The Design And Simulation Of Down-hole Torsional Impactor

Torsional impact drilling technology is one of the effective ways to improve the rate of penetration under the condition of the existing drilling process.This article is based on train of thought of design on existing torsional impactor and drilling string shock absorption&down hole hydraulic pressurizing system(DSSA&DHHPS)and a torsional shock impactor which will integrate drilling string vibration reducing with adding bit torque is designed.The device uses WOB fluctuation which is caused by longitudinal vibration of the drill string during drilling process as energy source to drive the institution to produce a high frequency torsional impact to the bit,which will relieve stick-slip phenomenon during drilling the deep formation and provide a new choice to improve the drilling efficiency in deep hard formation.In order to study the effect of torsional impact load on the rock fragmentation efficiency,We designed a ground simulation experiment system for torsional impact device and measured torque fluctuation produced by the torsional impactor on bit indirectly.Rock breaking experiment has been conducted with simulation experiment system and the relationship between rock fragmentation efficiency and different torsional impact has been anslyzed.In order to make full use of the drill string longitudinal vibration energy in the process of drilling,the torsional impact generator based on drill string vibration has been designed and simulated.In this paper,we firstly put forward three transformation schemes which can achieve transforming from the reciprocating movement of the drill string to shock parts rotation movement considering dynamic characteristics and the machining difficulty of the device,using the working principle of cam mechanism and optimize mechanisms,whcin is based on the relevant principle of mechanical design and test results of the law of drill string longitudinal vibration.After vibration conversion institutions determined,we made up with a torsional impact device which is based on the existing research results about the DSSA&DHHPS,designed its overall structure of the scheme.The impact frequency of the tool has been determined by the analysis of the drilling pressure fluctuation frequency,stroke of the upper shock absorber has been determined by referencing to the existing shock absorber industry standards and weighing the influence of the shock absorber stroke on impact energy,the related parameters of disc spring also has been determined by analyzing the WOB fluctuation amplitude and considering stroke size of shock absorber.And the impact energy under different impact hammer rotation angle has been calculated in order to adjuste the magnitude of the impact energy effectively in the process of tool being used,and then strength check with Ansys software for key important parts have been performed.3D models for each parts of the torsional impact device and virtual assembles are made by Creo software.The realization of the movement characteristics of tool has been forecasted.The intervene problem of the mechanism has been checked and verified.Collision detection for tool movement has been carried out.The feasibility of the design has been improved and the development period of product has been shortened.