... debris, slipping type of rocks and ferroconcrete. Drill bit standard: Q series, T series, nonferrous metal metallurgy standard and ... of ractured congested the core of double tube bit.3. The strata of above cases, the ... BQ3,NQ,HQPQ,PQ3Double tube electroplated diamond core bit and reaming shellΦ46,Φ56,Φ59,Φ66,Φ75 ... BQ3,NQ,HQPQ,PQ3Wire-line electroplated diamond core bit reaming shellΦ56,Φ59,Φ75,Φ91,Φ95 AQ ...