柔性马达载荷传递中挠轴力学特性研究

Mechanical characteristics of flexible shaft in flexible motor load transfer

摘要:

挠轴是超短半径柔性马达单元节间扭矩传递的关键部件。针对超短半径柔性马达钻进过程中存在挠轴断裂等失效现象，本文对柔性马达内部挠轴进行了力学建模和设计强度校核，采用有限元仿真对柔性马达单元节间扭矩传递过程中挠轴的力学特性进行应力分析，并通过室内试验测试柔性马达的机械性能进而分析挠轴的力学特性。结果表明，挠轴在传递扭矩中，其根部及花键接触面是扭矩传递中的应力集中区域，且挠轴疲劳寿命可满足井下连续作业需求。有限元分析和室内测试均表明挠轴可传递扭矩500 N·m，可实现交变弯扭应力下柔性马达内部扭矩载荷传递。这为超短半径柔性马达在水平井开发中的钻进工艺提供了重要的理论依据，对提高超短半径水平井水平段的钻进长度和钻进效率提供了新型的技术手段。

Abstract:

Flexure shaft is a key component for torque transfer between the joints of ultra-short radius flexible motor units. Aiming at the failure phenomena such as fracture of flexure shaft in the drilling process of ultra-short radius flexible motor， this paper carries out mechanical modelling and design strength checking of the internal flexure shaft of the flexible motor， uses finite element simulation to carry out stress analysis on the stress state of the flexure shaft in the torque transmission process of the flexible motor， and tests the mechanical properties of the flexible motor through indoor teststo analyse the mechanical properties of flexure shafts. The results show that the root and spline contact surfaces of the flexure shaft are the stress concentration areas in torque transmission， and the fatigue life of the flexure shaft can meet the requirements of continuous downhole operation. The finite element analysis and indoor tests show that the flexure shaft can transmit torque of 500N·m， which can realise the internal torque load transmission of the flexible motor under alternating bending and torsional stresses. This provides an important theoretical basis for the drilling process of ultra-short radius flexible motors in the development of horizontal wells， and provides a new type of technical means to improve the drilling length and drilling efficiency of the horizontal section of ultra-short radius horizontal wells.