During the operation of the swivel joint in the oilfield,pitting and obvious indentation of the ball bearing at the joint were observed and affected its operation.In order to analyze the inherent causes of the damage,the stress-strain data of the material under the room temperature compression were obtained.Then,the ball bearings of the three types of swivel joints were subjected to the elasto-plastic finite element contact analysis to determine the contact stress distribution of the inner ring raceway.Comparison was then made to select the best structure.The analysis results show that the structure of three-step swivel joint is relatively reasonable,but has an uneven stress distribution on the three raceways.According to the analysis results and the actual application,the existing structure has been improved.A new type of swivel joint structure has been proposed and its finite element contact analysis has been carried out.Analysis shows that the improved structure not only reduces the overall stress,but also has a more evenly distributed stress on the three raceways.The results of the study have guiding significance for the structural improvement and the field application of the swivel joint.%活动弯头在油田现场使用过程中,接头处的滚珠轴承出现点蚀及明显的压痕,影响其正常使用.为分析其破坏的内在原因,先试验得出材料在室温压缩下的应力应变数据,然后对现有3类活动弯头的滚珠轴承进行弹塑性有限元接触分析,测出其内圈滚道接触应力的分布,对比得出相对优良的结构.分析结果表明:三台阶活动弯头的结构相对合理,但存在3列滚道应力分配不均匀现象.根据分析结果及实际情况,对现有的结构进行改进设计,提出一种新型活动弯头结构,并对其进行有限元接触分析.分析结果显示,改进后的结构不仅整体应力水平降低,三列滚道的应力分配也更加均匀.研究结果对活动弯头的结构改进及现场应用具有一定的指导意义.
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