Study of the Influence of Structural Parameters on the Output Characteristics of Torsional Impact Tools

ABSTRACT Torsional impact tools can effectively eliminate the stick-slip vibration of the drill bit, which can effectively increase the mechanical drilling speed. In this paper, a mathematical model of the motion of a torque-influenced tool is developed based on an analysis of the structure and working principle of the tool. The influence of structural parameters on the output characteristics of the tool was analyzed by taking the shock frequency and impact work as the evaluation criteria for the output characteristics of the tool. The results show that the motion of the pendulum and reversing value are non-linear at different stages. The impact frequency and impact power of the tool decrease with the increase of the nozzle diameter, increasing first and then decreasing with the increase of the gap between the pendulum and the outer casing, increasing with the increase of the drain hole area on the wall of the baffle and pendulum, and remain stable after reaching the peak and no longer increase. To obtain better output performance, the pendulum clearance and drain area of the tool have optimal values in the design of structural parameters. The research results have important reference significance for the design of torque impact tools. INTRODUCTION The PDC bit is prone to stick-slip vibration when drilling in hard strata, which seriously affects the mechanical drilling speed and bit life. Torsional impact tools produce high frequency, low amplitude impacts and are often used on the top of the drill to reduce or eliminate stick-slip vibration. Various structures of torsional impact tools have been designed. The field application practice shows that in order to achieve good drilling speed, different areas have different requirements for the impact power and frequency of the tools (Zhou et al, 2012). Scholars have conducted some research on the analysis of the kinematic characteristics of torsional impact tools and the calculation of output characteristics. Tian Jialin established a kinematic calculation model of torsional impact tools and analyzed the influence of inlet pressure and flow rate changes on the tool impact frequency (Tian et al, 2016). Wang Wei and established a kinematic mathematical model of impact tools and analyzed the nozzle size and displacement on the tool output characteristics. The effect of nozzle size and displacement on the output characteristics of the tool was analyzed (Wang et al, 2019).