What Are Our Concerns About Bearings（26）

Q1:What are the components of rolling bearings?

• 1) Basic code imported bearings  
• A basic code used to show the bearing diameter, diameter series, width series and type, generally five digits, first described as follows:  
• Bearing inner diameter is represented by basic code number one from the right and H digit.  For the common inner diameter d=20~480mm bearing inner diameter is generally a multiple of 5, these two numbers represent the bearing inner diameter size divided by 5 quotient, such as 04 represents D = 20mm;  12 means d = 60mm and so on.  
• For bearings with inner diameters of 10mm, 12mm, 15mm and 17mm, the inner diameters are 00, 01, 02 and 03 respectively.  For bearings with inner diameter less than 10mm and greater than 500mm, the inner diameter expression method is otherwise stipulated, which can be referred to GB/T272-93.  

• 2) The diameter series of bearings (that is, the bearing with the same structure and the same inner diameter changes in the outer diameter and width series) are represented by the third digit from the right of the basic code.  For example, for centripetal bearings and centripetal thrust bearings, 0 and 1 represent extra-light series;  2 indicates light series;  3 indicates the medium series.  4 indicates the repeated series.  The size pairs between the series are shown in the figure below.  The thrust bearing is the same as the centripetal bearing except that 1 is used to represent the extra-light series.  

• 3) The width series of bearings (that is, the change series of bearing width with the same structure, inner diameter and diameter series) is represented by the fourth digit from the right of the basic code.  When the width series as shown in Figure 13-4 is listed as series 0 (normal series), the width series code O can not be marked in the code for most bearings, but for self-aligning roller bearings and tapered roller bearings, the width series code 0 should be marked. Diameter series code and width series code collectively referred to as size series code.  
• 4) Bearing type codes are represented by the fifth digit from the right of the basic code (for cylindrical roller bearings and needle roller bearings and other types of codes are letters).  
• 2.  Post code  
• Bearing postcode is to use letters and numbers to express the bearing structure, tolerance and special requirements of materials, etc.  Postcode is a lot of content, here are a few commonly used code.  
• 1) The internal structure code refers to the different internal structure of the same type of bearing, which is represented by letters followed by the basic code.  For example, angular contact ball bearings with contact angles of 15°, 25° and 40° are denoted by C, AC and B respectively.  
• 2) The tolerance grade of bearings is divided into class 2, class 4, class 5, class 6, class 6X and class 0, a total of 6 grades, successively from high to low, and its codes are/PZ, / P4 ‘/ PS, / P6, / P6X and/PO respectively.  In the tolerance class, class 6X is only applicable to tapered roller bearings;  Grade 0 is general grade and is not marked in the wheel bearing code.  
• 3) The commonly used radial clearance series of bearings are divided into 6 groups, namely group 1, group 2, group 0, group 3, group 4 and group 5. The radial clearance is successively from small to large.  O group clearance is a commonly used clearance group, which is not marked in the bearing code, and the other clearance groups are respectively represented by/CI, / CZ, / C3, / C4 and/CS in the bearing code.  
• 3.  Front code  
• Bearing prefix code used to represent bearing parts, with letters.  For example, L represents the separable ring of the separable bearing;  K represents the rolling body and cage components of bearings, etc.  

Q2:What is the new model of 942/40 needle roller bearing

A:HK4050*32mm

Q3:What are the common types of rolling bearings?

A: Self-aligning ball bearing, spherical roller bearings, thrust spherical roller bearing, tapered roller bearings, big cone Angle tapered roller bearings, thrust ball bearings, two-way thrust ball bearings, deep groove ball bearings, angular contact ball bearings, cylindrical roller bearing outer ring without a guard, no guard of cylindrical roller bearing inner ring, inner ring has a single guard of cylindrical roller bearings, needle roller bearings, insert ball bearing units with the top wire  Etc.  

Q4:What is the main function of the cage?  

A:The main function of cage is to evenly separate the rolling body, make the rolling body evenly distributed and reduce the friction and wear between the rolling body.  If there is no cage, the adjacent rolling bodies will be worn due to large relative sliding speed at the contact point when rotating.  

Q5:What are the main factors that should be considered when choosing rolling bearing types?

A:1) Bearing load: the size, direction and nature of the load on the bearing is the main basis for selecting the bearing type.；
Bearing speed: under the general speed, the speed level has no effect on the selection of type, only when the speed is high, there will be a significant impact；  
The self-aligning performance of bearings;  
Installation and disassembly of bearings. 

Q6:What is the life of bearings?

A:For a single bearing, the number of revolutions of one ring relative to another is called the life of the bearing before the first fatigue expansion of one ring or rolling material.  Due to the differences in manufacturing accuracy and material homogeneity, even if the bearings produced by the same material, the same size and the same batch work under the same conditions, their life will be very different.

Q7:What are the bearings of class 0~8?

A:There are 9 categories from 0 to 8.  Class 0 is double row angular contact ball bearings;  1 Aligning ball bearing;  2 Self-aligning roller bearing and thrust self-aligning roller bearing;  3 Tapered roller bearing;  4 Double row deep groove ball bearings; 5thrust ball bearing; 6 deep groove ball bearing;  7 Angular contact ball bearing;Thrust assistance roller bearing.  

Q8:What are the main failure forms of rolling bearings?

A:Mainly: pitting corrosion, plastic deformation, abrasive wear, adhesive wear, rust, bearing burn and so on.  

Q9:What is the basic rated life of a bearing?

A：According to a group of bearings in 10% of the bearing pitting damage, and 90% of the bearings do not occur pitting damage before the revolution (in millions of units) or the number of working hours as the bearing life, and this life is called the basic rated life, expressed by L10.  

Q10:According to the bearing bearing different external load, what kinds of rolling bearings can be divided into? 

A: It can be generally divided into three categories: centripetal bearing, thrust bearing and centripetal thrust bearing. 

Q11:What is the basic dynamic load rating of bearings?

A:When the basic rated life of the bearing is exactly one million revolutions, the load value that the bearing can bear is called the basic rated dynamic load of the bearing, which is expressed by C.Centripetal bearing, refers to the pure radial load, expressed by Cr;  For thrust bearings, the pure axial load is expressed by Ca.

Q12:Why should rolling bearings carry out static load calculation?

A:Static load refers to the load on the bearing when the relative speed of the bearing ring is zero or extremely low.  In order to limit the excessive contact stress and permanent deformation of rolling bearings under static load, static load calculation is needed.

Q13:When the rolling bearing is lubricated with grease, what is the amount of grease generally?

A:The amount of grease in rolling bearings is generally 1/3 to 2/3 of the internal space of bearings.

Q14:Why do rolling bearings need to use sealing devices?  What are the commonly used sealing devices? 

A:The sealing device of the bearing is set up to prevent dust, water, acid gas and other sundries from entering the bearing and prevent the loss of lubricant.  Sealing device can be divided into contact type and non-contact type two categories.