[Miniature motor bearings] Senior engineers from the Ministry of Micro-Technology tell you about bearings
Release time: 2017-11-06 21:36:48 Views: 1203
|Overview: Before exchanging bearing knowledge with you, let us first understand some gaps between our bearings and foreign bearings:|
China is one of the earliest countries inventing rolling bearings in the world. From archeological relics and materials, China's oldest bearing with a prototype of a modern rolling bearing structure appeared in Xuejiaya Village, Yongji County, Shanxi Province, from 221 to 207 BC (Qin Dynasty). In 1280 (Yuan dynasty), cylindrical rolling bearings were also used in ancient Chinese astronomical instruments. Although China has historically been at the forefront of world civilization in the field of rolling bearing technology, it really started in 1950.
China's bearings have just started in 1950 and are currently the fourth largest country after the United States, Japan and Germany, but the differences are still obvious.
First, in terms of varieties, there are 150,000 species in the world in terms of specifications. China has only accumulated more than 20,000, and it is basically currency or ordinary products.
Second, in terms of production capacity, China now has more than 2,000 companies, which is 5-6 times that of enterprises in other countries, but the total output value is more than ten percent of Japan's NSK.
Third, in terms of dimensional tolerance and rotational accuracy, China is close to the world level, but the dimensional dispersion is far from some international brands.
Fourth, the high-speed performance is low, which means that the speed is not high,
Fifth, the control of vibration and noise and abnormal sound is more than 10db (decibel) from Japan. We are generally about 35 now, (our company's noise control ???) A better 32, which is about 25 or less for Japanese companies,
Sixth, in terms of life and reliability, taking deep groove ball bearings as an example, foreign countries are more than 8 times domestic, and at most 30 times.
Seven, bearing application technology in special conditions, the gap is large, large equipment, key equipment are basically imported bearings.
China's three major bearing manufacturers: Havalo, find out. More reserves, more income.
Now I will start with some small knowledge. I hope these are helpful to everyone's work. Only by understanding the history of products and products can you and I fall in love with this profession that we are engaged in. We work for the operation of history. sacred!
1, the expression of angular contact bearings: C-36 (15 degrees), AC-46 (25 degrees), B-66 (40 degrees), A-30 (30 degrees), such as 7208AC = 46208, can you ask questions?
2. Small knowledge of clearance: C0, basic group (CN)
C2, auxiliary group, radial clearance value is smaller than basic group.
C3, ............... is larger than the basic group.
The basic clearance is what our company currently has clearance: 6-13um (micron)
CM ....... Motor level clearance, higher requirements.
The clearance values are divided into three groups based on size. One group is the basic group (or common group), the small clearance group (C2), and the large clearance group (C3, C4). 的NSK、NTN等品牌还有专门的CM组（电机专用游隙）。 Japan 's NSK, NTN and other brands also have a special CM group (motor-specific clearance).
(1, tolerance of inner diameter, outer diameter, thickness, assembly width)
Tolerance limits for chamfer dimensions, etc. Inner and outer holes
Tolerance of circle diameter
Rolling Bearing Accuracy Rotation Accuracy: Necessary to suppress the bouncing of the rotating body.
1. Tolerance of radial runout / axial runout of inner ring and outer ring,
2. Tolerance of lateral runout of the inner ring.
3. Different tolerance values for thrust bearing raceway thickness.
*** (For example, if the customer wants a tolerance of P5, only the dimensional accuracy can be selected, which is completely unachievable.)
4, the specific meaning of UG:
UG refers to a bearing that has a sealing groove in Class 0 but has not been glandized or oiled. For example, UG205 refers to 6205 that can be glandized or oil-sealed, which is different from the open type 6205.
冷轧 碳钢 薄板 及钢带”钢材名称，也有304的盖子，但是相对GCR15中应用较少！烈力轴承目前采用活盖304材质。 5. Material of bearing dust cover: Dead cover: SPCC material (Earth language: yellow leather cover, cold rolled carbon steel sheet and steel strip). There is also a 304 cover, but it is less applied than GCR15! The bearing is currently made of 304 cover.
6, bearing quenching and tempering. Quenching temperature: 820-840 degrees, tempering temperature: 150 degrees, tempering time: 1-2H,
Low temperature tempering: 150-250 degrees:
Tempering at moderate temperature: 300-450 degrees
High-temperature tempering: 500-650 degrees The purpose of quenching is to make all or most of its structure into martensite, obtain high hardness, and then temper at an appropriate temperature, so that the workpiece has the expected properties.
Tempering: The operation of reheating the quenched workpiece to a certain temperature range and holding it in oil or air is called tempering.
In short, in order to improve the performance of the bearing, you can understand it.
7. The distinction between stainless steel and the composition of bearing steel (question link)
(1), 440C bearing: (S694ZZ bearing material: inner and outer ring, tight ring, cage ball material, tight ring, cage, cover 304)
保持架 及紧圈，防尘盖材料采用AISI304不锈钢（国内编号：1Cr18）。 The bearing ring and rolling element are made of AISI SUS440C stainless steel (domestic number: 9Cr18Mo, 9Cr18) after vacuum quenching and tempering, the cage and tight ring, and the dust cover material is AISI304 stainless steel (domestic number: 1Cr18).
(2) GCR15 bearing: The composition of bearing steel bearing accessories such as: 693ZZ bearing bearing. (Inner and outer ring, tight ring, dust cover, cage, rolling body) Question model? Inner and outer ring, the ball is GCR15, cage 08F, tight ring: 65Mn, dust cover: 1CR18NI9-domestic (304 material). F in 08F means boiling steel, 08 means that the carbon content is 8 / 10,000, Mn: transition metal, silver-white metal, firm and brittle. The 65Mn steel plate has higher strength, hardness, elasticity and hardenability than the 65 steel, and it has the tendency of overheating sensitivity and temper brittleness. The water quenching has the tendency to form cracks.
8, the carbon content of bearing steel: general bearing steel is mainly high-carbon chromium bearing steel, that is, the carbon content of about 1%, adding about 1.5% of chromium, but also contains a small amount of manganese, silicon elements.
9, size conversion: 1UM (micron also called Miao) = 0.001MM, 1 wire = 10 microns, 1 track = 0.01MM = 10UM = 1 wire 1 inch = 25.4MM that is 1 wire = 0.1 mm? right? Correct
10, the issue of serial code. , Flexible understanding of bearings, a lot of benefits for familiarizing with bearing models.
6700 (25 ¡Á 32 ¡Á 4), 6805 (25 ¡Á 37 ¡Á 7), 6905 (25 ¡Á 42 ¡Á 9), 16005, (25 * 47 * 8), 6005 (25 * 47 * 8), 6205 (25 ¡Á 52 ¡Á 15), 6305 (25 ¡Á 62 ¡Á 17), 6405 (25 ¡Á 80 ¡Á 21), the difference in shape is getting bigger and thicker, and the inner diameter is 25. . . . The outer diameter becomes larger and the thickness becomes larger.
11. Why is a nylon cage sometimes needed:
Noise control will be better than iron guard or stainless steel cage, but too small to operate.
First, the light weight makes the flexibility of the bearing better. If it is used in electrical appliances or power consumption products, it has a great effect on energy saving;
Second, low noise is the first choice for silent bearings, especially home appliances that have strict requirements on noise, and its application can significantly improve the low noise performance of home appliances;
Third, it can effectively extend the service life of the bearing and reduce the friction between the cage and the rolling body;
Fourth, it has good properties such as wear resistance, anti-magnetic and low friction.
Disadvantages: 1. The nylon cage can only work at normal temperature, and a slightly higher temperature will easily cause the bearing to lock up.
Second, the compressive strength of the nylon cage is not as strong as the metal steel cage, and the load capacity is not high.
3. Nylon cage bearings cannot be used in environments where they have a corrosive effect.
2. Hardness of bearing steel (GCR15): HRC60-65, chromium hardness. G is the first letter of the scroll, one percent carbon, 0.5 percent chromium
The hardness of stainless steel 440C: HRC56-58.
304 material: The name comes from the United States. 304 is a food-grade bearing. In the true meaning, a CR (chromium) content greater than 18% can be considered a 304 stainless steel bearing. This is also because the industry will call this type of stainless steel 18/8. The reason for stainless steel. CR-18-20
13, the representation of the inner diameter code:
Example: 10-17MM inner diameter size
(7,8) Ultra light series (0,1) Extra light, light load, high speed, light series (2), medium (3), heavy (4), low speed
Such as: 6 2 0 1 6; type code (bearing) deep groove ball bearing, 2, size series, (02 code), 01 = inner diameter, (inner diameter 12 mm), tolerance level is 0, clearance standard is C0, why What about 6201? What does it mean, randomly?
A, bearing load, B, speed, C, self-aligning performance, D, bearing rigidity, E, bearing movement, F, allowable space, G, installation and disassembly.
15. Filling with grease. Lubrication method.
First, one-third to two-thirds of the space between the general bearing and the housing (or the filling amount accounts for the free space of the bearing).
Second, when running at high speed, the filling is less than one-half,
Third, it can fill the space at heavy load and low speed.
Question: What happens if there is less fat? What happens when there is more?
1. Less, it will cause the lack of effective oil film protection between the raceway of the ring and the surface of the rolling element, and the rolling surface of the bearing will soon be worn and damaged.
2, more, it will cause the bearing to generate a lot of heat during operation, it is easy to generate heat, which will cause the bearing to be damaged due to excessive heating.
16. What is the difference or difference between ZZ and ZZS? Question?
ZZ is a dust cover. What does S mean? It means that the dust cover can be removed, that is, it can be moved, that is, a live cover, which is usually not distinguished in detail. However, the cover does not have a tight ring, such as a micro-bearing, it is easy to fall off. But the processing structure may also be different.
17, such as the difference between R3HZZ and R3ZZ?
The difference between the fixed cover and the live cover is that the former refers to the fixed cover, which is usually not distinguished.
18. Comparison of new and old models:
1000822 --- 61822, 106 --- 6006, 112--6012, 180201-6201-2RS, 80201-6201ZZ, 60201-6201Z, 160201--6201RS, 50201-6201N (stop groove), 8100-51100, 608 -18,619 / 6--696--1000096,618 / 8--688 --- 1000088,618 / 4--684--1000084.
19, bearing radial clearance and axial clearance
The radial clearance of the bearing is generally 6-13 microns, so often the axial clearance we rarely pay attention to? Customers often ask, how do we answer?
The actual axial clearance is generally 10 wires (1 wire = 10 mu or micrometers)
The implication is that the axial clearance is about 10 times the radial clearance, that is, 10 wires / 0.1 mm.
Misunderstandings of 20, 2RZ and 2RS
RS and RZ both indicate bearings with dust cover, contact and non-contact. In popular terms, there is a problem of full sealing and partial sealing.
Contact sealed bearings: large internal friction, not easy to lubricate. When these two types of bearings are used, the influence of environmental factors on the use of the bearings is mainly considered. If they are fully lubricated in the box, these two types of bearings are generally not used.
At present, the 2RS we write when writing an order is actually 2RZ. It is enough to understand. There is no special distinction. Contact type is difficult to do and can be done.
21, the problem of the same load force with the inner diameter: small depth, but high speed is the first choice.
Deep groove ball <Angular contact bearing <Cylindrical roller bearing <Tapered roller bearing <Spherical roller bearing
22, bearing life
Even if the bearing has the same structure, size, material and processing method, the bearing fatigue life will still have a large difference when rotating under the same conditions.
This is because the material fatigue itself has a discrete type, which should be considered from a statistical perspective. The director of the factory also said that it is generally half a year. (I will give you a relatively reference bearing life table at that time, which can be flexibly used in the sales process. To avoid communication misunderstanding)
Go down and give everyone a copy of the table when the time comes!
23, Stock model comparison
TMR63ZZ = MR63ZZ / ABEC-5 = MR63ZZ / A5, but the T outer ring has to be specially treated. What is polished may be better in appearance and use! For example, on the instrument.
24. The suffix code question:
LS: contact oil seal on the bearing side, 2LS: contact oil seal on both sides of the bearing, N; stop groove on the outer ring, NR: stop groove and stop ring on the outer ring, Z: dust-proof on the bearing side Cover; 2Z: dust cover on both sides of the bearing; ZN: dust cover on the opposite side of the stop groove; 2ZN: dust cover on the two side of the bearing, stop groove on the outer ring, W200, W210, W302, W are The meaning of widening, for example, the bearing of our company F683 ZZW2.5 is 2.5.
Are 25, 7206 and 6206 interchangeable?
The two models are the same size, but their applications are different depending on the force, and the 7206 is usually used in pairs.
In general, 6206 is not suitable to replace 7206, but 7206 can replace 6206 (but it must be replaced in pairs)
Back to back DB small to small AC 25 degrees
Face to face DF large to large B 40 degrees
DT tandem large to small C 15 degrees
What is the angle of 7206AC, 7206B, 7206C and the maximum? (Angular contact bearings are used for combined load, the larger the angle, the greater the axial load), which is the maximum 7206B load
26. Bearing selection principle.
1. The ball bearing has a higher limit speed than the roller support. Ball bearings should be preferred.
2. At high speeds, ultra-light series and extra-light series should be preferred (same inner diameter, smaller outer diameter, lighter and smaller rolling elements, and smaller centrifugal inertia).
3, the material of the cage has a great impact on the speed of the bearing, the solid cage has a higher speed than the stamped cage,
4. Thrust bearing's limit speed is very low. When the working speed is high, if the axial load is very large, angular contact bearings can be used to bear pure axial load.
5. If the working speed exceeds the bearing sample, you can increase the tolerance level, increase the clearance appropriately, and choose the method of cyclic cooling.
，在这里上海御微轴承有限公 司高级工程师唐工 整理这些和广大客户 一起学习，由于时间有限，下次给大家讲一下轴承销售方面的知识，希望今天的学习能让大家进一步的了解轴承，对业务知识的储备有一定作用，最后谢谢所有读者 ，有什么好的建议以后也可以提出来，共同进步！ The knowledge points I talked about today are relatively scattered, and many of them are easy to come across. Here , Tang Gong , a senior engineer at Shanghai Yuwei Bearing Co., Ltd. organizes these and learns with our customers . Due to limited time, I will tell you about bearing sales next time. I hope that today ’s study will help everyone to further understand the bearing, which will have a certain effect on the reserve of business knowledge. Finally, thank you all readers . Any good suggestions can be put forward later and make progress together! 您可以持续关注御微轴承公众号以及御微热线：021-51099639 邮箱： firstname.lastname@example.org ,企业网站： gifudayo.com To learn about Shanghai Yuwei Bearing Co., Ltd.'s bearing information or customers who purchase bearings, you can continue to pay attention to Yuwei Bearing's public account and Yuwei Hotline: 021-51099639 Email: email@example.com , corporate website: www.yw-brg .com