Support Placement for Machine Tools Using Stiffness Model

The support stiffness model and the stiffness tuning technique are applied to a practical situation. The support stiffness model is integrated with finite element analysis (FEA) to simulate the rocking vibration mode. The support stiffness of a machining center prototype is calculated based on the support stiffness model. The stiffness tuning technique is used to determine the placement of support structures in the simulation. The calculated support stiffness is integrated into a three dimensional model as springs. Rocking vibration modes are obtained from simulations by using the support stiffness model. To compare the results, a simulation without the support stiffness model is conducted. An experiment is also conducted on the same machining center that is used in the simulation. Without the support stiffness model, the difference between the experimental and simulation natural frequencies was above 19%. In contrast, the difference is under 10% when the support stiffness model is included. The experimental and the simulation results were in good agreement with respect to the rocking vibration modes. These results demonstrate that incorporating the support stiffness model into finite element analysis increases the calculation accuracy of the rocking-vibration-mode natural frequencies. Consequently, the support stiffness model and the stiffness tuning technique are effective for designing the support systems of machine tools.