Abstract: This paper focuses on some details that should be paid attention to in the practical work of single row angular contact ball bearings, from the acceptance of bearing quality, to the best installation method, and then to the correct operation of maintenance, to ensure the service life of bearings, add bricks for the development of enterprises.

Key words: angular contact ball bearing; Bearing installation; Bearing lubrication; Energy saving benefits; Selection principle

1. Classification of bearings

Bearing plays a decisive role in modern machinery and equipment, is a very important part of machinery and equipment. Its main function is to support the rotating shaft or other moving body, guide the rotation or moving motion and bear the load transmitted by the shaft or the parts on the shaft.

According to the different friction properties of moving components, bearings can be divided into rolling bearings and sliding bearings. According to the direction of the load it can bear, it can be divided into: (1) radial bearings, also known as centripetal bearings, bear radial load; (2) Thrust bearing, also known as thrust bearing, bears axial load; (3) Radial thrust bearing, also known as centripetal thrust bearing, bears both radial load and axial load. Here is mainly described rolling bearings, according to the function of rolling bearings, design and function of the different, there are many types of bearings, including: needle roller bearings, aligning ball bearings, deep groove ball bearings, aligning roller bearings, thrust bearings, bearing with seat, joint bearings, combination bearings, rolling mill bearings, etc. Different bearings have different functions and play a role that can not be underestimated in different mechanical equipment.

In order to better identify and distinguish bearings, experts and scholars give different types of bearings a name - bearing code. A complete bearing code is composed of the basic code plus one or more supplementary code. Basic code is used to indicate the type of bearing, the basic design of bearing, bearing size. Supplementary code refers to a bearing component, a variant that has a different structure from the basic design or other characteristics.

2. Classification of rolling bearings

What is rolling bearing? Simply speaking, rolling bearings are supporting parts that work on the principle of friction. Due to the lubricating effect of lubricating oil, they have small friction, easy to start, fast rising speed, compact structure and wide range of adaptation. For example, it is widely used in industry, agriculture, transportation, national defense, aerospace, household appliances and other industries, which is closely related to the national economy and people's livelihood.

Most of the bearings we often encounter in our daily work are rolling bearings, of course, sliding bearings will also be encountered, but relatively speaking, rolling bearings are used in practical work. There are many kinds of rolling bearings, as described in the above bearing code, such as: Deep groove ball bearings, angular contact ball bearings, tapered roller bearings, thrust ball bearings, self-aligning roller bearings, self-aligning ball bearings and so on, according to their respective functions, design and function of the different, are playing their respective roles, are in the development of the national economy has an irreplaceable role, for the motherland's economic take-off and quietly working.

3. Structure of angular contact ball bearings

As is known to all, general bearings are composed of four parts: inner ring, outer ring, cage, rolling body, and some also contain dustproof disc. Angular contact ball bearings are no exception, and their basic components are inner ring, outer ring, cage and rolling ball. Angular contact ball bearings have two forms: single row and double row angular contact ball bearings, which play different roles. But no matter the form is different, they are paired for installation. For some reason, according to the basic design requirements, there is a single use, but it is not common. The following is a brief introduction to the single row angular contact ball bearings.

Single row angular contact ball bearings are used very much at present, mainly because it can bear axial load and radial load at the same time, as well as pure axial load, the limit speed is very high, and the size of the axial load is related to the size of its contact Angle, the greater the contact Angle, the greater the axial load. What is the contact Angle, simply said is the Angle between the line connecting the ball and the raceway contact on the radial plane and a line perpendicular to the bearing shaft. This kind of bearing can be roughly divided into two forms: separable and non-separable. Here I mainly talk about single row angular contact ball bearings non - separable 7000 series.

4. There are problems that should be paid attention to in the actual installation and use of angular contact ball bearings

We know that angular contact ball bearings can be divided into three kinds according to their contact Angle: ①7000C, contact Angle alpha =15°, which is mainly used in large size precision bearings; (2) Type 7000AC, contact Angle =25°, suitable for precision spindle bearings; ③ Type 7000B, alpha =40°, suitable for large axial load.

The installation of angular contact ball bearings can generally be divided into three main types:

4.1 Back-to-back configuration, followed by DB

What is back-to-back configuration, simply refers to the bearing outer ring wide face wide surface, or refers to the installation of the bearing inner ring small end face small end face. This is a kind of installation mode that we should often use. Compared with the other two ways, it has the following advantages: (1) The load it bears is separated from the bearing shaft, and note that it is separated; (2) It can bear the axial load acting on two directions, but the load in each direction can only be borne by one bearing; ③ Can adapt to the bearing configuration with relatively high rigidity, but also can withstand overturning moment.

Combined with these 3 advantages, it is not difficult to find that back-to-back configuration installation is to separate the load to the bearing shaft, the bearing and shaft have the advantage of separating the load, plus its withstand overturning moment, if coupled with the choice of appropriate contact Angle, can imagine, in actual operation, can save how much maintenance labor, can avoid how many possible equipment accidents? Therefore, based on the actual situation, I recommend the first choice of back-to-back configuration. Such as methanol refining area rectification device 14 pumps, is the use of angular contact bearings and deep groove ball bearings, operation in recent years is very good use.

4.2 Face to Face Configuration, and the trailing code is DF

What is face to face configuration, is the opposite of back to back configuration, refers to the bearing inner ring big end face big end face, or refers to the bearing outer ring narrow face narrow surface installation. This way is often used, but it does not have the advantage of back-to-back matching, the load it bears is converged to the bearing shaft, and the configuration is not as rigid as the back-to-back configuration, it is not suitable for bearing overturning moment.

4.3 Series configuration, followed by the code DT

What is series configuration, as the name implies, is in one direction, a smooth. This configuration is rarely used in practice.

In fact, through the bearing after the code can distinguish the installation of this angular contact ball bearing, coupled with the correct and reasonable installation method, commonly used hot installation method, through the bearing electric heater to heat the bearing to the appropriate temperature, immediately install, so as to avoid bearing deformation caused by excessive beating bearing, or due to the inner and outer ring asynchronous bearing life reduction, Long cycle operation that affects production. Rolling bearings are precision parts, assembly and disassembly should be standardized, otherwise it will cause the accuracy of the reduction, and even damage bearings and other parts. When assembling and disassembling, the rolling body must not be subjected to external force. The assembling and disassembling force should be symmetrical and uniform on the end face of the ring. Two methods are usually available: one is the hot installation method, as described above; The other is the cold pressing method, which is a small bearing with true interference fit. The inner and outer rings of the bearing are pressed with special pressing sleeves, and the bearing is pressed onto the shaft or the shell. Therefore, we must use the correct installation method, can not be opportunistic, fool themselves, so as to eliminate the damage caused by the installation quality of bearing.

5. Selection principle of angular contact ball bearing in practice

(1) The size, direction, nature and service life of the load are the main basis for choosing the type of bearing;

(2) Speed has little effect on the selection of bearing type, only when the speed is higher. It is emphasized here that the cage material and structure of the bearing have a great impact on the speed of the bearing;

(3) The selection and lubrication method of lubricating oil, whether to choose grease, solid lubricant, or lubricating oil, choose the appropriate lubrication method, you can avoid direct contact between raceway and the surface of the rolling body, reduce friction and wear, prolong life, but also play a cooling, vibration absorption, rust prevention and reduce noise. The specific lubrication method and lubricant selection can be selected according to the following table. Generally according to the site working environment to determine, there is no uniform regulations, but must ensure that the lubrication is good. Lubrication maintenance is directly related to the service life of bearings, which I have deep experience, we must do timing, fixed point, fixed quality, quantitative, fixed person, regular analysis of oil products, to ensure that the equipment bearing lubrication is good, so as to ensure the continuous production of equipment, but also to ensure the safety of the environment and everyone's happy life;

(4) According to the matching of bearing installation, considering the size, direction and nature of load, speed, rotation accuracy and installation factors, the general selection principle is: when the load direction is unchanged, the inner ring is tighter than the outer ring; The greater the load, the higher the speed, and vibration and impact, the tighter the fit should be; When the rotation accuracy of the bearing is higher, a tighter fit should be used; When the bearing must consider axial swimming, the match between the outer ring and the shell hole should be loosened. In a word, suitable is right, in the work to be good at summing up, to constantly improve their business ability in the work, skillfully do each job, do their own thing, is to make contributions to the enterprise.

6. Conclusion and Prospect

How to prolong the service life of bearings, this is a permanent topic, for the present, we can do is as mentioned above, first of all, to ensure that the acceptance of bearings to scientific norms, listen to, touch, check, look, measure, carefully check the quality of bearings, to ensure that the quality of the new bearing without any problems; Secondly, strengthen the improvement of the installation quality level, to have a rigorous attitude, serious installation of bearings, so that the installed bearings can run for a long period of time; Secondly, daily maintenance is also very important, to ensure that the "five" do, good lubrication. Under normal circumstances, when rolling bearings are running, the sound is stable and the temperature is normal. Once the sound is abnormal, or there is abnormal noise, and the temperature rise is high, this is the more common situation of abnormal rolling bearings. We should always pay attention to the sound and temperature changes of bearings, quickly and accurately judge the bearing fault, so as to deal with it in time, it should be repaired and repaired. Finally, it is a common phenomenon in China that the service cycle of bearings is not well executed. It is not right to replace bearings until they are abnormal. After all, everything has its internal service life, which we can not violate.

In short, the correct use and maintenance of bearings in the process of use will have positive significance for ensuring the running state of bearings and reducing the failure of mechanical equipment.

Author: Qiao Youfu

Source: China Chemical Trade · Mid-Day Issue, Issue 08, 2018

References:

[1] HE Xiaoyan. Discussion on Lubrication and Sealing of Rolling Bearing [J]. Friends of Science and Technology, 2006, 2 (12).

[2] Xiao Yongxiao, Lv Maoyan. General Principles of Rolling Bearing Selection [J]. China Equipment Engineering, 2004 (6).