Parallel gripper

Fig. 6.60. Parallel gripper with interchangeable jaws [88] actuators...

SM actuators may have very many different shapes and offer a variety of shape changes (i. e. actuator strokes). This property can be exploited so as to adapt the SM elements shape to the actuating task. As an application example, a miniature parallel gripper with electrically heated SM wires integrated into its mechanical structure was presented. Further on the performance of pseudo-elastic shape memory flexure hinges in parallel robots for micro-assembly tasks was shown. The future opportunity for thin-fllm SM actuators to drive micromechanical systems and devices was demonstrated by a miniature silicon gripper. 

If the duplex cell is used, the assembly tasks will be distributed over two handling units. These always have the full variant flexibility. With regard to function, the cells need not be completely flexible. They must be able to carry out only a part of the assembly tasks. The function size of the multiple grippers (in the case of unchangeable variation of the functions) can be increased by parallel assembly with two independent handling devices. Even shorter cycle times can be achieved than with the flexible cell. 

Assumptions A uniform cylindrical peg has been selected. It is assumed that the peg itself is rigid and undergoes negligible elastic deformation during the insertion process. This assumption will be established to be valid during the finite element study to be reported separately. It is further stipulated that coefficient of friction (/x) between the gripper jaws and the peg is the same at each point of contact. The insertion is attempted when the axes of the peg and hole are parallel/co-axial. A double v-block jaw configuration has been selected after considerable deflection analysis of other forms. 

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