Configuration design and accuracy analysis of special grinding machine for thin-walled small concave surfaces

Abstract

In this work, a special grinding machine tool using a small ball-end grinding wheel is designed to achieve ultra-precision grinding of complex components with small concave surfaces. A comprehensive error propagation model is established, considering kinematic errors, setup errors and structure parameters. Sensitivity analysis is performed by the Sobol' method to quantify the relationship between the errors, structure parameters and geometric accuracy of the machine tool. On this basis, error allocation is carried out, and the inclination angle of the grinding wheel spindle and the working range of the C-axis are optimized to reduce the influence of the setup errors on machining accuracy. Then, the predicted geometric accuracy of the machine is 0.3 μm, contributing only to half of the profile accuracy requirement for peak-to-valley PV < 0.6 μm. The developed machine is tested by grinding ψ-shaped components to achieve an average profile accuracy of 0.589 μm and a surface roughness of 40.2 nm, which means that the machine tool developed by the error model and sensitivity analysis meets the design requirements. By compensating the setup errors and linear errors based on the error propagation model, the profile accuracy of the ground component reaches 0.34 μm, indicating that the error propagation model can accurately represent the geometric accuracy of the machine tool.