Development of Miniature Gripper Using Buckling Phenomenon of Long Column

This paper developed the element technologies for commercialization of the miniature gripper which was considered in the previous paper. There, making use of buckling phenomenon of a long column was tried for the opening and closing mechanism of the miniature gripper. As a result, it was verified which was useful as the opening and closing mechanism of the fingers because it does not need a special mechanism for displacement enlargement, so unique, original and simple. The results obtained are as follows. (1) In the manufacturing of a multi-finger hand, the way for a blank cut from the elastic plate by wire-cut electrical discharge machine to be bent like a telescopic umbrella folded was devised. According to the way, not only will the finger with uneven division or variant be manufactured, but also could further miniaturization be made in similarity. (2) As for the adjustment technique of the gripping force, a positioning nut enabled translational displacement of a screw axis nut to be mechanically set. Consequently, the gripping force changes corresponding to the closing amount of the finger with 0 to maximum (solid contact). (3) In the application of this opening and closing mechanism, a pair of electric tweezers, which finger is automatically opened and closed approximately 5mm by one way rotation drive of a motor, was prototyped. Reciprocating translational displacement h₀ of the hand center was realized by simple spherical cam mechanism comprising two small steel balls only with eccentricity each other which are in contact. Radii r_c and r_f of the steel balls of the prototype are 0.5mm, maximum lift h₀ 0.3mm and eccentricity 0.357mm.