Mechanical properties of ordinary bolts and high strength nuts

Mechanical properties of ordinary bolts and high strength nuts

It is used for high-strength nuts and bolts. The strength grade (after heat treatment) is grade 10. It is used with grade 10.9 bolts.

The mechanical properties and calculation methods of ordinary bolts and high-strength nuts are different. The high-strength nut is stressed by applying a preload P inside it, and then generating friction resistance on the contact surface between the connectors to bear the external load, while the ordinary bolt directly bears the external load.

High strength nut connection has the advantages of simple structure, good mechanical performance, replaceable, anti fatigue, and no loosening under dynamic load. This is a promising connection method.

The high-strength nut is tightened with a special wrench, so that the bolt has a huge and controllable pre tightening force. The same amount of pre pressure is generated on the connecting parts through nuts and backing plates. Under the action of preload, the surface of the connector will produce greater friction. Obviously, as long as the axial force is less than this friction, the component will not slide and the connection will not be damaged. This is the principle of high-strength nut connection.

High strength nut connections are prevented by friction between the connector contact surfaces. In order to make the contact surface have enough friction, it is necessary to increase the clamping force of the element and the friction coefficient of the contact surface. The clamping force between components is achieved by applying pre tightening force to the bolt, so the bolt must be made of high-strength steel, which is why it is called high-strength bolt connection.

In high-strength bolted connections, the friction coefficient has a great influence on its bearing capacity. The results show that the friction coefficient is mainly affected by the shape of the contact surface and the material of the component. In order to improve the friction coefficient of the contact surface, the contact surface of parts within the connection range is usually treated by sand blasting and wire brush cleaning.

In fact, there are two types of high-strength nuts: friction type and pressure bearing type.

The shear force criterion of friction type high strength bolt is that the shear force generated by the design load does not exceed the friction force.

Bearing type high-strength bolts are designed according to the principle that the rod body is not damaged or the plate is not crushed.

In addition, high-strength bolts cannot be reused.

The company is mainly engaged in high-strength bolts, high-strength nuts, steel structure bolts, steel structure nuts, space frame sealing plate, space frame bolts, etc.