Abstract

Large numbers of steel balls are used in a variety of bearing applications. Surface defects such as pits, scratches, and rust which occur at various stages in a ball manufacturing process can be detected optically since they scatter light differently from a good surface region. An optical ball scanner was designed to detect defects as small as 0.25 mm on 6-mm balls with emphasis on design simplicity and ease of alignment. The scanner employs a semicircular array of light sources around the ball to illuminate the ball’s surface. An adjacent array of light detectors senses the change in the reflected light produced by a defect as the ball spins on a pair of tapered sizing rails (Fig. 1). The ball scanner must be able to inspect (track) balls, which translate slightly as they rotate. Each detector signal is processed separately by a separate channel of threshold detection electronics.

© 1981 Optical Society of America