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Metallurgical gearbox bearing application technology (1)
Source: Bearing network time: 2013-06-21
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Bearing selection 1. Choosing the Right Bearing Type--Double-row Roller Bearings Metallurgical gearbox bearings generally use double-row roller bearing combinations to satisfy heavy-duty, high-power power transmission requirements. Roller bearings with tapered roller bearings; cylindrical roller bearings and adjustments The core roller bearing is mainly used. The bearing type of metallurgical gear box should be determined by the force condition of the gear shaft and the characteristics of each type of bearing. The double row tapered roller bearing has outstanding radial and axial composite load. The internal clearance of the bearing can be adjusted; the other is conducive to enhancing the rigidity of the transmission system; therefore, the tapered roller bearing is a bearing type that is considered by the metallurgical gearbox. The tapered roller bearing also has disadvantages; for example, the price is high and does not have self Self-aligning and anti-biasing ability; therefore, many other types of bearings are used in metallurgical gearboxes; such as self-aligning and cylindrical roller bearings.
Metallurgical gearboxes often use different types of bearings to achieve optimal drawing intentions. Compared with tapered roller bearings; spherical roller bearings have lower cost; the bearings can also accept radial axial composite loads under specific stress conditions. The biggest advantage of the heart roller bearing is that it has self-aligning ability; it can work normally under the condition of partial pain. When the bearing is about the same size; the double row cylindrical roller bearing can be used to obtain higher radial bearing capacity; but this type The bearing can not accept the axial load. Generally, when the cylindrical roller bearing is used for the radial and axial combined load conditions; the thrust bearing or other type of bearing is required to accept the axial load.
2. When the double row tapered roller bearing combination method adopts the double row tapered roller bearing combination, one end of the bearing is generally set as the "fixed end"; that is, the end faces of the inner and outer rings of the bearing are all tightly packed without leaving a gap; Load effect; the other end of the bearing is "floating end"; used to absorb the thermal expansion of the gear shaft and accumulate public service. "Floating end" bearings only accept radial load; bearing outer ring end face and bearing end cap and shoulder Should meet the clearance; to offset the axial displacement of the gear shaft after the thermal expansion; the detailed layout is shown in Figure 1. The torque is transmitted for progress; many metallurgical gearboxes use the helical gear meshing method. Under heavy load conditions; The helical gear is less prone to shock oscillation noise, stable operation and large bearing capacity; therefore, the helical gear is superior to the spur gear transmission under heavy load transmission conditions. However, additional axial thrust occurs when the helical gear meshes and the effect is to the "fixed end" bearing. When the axial thrust is large; double row tapered roller bearings are selected as the "fixed end"; perhaps increasing the thrust bearing is a ambition solution. When the gear shaft is only a single helical gear meshing; and the gear When the "fixed end" selects the spherical roller bearing; it should pay attention to the maximum axial and radial force ratio of the bearing. The spherical roller bearing has its own layout characteristics; when the bearing receives the axial force beyond itself When the radial force is 1/3 or 1/4 (depending on the detailed bearing series); the bearing will exhibit a single-sided roller force; the other roller will be unloaded. The force-free roller cannot rotate during the rotation. Guide and position in the raceway; it will show the situation of roller tilting, slipping, impact cage, etc.; in severe cases, it can cause premature failure of the cage cracking bearing. Double row tapered roller bearing adopts pure tumbling and roller end rib guide to depict After the operation of the bearing device clearance; can be used for large axial force and single row roller bearing conditions; the characteristics and differences of the two types of bearings can be seen in Figure 2. "Fixed end" bearing receives axial axial composite load In order to take over the shaft to accept the force and improve the life of the life; the "fixed end" is generally placed on the side with less radial force; the "floating end" is placed at the end of the radial force. Sometimes the centering roll is used. The sub-bearing is the axial bearing capacity of the progressive bearing The "fixed end" will also be placed on the side with greater radial force; in this case; the "fixed end" spherical roller bearing bearing capacity should be higher than the "floating end" bearing.
3 Thinking practical conditions and axial load cone-type bevel gear transmission is similar to helical gear; large axial load will also occur when gear is meshed; bearing selection should also be considered in practical conditions and axial load size. Type gear transmission can be used as paired bevel gears in opposite directions; the axial thrust will not occur when the herringbone gears mesh; it is widely used in rolling mill gearboxes. When using herringbone gear meshing transmission; input and output The shaft only needs to set a “fixed end†to axially position the gear. Other orientations should be set to “floating endâ€; “floating end†bearings can be used with cylindrical or spherical roller bearings; “fixed end†should be The double-row tapered roller bearing with strong axial load can be selected. The bearing optimization selection is depicted in Figure 3; the "floating end" bearings are all selected as single-row cylindrical roller bearings. Others; in high-speed rod and wire mill gearbox In operation; high-speed input shafts often use specially-lined double-row tapered roller bearings to serve as high-speed, frequent-acceleration, deceleration; forward bearing and rotary and other harsh bearing operating conditions.
4. Considering the bearing capacity of the bearing, in addition to correctly selecting the bearing type; whether the selected bearing can meet the bearing capacity is also a key factor to consider. Calculating the bearing capacity of the bearing is the most commonly used measure bearing bearing capacity. Method. Metallurgical gearboxes are used according to different requirements; generally there will be minimum theoretical lifespan requirements for bearings; for example, some gearboxes require bearings with a minimum life of not less than 50,000 hours; some applications require no less than 30,000 hours. When the bearing life is reached; in order to obtain the bearing life; the general bearing rotation speed is selected to replace the maximum rotation speed. The gearbox transmission is under power stability; the rotation speed will lead to torque improvement; and the torque advancement will lead to the shaft. Responsive progress. About the life count of the bearing; the bearing life is inversely proportional to the speed of 1:1; but it is related to the force 10 times; that is, the shaft receiving force is doubled; the bearing life will be reduced by 10 times. Some heavy-duty and low-speed applications; theoretical bearing life results can not really reflect the bearing function; Receiving the axial force ratio can be greater than the safety factor; approach is more accurate calculation software analysis through roller bearing maximum contact stress.
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