A survey of non-destructive techniques used for inspection of bearing steel balls

Bearing steel ball is the basic part of rolling bearing, and its surface quality has a vital impact on the service performance, life and safety of rolling bearing. Therefore, the surface quality of bearing steel balls must be fully tested before leaving the factory. The unfolding mechanism and inspection sensor of steel ball surface are mainly described in this paper. First of all, the inspection methods of steel ball surface quality are analyzed in detail, including visual inspection, eddy current inspection, optical fiber sensor inspection, capacitance sensor inspection, ultrasonic sensor inspection, etc. Then, the methods of steel ball surface unfolding methods are introduced, including meridian unfolding method, one-dimensional orbit unfolding method, disk unfolding method, one-dimensional wheel unfolding method and rotating magnetic field unfolding method. Finally, the future development direction of steel ball detection technology is pointed out, which provides theoretical basis and technical reference for the realization of bearing steel ball surface micro-defect inspection system.