High Speed and High Precision Feed Drive of NC Machine Tools by Dual Actuation

高速进给驱动正被引入加工中心，以实现高速、高生产率的加工。高导程滚珠丝杠驱动器通常用于实际应用中，因为它们具有成本效益，并且对切削力等干扰具有很强的耐用性。然而，滚珠丝杠传动由于高速进给传动中常用的滚珠导轨或滚子导轨的低阻尼而受到振动的影响。本研究针对的是一种双驱动传动，它的传动台上除了有传统的滚珠丝杠传动机构外，还有副执行器。我们研究中使用的实际执行器是直线电机和摩擦控制导轨(智能导轨)。通过仿真和实验，得出以下结论：(1)直接对工作台执行器(主动阻尼器)和电机(传统的速度反馈)进行速度反馈不能独立控制振杆。反之，电机和工作台的相对速度反馈可以独立控制振杆。(2)从运动控制的角度看，对工作台执行器的速度反馈可以控制零位置。(3)双质量振动系统的阻尼比由惯性比和速度反馈增益决定。双驱动器的相对速度反馈在较宽的惯性比范围内提供了较高的阻尼。(4)由于对工作台驱动器的相对速度反馈不增加导向力，可以降低主运动电机的功率。(5)当子驱动器存在饱和时，非线性速度反馈控制可以提供比线性反馈控制更好的减振性能。结论(1)-(3)有助于高种子、高精度进给传动的设计性能，结论(3)-(5)有助于提高整个系统的性价比和紧凑性。

High speed feed drives are being introduced to machining centers for aiming high speed and high productive machining. High lead ballscrew drives are generally used in practical applications, as they are cost-effective and robust to disturbances such as cutting forces. However, ballscrew drives suffer from vibration due to low damping of ball or roller guideways which are commonly used in high speed feed drives. This study deals with a dual actuation drive, which has sub actuators in the drive table as well as conventional ballscrew drive mechanism. Actual Actuators used in our study are a linear motor and a friction control guide (an intelligent guide) . Following facts are obtained by simulations and experiments.(1) Direct velocity feedback to the table actuator (active damper) and to motor (conventional velocity feedback) can't control vibration poles independently. On the contrary, relative velocity feedback of motor and table can control vibration pole independently.(2) Velocity feedback to the table actuator can control zero positions from motion control view.(3) Damping ratio of 2 mass vibration system is decided by inertia ratio and velocity feedback gain. Relative velocity feedback to dual actuators provides high damping in wide range of inertia ratio.(4) As relative velocity feedback to the table actuator doesn' t increase guide force, the power of main motion motor can be lowered.(5) If saturation of a sub actuator exists, nonlinear velocity feedback control may offer better damping performance to suppress vibration compared to linear feedback control. The conclusions (1)-(3) contribute to design performance of high seed and high precision feed drive and the conclusions (3)-(5) contribute to cost-effectiveness and compactness of the total system.