Structural Strength and Fatigue Strength Analysis of Roller Arm

Abstract

The cone reamer is used for underhole reaming, mainly through the impact crushing and cutting of teeth to complete rock breaking, easy to produce vibration. At the same time, the underground topography is complex and rock materials are changing. Therefore, the force of the cone reamer is complex and easy to damage. According to the statistics of the field use, the main failure form is the failure of the roller arm. The reaming arm consists of two parts: a cone arm and a bearing. As for the reaming arm, it is subjected to the reaction force of rock on teeth and the support force of piston when working. When the teeth eat into the rock alternately, longitudinal vibration will be generated, so that the force of the cone arm is random impact load. Due to the instability of bit weight, additional dynamic load is caused, resulting in the piston support force is also random impact load. Thus causing the fracture of the cone arm. For bearings, reamers are used to drill stepped holes and rely on the outer teeth of the cone as opposed to the cone bit. When the teeth eat into the rock alternately, the longitudinal vibration is generated, and the rock is broken through the impact and cutting of the teeth. And the axial acceleration of the cone reamer is greater than the longitudinal acceleration, so the axial vibration is severe and the bearing bears the impact load. At the same time, the wall morphology and rock material are changing, so the bearing is subjected to random contact fatigue load. The piston cracks under the repeated action of random load, leading to fatigue failure. It can be seen from the structure characteristics and working principle of the cone reamer that the cone arm is the core functional component of the cone reamer. Therefore, abnormal failure of the above components should be avoided as far as possible. Therefore, this paper completed the simulation analysis of the cone arm, obtained the stress and strain distribution of the cone arm, and established the finite element analysis specification and safety evaluation index of the cone arm.