Analysis of Resonance of a Surface Grinder

The structure of a surface grinder comprises of a base, all the other machine members like column, the reciprocating table, the grinding wheel, spindle and spindle motor are all supported on the base. In the design of one such surface grinder waviness was observed on the ground surface. It has become necessary to investigate into the behavior of the machine under working conditions. Investigation showed that some machine components are getting into excessive vibrations. This waviness could arise due to vibrations of the machine structure while working. It is observed that the cause of such waviness is due to resonance which leads to abrupt vibrations that intern affect the surface finish and the structure itself. The present project focuses on redesigning of the surface grinder model which has maximum working speed of 3000 rpm. In order to avoid resonance the dimensions are changed in such a way that the natural frequency of the model is either reduced or increased. One method of investigation is through the experimental approach. However this approach is expensive and requires good amount of lead time. The present project employs Finite element method for investigating into the vibration characteristic of the machine. Using the FEM, surface grinder is modeled and analyzed to find out the weak links causing vibrations by modal analysis method. The design of the weak links is improved and the analysis is repeated to bring down the vibration to admissible level. The harmonic analysis is also carried out to find out the vibration amplitude and velocity. Analytical procedure is used to confirm the predicted FEM results.