During the running process of the rail train gearbox, the bearing bears the extremely high load and high-speed rotation condition. In order to ensure its long-term and reliable operation, the selection of lubricating oil and the control of the lubrication film thickness are crucial. The lubricating film not only affects the friction characteristics of the bearing, but also directly determines the change of the coordination gap and its influence on the bearing life. This topic discusses the best design of lubricating film and bearing coordination gap under different load conditions to optimize the performance and reliability of bearings.

1. The formation and function of the lubrication film

Lubrication film refers to the oil film layer formed by the lubricating oil between the bearing rolling body and the rolling way. Its main functions include:

Reduce friction and wear In a good lubrication state, the lubrication film can effectively isolate the metal surface and reduce the wear rate.

Absorption vibration and shock lubrication film has a certain elasticity, which can buffer the small vibration and impact force in the process of bearing operation.

Heat dissipation and corrosion prevention lubricating oil can take away part of the heat during operation, and form a protective layer on the bearing surface to prevent corrosion and oxidation.

2. Influence of the bearing fit gap on the thickness of the lubrication film

The coordination gap of the bearing refers to the gap between the inner and outer ring of the bearing and the rolling body. The size of the gap will significantly affect the formation of the lubrication film.

2.1 Too small coordination clearance

It may lead to insufficient thickness of lubricating oil film, increase the probability of metal contact, and aggravate friction and wear.

In the high temperature environment, the gap is further reduced due to thermal expansion, and even the phenomenon of "stuck" appears.

Affects the fluidity of lubricating oil and may lead to insufficient local lubrication, pitting or flaation failure.

2.2 Too large coordination clearance

It may cause the lubricating oil film, which reduces the rigidity of the bearing during operation and produces vibration and noise.

Under heavy loading conditions, the oil film may not effectively support the load, resulting in boundary lubrication or dry friction and affecting the bearing life.

The bearing internal lubricating oil circulation is too fast, it is difficult to form a stable lubricating oil film, affecting the long-term operation stability.

3. The pling of load on the lubrication film and the coordination gap

In the actual operation, the bearing is not only affected by the rotational movement, but also bears the compound effect of the radial load and the axial load. The relationship between the lubrication film thickness and the bearing gap shows different characteristics at different load levels:

• 3.1 Light-load working condition
• When light load, the lubrication film is thicker, the contact stress between the rolling body and the rolling way is smaller, and the lubrication effect is better.
• The bearing clearance leads to the rapid loss of lubricating oil, affecting the stability of the lubrication film.
• Moderate lubricating oil viscosity is recommended to maintain the oil film integrity.
• 3.2 Heavy-load working condition
• In the high load state, the contact stress between the rolling body and the rolling path increases, the oil film thickness thinner, and may even enter the boundary lubrication state.
• Appropriate reduction of the bearing clearance can improve the rigidity of the bearing, but it needs to ensure that the oil film is not excessively thin.高载荷下推荐使用高粘度润滑Oil, to ensure the carrying capacity of the oil film in a high-pressure environment.
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• 4. Optimize the design method of the lubrication film thickness and the coordination gap
• In order to improve the service life of the bearing, it is necessary to find the best balance between the lubrication film thickness and the coordination gap. The main optimization strategies include:
• 4.1 Precise control of the bearing clearance
• High-precision machining technology is adopted to ensure the dimensional stability of the inner and outer rings of bearings.
• Combined with the operating environment, the initial clearance of the bearing is reasonably selected to avoid the clearance runaway caused by temperature rise.

4.2 Select the appropriate lubricating oil

Under light-load and high-speed working conditions, it is recommended to choose low-viscosity lubricating oil to reduce the fluid resistance and improve the cooling effect.

Under heavy load and low speed conditions, high viscosity lubricant is recommended to ensure that the oil film is stable under high pressure.