Time：2020.01.20 Source：Roller Bearings Suppliers
Generally, the bearing is composed of an inner ring, outer ring, rolling body, and retainer. For sealed bearings, add lubricant and sealing ring (or dust cap). That all the bearings are made. Choose different types of bearings according to the working conditions of bearings, to better play the function of bearings, and extend the service life of bearings. The following elements should be considered in the selection of bearings: Radial load; Axial load; Speed requirement; Radial runout; Axial pulsation; Operating temperature; Noise requirements; Lubrication conditions.
The bearing type generally has the front code, the basic code, and the rear code. In general, the bearing type is only represented by the basic type. The basic model generally contains three parts, type code, size code, and inside diameter code. The rear code is to use letters and numbers to indicate bearing structure, tolerances, and special material requirements. The leading code is used to indicate the parts of a bearing, represented by letters. Universal bearing (rolling bearing) code method, divided into front code, basic code, and rear code.
Bearing inside diameter, outside diameter series, width series, model and other basic code, usually a maximum of five digits, first described as follows:
1. Bearing inner diameter is indicated by the first digit from the right of the basic code. For bearings with standard internal diameter d=20 ~ 480mm, the internal diameter is usually a multiple of 5. These two digits represent the quotient of bearing internal diameter divided by 5. For example, 04 represents d= 20mm.12 means d equals 60mm, and so on. Bearing with an inner diameter of 10mm, 12mm, 15mm and 17mm, inner diameters are 00, 01, 02 and 03, respectively. For bearings with inner diameter less than 10mm and greater than 500mm, the inner diameter representation method is otherwise specified, see GB/T272 -- 93.
2. The diameter series of bearings (i.e., the series of variations in the outside diameter and width of bearings of the same structure and inner diameter) is indicated by the third digit from the right of the basic code. For example, for radial bearings and radial thrust bearings, 0 and 1 represent the extra-light series;2 represents the light series;3 represents medium series;4 means heavy series. The size pairs between the series are shown below. The thrust bearing is consistent with the centripetal bearing except that 1 represents the extra-light series.
3. The bearing width series (i.e., bearing width variation series with the same structure, inner diameter, and diameter series) is indicated by the fourth digit from the right of the basic code. When the comparison of the diameter series in the width series are shown in figure 13-4 is listed as series 0 (normal series), the width series O may not be indicated in the code for most bearings, but the width series 0 shall be indicated for the aligning roller bearing and the tapered roller bearing. Diameter series code and width series code are collectively referred to as size series code.
4. The fifth digit indicates bearing type codes from the right of the basic code (for cylindrical roller bearings, needle roller bearings, and other type codes are letters).
·After the code
The rear code of the bearing is to use letters and numbers to indicate the bearing's structure, tolerances, and special material requirements. The content of postcode is a lot; the following several commonly used code.
1. Internal structure code refers to different internal structures of the same type of bearing, which are indicated by letters following the basic code. For example, angular contact ball bearings with contact angles of 15°, 25°, and 40° are respectively represented by C, AC, and B for different internal structures.
2. Bearing tolerance classes are 2, 4, 5, 6, 6X and 0
a total of 6 grades, from high to low, the codes are/PZ, / P4, / PS, / P6, / P6X and/PO.In the tolerance class, class 6X is only applicable to tapered roller bearings; Class 0 is a regular class and is not marked in the wheel bearing code.
3. The commonly used radial clearance series of bearings can be divided into 1 group, two groups, 0 groups, three groups, four groups, and five groups, a total of 6 groups, with radial clearance successively from small to large. Group o clearance is a commonly used clearance group, which is not marked in the bearing code. The rest clearance groups are represented by/CI, / CZ, / C3, / C4 and/CS in the bearing code.
The leading code of a bearing is used to indicate the parts of the bearing and is indicated by letters. If L represents the separable ring of the separable bearing, K represents the rolling body of the bearing, the cage assembly, and so on.
In practice, there are many types of rolling bearing, and the corresponding bearing code is more complicated.The system introduced above is the most basic, most commonly used part of the bearing code, familiar with this part of the law, you can identify and check the widely used bearing. The complete system for rolling bearings can be found in gbt272-93.
·Bearing selection method
The use of rolling bearing of various mechanical devices, instruments, and other market performance requirements are increasingly strict, the requirements for bearing conditions, performance is increasingly diversified. For choosing the most suitable bearing from a large number of structures and sizes, It needs to be studied from different angles.In the selection of bearing, generally, bearing structure is determined by considering the ease of arrangement, installation, and disassembly of the bearing as a shafting, the allowable space, and size of the bearing and the marketability of the bearing.
Secondly, the design life of various machines using bearings and different endurance limits of bearings are compared, and the bearing size is determined at the same time. When choosing bearings, only the fatigue life of the bearings is usually considered. The grease life, wear, and noise caused by the aging of the grease also need to be thoroughly studied.
Furthermore, it is necessary to select bearings specially designed for precision, clearance, cage structure, grease, etc., according to different purposes. However, there is no particular order and rule in the selection of bearings. The priority should be given to the conditions, performance, and most relevant matters required by the bearings, which is especially practical.
·Precautions forbearing use
The rolling bearing is a precise part, which should be used with due care. How do you use high-performance bearings anyway, if they are not used properly, the expected high performance will not be achieved.
1. Keep the bearing and its surroundings clean.
Even if the eyes can not see the small dust, also can bring adverse effect to the bearing. Therefore, keep the surroundings clean so that dirt does not invade the bearing.
2. Use with caution.
In use to give the bearing strong impact, will produce scars and indentation, become the cause of the accident. In severe cases, cracks and fractures will occur, so attention must be paid.
3. Use appropriate operating tools.
Avoid replacing existing tools with appropriate ones.
4. Notice corrosion of bearing.
When handling bearings, sweat on the hands can become a cause of rust. Use clean hands and wear gloves.
·Proper mounting of bearings
Bearing installation is correct, affecting accuracy, life, performance. Therefore, the design and assembly department has made a comprehensive research on the bearing installation. You want to install according to operating standards. Standard items are usually as follows :
1. Cleaning of bearings and bearing-related parts
2. Checking of dimensions and processing of relevant parts
4.Inspection of bearings after installation
Before installation, open the package. General grease lubrication, do not clean, directly fill the grease. Lubricating oil lubrication, ordinary do not have to clean, but with instruments or high-speed bearings, such as, to wash with clean oil, remove the rusting agent coated on the bearings. The bearing that removed antirust agent, natural rust, so cannot place ignore. Furthermore, bearings sealed with grease are not cleaned for direct use.
Bearing mounting method, bearing structure, fit, conditions, and different, generally, because of the shaft rotation, so the inner ring needs interference fit: cylindrical bore bearing, multi-purposes press, or multi-purposes hot mounting method. For taper holes, install directly on the tapered shaft, or connect with a sleeve.
When mounting to the shell, there is usually more clearance fit and interference in the outer ring, which is often pressed in with a press machine, or there is also a cold shrink-fit method for installation after cooling. With dry ice as coolant, severe shrinkage with the fitting of the occasion, the moisture in the air will condense on the surface of the bearing. So, need proper antirust measure.
·The bearing maintenance method
In order to maintain the original performance of the bearing in good condition for as long as possible, maintenance is necessary and repair the bearing to avoid accidents, ensure the reliability of operation, and improve the production and economy. Maintenance of the best operating standards corresponding to the working conditions of machinery, regular. This includes monitoring the operation status, replenishing or replacing lubricants, and periodic disassembly checks. As a running maintenance matter, there are bearing rotation sound, vibration, temperature, lubricant status, and so on.