凹形钻头
comsumption factor
saddle reef
环形钻头
annular bit
ring auger 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
cross bit
star bit
cross-edged bit
crosscut bit
four point bit
CrossBit
星形钻头
star bit
star drill
bit spudding
staple shaft
形钻头
cross bit x
x bit x
x chisel x