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By certification 
The introduction of screw drilling tools：
Connection drill rods were applied with hydraulic jumbo mainly. Light drill rods and connection drill rods connected with wave shape thread connecting sleeve were widely applied in medium and deep hole mining, exploring water, shaft digging and other areas which have three kinds they are tail drill rods, body drill rods and head drill rods. The types of light drill rods and connection drill rods usually be the drill rods with thread type such as R22, R25, R28, R32, R38, T38, T45 ,T51,ST58 and T60 whose length also be in the range from 600mm to 6400mm.
