摘要
多年以来钻具过早失效问题一直困扰着钻井界。在钻具失效案例中 ,连接螺纹疲劳失效占很大的比例。钻具连接螺纹疲劳失效是由于交变弯曲应力引起的 ,这些交变应力集中在连接螺纹消失处附近。减少连接螺纹弯曲应力可以延长钻具连接螺纹的疲劳寿命。文章提出并研究了一种新的钻具连接螺纹减应力区 ,它是通过在钻柱稳定器本体上设置减应力区 ,来解决钻具连接螺纹疲劳失效问题。与其它减应力区不同的是 ,新的减应力区的轮廓线为连续的光滑的二次曲线 ,圆弧线 ,抛物线和椭圆线。这可以避免在减应力区出现应力集中和出现“细脖子”现象。并且这些曲线在机械加工上是可行的。用有限元技术优化了减应力区的几何形状 ,并分析了减应力区的开口位置、开口深度和开口宽度等几何参数对应力释放效果的影响。并对减应力区的强度进行了分析。
The drilling circles have been plagued with the premature failures in drill tools for many years.Caused by cyclic bending stress,the fatigue failures of threaded connections accounted for a very large proportion in the drill tool failure cases.These cyclic bending stresses are concentrated near the last-engaged thread and the fatigue life of the threaded connections may be extended by reducing their bending stresses.A novel drill tool threaded connection stress relief groove is proposed in the paper.The problem of the fatigue failures of drill tool threaded connections has been solved through setting up the stress relief groove at the drillstem stabilizer.Unlike other stress relief grooves,the contour of the novel stress relief groove is a continuous and smooth quadratic curve,as arc,parabola and ellipse,which may avoid the appearance of stress concentration and 'thin neck' at the stress relief groove.And these curves are feasible in machine work.Finally,the geometric shape of the stress relief groove is optimized by use of finite element method;the influence of the geometric parameters,such as the opening position,opening length and opening depth,of the stress relief groove on the stress release is analyzed;and the strength of the stress relief groove is evaluated also in the paper.
出处
《天然气工业》
EI
CAS
CSCD
北大核心
2002年第2期48-50,共3页
Natural Gas Industry
基金
CNPC"九五"科研项目"钻柱动力学研究与现场应用"的研究内容
关键词
新型
钻柱稳定器
连接螺纹
减应力区
研究
应力集中
有限元分析
Drill stem stabilizer,Threaded connection,Stress concentration,Stress relief groove,Finite element analysis
