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

高速进给传动正在被引入加工中心，以实现高速、高产加工。高铅滚珠丝杠传动通常用于实际应用，因为它们具有成本效益和对诸如切削力等干扰的鲁棒性。然而，滚珠丝杠传动由于通常用于高速进给传动的滚珠或滚子导轨的低阻尼而遭受振动。本文研究的是一种双驱动机构，即在驱动台上既有副驱动机构，又有常规的滚珠丝杠驱动机构。在我们的研究中实际使用的执行器是一个直线电机和一个摩擦控制导轨（智能导轨）。通过模拟和实验得出以下事实：(1)直接反馈给工作台执行机构（主动阻尼器）和电机（常规速度反馈）的速度不能独立控制振动杆。相反，电机和工作台的相对速度反馈可以独立控制振动杆。(2)速度反馈给工作台执行器，可以从运动控制的角度控制零位。(3)两质量振动系统的阻尼比由惯量比和速度反馈增益决定。双作动器的相对速度反馈在大惯性比范围内提供了高阻尼。(4)由于反馈给工作台执行机构的相对速度不增加导向力，可以降低主运动电机的功率。(5)当子驱动器饱和时，非线性速度反馈控制比线性反馈控制具有更好的阻尼抑制振动性能。结论(1)-(3)有助于高种子和高精度饲料驱动的设计性能，结论(3)-(5)有助于整个系统的成本效益和紧凑性。

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.