螺杆钻具特性分析

螺杆钻具采用容积式单螺杆液马达作为动力机。无工作液漏失、无摩擦的理想马达是不存在的。马达工作液的漏失使得螺杆钻具总效率降低，并导致其实际工作特性偏离理论工作特性。在相同负载下，马达副的配合间隙对螺杆钻具的流量—转速特性影响很大，配合过盈量在０～０．３０ｍｍ范围内，螺杆钻具的功率及总效率较高；对漏失量超过２Ｌ／ｍｉｎ的液马达，建议不要继续使用。负载（转子输出扭矩）是影响流量—转速特性的另一重要因素，试验表明，螺杆钻具在最佳工况时的扭矩是制动扭矩的５０％～７０％。按螺杆钻具在不同流量下的扭矩—转速特性，为适应牙轮钻头钻井工况的要求，设计马达时应尽量降低转速，提高输出扭矩。

Characteristic analysis of screwdrills

Leakage of the working fluid from the hydro-motor on a screwdrill causes overall efficiency drop of the screwdrill and results in deviation of its actual working characteristics from theoretical. Under the same load,the clearance fit of the coupled pair of the motor has great influence on the flow-speed characteristic of the screwdrill. A fit of 0～0. 30mm interference provides high power and high efficiency, and motors with leakage of over 2L/min are not recommended to be used any more. Load (output torque of the rotor) is another factor influencing the flow-speed characteristic. Tests show that the torque of the screwdrill under the optimum working condition is 50～70 percent of the braking torque.