... high, medium and low air pressure, symmetric drilling tools, eccentric drilling tools, standardized API system casings, bit shanks and casing ... electro-hydraulic forging hammer, seal chamber furnace lines, precision machine tools and so on. We adopt numerical control process to all ... ,T45,T51Face Shape---Plate, Concave, Convex.Bit Shank & Coupling sleeve---R22,R25,R28,R32,R38,T38,T45,T51Down-The-Hole ...