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

A system for indirectly measuring geometric dimensions related to openings in apertured exterior surfaces of a part based on direct measurements of the part when fixtured at a measurement station, the system comprising:

• first and second holding devices for holding a part therebetween in a part-retaining position in which the part is firmly held between the devices at the apertured exterior surfaces of the part wherein a portion of each of the holding devices extends into its respective opening in the part-retaining position;
• a head apparatus including a plurality of radiation sources for successively directing a first array of planes of radiation at the first holding device, a second array of planes of radiation at the part and a third array of planes of radiation at the second holding device in the part-retaining position so that the holding devices and the part occlude their respective planes of radiation to create corresponding arrays of unobstructed planar portions of the planes of radiation wherein each of the unobstructed planar portions contains an amount of radiation which is representative of a respective external geometric dimension of one of the holding devices or the part, the head apparatus further including a plurality of receiver modules for measuring the amount of radiation present in each of the unobstructed planar portions to obtain holding device and part signals;
• a movable stage subsystem coupled to the head apparatus for translating the head apparatus relative to the holding devices and the part so that the planes of radiation scan the holding devices and the part in the part-retaining position;
• 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 determining the geometric dimensions related to the openings based on the direct measurements.

A system for indirectly measuring geometric dimensions related to openings in apertured end surfaces of an ammunition case based on direct measurements of the case when fixtured at a measurement station, one end surface of the case being located at a mouth end of the case and the other end surface being located at a primer end of the case, the system comprising:

• first and second holding devices for holding the case therebetween in a case-retaining position in which the case is firmly held between the devices at the end surfaces of the case, wherein a portion of each of the holding devices extends into its respective opening in the case-retaining position;
• a head apparatus including a plurality of radiation sources for successively directing a first array of planes of radiation at the first holding device, a second array of planes of radiation at the case and a third array of planes of radiation at the second holding device in the case-retaining position so that the holding devices and the case occlude their respective planes of radiation to create corresponding arrays of unobstructed planar portions of the planes of radiation wherein each of the unobstructed planar portions contains an amount of radiation which is representative of a respective external geometric dimension of one of the holding devices or the case, the head apparatus further including a plurality of receiver modules for measuring the amount of radiation present in each of the unobstructed planar portions to obtain holding device and case signals;
• a movable stage subsystem coupled to the head apparatus for translating the head apparatus relative to the holding devices and the case so that the planes of radiation scan the holding devices and the case in the case-retaining position;
• a signal processor for processing the holding device and case signals to obtain data;
• and
• a data processor for processing the data to obtain the direct measurements, the data processor determining geometric dimensions related to the openings based on the direct measurements.