In-process inspection of internal threads of machined automotive parts

This paper presents a methodology for the non-contact inspection of geometric features of internal threads in machined automotive parts. The method enables in-process internal thread quality verification using a high-precision laser sensor. It allows extracting thread pitch, major and minor diameters, thread height and even allows finding the angular location of the starting point of a thread with respect to a reference point on the perimeter. An in-process thread inspection prototype possessing five axes of motion is presented to demonstrate the capabilities of this method. The validation of this method and the self-calibration approach for system alignment were tested on several internal threads showing a high degree of repeatability.