Study On Ultra-Precision Feeding System And Its Application In Grinding Machine

Creeping, low resolution and response speed are key factors of grinding. This article based on project 'piezo-actuated ultra-precision feeding system applied to grinding', combine with the requirements of grinding, presents an ultra-precision feeding system which is made up of piezo-actuator, flexure hinge, closed loop control system and detecting system. Take MCU as the central processor of closed loop control system. Connecting coarse stage (large stroke) and precision stage (high resolution) in series to form a dual-stage feeding drive system, feeding precision achieved±0.03μm.Some researches have been done included:(1) A flexure-hinge-based guide unit is designed according to traditional mechanics and the character of the piezo stack, analytical and finite element models of the flexures are presented to optimize design. Put a pre-load on flexure hinge to keep piezo stack from being damaged by pull-stress. This guide unit combined with piezo stack makes up the ultra-precision feeding platform.(2) The dynamic model of the platform is established. Based on this model and characteristics of piezo stack, a closed-loop control system is designed, including A/D module, D/A module, interface processing module and so on. The instruments, such as power supplier, sensor and so on are configured according with the demands and cost. The hardware and software of the system is designed obey to the rule of modularization.(3) According to the character and demands of grinding, software of control system is specially designed, it sets two working modes, flow of working is described in detail.(4) Experiments for testing the performance of ultra-precision feeding system is designed to copelete the test of performance, for example, the test of static and dynamic performance.It is displayed that the ultra-precision feeding system can meet the requirements of high stiffness and accuracy. The flexure has a 5.2N/μm stiffness and 440Hz natural frequency. The system has a 30μm stoke , 0.01μm resolution,±0.03μm precision and static stiffness of 207N/μm. It is proved that the system has a good performance with low cost, small volume, high reliability and friendly interface. The system has been completed, and it is being tested in the factory at the present time.