Abstract: The load inertia ratio is important for performance analysis and design of computer numerical control (CNC) machine tools feed drive system. Under the high-speed and high-precision trends of machine tool, the optimization of the load inertia raitio become crucial. The systematic analysis of the relationship between the load inertia ratio and performance of its feed drive system is necessary, and a precise design method for inertia ratio is asked for. Using double mass mechanical model, an approach combined analytic and numerical simulation is presented. The relationship between inertia ratio and energy matching efficiency, relationship between inertia ratio and controller gain, and closed loop frequency characteristic, anti-disturbance dynamic stiffness under semi-closed and fully-closed loop control structures are analyzed respectively. Based on these analyses, a brief description of design approach is given. For CNC machine tool designer, methods to choose the optimal load inertia ratio based on specific performance requirements under multi-factors are formed, which bare theoretical and practical engineering values.

Key words: CNC machine tools;feed drive system;load inertia ratio;controller gain limit;anti-disturbance dynamic stiffness