Optical method for inspecting spherical parts

摘要

Spherical parts such as ball bearings are inspected by rolling the parts down sizing rails so that they rotate rapidly with minimal translational motion at a point where they drop through the sizing rails. In a region of rapid rotation the part is inspected by an array of optical systems covering the entire area of the part. Each system focuses a small line of light on the part and in a direction slightly misaligned with the center of the part and the same optics focuses specularly reflected light from the part to a detection region where the light level is measured and a corresponding electrical signal is produced. When the line image scans over a defect, the resulting absorption or scattering of the light causes a rapid decrease in the light received at the measuring location so that a detectable change in the electrical signal occurs.