Abstract:

：A structure scheme for a novel 3T2R gantry hybrid machine tool (HMT) is proposed. In this scheme, a novel 2-RPU&2-UPS parallel mechanism is proposed as the machine tool main mechanism, which can realize two-dimensional translations alongX, Z-axis and two-dimensional rotations aboutX, Y-axis, with assistance of aY-axis direction linear guide, 5-axis machining can be realized. The three-dimensional translations and two-dimensional rotations motion of this machine tool are analyzed based on screw theory. The DOF of the mechanism is calculated, and the driving joints are chosen and discussed. The motion singularity is analyzed and the parameter design conditions are presented to decrease motion singularity. The reverse solution of position analysis for this machine tool is presented. On this basis, the Jacobian matrix and acceleration equation are derived, and the inverse position, velocity and acceleration of this machine tool are obtained. The dynamics model is established on the basis of the principle of virtual work and the kinematics model of this machine tool, and the simulation of mechanism dynamics is implemented by using Adams software. The simulation results testify the validity of the analytic model.

Key words: dynamics, kinematics, principle of virtual work, singularity, gantry hybrid machine tool