High strength nut is also called high strength bolt. It is a kind of standard part. Generally, high strength bolt can bear more load than general bolt. The appearance and connection structure of high-strength nuts are basically the same as those of ordinary bolts. The basic working principle of high-strength nut connection is to deliberately increase the very large tensile force to the bolts, so that the middle of the connected contact area will cause squeezing pressure. Therefore, there is a very large friction force in the direction of the vertical split screw rod. This kind of friction force is used to transmit the connection shear stress.
Generally, the bolt connection carries the shear stress by bearing the pressure and bending resistance of the rod body. When the nut is tightened, the pre tensile force caused by the bolt is not large, and its harm is not considered; The simple overview is that the pre tension of high-strength nuts must be tightened, while the torque method and corner method are generally used.
According to its acceptance force, it can be divided into pressure bearing type and friction type; In fact, there is a difference between the two calculation methods of the design scheme. For friction type, rolling between layers is taken as the limit of bearing capacity, and for load-bearing type, rolling between layers is taken as the criterion for all normal application limit cases. Friction type nuts cannot fully utilize the potential of nuts. In specific application, friction type high-strength bolts should be used for key structures, especially for the structure of load due to its reverse internal stress. At this time, the potential of bolts can not be fully utilized as a safety reserve. In other regions, high-strength nut connection with bearing pressure can be selected to save project cost.
According to the classification of processing technology, it can be divided into big hexagon and torsional shear type; The big hexagon belongs to the advanced compressive strength of ordinary screws. The torsional shear type is an improved version of the big hexagon for better and faster engineering construction. One nut, one bolt and one sealing ring form a torsion reduced high-strength nut. One nut, one bolt and two sealing rings form a large hexagon strong bolt.