How does a cone bit break rocks

During drilling, the bit and its cone rotate around the axis of the bit, the cone teeth rotate around their own axis under the action of the formation rock resistance, and the teeth alternately contact the bottom of the well with single and double teeth.

When the cone contacts the bottom of the well from the single tooth to the double tooth, the center of the cone falls from the high position to the low position; when the cone contacts the bottom of the well from the double tooth to the single tooth again, the center of the cone rises from the low position to the high position. Such repeated movement will periodically raise and lower the roller axis, which will cause the drill to produce longitudinal vibration, and the amplitude is the vertical displacement of the wheel center. In each longitudinal vibration process, the upward movement of the axis will compress the accumulated elastic property of the lower drill string, and the downward movement of the axis will make the elastic elongation of the lower drill string release the elastic property. For several reasons, when the rock is broken by the cone bit at the bottom of the well, the force exerted by the teeth on the rock not only has the static load generated by the bit pressure, but also the dynamic load generated by the teeth rushing to the rock at a high speed due to the longitudinal vibration. The former causes the teeth to crush the rock, which is called crushing effect; the latter causes the teeth to impact the rock, which is called impact effect.