凹形钻头
comsumption factor
saddle reef
环形钻头
ring auger bit
annular bit
棱锥形钻头
sprayed Drill
sprayed boring tool
螺旋形钻头
spiral bit
helical-shaped bit
十字形钻头
four point bit
cross bit
star bit
cross-edged bit
crosscut bit
CrossBit
星形钻头
star bit
staple shaft
bit spudding
star drill
形钻头
cross bit x
x chisel x
x bit x