螺杆钻具双等壁厚金属定子外高压成形方法研究

Research on External High-Pressure Forming Method of Double Equal Wall Thickness Metal Stator of Positive Displacement Motor

为了解决页岩气开采用螺杆钻具双等壁厚定子内螺旋曲面难加工的问题,建立双等壁厚定子的外高压成形数值模拟模型,研究管坯几何尺寸、液压力大小和回弹对定子成形质量的影响规律,通过实验和三维测量验证了数值模拟模型的准确性。结果表明:管坯几何尺寸与壁厚、等效塑性应变、位移、残余应力和间隙值成正比;成形液压力达到150 MPa及以上对等效塑性应变、壁厚几乎没有影响;定子胀型区域的回弹量大于过渡区域和接触区域;当成形液压力为210 MPa,管坯内径为88 mm,定子成形质量最优。

In order to solve the difficult machining problem of the inner spiral surface of double equal wall thickness stator of positive displacement motor in shale gas development,the numerical simulation model of the external high-pressure forming of the double equal wall thickness stator was established.The influence rules of the geometric size of the tube blank,the hydraulic pressure magnitude and springback on the forming quality of the stator were studied.The accuracy of the numerical simulation model was verified by experiments and 3D measurement.The results show that the tube blank geometry size is proportional to wall thickness,equivalent plastic strain,displacement,residual stress and clearance value.The forming hydraulic pressure of 150 MPa or above has almost no effect on the equivalent plastic strain and wall thickness.The springback of stator bulging area is greater than that of transition area and contact area.When the forming hydraulic pressure is 210 MPa and the inner diameter of the tube blank is 88 mm,the forming quality of the stator is the best.