In petroleum drilling, the tricone roller bit can be adapted to drilling in various formations and is one of the main rock breaking tools. The motion state and force state of the roller cone bit when working at the bottom of the well are quite complicated. A lot of work has been done internationally on the working principle of roller cone bits, whether in theoretical research or experimental research. These research results provide a basis for the design and use of cone bits. The movement of the tricone roller bit at the bottom of the well determines the movement of the cone and gear, which directly determines the crushing effect of the gear on the stratum rock. Therefore, before understanding the working principle of the drill bit breaking rock, one should first understand the movement of the tricone roller bit at the bottom of the well.
1. Autorotation of the tricone roller bit
When the tricone roller bit rotates, looking from the bottom plane of the cone to the tip of, the cone rotates counterclockwise around its own axis, which is called autorotation. The rotation of the cone is the result of the impact of the rock on the gears. The influencing factors of the rotation speed of the cone include revolution speed, bit structure, gear surface structure, drilling parameters and rock properties. Under normal circumstances, the autorotation speed of the cone bit is faster than its revolution speed. The ratio of the autorotational speed of the cone bit to the revolution speed of the bit is called the gear head ratio, and the value of the gear head ratio is generally between 1 and 1.5.
2. Revolution of the tricone roller bit
The movement of the tricone roller bit rotating clockwise around the bit axis is referred to as the revolution of the bit. The revolution speed of the bit is the rotation speed of the turntable or downhole power drilling tool. When the bit revolves, the cone rotates around the axis of the bit, and the linear speed of each row of gears on the cone rotates around the axis of the bit is different, and the linear speed of the outer row of gears is higher.