Development of Automatic Bolt Supply and Tightening Robot for Automatic Segment Assembly System

We have developed an automatic bolt supply and tightening robot for an automatic segment assembly system that can support work in small-diameter tunnels. The segments are hex-head types, and the prototype handles segments with an inside diameter of 4.8 meters. The automatic bolt supply and tightening robot is separate from the erector used for positioning of the segment, which makes possible a compact segment gripper suitable for small-diameter tunnels. The bolt tightening robot consists of bolt tighteners that tighten bolts using AC servo motors, and a positioner that uses hydraulic servos. All bolts for the segment can be supplied automatically with higli precision, and tightening torques is controllable. The bolt supply robot employs an pneumatic actuator. Bolts are equipped with the bolt cartridges in sets made up of all the bolts required by an entire ring, and a set is automatically supplied to the tightening robot for each segment. Bolt supply is performed in parallel with segment supply, which contributes to overall work efficiency.