At present, the demand for bearings in my country has greatly increased, and some large and small and medium-sized enterprises have begun to vigorously develop the manufacture of spherical plain bearings. Not only have great development in style, structure and variety, but also become more and more rich. At the same time, with the improvement of my country's current manufacturing quality, the number of products exported abroad is also increasing year by year. In addition, my country's aviation and aerospace technology is becoming more and more developed, and the application of bearings is also increasing, and its quality requirements are also getting higher and higher. However, when some high technologies are applied to bearings, due to the swinging and twisting actions they are subjected to, it is easy to increase the friction force due to the interaction between the two sides, and sometimes stiffness occurs. In these bearings applied to self-lubricating shutdown, serious losses will occur if the friction effect fails. Therefore, many domestic and foreign experts have conducted in-depth research and discussion on this issue. This paper points out the factor analysis of friction and wear of self-lubricating spherical plain bearings from the aspects of environmental temperature, speed, material, etc. At the same time, it makes a certain analysis of the current problems of friction and wear performance of self-lubricating spherical plain bearings and its future development direction. .

1 Factors affecting the friction and wear performance of self-lubricating spherical plain bearings

There are many factors affecting the friction and wear performance of self-lubricating joints of bearings, and there are many ways of wearing them, which are mainly affected by environmental temperature, speed, load, pad material and other factors. Among them, the temperature of the environment has the most significant impact on it.

1.1 Speed

The spherical plain bearing has its own unique swinging direction. Due to the different friction and wear properties of the self-lubricating spherical plain bearing, the speed of the bearing's swing is caused. Assuming that the conditions of temperature, swing and load are the same, experiments are performed on three different swing frequencies, and the results are shown in Figure 1. We can see that when the swing frequency is at P1 and P2, the coefficient of friction is similar, and P2 is slightly higher than P1. At the same time, at the 800th swing, the coefficient of friction reaches the first peak, maybe This phenomenon is related to the friction surface generated by the interaction between the rotating film and the free grinding. As it continues to rub, the particles enter the surface of the pad and the P value gradually decreases. It can be concluded that the higher the frequency of oscillation, the higher the friction value.

1.2 Load

Due to the particularity of the self-lubricating bearing joint, its swing mode is also different from other bearing movements, and its friction and wear degree is affected by its load. Experiments done by relevant experts show that with the continuous increase of load, the friction and wear performance of self-lubricating spherical plain bearings will increase. When the load is 30kn, the friction coefficient is smaller than the load of 20kn at the beginning. With the continuous increase of swing, it will be higher than that of 20kn. As the number of swings continues to increase, some black chips will appear. At this time, the degree of wear and tear on the object will also increase. At this time, the degree of wear will become particularly serious. As the load continues to increase, the friction damage will become more and more serious, and there will also be special fluctuations. It can be concluded from the above that with the increase of the load, the reduction speed of the wear coefficient will become slower, and the friction coefficient will become conserved after running for 33 hours, and the faster the speed, the more serious the wear will be. At the fifth to twelfth hours it returns to the conserved value.

1.3 Padding material

During the rotation of the bearing, the inner and outer rings and the pads rub against each other to run. Therefore, pads of different materials have a very important influence on their friction and wear performance. An in-depth understanding of different gasket materials is of great significance to enhance the friction capacity of the bearing and prolong its service life.

1.3.1 PTFE composite materials: 

Relevant experts pointed out that there are two main types of friction for composite materials: adhesive friction and abrasive friction. For the composition of the internal material, the friction performance of the composite material is also different. When the content of FEP in the material is 10% to 35%, it has an important ability to improve the performance of the composite material, and the two can be reasonably integrated. Among them, mixed materials are more effective than single materials in improving their frictional capacity, which is mainly due to the efficacy of the synergistic interaction between the various materials.

1.3.2 PTFE braided material: 

PTFE braided material has high friction and wear performance, and relevant research data show that it is a material with a low friction coefficient so far, and its wear resistance and friction effect is very good. When it rubs against a metal object, its temperature becomes higher and higher, and the toughness of the shear segment becomes smaller, so that the internal components of the PTFE material stick to the surface layer, move to the surface layer of the metal and fill the existing pits , which is why it exhibits a lower coefficient of friction.

From the above discussion, we found that the choice of the bearing pad material is very important for its friction and wear performance, and it is also a key determining effect; the impact of composite materials or woven materials on the friction and wear performance of self-lubricating spherical plain bearings is also very important. major. Therefore, only by understanding several important reasons that affect its performance, can we deepen the understanding and degree of it, and can effectively take corresponding measures to strengthen the friction and wear performance of self-lubricating bearings.

2. Existing problems and research prospects

At present, my country's research on the friction and wear performance of self-lubricating spherical plain bearings has entered a deep level. At the same time, there are still quite a few researches that are not mature enough, and there are still some problems. For example, the practice of the spherical plain bearing testing machine is insufficient during the test, so that a large part of the newly developed self-lubricating spherical plain bearing products cannot really enter the practical manufacturing and use, which has caused the development of new products. It is very inconvenient; the friction of various materials under various conditions should be further improved. At present, the research we conduct is generally only the research and development of a single material in a monotonous atmosphere. It is good to carry out further development from multiple angles and aspects. Therefore, in the next development test, it is necessary to carry out product development and manufacturing development in response to specific problems in reality and specific problems, which is of great significance for the future development of the bearing industry. Let's discuss the future development trend and direction of bearing research in the future.

2.1 Research on the tribological characteristics of self-lubricating spherical plain bearings under special working conditions

At present, the frictional manufacturing effects of self-lubricating spherical plain bearings in various situations are different. For example, in an environment with a large temperature difference, the life of the bearing products developed by it is relatively short; the use of the gasket produced in a particle environment is not good; in an environment with a high swing frequency, the wear capacity of the bearing will decrease; these different The results of R&D carried out in the work environment are not the same and are affected by different environmental conditions. Therefore, it is very meaningful for experts to conduct specific and in-depth research for different situations.

2.2 Development of friction pair materials for self-lubricating spherical plain bearings

With the improvement of the economy, there are new requirements for products, and there is a new layer of requirements for the auxiliary materials of bearing friction of self-lubricating joints, which must have deep performance, excellent wear degree, and high-quality anti-friction. Fatigue capability and good noise. For example, the current composite material, although its friction coefficient is low, its toughness has not yet reached the target, and measures should be taken to integrate it with other corresponding materials to produce good results. For various materials, further optimization and improvement should be carried out, which is conducive to the truly excellent effect of the bearing.

2.3 Research on online dynamic measurement method of self-lubricating spherical plain bearing wear under high frequency swing

Anyone who has done related experiments has this feeling. It is easier to directly observe and record the swing when the swing is slow. When the frequency of the swing reaches a certain height, it is very useful for data measurement. It is very difficult, and with the increase of the frequency, it will also produce strong vibration, which also has a considerable impact on the actual detection and measurement. Therefore, further analysis and innovation should be carried out on this aspect of research.

3 Conclusion

With the continuous improvement of social economy, the demand for spherical plain bearings in today's continuous development of science and technology is also getting higher and higher, and the requirements for their quality are also getting higher and higher. Therefore, experts and bearing manufacturers should rationally and scientifically improve the friction and wear performance of self-lubricating spherical plain bearings with the attitude of serving the interests of the people and contributing to the economic development of society. This requires a scientific understanding and reasonable selection of the bearing pad material selection, speed, ambient temperature, etc., in order to ensure the quality of its manufacturing.