On-machine contact measurement for the main-push propeller blade with belt grinding

A main-push propeller blade (MPPB) with a free-form surface has great volume and weight, severe casting deformation and pore shrinkage, and loading and unloading difficulties. It is thus difficult to measure and evaluate accurately for manufacturing, especially for precision grinding. On-machine contact measurement (OMCM) is proposed in this paper and has been used successfully for belt grinding equipment. This paper establishes a method of improving the surface precision of the MPPB. First, the principle of the five-axis OMCM for the MPPB surface with belt grinding is illustrated. The path planning, point distribution, and radius error compensation are then analyzed and optimized for OMCM. Finally, an experiment for the belt grinding of an MPPB is conducted after OMCM. The experimental results show that the measurement precision is enhanced, and the measuring efficiency is advanced, the surface roughness Ra < 0.6 μm, the errors of profile precision of the MPPB are ±0.5 mm, and the tolerances on the curvature geometry and the surface finish all meet requirements of OMCM after belt grinding. The effectiveness and practicability of the method are thus fully verified.