In recent years, under the background of tight international energy supply, China has increased investment in new energy fields represented by wind energy, which has gradually increased the output of new energy. However, for a long time, China’s coal-based energy sources The structure will continue. Compared with underground coal mining, open-pit coal mining has high productivity, low accident rate, and easy equipment maintenance and other objective advantages. Whether at home or internationally, vigorous development of open pit mining is a major trend. Mine trucks, one of the important equipment necessary for open pit mining, will also have a bright future with the development of open pit mines.
The tapered roller bearings produced by TIMKEN Bearings have decades of application history in mining trucks and have accumulated considerable application experience. This article will briefly analyze the problems that should be paid attention to when using tapered roller bearings for mining trucks. It is hoped that it will help the majority of mine truck designers and users to better select and use bearings and improve the reliability of mining trucks.
In addition to the factors of system design matching and installation adjustment, there are three main factors that determine the performance of tapered roller bearings: 1) the material of the bearing 2) the roughness of the bearing raceway 3) the surface modification of the bearing raceway . Next, a detailed analysis of the factors that should be considered in these three aspects of
bearing selection during mine truck conditions.
First, the material of the bearing
Two considerations are taken into account when considering the material of the bearing: the purity of the steel and the heat treatment process of the steel.
When the bearing is in normal operation, when the surface of the raceway is peeled off by 6mm2, we say that the bearing has failed. The running time of this bearing is its fatigue life. The occurrence of spalling is mainly due to the presence of non-metallic inclusions inside the bearing steel. When the bearing is working, non-metallic inclusions will cause stress concentration inside the steel, resulting in weak points. As the bearing runs day after day, these weak points gradually develop into fine cracks, which eventually cause the surface of the raceway to peel off. Therefore, the purity of the steel is critical to the bearing. The smaller the particle size of the inclusions inside the steel, the smaller the number of particles, the smaller the probability of crack occurrence and the higher the fatigue life of the bearing.
With the development of modern smelting technology, the bearing manufacturers of world-class brands have reached a very high level in the purity of bearing steel. In addition to bearing materials that meet ISO and ABMA standards, they also use materials that are cleaner than pure steel to improve the reliability of bearings under high loads. With the hub bearing application in a mining truck, the bearing carries a very high force. Taking the load of 200 tons as an example, the whole vehicle is about 350 tons after full load, and the force of the one-side rear wheel hub bearing reaches about 120 tons. Therefore, if a standard material bearing is selected, its size will be very large. In order to minimize the size of the hub and make the design more compact, bearings with high purity precision materials are often used in this position. Even so, the inner diameter of the bearing is about 500mm.
In addition to the purity of the bearing steel, the heat treatment process of the bearing has a considerable influence on the performance of the
bearing. There are two main heat treatment processes for bearings on the market today: full hardening and surface carburizing. The material of the full hardening heat treatment is high carbon steel. After the full hardening heat treatment, the internal and external hardness of the steel reaches 58-64HRC, and the tensile stress is generated on the steel surface. When a large impact load is encountered, it is easy to produce. Cracks, even breaking directly. The raw material of the carburizing heat treatment is low carbon steel, and the heat treatment process is surface carburizing. The material is characterized in that the surface is 58-64HRC hard and wear resistant, while the inner part is soft 30-35HRC, and the surface of the steel is subjected to compressive stress, which can be buffered. Impact load reduces the possibility of impact cracking.
The tapered roller bearings used in mining trucks are mainly used in bridges and wheel ends. The working environment in these two places is very harsh, often accompanied by impact loads and heavy loads. Coupled with the inability of the casting itself to avoid the abrasive particles, as well as the external contamination caused by the failure of the oil seal, these have brought a huge test to the bearing itself. In the case of abrasive particles and heavy loads, the raceway surface of the bearing inevitably produces pits. If a fully hardened bearing is used, the development of this pit will be under the dual influence of the material itself being brittle and surface tensile stress. Relatively fast, the bearing fails prematurely before it reaches the fatigue life. If a carburized bearing is selected, the pit is not easily expanded due to the toughness and surface compressive stress of the material itself, so that the bearing can still achieve a good fatigue life. Timken Company tested the bearing life comparison of the fully hardened bearing and the carburized bearing in the case of damage to the raceway surface. The results show that the surface carburized bearing can achieve higher fatigue life than the fully hardened bearing. For the above reasons, we should use carburized bearings when selecting the bearings used in mining trucks. Analysis of Bearings in Mine Truck Application
[Chinese bearing net] 12/6/2010 Author: China Bearing Network
In recent years, under the background of tight international energy supply, China has increased investment in new energy fields represented by wind energy, which has gradually increased the output of new energy. However, for a long time, China’s coal-based energy sources The structure will continue. Compared with underground coal mining, open-pit coal mining has high productivity, low accident rate, and easy equipment maintenance and other objective advantages. Whether at home or internationally, vigorous development of open pit mining is a major trend. Mine trucks, one of the important equipment necessary for open pit mining, will also have a bright future with the development of open pit mines.
The tapered roller bearings produced by TIMKEN Bearings have decades of application history in mining trucks and have accumulated considerable application experience. This article will briefly analyze the problems that should be paid attention to when using tapered roller bearings for mining trucks. It is hoped that it will help the majority of mine truck designers and users to better select and use bearings and improve the reliability of mining trucks.
In addition to the factors of system design matching and installation adjustment, there are three main factors that determine the performance of tapered roller bearings: 1) the material of the bearing 2) the roughness of the bearing raceway 3) the surface modification of the bearing raceway . Next, a detailed analysis of the factors that should be considered in these three aspects of bearing selection during mine truck conditions.
First, the material of the bearing
Two considerations are taken into account when considering the material of the bearing: the purity of the steel and the heat treatment process of the steel.
When the bearing is in normal operation, when the surface of the raceway is peeled off by 6mm2, we say that the bearing has failed. The running time of this bearing is its fatigue life. The occurrence of spalling is mainly due to the presence of non-metallic inclusions inside the bearing steel. When the bearing is working, non-metallic inclusions will cause stress concentration inside the steel, resulting in weak points. As the bearing runs day after day, these weak points gradually develop into fine cracks, which eventually cause the surface of the raceway to peel off. Therefore, the purity of the steel is critical to the bearing. The smaller the particle size of the inclusions inside the steel, the smaller the number of particles, the smaller the probability of crack occurrence and the higher the fatigue life of the bearing.
With the development of modern smelting technology, the bearing manufacturers of world-class brands have reached a very high level in the purity of bearing steel. In addition to bearing materials that meet ISO and ABMA standards, they also use materials that are cleaner than pure steel to improve the reliability of bearings under high loads. With the hub bearing application in a mining truck, the bearing carries a very high force. Taking the load of 200 tons as an example, the whole vehicle is about 350 tons after full load, and the force of the one-side rear wheel hub bearing reaches about 120 tons. Therefore, if a standard material bearing is selected, its size will be very large. In order to minimize the size of the hub and make the design more compact, bearings with high purity precision materials are often used in this position. Even so, the inner diameter of the bearing is about 500mm.
In addition to the purity of the bearing steel, the heat treatment process of the bearing has a considerable influence on the performance of the bearing. There are two main heat treatment processes for bearings on the market today: full hardening and surface carburizing. The material of the full hardening heat treatment is high carbon steel. After the full hardening heat treatment, the internal and external hardness of the steel reaches 58-64HRC, and the tensile stress is generated on the steel surface. When a large impact load is encountered, it is easy to produce. Cracks, even breaking directly. The raw material of the carburizing heat treatment is low carbon steel, and the heat treatment process is surface carburizing. The material is characterized in that the surface is 58-64HRC hard and wear resistant, while the inner part is soft 30-35HRC, and the surface of the steel is subjected to compressive stress, which can be buffered. Impact load reduces the possibility of impact cracking.
The tapered roller bearings used in mining trucks are mainly used in bridges and wheel ends. The working environment in these two places is very harsh, often accompanied by impact loads and heavy loads. Coupled with the inability of the casting itself to avoid the abrasive particles, as well as the external contamination caused by the failure of the oil seal, these have brought a huge test to the bearing itself. In the case of abrasive particles and heavy loads, the raceway surface of the bearing inevitably produces pits. If a fully hardened bearing is used, the development of this pit will be under the dual influence of the material itself being brittle and surface tensile stress. Relatively fast, the bearing fails prematurely before it reaches the fatigue life. If a carburized bearing is selected, the pit is not easily expanded due to the toughness and surface compressive stress of the material itself, so that the bearing can still achieve a good fatigue life. Timken Company tested the bearing life comparison of the fully hardened bearing and the carburized bearing in the case of damage to the raceway surface. The results show that the surface carburized bearing can achieve higher fatigue life than the fully hardened bearing. For the above reasons, we should use carburized bearings when selecting the bearings used in mining trucks.
