本文介绍了螺杆钻具的工作原理及分类方法,分析了容积式液马达转子与定子必须满足的条件,并对转子轴向力、马达最小长度和万向轴内交变应力循环频率的计算进行了探讨。在对螺杆钻具的实际特性进行一系列研究的基础上,文章还提出了“负載效率”这个概念,并给出一组换算关系式。本文所推导的计算公式适用于任何线型的i=N/(N+1)的单螺杆马达和螺杆钻具。 This paper introduces the working principle and classification method of screwdriver, analyzes the conditions that must be satisfied for the rotor and stator of the displacement liquid motor, and makes the calculation of the rotor axial force, the minimum length of the motor and the cycle frequency of the alternating stress in the cardan shaft Exploring. Based on a series of researches on the actual characteristics of screw drilling tools, the paper also proposed the concept of “load efficiency” and gave a set of conversion formulas. The calculation formula derived in this paper is applicable to any linear single screw motor and screwdriver with i = N / (N + 1).