The influence of oil source pressure fluctuation on the waviness error of potassium dihydrogen phosphate in ultra-precision machining

The performance of potassium dihydrogen phosphate optical components is very sensitive to the waviness error. The time-varying oil source pressure leads to dynamic change in the eccentricity of hydrostatic slide; waviness errors can be induced on the finished surface of potassium dihydrogen phosphate consequently. The relationship between unsteady oil source pressure and the waviness errors of potassium dihydrogen phosphate is studied in this article. A mathematical model is built to calculate the displacement of hydrostatic slide induced by unsteady oil supply pressure. Moreover, a comprehensive fluid–structure interaction model is built to consider the influence of structural deformation of slide on the pressure distribution of oil film. Experiments are carried out to verify the proposed model. The calculated results agree well with the experimental results, and it is found that the calculated results show better accuracy when fluid–structure interaction is considered, which validates the reliability of this model.