Design and Optimization Analysis of Downhole Robot Support Mechanism Based on Finite Element Method

Abstract

 To increase the traction force of the telescopic downhole robot, the support mechanism of the downhole robot was optimized, and a slider-spring transmission mechanism was introduced to solve the problem of jamming. A mathematical model of the support mechanism was established, covering the relationship between the contact normal pressure and the hydraulic cylinder load. The finite element simulation model of the friction block of the support mechanism was established based on Ansys software. Stress analysis of the casing under different contact normal pressures was carried out, and the frictional characteristics of the support mechanism friction block were obtained. The results show that the support mechanism composed of four linkages and friction locking blocks proposed in this paper can adapt well to casing of different diameters. The slider spring, as a transmission mechanism, has the elasticity and buffering effect, which makes the support mechanism have a certain flexibility, alleviating the vibration impact during obstacle crossing and reducing the impact on logging instruments. It enables the robot to passively adjust during obstacle crossing, effectively improving the traction capability of the downhole robot. Through finite element simulation, it was found that the depth of the plow groove produced by the friction block under normal pressure is basically proportional to the normal pressure. The greater the normal pressure, the deeper the plow groove, and the plow groove friction coefficient increases continuously with the increase of normal pressure, but the change in the plow groove friction coefficient gradually decreases as the pressure increases.