Two-fingered micro hand for micro assembly in micro factory

摘要

Micro-factories have great potential for innovating manufacturing systems for small products. They were initially proposed by the Mechanical Engineering Laboratory (MEL) in 1990, and since then, the Micro Machine Center (MMC) and MEL have been involved in R&D on micro-factories at AIST, MITI. A prototype of micro-factory in MEL was presented at Oct. 6, 1999. The micro-factory means a miniaturized factory. The micro-factory, due to the miniaturization of its constituent machining tools, has realized not only energy conservation, space conservation and raw material conservation, but also features an excellent flexibility when rearranging constituent of machining tools in conformance with various specifications. In addition, it considerably decreases the devices and its energy consumption for the attainment of a good working environment in the aspects of temperature, humidity and cleanliness. The micro-factory of machining integrated as a desktop type consists of a lathe, a milling machine and a press for ultra miniature machining tools, also an arm for feeding small parts, and a two-fingered micro-hand for assembling tools. The paper mainly describes on the two-fingered micro-hand for micro assembly in the micro-factory and an assembly process of a pivot ball bearing by the micro hand. The two-fingered micro-hand has two fingers which are controlled with multi-degree motion and high accuracy positioning. A parallel mechanism is applied to the drive mechanism in the micro hand. Also, a flexure hinges is used to passive joint in the parallel mechanism. A compact micro hand is achieved with 65[mm] in height and 48[mm] in outside diameter. Its available workspace is 100 × 100 × 30[μm] and the resolution is 1 [μm], when each piezo actuator has 36[μm] elongation in maximum. A pivot ball bearing with an outside diameter of 900[μm] and a shaft length of 3[mm] can be assembled by the two-fingered micro-hand.