有着非常重要的影响。非线性摩擦使CDFS在低速运行时出现爬行现象，从而严重影响其低速性能。为了克服CDFS的精度极限，提出一种新型的双轴差速式微量驱动进给系统（Dual-axis differential micro-feed system，DDMS）。在DDMS中，将常规"丝杠旋转型"滚珠丝杠副替换为"螺母旋转主驱动型"滚珠丝杠副，丝杠和螺母均由伺服电动机驱动。两个驱动轴（电动机驱动丝杠和电动机驱动螺母）的运动方向一致，速度几乎一样，通过"螺母和丝杠复合驱动"的差速式传动结构进行合成，可以使被驱动件在极低速下获得均匀、稳定的微量进给。和CDFS相比，丝杠和螺母都在高速下旋转，所以滚珠丝杠副的非线性摩擦干扰会显著降低。系统的摩擦特性用LuGre模型来描述，而且对滚珠丝杠传动副和直线运动导轨处的摩擦分别进行建模。通过仿真和试验研究发现，和CDFS相比，DDMS可以使工作台在极低速下获得稳定的速度响应和极高的分辨率。并且，DDMS在低速下的位置跟踪精度也比CDFS高。因此，提出的DDMS可以有效降低摩擦对系统的不利影响，为低速下驱动进给系统动态性能提高建立了基础。
杜付鑫
,
冯显英
,
李沛刚
,
岳明君
,
王兆国
. 一种新型双轴差速式微量进给系统的建模与分析[J]. 机械工程学报, 2018
, 54(9)
: 195
-204
.
DOI: 10.3901/JME.2018.09.195
Nonlinear friction in a conventional-drive feed system (CDFS) feeding at low speed is a main factor that contributes to feed-drive complexity. A novel dual-axis differential micro-feed system (DDMS) is developed to overcome the accuracy limitation of CDFS. Instead of the screw-rotating-type ball screw adopted in CDFS, the transmission component of the proposed DDMS is a nut-rotating-type ball screw. In this setup, not only the screw but the nut is also driven by a servo motor. By superposing the two high-speed rotary motions (motor-drive-screw and motor-drive-nut) with equivalent high velocity and the same rotating direction through the novel transmission mechanism, the nonlinear disturbance from the ball screw can be reduced significantly. The friction characteristics of the system are described based on LuGre model which is composed of models of individual feed drive components such as "nut rotating type" ball screw and LM guide including their friction behaviors. The simulation and experimental results show that, comparing with CDFS, DDMS enables the table feeding at a lower steady velocity. Besides that, improved tracking accuracy can be obtained when using the DDMS. Therefore, the proposed DDMS can effectively inhibit the disadvantageous influence of friction and lay the foundation for improvement of dynamic performance of servo system at low speeds.
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