Taking You to Understand Roller Cone Bits

Since the first roller cone bit was introduced in 1909, roller cone bits have been widely used all over the world. The roller cone bit is currently the most commonly used bit in rotary drilling operations. This type of bit has different tooth designs and bearing configurations, making it adaptable to various types of formations. In drilling operations, selecting the proper structure of the roller cone bit based on the characteristics of the formation being drilled can achieve satisfactory drilling speed and penetration rate.

Basic Structure of the Roller Cone Bit

• Bit Body: Assembled and welded from three blades, with a connecting thread on the upper part.

  
  

• Cones: Composed of a cone body and teeth, forming a conical metal body. The teeth are divided into milling cutter teeth and insert teeth types.

  
  

• Bearings and their lubrication sealing devices.

  
  

• Nozzles.
  

Working Principle of the Roller Cone Bit

Roller cone bits work at the bottom of the well with the entire bit rotating around its axis, known as revolution, while the three cones roll around their own axes at the bottom, known as rotation. The weight on the bit exerts pressure on the rock through the teeth, causing it to fracture (crushing action). As the cones roll, the single and double teeth alternately contact the bottom of the well, causing vertical vibrations in the bit. This vertical vibration makes the drill string compress and stretch continuously, with the lower drill string converting this periodic elastic deformation energy through the teeth into impact force to break the rock. This impact and crushing action is the primary way roller cone bits break rock.

In addition toimpact and crushing, roller cone bits also shear the rock at the bottom. While rolling at the bottom, the teeth slide against the rock, creating a shearing action that scrapes the bottom like a scraper bit. The sliding of the teeth is mainly caused by the arrangement of the cone's apex over, auxiliary cones, and axial displacement. The apex over arrangement of the cone and auxiliary cones causes tangential sliding, while axial displacement causes axial sliding. Generally, bits for soft to medium formations have apex over, auxiliary cones, and axial displacement; bits for medium-hard to hard formations are designed with apex over and auxiliary cones; and bits for very hard and abrasive formations usually use single cone bits without apex over or axial displacement.

Features of Roller Cone Bits

• The dual action of impact and shearing to break rock, with both impact from the teeth and shear caused by sliding, results in high rock-breaking efficiency.

  
  

• Wide adaptability to various formations, suitable for drilling in all types of formations.

  
  

• Excellent self-cleaning effect of the bit, not easily clogged with mud.

  
  

• Lower bit cost.

GREAT produces various types of roller cone bits. Our roller cone bits include the 90° U-shaped and 120° U-shaped series, both designed with starry sky roller positions. If you have your own designs and a confidentiality agreement in the contract, we also offer OEM services. If you are in need of roller cone bits, please feel free to contact us.