膨胀管塑性膨胀过程摩擦问题研究

关于膨胀管膨胀过程中的摩擦问题，目前还没有文献考虑各因素对摩擦因素的影响，而摩擦因素对膨胀管的膨胀过程有直接的影响.根据膨胀管膨胀过程塑性成形特点，分析了膨胀管膨胀过程摩擦力的构成，讨论了管材材料、膨胀速度、膨胀锥表面状态、膨胀率等因素对摩擦因素的影响.在此基础上建立了膨胀过程摩擦力学模型，并用有限元建立了一个N80实体膨胀管模型验证膨胀管膨胀过程中摩擦因素对套管膨胀过程的影响，给出了摩擦因数分别为0.1，0.15，0.2，0.25，0.3时的等效应力云图.通过对等效应力云图分析发现，摩擦因数大于0.25时膨胀管内出现了明显的犁沟，而摩擦因数小于0.25时膨胀管内不会出现犁沟.有限元计算结果与膨胀管实际膨胀过程特点相吻合，在摩擦因素较大时很容易出现犁沟而使摩擦力增加.因此，在设计膨胀工艺时，应综合考虑各种情况，降低摩擦因素，以满足实际的工程需求.

Friction research on plastic expanding process of expandable tubular

About the friction problem during expanding process of expandable tubular， current literature hadn't focused on the factors which impact coefficient factors but the friction coefficient has obvious effect on the expanding process. Based on plastic formation feature during expanding process， the constitute of friction force was analyzed; the factors impacting friction coefficient such as tubular material, expansion rate, state of expanding cone surface and expandsion ratio, and so on, were discussed; a friction force model of expanding process was built and a N80 expanding solid tubular finite model was use to verify the influence of friction coefficient during expansion process. From the finite model， the equivalent stress contour plot of friction coefficient 0.1,0.15,0.2,0.25,0.3 was obtained. Conclusion could be made by analyzing the equivalent stress contour plot that the plow appears in the expandable tubular at friction coefficient 0.25 or above， but the plow doesn't  appear when friction coefficient is below 0.25.The result calculated by finite element method is consistent with actual situation of expanding process that the plow appears at high friction coefficient.  Conclusion can be drawn that factors effecting the expansion technology in designing should be considered to reduce the friction coefficient．