| 摘要 |
PROBLEM TO BE SOLVED: To provide a bolt which is fastened without a special tool and makes loosening (removal) after fastening extremely difficult.SOLUTION: Each bolt (A, B) of the invention comprises: a fastening bolt (1); a tightening bolt (2); and a lock part (3). A first engagement part (13) is provided at one end of a fastening bolt shaft (11) and a recessed part (14) is provided at a bolt shaft center part. The tightening bolt (2) includes a second engagement part (23) and a fastening shaft (22), which is slidably inserted into the recessed part (14), on a surface facing the first engagement part (13). When the tightening bolt is rotated only in one direction, the first engagement part and the second engagement part engage with each other to rotate the fastening bolt. However, when a tightening force for rotating the fastening bolt only in the one direction reaches predetermined torque, a portion in which the strength is deteriorated is broken and the tightening force of the tightening bolt is not transmitted to the fastening bolt. |
