Research on the Friction and Wear Performance of Self lubricating Joint Bearings

Abstract: The article analyzes and summarizes the research results on the friction and wear of self-lubricating joint bearings both domestically and internationally in recent years. The principles of friction and wear for bearings with different environments are different. At the same time, the influencing factors of friction and wear phenomenon in self-lubricating joint bearings have been studied separately, and the existing problems and development trends in the analysis have been discussed.

Keywords: self-lubricating joints; Friction and wear of bearings; Bearing performance

At present, the demand for bearings in China has greatly increased, and some large and medium-sized enterprises have begun to vigorously develop the manufacturing of joint bearings. Not only has there been significant development in terms of style, structure, and variety, but it has become increasingly diverse and diverse. Meanwhile, with the improvement of manufacturing quality in China, the number of products exported to foreign countries is also increasing year by year. In addition, China's aviation and aerospace technology is becoming increasingly developed, and the application of bearings is also increasing, with higher quality requirements. However, when some high-tech applications are applied to bearings, due to the swinging and twisting movements they bear, it is easy to increase the friction force due to the interaction between the two sides, and sometimes stiffness may occur. In these bearings applied to self-lubricating shutdown, if the friction effect fails, serious losses will occur. Therefore, many domestic and foreign experts have conducted in-depth research and exploration on this issue. This article analyzes the factors affecting the friction and wear of self-lubricating joint bearings from the perspectives of environmental temperature, speed, materials, etc. At the same time, it analyzes several problems in the current friction and wear performance of self-lubricating joint bearings and their future development direction.

1.Factors affecting the friction and wear performance of self-lubricating joint bearings

There are many factors that affect the friction and wear performance of self-lubricating joints in bearings, and there are also many ways of wear. It is mainly influenced by factors such as environmental temperature, speed, load, and gasket material. Among them, the temperature of the environment has a significant impact on it.

1.1 Speed

Joint bearings have their unique swing direction, and the different friction and wear properties of self-lubricating joint bearings result in the speed of bearing swing. Assuming that the temperature, swing, and load conditions are the same, experiments are conducted on three different swing frequencies, and the results are shown in Figure 1. We can see that when the swing frequency is between P1 and P2, the coefficient of friction is similar, and P2 is slightly higher than P1. At the same time, during the 800th swing, the coefficient reaches a peak. Perhaps this phenomenon is related to the friction surface generated by the interaction between the rotating film and free grinding. As it continues to friction, particles enter the surface of the liner, and the P-value gradually decreases. From this, it can be concluded that the higher the frequency of oscillation, the higher the value of friction.

1.2 Load

Due to the unique nature of self-lubricating bearing joints, their oscillation mode is also different from other bearing movements, and their degree of friction and wear is influenced by their load. The experiments conducted by experts have shown that as the load continues to increase, the friction and wear performance of self-lubricating joint bearings will increase. When the load is at 30kn, the friction coefficient is initially smaller than the load of 20kn. As the swing increases, it will also increase compared to 20kn. As the number of swings increases, some black debris will appear, which will also increase the degree of wear on the object. At this point, the degree of wear will become particularly severe, and as the load continues to increase, the degree of friction damage will become increasingly severe, and there will also be special fluctuations. From the above, it can be concluded that as the load increases, the reduction speed of the wear coefficient will slow down. After running for 33 hours, the friction coefficient becomes conserved, and the faster the speed, the more severe the wear. At the fifth to twelfth hour, it returns to a conserved value.

1.3 Liner Materials

During the rotation process of bearings, their inner and outer rings and pads rub against each other to operate. Therefore, pads of different materials have a very important impact on their friction and wear performance. Having a deep understanding of different gasket materials is of great significance for enhancing the friction capacity of bearings and extending their service life.

1.3.1 PTFE composite materials: Relevant experts point out that there are mainly two types of friction in composite materials: adhesive friction and abrasive friction. The friction performance of composite materials varies depending on the composition of their internal materials. When the content of FEP in the composite material ranges from 10% to 35%, it has an important ability to improve the performance of the composite material and can be reasonably integrated. Among them, mixed materials are more effective in improving their friction ability than single materials, mainly due to the combined effects between various materials.

1.3.2 PTFE woven material: PTFE woven material has high friction and wear performance, and relevant research data shows that it is the material with the lowest friction coefficient so far, and its wear and friction resistance effect is very good. When it rubs against metal objects, its temperature increases and the toughness of the shear section decreases, causing the internal components of the PTEF material to adhere to the surface and move to the metal surface while filling the existing pits. This is why it exhibits a lower friction coefficient.

From the above discussion, we found that the selection of lining materials for bearings plays a very important and crucial role in determining their friction and wear performance; The impact of composite or woven materials on the friction and wear performance of self-lubricating joint bearings is also very significant. Therefore, only by understanding several important reasons that affect its performance can we deepen our understanding of it and take effective measures to enhance the friction and wear performance of self-lubricating bearings.

2.Existing problems and research prospects

At present, the research on the friction and wear performance of self-lubricating joint bearings in China has entered a deep level, and there are also quite a few studies that are not mature enough, and there are still some problems. For example, the lack of practical experience in joint bearing testing machines during testing has prevented a large portion of newly developed self-lubricating joint bearing products from truly entering the manufacturing and use of practical applications, causing great inconvenience to the development of new products; The friction situation of various materials under various conditions should be further improved. Currently, our research is generally only focused on the research and development of single materials in a monotonous atmosphere, and cannot effectively carry out further development from multiple angles and aspects. Therefore, in the subsequent development and testing, it is necessary to focus on the specific problems that arise in reality, and carry out targeted product research and manufacturing development. This is of great significance for the future development of the bearing industry. Let's discuss the future development trends and directions of bearing research in the future.

2.1 Research on the Tribological Characteristics of Self lubricating Joint Bearings under Special Working Conditions

At present, the friction manufacturing effects of self-lubricating joint bearings vary in various scenarios. For example, in environments with large temperature differences, the lifespan of the developed bearing products is relatively short; Poor use of pads produced in granular environments; In environments with high oscillation frequencies, the wear capacity of bearings will decrease; The results of research and development in these different working environments are different and are influenced by different environmental conditions. Therefore, it is very meaningful for experts to conduct specific and in-depth research based on different situations.

2.2 Development of Friction Pair Materials for Self lubricating Joint Bearings

With the improvement of the economy, there are new requirements for products, and there are new requirements for the friction materials of self-lubricating joint bearings, which should have deep performance, excellent wear resistance, high-quality fatigue resistance, and good noise. For example, in today's composite materials, although their friction coefficient is low, their toughness still cannot meet the target. Measures should be taken to fuse them with other corresponding materials to produce good results. Further optimization and improvement should be carried out for various materials in order to achieve truly excellent bearing performance.

2.3 Research on online dynamic measurement method for wear of self-lubricating joint bearings under high-frequency oscillation

People who have conducted relevant experiments have this feeling that under slow oscillations, it is relatively easy to directly observe and record the oscillations. However, when the oscillation frequency reaches a certain height, it becomes very difficult to measure the data, and as the frequency increases, strong vibrations will also occur, which has a significant impact on actual detection and measurement. Therefore, further analysis and innovation are needed in this area of research.

3. Conclusion

With the continuous improvement of the social economy, the demand for joint bearings in today's constantly developing technology is also increasing, and the requirements for their quality are also increasing. Therefore, experts and bearing manufacturers should adopt a reasonable and scientific approach to improve the friction and wear performance of self-lubricating joint bearings in the interest of the people and contribute to the economic development of society. This requires a scientific understanding and reasonable selection of bearing liner materials, speed, environmental temperature, etc., in order to ensure the quality of its manufacturing.

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Tapered roller bearing:

KYOCM tapered roller bearing adopts outer ring and inner ring components. The outer ring is composed of an outer ring, and the cone assembly is composed of an inner ring, a roller and a cage. This bearing structure can withstand combined loads and provide low friction during operation. Rigid bearing applications can be achieved by adjusting a single row tapered roller bearing to a second tapered roller bearing and applying preload. KYOCM tapered roller bearings include single row tapered roller bearing, double row tapered roller bearing and four row tapered roller bearing.