System For Indirectly Measuring A Geometric Dimension Related To An Opening In An Apertured Exterior Surface of A Part Based On Direct Measurements Of The Part When Fixtured At A Measurement Station

摘要

A system for indirectly measuring a geometric dimension related to an opening in an apertured exterior surface of a part such as an ammunition case based on direct measurements of the part when fixtured at a measurement station is provided. The system includes first and second holding devices for holding the part therebetween in a part-retaining position in which the part is firmly held between the devices at its end surfaces. In one embodiment, a portion of each of the holding devices extends into its respective opening in the part-retaining position. The system also includes a head apparatus which has a plurality of radiation sources for successively directing arrays of planes of radiation at the holding devices and at the part, and a plurality of receiver modules for measuring the amount of radiation present in unobstructed planar portions of the planes to obtain holding device and part signals. The system further includes a movable stage subsystem coupled to the head apparatus for translating the head apparatus. The system still further includes a signal processor for processing the holding device and part signals to obtain data and a data processor for processing the data to obtain the direct measurements. The data processor determines the geometric dimensions related to the openings based on the direct measurements.