Rock bits

GJ/GJT rock bits
METAL SEALED BIT WITH ROLLER BEATING

GJ/GJT series rock bit adopts metal seal with roller bearing ,which can drill stably with middle to low WOB and middle to high RPM,it is the ideal choice for higher part of well section.
The size range of GJ/GJT series rock bit is from8 1/2 to 17 1/2 inch, and IADC varies from 115 to 545.For example:17 1/2 GJT515GC.
MAIN STRUCTURE FEATURES
1.sizes of bearing journal and rollers are made larger by arranging the rollers in recesses in cone body.
2.All rubber compensator is used which can limit pressure differential and prevent drilling fluid from entering the lubrication system and this provides the bearing system with good assurance of lubrication.
3.Shirttail and head OD are hardfaced for enhanced gage protection. Center nozzle is equipped for bits of larger sizes.
4.For GJT,a row of inserts is added between gage row and heel row to trim borehole wall and protect cone shell.
Bit type GJ 617G
Applicable formation soft with low compressive strength and high drillability,such as soft shale ,clay,sandstone and soft limestone ,etc.
Main characteristics of the bit &Cutting Stracture Large dia,offset crested scoop compacts in inner roe wedge compacts in outer row ,and a row of trimmers is added between gage row and heel row
Normal WOB Kn/mm(bit dia) 0.35~1.05
Rotary Speed（rpm） 120~50