Design and application of a gripper for microparts using flexure hinges and pneumatic actuation

摘要

In this paper a new gripper for microparts with dimensions of 200 to 3500 micrometers is presented that is especially designed for industrial suitability. This covers beside repeatability of position and force robustness of the mechanical structure, simple interfaces of the gripper's control structure and long service life. The minimization of the grippers size and weight is no superior objective because today's precision robots usually have sufficient payload and working space. To achieve this goal well tested technology from micro- an macro handling devices are combined. The new gripper is made up of a symmetrical guiding mechanism based on flexure hinges of aluminum and it is driven by a pneumatic actuator. In the first step the maximal gripping force can easily be limited by the working pressure of the pneumatic actuator. Standard open/ close commands provide a robust control interface. The technology of pneumatic actuation is well known and reliable. Since minimization of size is not the primary goal, a long service life can be achieved by limiting the mechanical stress in the flexure hinges. A skirt of aluminum protects the guiding device against destruction caused by collisions. The new gripper has been realized and has been used in a microassembly station where it proved its reliability and robustness in thousands of gripping cycles thus demonstrating its industrial suitability. An experimental evaluation was carried out in order to assess the properties of the gripper.