초음파 이송 시스템의 동특성 해석에 관한 연구

Abstract

Methods of major transport system used in many industry field are conveyor belt, magnetic levitation system and indexing system. It is an indispensable device in many fields and especially it is very important in the factory automation. As the information and telecommunication industry starts to develop, the semiconductor and the optical industry are growing. In recent years, the faster network is required, the more demand of optical components is growing. However the conventional transport system is not adequate for transporting the precision optical component and the semiconductor. Since the magnetic fields cause damage to semiconductor and the contact force can cause scratch on the optical lens, the new transport system for transporting the optical component and the semiconductor without damage is required and the ultrasonic wave transport system has been proposed to replace the previous transport system. Actuators using the ultrasonic wave have been examined mainly in the USA and Japan since 1980. So far, most studies have developed for the purpose of reducing motor noises. In this thesis, the object transport system using the ultrasonic wave is developed for transporting precision elements without damage. Two ultrasonic wave generators are used. It consists of the piezoelectric actuator which uses the bolted langevin-type transducer(BLT) and the horns. The ultrasonic transport system is a device that transports objects on the elastic body using ultrasonic wave. When ultrasonic wave is applied to flexural beam, the flexural beam vibrates to excite air layer, which lifts up the object on the beam to transport. The principle of the object transportation is similar to the ultrasonic motor. The traveling wave which is produced on the flexural beam consists of the longitudinal wave and the transverse wave. Traveling wave of the ultrasonic transport system is theoretically analyzed. To observe a modeling equation for the vibration displacement of the flexural beam excited by two modes with the same frequency but a phase difference of 90˚, the normal mode expansion is used. The modeling equation on steady state response of ultrasonic vibration is expressed and natural frequency of flexural beam in each mode is also estimated using the Euler-Bernoulli theory. In addition, the transport direction of objects depending on phase difference and frequency is theoretically analyzed and is verified the theoretical results by experiments. The optimal traveling frequency to generate traveling wave on the beam is measured.