Preliminary Studies for Precision Polishing of Micro Structured Mold by Using Three-Dimensional Low Frequency Vibration Utilizing Piezoelectric Actuator Incorporated with Mechanical Amplitude Magnified Mechanism

Abstract

Precision polishing of micro structured mold has been highly demanded due to the increasing demand for optics manufacturing such as solar optics and DVD pick-up system, and medical devices like μ-TAS [1-5]. These micro structured molds usually have complicated structure and need to be polished after grinding or cutting. In this paper, a three-axis low frequency vibration (3DLFV) polishing actuator is proposed. The actuator consists of 3 multilayers-stacked piezoelectric actuators (PZT) incorporated with mechanical amplitude magnified mechanism. The mechanical amplitude magnified mechanism utilizes mechanical structures which is also called mechanical transformer, which is capable to elongate the stroke of the piezoelectric actuator to almost 13 times to 225 m. By driving the PZT in sine wave with particular phase different, dual direction trajectory such as circle can be achieved, and is proved to be effective in precision mold polishing [8]. With the 3DLFV actuations, polishing tool with polyurethane is actuated to stir the diamond slurry to achieve polishing effects. In polishing experiments, nickel-plating metal used as work pieces are polished with diamond slurry and the polished depths are measured. As a result, three-axis low frequency vibration (3DLFV) is proposed and developed. Its capability in polishing precise mold is studied and confirmed to be efficient. In order to improve the work piece surface, a dwell time control method can be applied with the 3DLFV.