Improving the Working Capacity Resource for a Roller Cone–Drill Rod Joint of a Drill Bit

Abstract

The results of the experimental development and studies on the structure, rigidity and damping capacity of a joint between a roller cone and a drill bit (C–D) are presented. A single-mass and a two-mass mathematical model for the C–D junction dynamics are developed. It is shown, taking into account the experimental data, that the single-mass model is significantly less accurate than the two-mass one in modeling the junction dynamics and, therefore, the two-mass model can be adopted as the basic one for performing calculations concerning the longevity of a modernized drill bit. To increase the service life of the joints, a technical solution is developed that increases the load capacity and longevity of the drill bits, based on introducing a three-layer damping package of intermediate washers into the modernized C–D junction and the use of multilubrication technology. As shown by the tests and calculations, such a modification makes it possible to reduce the deformation energy by 60% compared to the scheme adopted earlier (with one intermediate washer in the joint), which provides an increase in the service life and load capacity of the junction.