Coordinated kinematic modelling for motion planning of heavy-duty manipulators in an integrated open-die forging centre

Abstract

An integrated open-die forging centre can realize programmed incremental forging processes to improve safety and efficiency; the centre consists of a forging press and one or two heavy-duty manipulators. This paper focuses on the coordinated kinematic modelling of the integrated system. First a newly designed serial—parallel forging manipulator is presented and the closed-form inverse kinematic solution is derived based on homogeneous co-ordinate transformation. Then the deformation of the forged workpiece is investigated by the spread coefficient method of plastic deformation theory, and the relation between the motion of the holding end of the workpiece and the movement of the upper die is formulated. Finally, the coordinated kinematic modelling of the integrated system is established, where the press and the manipulator are coordinated in movement. Simulation of a typical open-die forging process shows that the gripper of the manipulator should have good compliance abilities in horizontal and vertical directions during forging; however, it should have high rotation stiffness with respect to the transverse axis. The automatic programmed forging plan and coordination control strategy can be pre-designed based on this model.