6-inch inlaid roller bit crossing steel roller bit horizontal well bit

  WOB is a necessary condition for rock breaking at the bottom of three cone bit
The weight on bit affects the drilling speed and damage mode
During drilling, the bit is subjected to two layers of axial pressure and reversal force, and the cutting teeth are worn and blunt, which affects the drilling speed
The increase of WOB and the progress of ROP will also accelerate the wear of cutting teeth and affect the ROP
Please look at the following three periods: appearance period: the WOB is less than the rock indentation hardness, and the rock can only be broken by friction on the rock surface, with great wear
Fatigue period: the WOB is close to the hardness of the rock, and many cracks occur on the rock surface
After the repeated action of cutting teeth, the volume is also broken
Volume crushing: the WOB is greater than the indentation hardness, and the cutting teeth cut into the rock to produce volume crushing
The drilling effect is significant, which belongs to normal drilling
The specific situation of mining tri cone bit drilling different grades of rock is usually doubled WOB
Practice has proved that the hardness increases gradually and the drilling rate curve increases Working principle of three cone bit: it is under the effect of WOB and drill string winding
After crushing, the teeth also eat into the rock, and there is a certain sliding and shearing the rock at the same time
When it is rolling at the bottom of the well, its upper teeth will successively impact and press into the formation
This effect can crush part of the rock at the bottom of the well
At the same time, relying on its sliding, the shear effect will weaken the remaining rocks between the teeth, so that the rock at the bottom of the well can be completely broken and the well can be extended
The main mode of rock breaking action of tri cone bit & mdash& mdash; Impact and crushing: the impact force and static pressure caused by its longitudinal oscillation all lead to the impact and crushing effect of teeth on the land, forming a volume crushing pit
Auxiliary methods & mdash& mdash; Sliding and shearing action: the radial and tangential movement of its teeth causes the effect of shearing underground and breaks the rock between teeth
Erosion effect of jet: the rapid jet ejected through the nozzle has an impact effect on the rock underground, helping to break the rock