Kinematics Performance and Structural Analysis for the Design of a Serial-Parallel Manipulator Transferring a Billet for a Hot Extrusion Forging Process

Abstract

To reduce the downtime and optimize the use of energy and manpower, a serial-parallel manipulator is designed for transferring heavy billets for a hot extrusion forging station. With the purpose of increasing the structural rigidity and restricting the end-effector (a gripper) so that it always moves in parallel with the ground surface, parallel links are added in between the serial links of the manipulator. This modification of the conventional structure must be considered in the modelling and analysis of the design. This paper addresses a methodology to investigate the kinematics performance and strength analysis of the designed robot. With respect to the parallel links, the constraint equation is derived and put together with the kinematical model. Based on the entire model that is formulated, the inverse kinematics, the transferring time, the reachable workspace, the degree of dexterity and the manipulability index are analysed and discussed to demonstrate its kinematical performance. In addition, to investigate the structural characteristics of the end-effector module, the static displacement and stress distributed on module's components are computed and simulated using the computer-aided finite element method (FEM). These research results are effective and useful in assessing and improving the robot's design.