Because the spherical sliding contact area of the spherical plain bearing is large, the inclination angle is large, and because most of the spherical plain bearings adopt special processing methods, the following article will introduce the calculation method of the spherical plain bearing. Let’s learn together!
Brief introduction of spherical plain bearing:
The structure of the spherical plain bearing is simpler than that of the rolling bearing, which is mainly composed of an inner ring with an outer spherical surface and an outer ring with an inner spherical surface. Joint bearings are generally used for low-speed swinging motion (ie angular motion). Since the sliding surface is spherical, it can also perform tilting motion (ie self-aligning motion) within a certain angle range. When the degree is large, it can still work normally.
Calculation method of spherical plain bearing:
A spherical plain bearing has two spherical contact surfaces that “fit” in what is called a coordinated contact. The calculation method of the mechanical properties of the spherical plain bearing plays an important role in the structural design and wear analysis of the spherical plain bearing. The calculation of the contact pressure on the coordination surface is a very complicated problem. The existing Hertz model cannot be used to calculate the spherical coordination contact pressure distribution because it is limited to an elastic half-space. At present, there is a unified spherical contact model, namely Fang model, which can better solve the problem of small deformation spherical contact pressure distribution. This model is suitable for both non-coordinated contact and coordinated contact. However, the contact area of the spherical plain bearing is not a complete spherical surface, and the calculation of the contact pressure distribution needs to be further calculated on the basis of the coordinated contact model of the complete spherical surface. In addition, the free boundary effect will also occur during the use of the spherical plain bearing, which will have a certain impact on the application of the spherical plain bearing. The free boundary effect produces a contact pressure concentration and a large pressure gradient at the edge of the outer ring of the spherical plain bearing.
How to repair the rod end?
Rod end joint bearing is a joint bearing with a rod end or mounted on the rod end, which belongs to a category of joint bearings. Rod ends are mainly composed of an inner ring with an outer spherical surface and an outer ring with an inner spherical surface, which can withstand large loads. According to the different types and structures of the rod end, it can bear radial load, axial load or combined radial and axial load at the same time. Rod ends are generally used for low-speed swing motion, and can also be used for tilt motion within a certain angle range.
According to its different types and structures, it can bear radial load, axial load or combined radial and axial load at the same time. Rod ends are widely used in engineering hydraulic cylinders, forging machine tools, engineering machinery, automation equipment, automotive shock absorbers, water conservancy machinery and other industries. To select a certain bearing type, to determine the required bearing size, the main factors that must be considered are the load, the load capacity of the bearing and the expected service life. The same is true when selecting rod ends.
With cylindrical welded rod end joint bearing (cylindrical type) (type code: SK);
Welded rod end joint bearing with flat base (square type) (type code: SF);
Rod ends with locking type (type code: SLR).
There are several types of regular maintenance for rod end maintenance:
In order to ensure the normal operation of the main engine, according to the requirements of the main engine and the design theory and application experience of the bearing, a maintenance cycle is set and regular maintenance is performed.
Fault maintenance: When the bearing fails, stop for inspection and maintenance.
Early warning maintenance: Using advanced bearing fault diagnosis technology, real-time monitoring of the bearing’s operating status, giving a warning before the bearing fault occurs, and stopping maintenance. During the operation of the bearing, there must be phenomena such as sound, temperature and vibration. Therefore, for the maintenance and maintenance of the bearing in operation, the abnormal changes of the bearing can be found by listening, touching, viewing, and using the bearing fault diagnosis instrument, etc., and whether the rod end joint bearing is in normal working state can be judged according to the changing state.
What are the properties of spherical plain bearings?
Spherical bearings can withstand large loads. According to its different types and structures, it can bear radial load, axial load or combined radial and axial load at the same time. The following article will introduce the performance of spherical plain bearings to you? For details, please see the introduction of this article!
Because the structure and working mechanism of spherical plain bearings are completely different from rolling bearings, spherical plain bearings have their own technical characteristics and maintenance requirements.
The allowable working temperature of the spherical plain bearing is mainly determined by the matching materials between the bearing sliding surfaces, especially the plastic sliding surface of the self-lubricating spherical plain bearing, its load carrying capacity will decrease at high temperature. For example, when the sliding surface material of lubricated spherical plain bearing is steel/steel, the allowable working temperature depends on the allowable working temperature of the lubricant. But for all lubricated and self-lubricating spherical plain bearings, they can be used in the temperature range of -30℃～+80℃, and maintain the correct bearing capacity.
The inclination angle of the spherical plain bearing is much larger than that of the general adjustable rolling bearing, and it is very suitable for use in the supporting parts where the concentricity requirement is not high. The range of inclination angle of radial spherical plain bearing is 3°～15°, the range of inclination angle of angular contact spherical plain bearing is 2°～3°, and the range of inclination angle of thrust spherical plain bearing is 6°～9°.
In any case, the selected fit of the spherical plain bearing shall not cause uneven deformation of the ring, and the selection of its fit and grade must be determined according to the working conditions such as bearing type, support form and load size.
loading and unloading
The assembly and disassembly of spherical plain bearings should follow the following principles, that is, the force exerted by assembly and disassembly cannot be transmitted directly through the spherical sliding surface. In addition, auxiliary loading and unloading tools, such as sleeves, disassemblers, etc., should be used to directly and uniformly apply the loading and unloading force exerted by the outside to the matching ferrule, or use auxiliary methods such as heating for unloaded loading and unloading.
When assembling the spherical plain bearing series, it is necessary to pay special attention to the position of the outer ring dividing surface. In order to prevent the coincidence from directly acting on the dividing surface, the dividing surface should be maintained at a right angle to the coincident direction.
Oil-fed spherical plain bearings can be operated without lubrication when the applied load and the velocities generated by the oscillating motion are very small. Nevertheless, under normal circumstances must be jacked up to add grease. In the initial installation and operation, it is recommended that the lubrication cycle should be appropriately shortened.
Oilless spherical plain bearings can be used without lubrication. However, the life of the spherical plain bearing can be extended even further when lithium soap-based grease is added before operation. If grease is injected into the space around the bearing, the spherical plain bearing will be more effective in preventing the intrusion of dust and foreign objects.