High-strength bolts

The shape and connection structure of the high-strength bolt are basically the same as those of the ordinary bolt. The main difference between the two is that the ordinary bolt connection relies on the pressure and shear of the shaft to transmit the shear force, and the pre-tension of the bolt is small when the nut is tightened. The effect of the high-strength bolt connection is to intentionally apply a large pre-tension to the bolt, so that a pressing force is generated between the contact surfaces of the connected parts, so that there is a large friction force perpendicular to the screw direction, relying on this Friction to transmit the connection shear. The pre-tension of the high-strength bolt is realized by tightening the nut. The ordinary high-strength bolt generally adopts the torque method and the corner method. Twist-cut high-strength bolts use a twisted bolt tail to control the pre-tension.
High-strength bolt-connected bolts are made of high-quality alloy structural steel of 10.9S or 8.8S and heat-treated. High-strength bolt holes should be drilled into holes. The diameter of the friction-type high-strength bolt is 1.5 to 2.0 mm larger than the nominal diameter d of the bolt; the diameter of the high-strength bolt connected by the pressure type is 1.0 to 1.5 mm larger than the nominal diameter d of the bolt.