What is the Effect of Nut Surface Treatment on Pre-Tightening Force?

The connection pair is an extremely important component for vehicle applications. Its function is to reliably connect the wheel and the hub-together, to ensure the safe driving of the vehicle. The failure of the wheel connection pair will cause serious consequences, not only will cause damage to the vehicle parts, but also may cause heavy economic losses and casualties.

Track Bolt

The main manifestations of the failure of the wheel connection pair are the connection pair loosening and bolt fracture. The direct result is that the wheels fly out and cause an accident. Through the analysis of the failure of multiple wheel bolt fractures, the loosening of the bolt pair before the fracture caused the pre-tightening force to drop, causing the relative movement between the wheel and the hub, and the fatigue fracture caused by the shear force of the wheel mounting hole on the bolt was the main reason. Therefore, a stable preload is an important factor to ensure the normal connection of the wheels.

The following Rail Clip Manufacturer will share with you the influence of different surface treatments on the friction coefficient of wheel nuts and improve the reliability of wheel fastening.

1) Through the analysis and calculation of the wheel bolt torque and pre-tightening force, it is concluded that the pre-tightening force in the fixed torque assembly depends on the friction coefficient of the thread surface and the friction coefficient of the contact surface, and the slight change in the friction coefficient has an effect on the pre-tightening force. Great influence.

2) Through the measurement of the friction coefficient, the friction coefficient of the contact surface of the wheel connection pair is much larger than that of the thread, and the friction coefficient of the contact surface has a greater influence on the comprehensive friction coefficient.

3) It can be seen from the test data that white zinc plating and yellow zinc plating have little effect on the contact surface friction coefficient, thread friction coefficient, and comprehensive friction coefficient. Without an external friction coefficient sealant, the thread friction coefficient is relatively stable. It shows that the thread processing and surface treatment processes of this batch of nuts are consistent, but the friction coefficient of the contact surface fluctuates greatly. Because of the anti-rust oil, the friction coefficient of the contact surface of the nut is very stable.

4) Through the test and inspection of the wheel nuts with different surface treatments in the normal supply state, it is concluded that the nuts with the phosphate treatment method can provide a very stable comprehensive friction coefficient without the use of a friction coefficient sealant. Provide a stable and controllable pre-tightening force to ensure reliable connection of the connection pair.

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