A PARALLEL LINK END-EFFECTOR FOR SCANNING ELECTRICAL-DISCHARGE MACHINING PROCESS

Because a parallel mechanism has a high-frequency response, multiple d egrees of freedom (DOF), and high stiffness, it can be applied to an e nd effector for electrical discharge machining (EDM) with a scanning m otion. A prototype has 3 DOF: two tilting angles around the x- and y-a xes, and the movement in the z-direction. It consists of, a base plate , a stage, a constraint link, and three inchworm devices that act as l inks. The inchworm devices are connected with the stage and the base p late. The z-position and inclination of the stage are changed by adjus ting the length of the inchworm devices. The electrode feeding is cont rolled by the combination of the steplike movement with the inchworm d evices and continuous extension of piezos. The frequency response of t he stage by the continuous extension of the piezos is up to 200 Hz. Th e positioning accuracy of the end effector is less than 30 mu m in hei ght and 0.04 degrees in inclination. Some examples of EDM by the scann ing motion are demonstrated. (C) 1998 Elsevier Science Inc.