A Piezoelectric Servo Feed Drive for Electro Discharge Machining System Industrial Applications Using Linear Ultrasonic Motor

A new servo drive for electro discharge machining industrial applications is presented in this paper. The development processes of the servo feed drive have passed through three main stages. The first stage focused on design and development of a linear piezoelectric ultrasonic motor. The second one concentrated on development of an electronic driver and its embedded software. The integration, testing, and validation in electro discharge machining system, was the last stage of the development lifecycle. The linear piezoelectric ultrasonic motor consists of three main parts, the stator, rotor, and sliding element. The motor design process, basic configuration, principles of motion, finite element analysis, and experimental examination of the main characteristics are discussed in this paper. The electronic driver of the ultrasonic motor consists of two main stages, the booster and piezoelectric amplifier. The piezo amplifier consists of four output transistors, a push-pull and bridge, connected in order to achieve the necessary electrical parameters to drive and control the motor servo feed drive traveling speed. The essential experimental arrangement to implement and examine the developed ultrasonic servo feed drive in an electro discharge machining system was carried out. The initial results showed that the servo drive is able to provide: a reversible directional of motion, no-load traveling speed equal to 28 mm per s, maximum load of 0.78 N, a resolution <50 μm, and a dynamic time response <10 ms. The electron microscopic micro examination into the machined samples showed that: ultrasonic servo drive showed a clear improvement in the surface profile finish, a notable reduction in the stability, processing time, material removal rate, arcing, and short-circuiting teething phenomena. This was verified by assessing the electrode movements, the variations of the inter electrode gap voltage, current, and feedback control signals.