精密磨床辅助工件平台的设计

Design of an auxiliary work-piece platform of a precision grinder

为补偿精密磨床砂轮的振动对加工精度的影响,设计了一台作为磨床辅助进给装置的微进给工件平台。该工作平台采用压电陶瓷作为驱动机构,弹性铰链作为预紧机构。为了避免压电陶瓷驱动器受到弯矩的作用,在压电陶瓷驱动器的顶部和动平台之间加了一个球形接头。利用弹性铰链的预紧力,实现驱动器和动平台之间的赫兹接触。高精度的电容式位移传感器用来测量动平台的实际输出并形成反馈控制系统。为了消除压电陶瓷的迟、蠕变等非线性,采用了非线性PID控制算法来实现微进给平台的实时控制。采用跟踪微分器对信号进行跟踪并得到其微分信号,提高了控制系统的鲁棒性。通过计算机仿真了所设计的微进给平台的特性和闭环控制算法的有效性。

For the sake of compensating upon the effect of processing precision affected by the vibration of grinding wheel of precision grinder, a micro-feeding work-piece platform, which serves as an auxiliary feeding device of the grinder, has been designed. This working platform adopted piezoelectric ceramics as the driving mechanism and elastic hinge as the pre-tightening mechanism. For the sake of avoiding the piezoelectric ceramics driver to be suffered from the effect of bending moment, a spherical joint is added between the top of piezoelectric ceramics driver and the moving platform. Utilizing the pre-tightened force of elastic hinge, to realize hertz contact between the driver and the moving platform. High precision capacitance displacement sensor is used to measure the actual output of moving platform and formed a system of feedback control. In order to eliminate the nonlinear features of lag and creep of piezoelectric ceramics, a nonlinear PID controlling algorithm is adopted to realize the real time control of the micro-feeding platform. By adopting the tracing differentiator to carry out trace against the signal, could enhance the robustness of controlling system. The characteristics of micro-feeding platform being designed and the effectiveness of loop-locked controlling algorithm are simulated by computer.