Abstract: The large amplitude compliance behavior of the parallel style forging manipulator is investigated during the initial stage of the workpiece drawing. The Lagrangian approach is used to establish the dynamic equations of the forging manipulator system, in which the change of the mechanism geometry and the nonlinear stiffness induced by the large amplitude motion are taken into consideration. The effects of the design parameters on the dynamic behavior of the forging manipulator are studied, including the clamp mass, the initial height of the air chamber and the area of the damping hole of the vertical buffer cylinder. Results show that the vertical force exerted to the clamp increases with the decreasing of the initial height of the air chamber of the vertical accumulator and the damping hole of the vertical buffer cylinder. But the damping hole of vertical buffer only works in a certain range. The similar trend also can be observed for the horizontal force transmitted to the clamp due to the coupling character of the manipulator mechanism, although the influence of the vertical parameter is comparatively limited. The forces in both directions marginally increase with the increasing of the clamp mass.

Key words: Compliance control, Dynamics, Forging manipulator