连续管作业注入头夹持机理研究

对连续管作业注入头夹持机理进行了分析,将夹持力简化为沿周向正弦分布的压力,利用级数形式的应力函数、应力边界条件和位移连续条件得到不规则外压作用下的应力分布,给出了连续管内、外表面关键点处的等效应力随着夹持力、轴向拉力、内压、连续管壁厚和外径变化而变化的规律:①等效应力随着夹持力的增大而迅速增大;②除了轴向拉力很小的情况以外,等效应力随轴向拉力F的增大而增大;③在连续管的不同位置,内压对等效应力的影响趋势不同。在内表面θ=0点和外表面θ=π/2点的等效应力随内压的增大而减小;而内表面θ=π/2和外表面θ=0点的等效应力随内压的增大而增大;④随着壁厚的增大连续管内、外表面的等效应力均有所减小;⑤在壁厚和夹持力一定时,等效应力随外径的增大出现先减小后增大的趋势;⑥随着内压由小逐渐增大,屈服极限曲线出现先外移后内移的现象,且弹性区的范围随着内压的增大逐渐减小。

Research on the Clamping Mechanism of CT Injector Head

The clamping principle of injector head for coiled tubing(CT) was analyzed in this paper.The clamping force is simplified as the circumferential sine distribution.The stress function in series form,the stress boundary condition and displacement continuous condition are used to obtain the stress distribution under the effect of irregular external pressure.The paper gives the laws on the change of equivalent stress with clamping force,axial tension,internal pressure,CT's wall thickness and external diameter.The first law is that the clamping force increases quickly with equivalent force.The second law is that the equivalent stress increases with the axial tension F,excluding the very small axial tension.The third law is that the internal pressure has different tendency effects on equivalent stress in different places of CT.In other words the equivalent stress decreases with the increase of internal pressure at the point of θ=0 of internal surface and the point of θ=π/2 of external surface.The equivalent stress increases with internal pressure at the point of θ=π/2 of internal surface and the point of θ=0 of external surface.The fourth law is that the equivalent stress of the internal and external surfaces of CT decreases slightly with the increase of wall thickness.The fifth law is that when wall thickness and clamping force are certain,the equivalent stress tends to decrease first and then increase with the increase of outer diameter.The sixth law is that when the internal pressure gradually increases,the yielding limit changes from out-shift to ingression and the range of the elastic zone gradually decreases with the increase of internal pressure.