Complete Bore Centerline Extractor and Surface Mapper

Abstract : Currently, a bore-riding laser target is used to measure gun barrel centerlines. A reference line is established from the center of the breech to the muzzle. The target is positioned at a number of stations down bore and the deviation of the centerline is determined. While accurate, the method requires the average of multiple measurements and physical contact with the barrel. A new measurement device that accurately and quickly finds the entire gun barrel centerline at once is being designed. It consists of an instrumented, sub-caliber, in-bore tube extending the entire length of the barrel. Non-contact displacement gauges are positioned lengthwise on the external surface of the tube. Rotating the in-bore tube provides a map of the surface from which the centerline can be extracted. Flaws in the bore surface and out-of-roundness can also be detected. The proof-of-principle experiments on this new technique are reported here.