レーザ偏心加工に用いる磁気・静圧ハイブリッドレンズ駆動アクチュエータ

概要

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This paper describes a magnetic/aerostatic hybrid lens drive actuator to realize off-axis laser beam cutting. In the off-axis cutting, the distance between an assist gas nozzle axis and a laser beam axis is speedily and widely controlled in order to improve the removal capability of the molten material by an assist gas jet. The proposed actuator supports a triangular-shaped lens holder with three aerostatic bearing pads placed under each vertex of the lens holder and drives it in two translational and one rotational directions with three pairs of electromagnetic actuators not facing each other. In order to realize the stable positioning of the lens holder in a wide range, a nonlinear positioning control method of the three pairs of electromagnetic actuators is proposed. Furthermore, a disturbance compensation method is discussed to cancel the inertia force on the lens holder while the lens actuator body is accelerated and decelerated by a laser cutting machine. Experimental results show the prototype actuator possesses a positioning stroke of ±1mm within 3μm of tracking error and bandwidths of nearly 90Hz in the controlled directions. In the acceleration test at a maximum acceleration of 4G driven by a linear motion system, the prototype actuator maintains the relative displacement between the lens holder and the actuator body within 30μm.