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The damage of turntable bearing is much more complicated than the damage of general mechanical parts. Its damage forms varied and different reasons. In addition to bearing design and manufacture.
Most of the reasons for damage are due to improper selection of bearings, unreasonable design of bearing supports, weak rigidity, poor flatness of continuous surfaces, overload operation and installation.
Improper use, poor lubrication and tight sealing are related factors.
The damage form of rotary bearing is analyzed, and the cause of failure is analyzed. On the one hand, it is possible to design and choose bearings correctly, provide detailed information and improve it.
Design, rationally select bearings, give full play to the functions of bearings, and improve economic efficiency. On the other hand, it is more important to improve safety and avoid serious problems.
This paper briefly introduces the common causes of malfunction of rotary bearing and its handling methods.
1 malfunction caused by improper selection of bearings
Proper and rational selection of bearings is the guarantee of giving full play to the functions of bearings. If the mechanical design is not well considered, overload will occur, resulting in rolling body crushing.
Cracks and raceway spalling or cracking. Bearing capacity is the first consideration. The design of internal parameters is the key factor, and reasonable selection of heat treatment for materials and materials.
State is also important. According to the actual working condition of the main engine, the space location, load size and property, rotation speed, rotation accuracy, friction torque and installation should be considered.
Ways and so on. Besides, the clearance of turntable bearing is also a factor that can not be ignored.
Generally speaking, bearings should be selected for larger applications in engineering machinery, mining machinery and lifting appliances. If the clearance is too small, the bearing is fixed.
Due to the poor flatness of bearing, the bearing clearance will be reduced, which will cause the bearing to run stuck or the rolling body will squeeze each other to produce noise.
The local stress of raceway is too high to cause failure. On the other hand, due to the influence of the flatness of the supporting surface, the fixed bearing appears "wavy" so that the rolling body is not in.
On the same plane, the friction torque is too large.
According to experience, under normal circumstances, the clearance of turntable bearing should not be less than 1.2 times the flatness of the mounting surface.
2 Failure caused by rigidity of supporting frame
The rotary bearing itself is not rigid. If the frame is not rigid enough, the turntable bearing will deform with the deformation of the frame, resulting in the inhomogeneity of the original clearance.
The bearing is unstable in operation and abnormal noise occurs. This situation is particularly obvious for cross cylindrical roller bearings, resulting in many parts of the bearing without clearance.
Rollers and rollers, between raceways and rollers, wear out due to mutual extrusion. At the same time, the deformation of the frame will not only cause the raceway to be separated and warped, but also affect the gear ring and pinion.
The meshing clearance and meshing performance will affect the working quality of the main engine and cause the edge stress of raceway and rolling body to cause early failure of bearing.
The rotary bearing is fixed by bolts and the main frame. The deformation caused by the rigidity of the frame is not uniform under the action of external loads.
The serious partial load caused the bolt to break, resulting in an accident.
3 Failure caused by poor flatness of installation plane.
Due to the poor rigidity of the slewing bearing and the weak bending capacity of the axle, the bearing will deform with the machining quality of the installation plane after installation.
The amount of deformation increases with the flatness of the mounting plane. After loading, warping deformation will cause partial deformation of raceway, causing rolling body to be stuck when rotating.
Or the bearing makes a percussion sound while turning, and at the same time, the stress concentration on the edge of the raceway causes the bearing to be damaged early.
Before the installation of the turntable bearing, check the installation plane of the supporting seat which is matched with it, and request that the supporting frame should have enough stiffness and even the connection.
The surface is machined, and surface debris and burr are removed. The technical requirements for the connection surfaces of supporting parts shall comply with the requirements of Table 1. For machines that cannot be machined.
The connection surface should be smoothed by injection molding.
4 Malfunction caused by improper installation
4.1 preload of bolts is not enough.
The turntable bearing is usually fixed on the frame with bolts. When installing bolts, the diagonal method should be used to install bolts. The bolt's pretightening force should reach the bolt.
About 70% of the yield limit. If the pre tightening force is not enough, it is easy to cause relative misalignment of the inner and outer rings when the bearing is loaded, causing the contact angle to change and cause the rolling load to be not.
Uniform or rolling body and raceway produce edge stress. For bearing with ring gear, it will cause the gear mesh clearance and mesh quality to change, and the tooth surface will be damaged early.
4.2 improper installation of soft belt.
The raceway of the rotary bearing ring is heat-treated by surface induction quenching. This method produces a soft zone between the beginning and the end of the quenching zone.
S is often used as a symbol. When installing, the soft belt should be placed in the non load area or the non constant load area. Take the crane as an example, that is, the soft belt of the ring should deviate from the main load direction 90 degrees.
It deviates from the maximum load rotary area and avoids the maximum working load in the soft belt position, so that the raceway does not produce plastic deformation and ensures the service life of the bearing.
5 malfunction caused by poor lubrication
Lubrication plays an important role in prolonging the fatigue life of rotary bearings and reducing friction, wear and temperature rise. Without proper lubrication, bearings can not work well.
The damage of many bearings is related to poor lubrication.
Turntable bearings are also used in the process.See the news list>>