Bearing is an important part of contemporary mechanical equipment. Its main function is to support the mechanical rotating body, reduce the friction coefficient during its movement, and ensure its rotation accuracy.
Next, the editor will introduce what should be paid attention to when buying bearings?
1. Load The size, direction and nature of the load of the bearing [The load of the bearing can be indicated by the basic load rating, and its value is contained in the bearing standard table] The bearing load is rich in changes, such as the size of the load, whether there is only radial load, axial load Is it one-way or two-way, the degree of oscillation or shock, etc. After considering these factors, let's choose the most suitable type of sliding bearing.
Generally speaking, the radial load of bearings with the same inner diameter can be increased in the following order: deep groove ball bearings <angular touch ball bearings <cylindrical roller bearings <tapered roller bearings <self-aligning roller bearings
2. Analyze the relative skew between the inner and outer rings of the elements that cause the inner and outer rings of the bearing to skew (such as the deflection of the shaft caused by the load, the poor accuracy of the shaft and the housing, or the device error), and select those who can get used to this The bearing type for the operating conditions. If the relative skew between the inner ring and the outer ring is too large, the bearing will be damaged due to the internal load generated by the self-lubricating bearing. Therefore, a bearing type that can accept this skew should be selected.
Generally speaking, the allowable skew angle (or centering angle) is increased in the following order:
Cylindrical roller bearings, tapered roller bearings, deep groove ball bearings (angular touch ball bearings), spherical roller (ball) bearings 3) The type of bearing whose rigid function meets the rigidity required by the mechanical shaft system [When the bearing receives a load, it rolls The touching part of the body and the raceway will be elastically deformed. "High rigidity" means that the amount of deformation due to this elastic deformation is small.] In parts such as machine tool spindles and car final reduction gears, while increasing the rigidity of the shaft, it is also necessary to increase the rigidity of the bearing.
Roller bearings receive less deformation than ball bearings. Preloading the bearing (negative clearance) can improve rigidity. This method is suitable for angular touch ball bearings and tapered roller bearings.
3. The bearing device space can be contained in the bearing device space. Because the rigidity and strength of the shaft are emphasized when designing the shaft system, the shaft diameter, that is, the inner diameter of the bearing, is generally determined first. However, there are many standard series and types of tumbling bearings, and the most suitable bearing type should be selected from them.
The following bearings are generally used: deep groove ball bearings, touch ball bearings, cylindrical roller bearings
4. Rotation accuracy The bearing type with the required rotation accuracy [The scale accuracy and rotation accuracy of the bearing have been standardized by GB according to the bearing type? Machine tool spindles, gas turbines and operating machines require high rotation accuracy, high speed and low conflict. Bearings with accuracy above grade 5 should be used.
5. The frequency and method of assembly and disassembly for timing check of device and disassembly. When assembly and disassembly are frequent, it is more convenient to use cylindrical roller bearings with separable inner and outer rings, needle roller bearings and tapered roller bearings.
6. The bearing type whose speed can be used to the mechanical speed [the limit value of the bearing speed is indicated by the limit speed, and the value is contained in the bearing standard table] The limit speed of the bearing is not only taken from the bearing type but also limited to the bearing size, cage type, and accuracy grade , Load conditions and smoothing methods, etc. Therefore, it is necessary to consider these factors when selecting.