Abstract: The key-techniques of the electrical eddy current method used in automatic cracks inspection instrument of bearing roller surface are discussed. The simple and quick mathematical model is set up by application of the helical conjugate axial theory. The analytic solution of the meshing point between roller and unfolding roller (or carrier roll) are worked out. By use the results, the accuracy machematical equation is got. The analytic solution equation can provide a useful geometrical model and a new calculation way to design and manufacture the unfolding roller (or carrier roll) or the superfinishing machine roll.

Key words: Bearing, Helical conjugate axial theory, Unfolding (scanning) mechanism