Research On Key Techniques Of Fast Tool Servo Turning

Complex-shaped surfaces and micro-structures used in optical parts,such as Micro-lens arrays, holographic lens, diffraction parts and gradient lens, are more and more widely applied, but it's difficult to manufacture them by traditional fabrication methods. Whereas Fast Tool Servo(FTS) turning system driven by Voice coil motor is particularly suitable for machining them efficiently and high qualitatively, owing to its high frequency response, ultra-precision movement and high stiffness.In this dissertation, according to the need of FTS, surface-shape generation, morphology simulation, servo control, system construction and other aspects of research were studied. The main contents are expressed as follow:1) Surface-shape generation: By simulating the tool spiral movment in face turning process, three-dimensional surface-shape of micro-structure is drawn, and surface-shape data is obtained. The speed, acceleration and frequency response requirements are calculated, for they should be met by servo turret to complete the machining, as the evaluation criterion for workpiece machinability, and as the guidance for the optimization of turning parameters.2 Topography simulation: Due to the tool tip radius, the actual surface machined by using the surface-shape data is different from the theoretical one. According to the surface-shape data, processing parameters and tool tip radius, residual area height is calculated for the surface machined at grid points dense enough, theoretical surface roughness of workpiece is calculated, and a simulation package based on MATLAB platform is developed for the surface-shape generation and morphology simulation over complex surface-shape/structure3) Voice coil motor control: To improve the shortcomings of the classic PID control method, the advantages of active disturbance rejection control(ADRC) for voice coil motor is explored, and a method to adjust ADRC parameters based on genetic algorithm is given.4) FST turning system constructing: Based on the surface-shape data, topography simulation, and control method, a FTS turning system is constructed and its validation is tested.