Past and present for Cone bit

Since the advent of the first cone bit in 1909, the cone bit has been the most widely used in the world. Tricone bit is the most common drill bit used in rotary drilling operations. This type of drill has different tooth designs and bearing junction types, so it can be adapted to various formation types. In the drilling operation, the proper structure of the cone bit can be correctly selected according to the properties of the drilled formation, and satisfactory drilling speed and bit footage can be obtained.

The working principle of the cone bit

When the cone bit works at the bottom of the hole, the whole bit rotates around the bit axis, which is called revolution, and the three cones roll at the bottom of the hole according to their own axis, which is called rotation. The weight on bit applied to the rock through the teeth causes the rock to break (crushing). In the rolling process, the cone alternately contacts the bottom of the hole with single teeth and double teeth, and the position of the center of the cone is higher and lower, which causes the bit to produce longitudinal vibration. This longitudinal vibration causes the drill string to compress and stretch continuously, and the lower drill string converts this cyclic elastic deformation into an impact force on the formation through the teeth to break the rock. This impact and crushing action is the main way of rock crushing by cone bit.

Besides impacting and crushing the rock at the bottom of the hole, the cone bit also produces shear effect on the rock at the bottom of the hole.

Classification and selection of cone bit

There are many manufacturers of cone bits, which offer a variety of types and structures of bits. In order to facilitate the selection and use of cone bits, the International Institute of Drilling Contractors (IADC) has developed a unified classification standard and numbering method for cone bits around the world.