Abstract: Type synthesis of forging manipulators is studied deeply and systematically based on the screw theory and practical engineering, several hybrid serial-parallel forging manipulators’s lifting mechanisms are configurated. Lifting and pitching motions of these lifting mechanisms are realized by the planar five-bar mechanism, lateral translation is realized by the lateral translation system of a typical DANGO & DIENENTHAL(DDS) forging manipulator, and motions of yawing and back-and-forward translation are realized by suspension system. Therefore, these lifting mechanisms are decoupled and can be given consideration in practical application. According to practical engineering experience, it is known that the suspension system is the parallel mechanism composed of forward suspension part and back suspension part. And forward suspension part contains two symmetrical suspension rods, back suspention part contains either one suspension rod or two symmetrical rods. Therefore, type synthesis of the forging manipulators can be divided into two situations corresponding to the number of the rods that back suspension part contains. Then, four configurations of the parallel mechanism are obtained by using the constraint-synthesis method based on the screw theory, and three of them are non-overconstrained mechanisms, which has extensive application prospect.

Key words: Forging manipulators, Non-overconstrained, Parallel manipulator, Screw theory, Type synthesis