Bearing basic knowledge of bearing design and application
Introduction to Bearings
Bearings are classified into two categories: sliding bearings and rolling bearings. Their purpose is to support the rotation of the shaft and to carry the weight along the shaft.
Rolling bearings are versatile, standardized and easily serialized, and have minimal friction. Bearings can be designed and manufactured according to working conditions and are widely used in various industries.
Various machines have different working conditions and put forward different requirements for rolling bearings in terms of load capacity, structure and performance. Although rolling bearings are required to have various structures, the most basic structure is still composed of four parts: inner ring, outer ring, cage, and rolling elements.
The four parts of a rolling bearing are the inner ring, the outer ring, the cage, and the rolling elements. The inner ring and the outer ring are usually made of steel, and the cage is usually made of steel or brass. The rolling elements are usually made of steel or ceramic. Rolling bearings are required to have various structures, but the most basic structure is still composed of these four parts.
The role of bearing parts in bearings
The bearing is one of the most important parts of a machine. It allows two moving parts to move smoothly and with little friction. Without bearings, machines would not be able to function properly.
Bearing parts are usually made out of metal, but they can also be made out of other materials such as plastics or ceramics. The most common type of bearing is the ball bearing, which uses small balls to reduce friction between two moving parts. Other types of bearings include roller bearings, sleeve bearings, and angular contact bearings.
Each type of bearing has its own unique set of properties and is used in different applications. For example, ball bearings are commonly used in wheels and roller bearings are used in conveyor belts. sleeve bearings are used in applications where space is limited, and angular contact bearings are used in high-load applications.
The inner ring is the ring on a bearing that is closest to the axis around which the bearing rotates. The inner ring provides support for the outer ring and helps keep the bearing running smoothly. without the inner ring, the bearing would not be able to function properly.
Inner rings are usually made from steel or another strong material. The material must be strong enough to withstand the loads placed on the bearing, as well as the high speeds at which the bearing can rotate. The inner ring also needs to be smooth so that it does not cause friction or damage to the outer ring.
Outer rings play a crucial role in bearings. They help to hold the inner ring in place and keep it from moving around. Outer rings also help to keep the bearings lubricated and prevent them from overheating. Bearings are essential components in many machines and without properly functioning outer rings, they would not be able to function properly.
Rolling elements, such as balls or rollers, are essential components of bearings. They allow the bearing to rotate with minimal friction and help to support the load that the bearing is carrying. Without rolling elements, bearings would not be able to function properly.
There are different types of rolling elements that can be used in bearings, depending on the application. For example, some bearings may use balls, while others may use rollers. The type of rolling element that is used will affect the performance of the bearing.
Rolling elements are an essential part of bearings and play a vital role in their function. Without rolling elements, bearings would not be able to rotate properly or support the load that they are carrying.
The cage separates a group of rolling elements in the bearing equidistantly, guides the rolling elements to move on the correct track, and improves the internal load, distribution, and lubrication performance of the bearing.
Shaft washers are components of bearings that help to distribute the load evenly. The main types of shaft washers are flat washers, conical washers, and thrust washers. Shaft washers help to keep the bearing surfaces level and prevent them from tilting. They also help to keep the load on the bearing evenly distributed, which helps to extend the life of the bearing.
The cage is a key component of bearings, as it serves several purposes. The cage holds the bearings in place and prevents them from moving around within the bearing. It also helps to keep the lubricant in place and prevent it from leaking out. In addition, the cage helps to dissipate heat, which is generated during operation.
There are several different types of cages used in bearings, each with its own benefits. The most common type of cage is the steel cage, which is strong and durable. However, steel cages can also be susceptible to corrosion. Another type of cage is the plastic cage, which is lighter and more resistant to corrosion. Plastic cages are also more commonly used in high-speed applications, as they can tolerate higher temperatures.
Classification of rolling bearings
Rolling bearings are essential components of machinery and equipment. Their main function is to support and guide rotating or oscillating machine parts, reducing friction between moving parts to enable smooth and efficient operation. Bearings are classified according to the load direction or nominal contact angle they can bear
Radial bearings include radial contact bearings and radial angular contact bearings.
Radial contact bearing
Radial contact bearings have a nominal contact angle of 0 degrees and are primarily used to support radial loads. They can also support small axial loads while bearing radial loads. (Radial loads are those that act perpendicular to the bearing’s axis while axial loads are those that act parallel to the axis.)
Radial angular contact bearing
A radial bearing with a nominal contact angle of 0° to 45°, which can withstand combined radial and axial loads. Generally, it mainly bears radial loads. In individual cases, it can also bear pure axial loads. load.
Thrust bearings include axial contact bearings and thrust angular contact bearings.
Axial contact bearing
A thrust bearing with a nominal contact angle of 90 degrees,
Thrust angular contact bearing
A thrust bearing with a nominal contact angle greater than 45 degrees and less than 90 degrees is mainly used to bear axial loads, and can also bear small radial loads while bearing axial loads. is only used to bear axial loads.
③ Sort by the outer diameter
- Miniature bearing (D<26mm);
- Small bearing (26mm≤D<60mm);
- Small and medium bearings (60mm≤D<120mm);
- Medium and large bearings (120mm≤D<200mm)
- Large bearing (200mm≤D<400mm);
- Extra large bearing (400mm≤D<2000mm);
- Heavy bearing (D≥2000mm).
Advantages of rolling bearings
Rolling bearings also have a number of other advantages. They offer smoother and quieter operation, as well as reduced vibration and noise. They are also more tolerant of misalignment and can handle higher loads. Overall, rolling bearings offer many benefits and are a key component in many different types of machinery.
Rolling bearings are used in a wide variety of applications, from automotive engines to medical equipment. They are well-known for their durability and long lifespan. In fact, rolling bearings typically last up to five times longer than plain bearings.
Compared with sliding bearings, rolling bearings mainly have the following advantages:
- The small friction coefficient of the rolling bearings results in less frictional resistance and dynamic friction torque, which in turn consumes less power and results in higher mechanical efficiency.
- The external dimensions can be standardized and interchangeable. Besides, its installation, disassembly, and maintenance are very convenient.
- The axial structure is compact, which greatly reduces the axial structure size of the machine.
- High precision, small wear, and long life, and can maintain the installation accuracy of the shaft for a long time.
- Rolling bearings with self-aligning characteristics can work normally when the main shaft is slightly deflected or the mating parts are a little different.
- Rolling bearings are suitable for specialized mass production, with stable and reliable quality, high production efficiency, and low cost.
Several common rolling bearings
Rolling bearings are common in machinery and equipment
There are several common types of rolling bearings including ball bearings, roller bearings, Needle roller bearings, and tapered roller bearings. Each type has its own advantages and disadvantages, so it is important to select the right type for your application.
Deep groove ball bearings
The deep groove ball bearing is a popular choice for many applications due to its simple structure and easy-to-use design.
It is the most produced type of bearing and can be used in a wide range of applications. Deep groove balls are able to bear radial loads and a small amount of bidirectional axial load.
The inner and outer rings of the bearing are allowed to have a slight deviation of 8-16 degrees.
While deep groove ball bearings have low frictional resistance and high-speed limits, they are not as effective in shock load bearing as other types of bearings.
Basic structure and characteristics
Tapered roller bearings
Tapered roller bearings are most suitable for combined radial and axial loads, but can also bear large radial loads alone. They have a low limit speed and the bearing’s inner and outer rings can be separated, allowing for adjustment of the bearing’s clearance during installation.
This kind of bearing is usually used in pairs, installed symmetrically, and is suitable for use in applications where the rotational speed is not too high and the shaft rigidity is good.
The size of the axial clearance of the tapered roller bearing has a great influence on whether the bearing works well. When the axial clearance is too small, the temperature roller bearings are best suited for combined radial and axial loads, but can also withstand large radial loads on their own.
They have a low limit speed and the bearing’s inner and outer rings can be separated, allowing for adjustment of the bearing’s clearance during installation. This kind of bearing is usually used in pairs, installed symmetrically, and is suitable for use in applications where the rotational speed.
Thrust ball bearing
Thrust ball bearings consist of separable rings and rolling elements, with a contact angle of 90 degrees. They come in one-way and two-way designs.
One-way thrust ball bearings can only bear axial loads in one direction, limiting the axial movement of the shaft and housing in one direction. The inner holes of the two ferrules are not of the same size, with the larger inner hole being the loose ring (seat ring) fixed with the machine base. One-way thrust ball bearings have a low limit speed and are suitable for installations where the axial force is large and the speed is low.
Two-way thrust ball bearings are designed to support axial loads in both directions and limit the movement of shafts and housing in two directions. The middle ring is a tight fit with the shaft, while the other two rings are loose.
This design can cause serious friction and heat build-up at high rotational speeds, leading to relatively short service life. Two-way thrust ball bearings are often used in applications where there is a large axial load but relatively low rotational speed.
Angular contact ball bearings
Angular contact bearings are designed to support high-speed and bidirectional loads. These bearings can withstand radial and axial loads simultaneously, as well as pure axial loads.
There are three types of angular contact bearings, based on the nominal contact angle (α): 15°, 25°, and 40°. Larger values of α correspond to greater axial load capacity, but reduced limit speed. Angular contact ball bearings are typically used in pairs and mounted symmetrically.
Self-aligning ball bearings
The self-aligning ball bearing has two rows of steel balls, two raceways in the inner ring, and an inner spherical raceway on the outer ring. This design gives the bearing self-aligning performance, meaning it can bear radial loads and a small amount of bidirectional axial loads.
The maximum deflection of the inner and outer ring axes is 2°, which is appropriate for shafts with low bending stiffness and supports that are difficult to accurately align.
Cylindrical roller bearings
The cylindrical roller bearings typically have two bearing rings that guide the rollers. The cage, rollers, and guide ring form an assembly that can be separated from the other bearing ring. This separable bearing can only bear radial loads and not axial loads.
However, only single-row bearings with ribs on both the inner and outer rings can bear a small directional axial load or a large clearance axial load. Cylindrical roller bearings usually have a greater load capacity than ball bearings of the same size. They are especially well suited for bearing strong shock loads and have higher limit speeds.
Spherical roller bearings
Spherical roller bearings are designed to withstand radial and axial loads. They are especially well-suited for use in high load or vibration environments. Spherical roller bearings have good self-aligning properties and can compensate for misalignment. They are commonly used in rolling mills and mining machinery.
Needle roller bearings
Needle roller bearings utilize a large number of needle rollers as rolling elements (the length of the roller is 3 to 10 times the diameter, and the diameter is generally not more than 5mm).
It has a compact radial structure, strong radial bearing capacity, and low price.
One downside of needle roller bearings is that they can’t handle axial loads. Additionally, there is friction between the needle rollers, which can lower the rotation accuracy and limit speed.
Lastly, the axis of the inner and outer rings is not allowed to be skewed during operation.
However, these bearings are often used in situations where rotational speeds are low and radial dimensions are limited.
The fields of application of rolling bearings are extremely wide. Combined bearings, special bearings, non-standard bearings, etc. are designed according to specific user requirements. Some bearings are whimsical in structural design, some are in a different way in terms of special materials, and some are in the field of application. Bearings will promote each other and develop together with the continuous progress of human science and technology.
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