The composition and working principle of deep groove ball bearings

Bearings can be divided into two types: sliding bearings and rolling bearings, and deep groove ball bearings are the most used, widely used, and most commonly produced type of rolling bearings. Deep groove ball bearings are relatively simple in structure and easy to mass produce, so it is less difficult to achieve higher manufacturing accuracy. Deep groove ball bearings are everywhere in people’s lives. For example, for high-end mountain bikes, deep groove ball bearings need deep groove ball bearings to support axles and spokes, ensure speed and rotation accuracy, and reduce rotor wear. This article discusses the application of deep groove ball bearings in people’s daily life from the aspects of composition principle and movement realization.

Although deep groove ball bearings have low load-bearing capacity, they have low friction and high limit speed. In actual use, the radial clearance can be appropriately increased to increase the axial load-bearing capacity. Therefore, deep groove ball bearings are widely used As far as the general machinery in life, people can easily find the shadow of deep groove ball bearings in mountain bikes and yo-yos, and even playful children know something about deep groove ball bearings. The author is a mountain bike enthusiast, owns a Giant ATX660, and understands the importance of different bearings to the performance of mountain bikes. ATX660 is equipped with a total of 6 bearings, of which the bottom bracket is VP-BC73 sealed bearing bottom shaft. In addition, the front fork headset, front and rear axles, pedals and rear shift guide wheels are all selected 60,000 02 series or 10 series. Deep groove ball bearings. Bearings are precision machinery around us. The correct selection of different types of bearings has an impact on the performance of mountain bikes. For the same reason, all kinds of machinery in life require proper bearings to be assembled, which requires us to have a considerable understanding of bearings.

The structure of deep groove ball bearings

The bearing is a component that fixes and reduces the friction coefficient of the load during the mechanical transmission process. The bearing can reduce the friction coefficient of other parts moving relative to each other on the shaft during power transmission, and keep the center position of the shaft fixed. According to the different friction properties of the moving elements, it can be divided into rolling bearings and sliding bearings.
First of all, deep groove ball bearings are classified as rolling bearings. Rolling bearings are usually composed of four parts: outer ring, inner ring, rolling element and cage. The inner ring is mounted on the journal, and the outer ring is mounted in the bearing housing hole. In most cases, the inner ring rotates with the shaft and the outer ring remains stationary. According to the different rolling elements, rolling bearings can be divided into roller bearings and ball bearings. The corresponding rolling elements are cylindrical rollers and spheres. Deep groove ball bearings are centripetal ball bearings in which each ring has a continuous groove raceway with a cross section of approximately one-third of the circumference of the ball.

The following figure is the CAD drawing of 6000 bearings and 6200 bearings commonly used in mountain bikes.

6000 bearing drawing

6200 bearing drawing

Deep groove ball bearings can also be deformed in their basic type. For example, it can be deformed into a deep groove ball bearing with a stop groove in the outer ring, a deep groove ball bearing with a sealing ring, a deep groove ball bearing with a dust-proof cup, and so on.

The working principle of deep groove ball bearings

When working, half of the inner ring rotates while the outer ring does not move, then the rolling elements roll between the inner and outer rings. At this time, the cage evenly separates the rolling elements to reduce friction and wear between the rolling elements. The cage also plays the role of equal distance distribution of rolling, thus reducing the friction and wear between the rolling elements. The rolling element not only rotates on its own axis, but also revolves along the raceway of the ring and around the axis of the bearing, and while rolling, it is accompanied by a certain amount of sliding. The rolling elements change the friction between the relative moving surfaces into rolling friction.
After understanding the movement of each part of the deep groove ball bearing mentioned above, the momentary force analysis of the deep groove ball bearing is carried out.

When the deep groove ball bearing is at rest, the contact surface between the rolling elements and the inner and outer rings bears a static load, while the outer ring raceway surface is always subjected to partial circulation or static force. When the rolling element is at the lowest point, the maximum stress appears on the rolling element, inner and outer rings. When the deep groove ball bearing starts to work and the inner ring rotates coaxially while the outer ring does not move, the rolling elements generate friction along the raceway of the ferrule, and the rolling elements and the inner ring are instantaneously before and after the contact, and the contact surface will produce cyclic intersections. Change pressure. It can be seen that the effects of deep groove ball bearings under load are different when they are stationary and in motion. Therefore, in actual assembly, the static load rating and the dynamic load rating of the bearing must be distinguished.

From the above analysis, it can be seen that the deep groove ball bearing mainly bears the radial load on the contact surface, but under certain circumstances it can also bear the radial load and the axial load at the same time, but its axial load capacity is relatively small. When it only bears radial load, the contact angle is zero, and when there is an axial force, the contact angle is greater than zero. Therefore, the deep groove ball bearing with larger radial clearance has the performance of an angular contact bearing, which can increase the axial load carrying capacity.

To sum up, in general, deep groove ball bearings are not resistant to impact and can not withstand heavy loads, but they have low friction coefficients and high limit speeds.

After the deep groove ball bearing is assembled, within the axial clearance range, the axial displacement of the shell or the shaft is restricted, so the deep groove ball bearing can be positioned in two directions. It is worth mentioning that deep groove ball bearings have a certain degree of self-aligning ability. For example, when the bearing is inclined 2’～10′ to the housing hole, the entire structure can still work normally regardless of the impact on the bearing life.
Of course, the deformed bodies modified based on the basic type of deep groove ball bearings also have similar working principles, but in order to meet the needs of certain mechanical movements, people have given them more functions. For example: a deep groove ball bearing with a stop groove, when the stop ring is installed in the stop groove, the position of the bearing is determined in the housing, thereby simplifying the bearing positioning mechanism.
The deep groove ball bearing with rubber sealing ring is based on the 60,000 type, and the rubber sealing ring with frame is added. The waterproof, dustproof and sealing reliability of the modified deep groove ball bearing are greatly improved. Such bearings are widely used in low-noise mechanical equipment. For deep groove ball bearings with dust-proof cups, a dust-proof cover is installed on the outer side of the rib on the basic structure. This type of bearing is usually used for one-time use, so an appropriate amount of grease is very important for its assembly. Therefore, it is frequently used in an environment with poor lubrication and dust, and can work for a long time without maintenance.

Although the bearing is small, it is very important. In the process of mechanical assembly, only a deep understanding of the composition and working principle of various types of bearings can maximize their functions.