The basic requirements for the material of the crossed roller bearing depend to a large extent on the working performance of the bearing. Whether the material selected to manufacture the crossed roller bearing is suitable will have a great influence on its performance and life. In general, the main failure forms of crossed roller bearings are fatigue spalling under alternating stress and loss of bearing accuracy due to friction and wear. In addition, there are also cracks, indentations, rust, and other reasons that cause abnormal damage to the bearing. Therefore, the material for making the crossed roller bearing must meet all the requirements of the crossed roller bearing. So, what properties should the material of the crossed roller bearing have?
1. High wear resistance
When a crossed roller bearing is working normally, in addition to rolling friction, there is also sliding friction. The main parts where sliding friction occurs are the contact surface between the rolling element and the raceway, the contact surface between the rolling element and the spacer block, and between the spacer block and the guide ribs of the ferrule, etc. Sliding friction in crossed roller bearings causes wears of bearing parts. If the wear resistance of the bearing steel is poor, the crossed roller bearing will lose its accuracy prematurely due to wear or reduce the rotation accuracy, which will increase the bearing vibration and reduce its life. Therefore, bearing steel should have high wear resistance.
2. Appropriate hardness
The hardness of the crossed roller bearing is also very important. The material contact fatigue strength, wear resistance and elasticity also affect the life of the crossed roller bearing. The hardness of the bearing is usually determined according to the general condition of the bearing's load bearing method and size, bearing size, and wall thickness. The hardness of the steel used for the crossed roller bearing should be appropriate, too large or too small will affect the service life of the bearing.
3. High contact fatigue strength
The normal form of bearing failure is contact fatigue failure. Under the operating state of the crossed roller bearing, the rolling elements roll between the raceways of the inner and outer rings of the bearing, and the contact part is subjected to periodic alternating loads. Under the repeated action of periodic alternating stress, fatigue spalling occurs on the contact surface. The vibration and noise of the bearing increase, the working temperature rises sharply, and the bearing is eventually damaged. These are the conditions that occur when the crossed roller bearing begins to peel off. The form of this damage is contact fatigue damage. Therefore, the steel for crossed roller bearings should have high contact fatigue strength.
4. High elastic limit
When the bearing bears a large load, the contact pressure is too large. In crossed roller bearings, plastic deformation will occur under high contact stress, which will lead to loss of bearing accuracy or surface cracks, so the bearing steel should have a high elastic limit.
Five, good process performance
The parts of the crossed roller bearing go through multiple cold and hot working processes. This requires that the bearing steel should have good process properties, such as cold and hot forming properties, cutting, grinding processing properties and heat treatment properties, etc., to meet the needs of large-scale, high-rate, low-cost, and high-quality production of bearings.
6. Certain impact toughness
Many crossed roller bearings will be subjected to a certain impact load during use, so the bearing steel is required to have a certain toughness to ensure that the bearing is not damaged due to impact. For bearings that bear large impact loads, such as rolling mill bearings, railway bearings, etc., the materials are required to have relatively high impact toughness and fracture toughness. Some of these bearings use a bainite quenching heat treatment process, and some use carburized steel materials. Ensure that these bearings have good impact toughness.
Seven, good anti-rust performance
Cross-roller bearings have many production processes and long production cycles. Some semi-finished or finished parts need to be stored for a long time before assembly. Therefore, bearing parts are prone to certain rust during the production process or in the storage of finished products. , not in the humid air. Therefore, the bearing steel is required to have good rust resistance.
Eight, good dimensional stability
Crossed roller bearings are precision mechanical parts, and their accuracy is measured in microns. During long-term storage and use, the bearing size will change due to changes in the internal structure or stress, resulting in the loss of accuracy of the bearing. Therefore, to ensure the dimensional accuracy of the bearing, the bearing steel should have good dimensional stability.
In addition, for grooved roller bearings used under special working conditions, in addition to the above basic requirements, the steel used must also have corresponding special performance requirements, such as high-temperature resistance, high-speed performance, corrosion resistance, and anti-magnetic performance.
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