Concentric Drill Steels for Noise Reduction of Percussion Drilling.
Ch in "Progress in Noise Control Inter-noise 86 " 1986 :333-336
This paper describes the design and test results of a prototype concentric drill steel used to reduce noise in large drills. Operational advantages of concentric vs. Conventional steel, and the problems in coupling performance, are also discussed.
Ch. in "Progress in Noise Control. Inter-noise 86," 1986, PP. 333- 336