Mechanism and analysis of a robotic bolting device for steel beam assembly

Tasks for steel beam assembly in construction field are usually performed by human labors that are exposed to various dangers. This research is about developing a robotic bolting device which assembles TS(Torque-Shear)-type bolt and nut used for steel beam assembly and prevents workers from operating in risky construction environments. The suggested robotic bolting device consists of a bolting end-effector, which actually conducts bolting tasks, and a gantry-type robotic manipulator, which places the bolting end-effector to each bolting position. The bolting process performed by the bolting end-effector, which furnishes two different bolting tools, has two assembly steps to increase the bolting productivity. In the first step, the first-assembly bolting tool assembles the bolt and nut with high speed but low torque, while, in the second step, the second-assembly bolting tool finishes the tightening task with high torque but low speed. Moreover, nut and washer feeder based on robotic manipulation are developed for automatic supply. The two bolting tools equip compliance mechanisms respectively for compensating an angular misalignment between the bolting tool axis and bolt axis which interferes the bolting tool completely grasps the bolt.