Producing and gauging precision railgun bores

The authors discuss the use and results of a bore finishing and measuring system for obtaining and quantifying precision bores in railguns. The bore finishing system has been specially designed and installed to enable honing of round-bore railguns in situ. The honing tool is equipped with six metal-bonded diamond abrasive stones to minimize bore ovaling, and the honing machine has infinite and separate adjustment on rotation and reciprocation (0 to 180 r.p.m. and 0 to 20 m/p min, respectively) of the tool. Experience has shown that bore ovaling can be reduced to only 80 μm difference between minimum and maximum diameters, and the bore diameter can be increased at the rate of about 0.1 m/hr. A tool for square-bore honing has been developed that greatly reduces the effort and time to finish bores, while improving bore accuracy. To quantify the round bores, diameter and straightness measuring tools have been developed. Using a calibrated dial bore gauge as reference, and accuracy of ±0.01 m has been achieved for measuring bore diameter