Design of a dynamic damper for a high precision numerical control machine

The paper presents the design of a dynamic damping device to reduce the vibration amplitude of a Cartesian robot prototype used for high-precision Computer Numerical Control (CNC) machining under high accelerations. Firstly, a Finite Element (FE) model of the entire machine was created in the MSC Apex CAE environment. Modal and frequency response analyses were performed, considering the machine in its most critical configuration. The analyses showed that the relevant vibration modes are the first two, i.e. column bending he proposed solution foresees a mounting on the column top, cylindrically shaped springs working in shear mode, thus making the stiffness independent of the angular coordinate, and a mass ratio (μ) of about 1% for compactness. The damper shifted the resonance frequencies of both modes and reduced the highest vibration amplitude by 50%.