目前隧道掘进机（TBM）施工过程的钢拱架安装均采用人工操作的形式完成，作业环境非常恶劣，导致钢拱架支护效率低、劳动强度大、施工风险高。为此，笔者及其所在团队前期设计了一种钢拱架快速封口安装机构，用于代替人工完成钢拱架的封口作业。抓取模块作为该封口安装机构中直接与钢拱架接触的核心部件，需要具有足够的传动性能，以满足夹持作业需求。为此，文中基于螺旋理论，建立了其运动学模型，推导了输入旋量和输出旋量之间的虚拟系数，研究得到了抓取模块的传动性能，并提出了相应的传动指标；在此基础上，建立了抓取模块的尺寸参数优化模型，结合钢拱架封口件的实际抓取需求，得到抓取模块各尺寸参数的优化结果如下：卡爪与连杆的初始夹角\alpha =\mathrm{88}°、导杆的初始位置l_{\text{??}\mathrm{F}\mathrm{J}}=\mathrm{170}\text{?}\mathrm{m}\mathrm{m}，导杆运动范围0 ~ 63 mm。利用ADAMS软件对抓取模块从夹持到张开的姿势变化过程进行分析，得到以下结论：卡爪末端间的距离从50.0 mm逐渐增加至234.6 mm，满足抓取空间需求；输出扭矩呈先增大后减小的趋势，卡爪完全张开时扭矩最小值为21.23 N·m，满足输出扭矩需求。钢拱架封口成环的样机实验表明：抓取模块尺寸参数的测量值与计算模型仅相差4.5 mm，说明模型是正确的；钢拱架的整个封口安装时间为8.6 min，与传统人工作业相比，钢拱架封口机构的作业效率提高了20% ~ 70%。

At present, the installation of steel arch during the construction of tunnel boring machine (TBM) is completed by manual operation, and the working environment is very harsh, thus leads to the problems of low support efficiency, high labor intensity and high construction risk. Therefore, the authors and their team had designed a steel arch rapid-looping installation mechanism to replace manual operation. As the core part of the looping installation mechanism that directly contacts with the steel arch, the grasping module demands sufficient transmission performance to meet the requirements of clamping operation. Based on the screw theory, the paper established a kinema-tics model of the grasping module, and deduced the virtual coefficient between the input screw and the output screw. Then, the transmission performance of the grasping module was obtained and its transmission index was proposed. On this basis, the size parameter optimization model of grasping module was established. According to the actual grasping requirements of the steel arch looping parts, the optimization results of each size parameter were obtained as follows: the initial included angle between the jaw and the connecting rod is α = 88°, the initial position of the guide rod is l_FJ = 170 mm, and the movement range of the guide rod is 0 ~ 63 mm. Using ADAMS software to analyze the posture change process of the grasping module from clamping to opening, it comes to the conclusion that, the distance between the ends of the jaws gradually increases from 50.0 mm to 234.6 mm, which meets the requirements of grasping space; the output torque increases first and then decreases. When the jaw is fully opened, the minimum torque is 21.23 N·m, which meets the output torque demand. Finally, the steel arch looping installation experiment shows that, the difference between the measured values and the calculated model is only 4.5 mm, which proves the correctness of the model; the whole looping installation time of the steel arch is 8.6 min. As compared with the traditional manual operation, the operation efficiency of the steel arch looping mechanism is improved by 20% ~ 70%.