china without gear bearing(no gear)

What is the working temperature of the gear bearing?

The gear bearing is a very important part in the machine. Basically, every machine needs this part. Because this part is relatively fragile, it can also be regarded as a kind of consumables. You need to buy it frequently to keep the machine in good condition. normal operation.

The gear bearing can work normally at -300C～+700C. If the user needs to adapt to the lower or higher temperature gear bearing, our company can make special design. If the gear bearing is used in particularly harsh environments, such as marine climate, dust or abrasive particles, sand, cement, coal powder, etc.

Special sealing rings, protective devices, and suitable oil passages should be selected. Therefore, in order to make your support function normally, it is hoped to do a good job in daily maintenance and maintenance.

The tooth surface of the gear bearing should be cleaned and changed every 8-10 working days, and foreign matter should not be mixed.

Features of gear bearing materials

The gear bearing is mainly composed of ferrules, rolling elements, cages, sealing rings, etc. Since different parts have special functions in practical applications, there are different considerations in the design and selection of materials.

In general, the rolling elements of the slewing ring are made of carbon-chromium bearing steel that is hardened as a whole. The slewing bearing ring is made of surface hardened steel. When the user has no special requirements, it is generally made of 50Mn steel.

However, sometimes in order to meet the needs of the host in some special applications, other grades of surface can also be selected according to the specific use conditions provided by the user. Hardened steel, such as 42CrMo, 5CrMnMo, etc.

For small and medium gear bearing forgings, round or square bars are used as blanks. The grain structure and mechanical properties of the bar are uniform and good, the shape and size are accurate, and the surface quality is good, which is convenient for mass production.

As long as the heating temperature and deformation conditions are reasonably controlled, forgings with excellent performance can be forged without large forging deformation. Ingots are only used for large forgings. The ingot is an as-cast structure with large columnar crystals and a loose center.

Therefore, through large plastic deformation, the columnar crystals must be broken into fine grains, and the loose compaction can be obtained in order to obtain excellent metal structure and mechanical properties.

The cages for Slewing Bearing have integral, segmented, spacer block and other structural forms. The integral and segmented cages are made of 20-gauge steel or ZL102 cast aluminum alloy. The spacer block type is made of polyamide 1010 resin, ZL102 cast aluminum alloy, etc. With the continuous development of the material industry, nylon GRPA66.25 has also been popularized and applied in the design of segmented cages.

The material of the gear bearing seal is made of oil-resistant nitrile rubber. The codes of the ferrule material and the supply status of the blank are as specified in the table. In the table, “T” means that the blank of the ring is supplied in a quenched and tempered state, and “Z” means that the blank of the ring is supplied in a normalized state.

2.How is gear bearing fatigue life affected? What are the influencing factors?

1. The effect of nitrides on gear bearing fatigue life
​​
It has been pointed out that when nitrogen is added to the steel, the volume fraction of nitrides decreases. This is because the average size of the inclusions in the steel decreases. Due to the limitation of technology, there are still a considerable number of small-volume inclusion particles that are not counted.

It is precisely the existence of these tiny nitride particles that has a direct impact on the fatigue life of bearing steel. Ti is one of the strongest elements to form nitrides. It has a small specific gravity and is easy to float. There will also be a part of Ti left in the steel to form multi-angular inclusions. Such inclusions are likely to cause local stress concentration and fatigue cracks, so it is necessary to control the occurrence of such inclusions.
​​
The test results show that the oxygen content in the steel is reduced to below 20ppm, the nitrogen content is increased, the size, type and distribution of non-metallic inclusions are improved, and the stable inclusions are significantly reduced.

Although the nitride particles in the steel increase, the particles are very small and are distributed in a dispersed state at the grain boundary or within the grain, which becomes a favorable factor, so that the strength and toughness of the bearing steel are well matched, and the hardness and strength of the steel are greatly increased. , especially the improvement effect on fatigue life exists objectively.

2. The influence of oxides on bearing fatigue life
​​
The oxygen content in the steel is an important factor affecting the material. The lower the oxygen content, the higher the purity and the longer the corresponding rated life. There is a close relationship between the oxygen content in steel and oxides.

During the solidification process of molten steel, the dissolved oxygen of aluminum, calcium, silicon and other elements forms oxides. The oxide inclusion content is a function of oxygen. As the oxygen content decreases, the oxide inclusions will decrease; the nitrogen content is the same as the oxygen content, and also has a functional relationship with the nitride, but because the oxide is more dispersed in the steel, it plays the same role as the carbide. , so it has no destructive effect on the fatigue life of steel.
​​
The existence of oxides destroys the continuity of the metal matrix, and because the expansion coefficient of oxides is smaller than the expansion coefficient of the bearing steel matrix, when subjected to alternating stress, it is easy to generate stress concentration and become the origin of metal fatigue. Most of the stress concentration occurs between oxides, point inclusions and the matrix. When the stress reaches a large enough value, cracks will occur, which will rapidly expand and destroy. The lower the plasticity of the inclusions and the sharper the shape, the greater the stress concentration.
​​
3. The effect of sulfide on fatigue life
​​
Almost all of the sulfur content in steel exists in the form of sulfides. When the sulfur content in the steel increases, the sulfide in the steel increases accordingly, but because the sulfide can be well surrounded by the oxide, the influence of the oxide on the fatigue life is reduced, so the number of inclusions has no effect on the fatigue life. , which is related to the nature, size and distribution of the inclusions.

It is not necessarily that the more inclusions, the lower the fatigue life, and other influencing factors must be considered comprehensively. In bearing steel, sulfides are dispersed and distributed in a fine shape, and are mixed with oxide inclusions, which are difficult to identify even by metallographic methods.

Experiments have confirmed that, on the basis of the original process, increasing the amount of Al has a positive effect on reducing oxides and sulfides. This is because Ca has a fairly strong desulfurization ability. Inclusions have little effect on the strength, but are more harmful to the toughness of the steel, and the degree of damage depends on the strength of the steel.