A novel long range fast tool servo for diamond turning

Single point diamond turning (SPDT) based on tool servo system is one of the significant techniques to fabricating the optical freeform surfaces. The conventional fast tool servo (FTS) actuated by piezoelectric actuator has the problem of short stroke, while the drawback of the slow tool servo (STS) is low frequency response. This paper briefly presents a novel long range fast tool servo (LRFTS) with high frequency response and long stroke. The total stroke can reach up to 30 mm. The LRFTS uses a voice coil motor as the actuating element and air bearings as the guide mechanism. The LRFTS utilizes a linear encoder to measure the displacement of the tool for closed loop control. The servo performance of the LRFTS system's amplitude and frequency response is analyzed. The physical model of the LRFTS is identified. A series of experiments have been conducted to verify the performance of the designed LRFTS. Micro-lens array fabrication experiments on an aluminum part are conducted using the designed LRFTS. The factors influencing the surface roughness have been analyzed.