夹紧力和摩擦系数对旋扣钳上扣的影响

On the Influence of Clamping Force and Friction Coefficient on the Make-up of Turnbuckle Pliers

为了研究夹紧力和摩擦系数对旋扣钳上扣过程中钻杆应力分布的影响,采用有限元分析方法对Φ139.7 mm×9.17 mm钻杆进行了非线性问题的弹塑性力学有限元模拟分析,得到上扣过程中钻杆的应力大小及分布规律,最大夹紧力及摩擦系数对钻杆应力的影响。结果表明,旋扣钳上扣过程中钻杆径向单元层的应力值呈现上下波动规律,内外壁的应力大于中间单元层,钻杆的最大应力出现位置和最大应力值是动态变化的,应力危险点转移到了滚轮与钻杆接触位置,最大应力出现位置也由未旋转时的外壁转移到了内壁,且最大应力值有所增加;滚轮旋转一周过程中,钻杆始终呈椭圆形,且钻杆的椭圆度是动态变化的,其值在1%至2.4%之间波动;当夹紧力为150284 N时,滚轮与钻杆接触位置虽有应力集中现象,但最大等效应力尚未超过钻杆材料的屈服强度。经过仿真发现,钻杆的最大夹紧力为190300 N;当夹紧力为150284 N时,改变摩擦系数对钻杆的最大von-Mises应力值有一定影响,当摩擦系数从0.15增加到0.27时,最大vonMises应力值增大,但最大von-Mises应力值的增量不大。

In order to study the influence of clamping force and friction coefficient on the stress distribution of drill pipe in the process of making up turnbuckle pliers,scholars used the finite element method to conduct the plastoelasticity finite element simulation analyses of nonlinear problem for the drill rods ofΦ139.7 mm×9.17 mm,and got the stress intensity and distribution law,and the influence of largest clamping force and friction coefficient on the stress of drilling pipes in the process of make-up.The results show that in the make-up of turnbuckle pliers,stress value takes on the law of up and down fluctuations from drill pipe to unit layer,the stress of inside and outside wall is larger than that of middle unit layer,the position in which the largest stress of drill rod appears and the biggest stress value are dynamic changing,dangerous points of stress transform to the contact position of roller and drilling rod,and the appearing position of the largest stress transforms from the outside wall before rotation to the inside wall,together with the increase of the largest stress value.Besides,in one cycle of roller rotation,drilling rod all along takes on the shape of oval,and the oval degree of drilling rod is changing dynamically,with its value fluctuation from 1%to2.4%.In addition,when clamping force is 150284 N,there is stress concentration in contact position of roller and drilling rod,but the largest equivalent stress hasn’t surpass yield intensity of drilling rod material.Finally,it is found by means of simulation that the largest clamping force is 190300 N;when the clamping force is 150284 N,changing friction coefficient has certain influence on the largest stress of von-Mises;namely,when friction coefficient increases from 0.15 to 0.27,the largest stress value of von-Mises is growing,but the increment of largest stress of von-Mises is not bigger.