Model of a new joint thread for a drilling tool and its stress analysis used in a slim borehole

The drilling pipe used in slim-borehole drilling performs well due to its low cost and high efficiency. Good sealing properties and coupling strength are the two keys to ensure that the pipe works correctly. In this paper, a 68 mm diameter drilling pipe and its joint are developed. On the basis of Lame's theory, the contact model of the joint thread is represented under different axial force, makeup torque, and pressure difference between inner and outer pipe. This model provides a good reference for judging the quality of sealing of the joint thread. The analysis software ANSYS\Workbench is applied to stimulate the distribution of contact stress and sealing properties. A premium condition for drilling has been proposed, which provides a good theoretical basis for slim-borehole drilling.