Falling prevention technology after outside joint breaking of bionic drill pipe with “bone tendon” characteristics

Abstract

In order to solve the problem of drilling falling caused by drill pipe fracture while drilling construction, taking the animal “bone tendon” structure as the bionic prototype based on the principle of bionics, the bionic drill pipe outside joint scheme with “bone tendon” characteristics is proposed. The composite double connection unit is formed by setting a self-locking connecting rod (tendon) in the inner hole of the outside joint (bone), and it meets the dual requirements of bearing load during normal drilling and maintaining axial connection after fracture, realizes the effect of “breaking bones and connecting tendons”. The working mechanism of bionic outside joint is expounded, and the design method of self-locking connecting rod is introduced, and ϕ73 mm bionic drill pipes are produced for torsion testes and tensile testes. The results show that the fracture position occurs at the large end of the outside joint when the torque reaches to 20.12 kN·m or the tension reaches to 1 444 kN. The study also demonstrates the bionic drill pipe with “bone tendon” characteristics can still maintain axial connection after fracture, and the tensile capacity after fracture exceeds 384 kN.

Keywords

• drill pipe
• bionic outside joint
• “bone tendon” characteristics
• self-locking connecting rod
• drill pipe falling