Development of an Assembly System by Using of the Effects of Ultrasonic Vibration

点击翻译按钮获取中文摘要

This study aims to realize an assembly system with a new method for inserting operations of the parts with very close clearance.In assembly process, it is difficult to realize full automation of parts insertion with close clearance less tan several micrometers because of jamming or wedging phenomena in the mating process. Very carefully designed mechanisms such as RCC mechanisms and high level control methods as state feedback control with stochastic models have been used in these processes with flexible robots. However, very close mating occasionally ends in failure even in use of above sophisticated systems. This is why the reciprocal force actions between peg and hole are considered as passive informations for the attainment of control in the traditional treatment.In this study, it is attempt to use the reciprocal force actively by means of the application of ultrasonic vibration onto the surface of the parts. Longitudinal vibration or bending vibration of a peg in inserting process decreases apparent friction at the contact point between the peg and a hole and generates surface force which drives the peg into the hole part as in a linear ultrasonic motor. Inserting motion becomes smooth and easy by the application of ultrasonic vibration to one of the peg or the hole to be mated. As for some concrete methods of the application of ultrasonic vibration onto the inserting process, periodical impact method and point supporting method for vibrating elastic bodies are invented. A prototype automatic assembly system with a scara type robot was developed in which the combination of longitudinal and bending vibration were applied. Smooth mating with the clearance of less than several micrometers was realized under rough control of about several hundred micrometers.