what is the meaning of SKF Bearing rated dynamic load Cr (n) and rated static load cor (n)? Is the dynamic load the load borne by SKF Bearing when the equipment is running?
refers to the constant radial load (or constant axial load) that the rolling SKF Bearing can bear theoretically. Under the action of this load, the rated life of SKF Bearing is one million revolutions. This mainly reflects the ability of SKF Bearing to resist rolling fatigue.
The basic rated dynamic load of centripetal SKF Bearing and thrust SKF Bearing are called radial basic rated dynamic load and axial basic rated dynamic load respectively, which are expressed by Cr and ca.
Radial (or axial) basic rated static load: refers to the radial static load (central axial static load) equivalent to the following calculated contact stress generated at the contact center of heavy load rolling element and raceway. 4600mpa for self-aligning ball SKF Bearing; 4200mpa for other types of centripetal ball SKF bearings and thrust ball SKF bearings; For centripetal and thrust roller SKF bearings, 4000mpa.
The total permanent deformation of the rolling element and raceway under these contact stresses is about 0.0001 times the diameter of the rolling element.
When SKF Bearing bears excessive static load or impact load at and low speed, the contact surface between rolling element and raceway will produce local permanent deformation. Its deformation increases with the increase of load. If it exceeds a certain limit, it will affect the normal rotation. The basic rated static loads of centripetal SKF Bearing and thrust SKF Bearing are radial basic rated static load and axial basic rated static load respectively, which are expressed by cor and COA.
Rated dynamic load and rated static load are designed differently by different manufacturers, and their values are also quite different. The values of each manufacturer are recorded in their respective samples. In the process of designing the equipment, the load borne by SKF Bearing is not the rated dynamic load of SKF Bearing, but the radial load or axial load acting on SKF Bearing.
Rating of SKF Bearing Accessories
Inclined retaining ring (separable): a separable ring with “L” shaped section, and its outer part is used as a retaining edge of the inner ring of centripetal cylindrical roller SKF Bearing.
Flat retaining ring: a separable basically flat washer with its inner or outer part as a retaining edge of the outer ring or inner ring of centripetal cylindrical roller SKF Bearing.
Stop ring: a single ring with constant cross-section, installed in an annular groove, to axially position the rolling SKF Bearing in the housing or on the shaft.
Middle retaining ring: a separable ring in a roller SKF Bearing with two or more rows of rollers, which is used to isolate the two rows of rollers and merge the rollers.
Spacer: it is an annular part used between two SKF Bearing Rings or SKF Bearing washers, or between two half SKF Bearing Rings or between two half SKF Bearing washers, so as to maintain the specified axial distance between them.
Seal ring: an annular cover composed of one or several parts, which is fixed on one ring or washer of SKF Bearing and contacts with another ring or washer or forms a narrow labyrinth gap to prevent leakage of lubricating oil and invasion of foreign objects.
Dust cover: it is an annular cover, usually stamped from thin metal plate, fixed on one ring or washer of SKF Bearing and extending towards another ring or washer to cover the internal space of SKF Bearing, but not in contact with another ring or washer.
Lock ring: a single ring with constant section, which is installed in the annular groove as a retaining ring to keep the roller or cage in the SKF Bearing.
Rolling element: a ball or roller that rolls between raceways.
Cage: SKF Bearing parts that partially wrap all or some rolling elements and move with them to isolate the rolling elements, and usually return the rolling elements and keep them in the SKF Bearing.
Retainer: a part attached to the inner ring or shaft ring. It uses centrifugal force to enhance the ability of rolling SKF Bearing to prevent foreign objects from invading.
Assembly of coupling rating of SKF Bearing
During the disassembly of the coupling, the difficult work is to remove the hub from the shaft. For the hub connected by key, it is generally disassembled with three foot puller or four foot puller. The selected puller should match the overall dimension of the wheel hub, and the right angle hook of each foot of the puller should be properly combined with the rear side of the wheel hub, so as not to slip when applying force.
This method is only used for the disassembly of the wheel hub with small interference ratio. For the wheel hub with large interference ratio, the heating method is often used or combined with the hydraulic jack
Cleaning, cleaning and quality evaluation of all parts of the coupling is a very important work after the disassembly of the coupling. The evaluation of parts and components refers to the comparison between the existing conditions of the size, shape and material properties of each part and the quality standards determined by the design of parts and components after operation, so as to determine which parts and components can continue to be used, which parts and components should be repaired and used, and which parts and components should be scrapped and updated.
When removing the coupling, generally remove the connecting bolts first. As a layer of oil dirt, corrosion products and other deposits are deposited on the thread surface, it is difficult to disassemble the bolts, especially for the bolts with serious corrosion. rating of SKF Bearing
Proper tools must be selected for the disassembly of the connecting bolt, because the bearing surface of the outer hexagon or inner hexagon of the bolt has been skidded and damaged, and the disassembly will be more difficult. It is easy for the solvent to penetrate into the loose part of the bolt (such as the loose part of the bolt) so that the rust can be removed easily. rating of SKF Bearing
The configuration of NSK bearing also has a great impact on the bearing rigidity. Generally speaking, for centripetal thrust ball NSK bearing and roller bearing, when used in pairs, it is appropriate to adopt the configuration with the large end face of the outer ring opposite (i.e. the pressure cone formed by its pressure line is outward).
In this way, the ability of anti overturning torque of the bearing is large, and the adjusted preload changes less when the temperature changes. rating of SKF Bearing
For needle roller NSK Bearings with only stamped outer rings, because the outer ring wall is very thin, it is not necessary to knock and install with a hammer, and it should be pressed in with a press. Because the pressure is uneven when the hammer is knocked, it is easy to cause local deformation of the outer ring of the needle roller bearing. rating of SKF Bearing
“Cross fixing” refers to an NSK bearing configuration in which each NSK bearing positions the shaft in one direction and in the opposite direction. The short shaft is mainly used for this combination.
All radial NSK Bearings that can bear axial load in at least one direction are applicable, including deep groove and angular contact ball bearings, tapered roller bearings and NJ cylindrical roller bearings. When using angular contact ball bearings or tapered roller bearings, preload must be applied on some occasions. rating of SKF Bearing
The shaft is supported radially and axially by two NSK Bearings. The NSK bearing on one side is called the fixed end NSK bearing. It bears both radial and axial loads and plays the role of relative axial displacement between the fixed shaft and the NSK bearing housing. The other side is called the free end, which only bears the radial load and can move relatively in the axial direction. rating of SKF Bearing
NSK Bearings at the fixed end must be fixed with the shaft and NSK bearing housing at the same time. The more suitable NSK Bearings are radial NSK Bearings that can bear composite loads, such as deep groove ball bearings, self-aligning roller bearings, double row or paired angular contact ball bearings or tapered roller bearings. rating of SKF Bearing
Radial NSK bearing combinations bearing simple radial load, such as cylindrical roller bearings with inner and outer rings without retaining edges, can also be used as fixed end NSK Bearings through combination with deep groove ball bearings, four point contact ball bearings or two-way thrust bearings. rating of SKF Bearing
At this time, the second NSK bearing provides two-way axial positioning, but it must be installed with a certain radial spacing from the NSK bearing housing. When the length of NSK bearing at the free end changes due to thermal expansion, there will be no extrusion in NSK bearing. Axial displacement can occur inside NSK bearing, NSK bearing ring and NSK bearing seat. rating of SKF Bearing
Speed and temperature rise rating of SKF Bearing
Selection standard of fag imported bearing for machine tool spindle
The development of machine tool industry in heavy industry is extremely rapid, which virtually drives the development of chain industry. As an important part of machine tool spindle, how to refer to the standard
With the development of science and technology, the speed of machine tool spindle is higher and higher, and the speed range is larger and larger. Therefore, the requirements for high-speed operation stability of fag imported bearings are higher and higher. Difference between dynamic load rating and static load rating of SKF Bearing
The temperature rise of fag imported bearing of machine tool spindle is an important factor limiting the speed of fag imported bearing. Generally, correct selection of fag imported bearing type, tolerance grade, configuration mode, clearance (preload), lubricant and lubrication mode can improve the high-speed performance of rolling fag imported bearing to a certain extent.Difference between dynamic load rating and static load rating of SKF Bearing
Service life rating of SKF Bearing
For general machine tools, the service life of the spindle assembly mainly refers to the service life of maintaining the spindle accuracy. Therefore, the accuracy maintenance performance of fag imported bearings is required to meet the requirements of the service life of the spindle assembly. For heavy machine tools or power cutting machine tools, the bearing capacity of fag imported bearings should be considered first.Difference between dynamic load rating and static load rating of SKF Bearing
Stiffness and vibration resistance
In order to ensure the machining quality of the machine tool, the spindle system must be rigid enough, otherwise it will produce large re mapping error and even flutter. Vibration resistance refers to the ability to resist forced vibration and self-excited vibration. Difference between dynamic load rating and static load rating of SKF Bearing
The vibration resistance of the spindle assembly depends on the stiffness and damping of the spindle and fag imported bearings. The use of preloaded rolling fag imported bearings can effectively improve the stiffness of the spindle system.Difference between dynamic load rating and static load rating of SKF Bearing
Noise rating of SKF Bearing
In high-speed grinding machine, the noise of fag imported bearing of grinding head is the main component of the noise of the whole machine, and low-noise rolling fag imported bearing should be selected.
Characteristics and application of fag imported bearing oil for main shaft
Fag imported bearing oil of spindle is a special lubricating oil for fag imported bearings of precision machine tools and similar equipment. It plays a very important role in ensuring the working accuracy and service performance of spindle and prolonging its service life. It is also called fag imported bearing oil.Difference between dynamic load rating and static load rating of SKF Bearing
Its main performance: rating of SKF Bearing
Suitable viscosity and good viscosity temperature characteristics
In order to prevent the spindle temperature of the machine tool from being too high and causing thermal deformation of the machine tool, affecting the machining accuracy or poor lubrication of the fag inlet bearing, select the lubricating oil with appropriate temperature according to the structure.
speed and clearance of the fag inlet bearing of the spindle, and require it to have good viscosity temperature characteristics, so as to prevent the lubricating performance from being affected by the excessive change of viscosity when the working temperature and ambient temperature of the spindle change greatly.Difference between dynamic load rating and static load rating of SKF Bearing
Good lubricity rating of SKF Bearing
In order to keep a uniform oil film between the main shaft and the fag inlet bearing contact surface, and the oil film will not be damaged when the main shaft starts or stops moving to produce impact load, and maintain good lubrication performance, which plays the role of reducing friction and friction heat, reducing the temperature rise of the main shaft and ensuring the machining accuracy, it is required to have good lubrication performance.Difference between dynamic load rating and static load rating of SKF Bearing
Good oxidation resistance
When circulating lubrication is adopted for the spindle of the machine tool, the fag imported bearing oil of the spindle is required to be used for a long time without deterioration, so it is required to have good oxidation resistance.Difference between dynamic load rating and static load rating of SKF Bearing
Good rust resistance
Because the oil will inevitably mix with condensed water in the air or machine tool coolant during the operation of the spindle lubrication system, the oil is required to have good rust resistance.Difference between dynamic load rating and static load rating of SKF Bearing
Difference between dynamic load rating and static load rating of SKF Bearing
The quality of heat treatment and quenching of IKO bearing parts mainly depends on the quenching heating conditions and cooling conditions, and the cooling conditions mainly depend on the selection of corresponding quenching oil and cooling technology.Difference between dynamic load rating and static load rating of SKF Bearing
IKO bearing parts are mainly quenched and cooled with mineral oil. Mineral oil is composed of paraffin, bad alkane, aromatic hydrocarbon, paraffin aromatic series hydrogen talking compounds and their derivatives.
Due to different composition and refining methods, special quenching oils with different characteristics and different uses are formed.Difference between dynamic load rating and static load rating of SKF Bearing
According to the use requirements (including cooling speed, service temperature, brightness, etc.), it can be divided into ordinary quenching oil, fast quenching oil, overspeed quenching oil, graded quenching oil, vacuum quenching oil, fast bright quenching oil and mechanical oil.Difference between dynamic load rating and static load rating of SKF Bearing
When selecting quenching oil, factors such as material, shape, size, deformation, hardening layer depth, process, brightness and heat treatment equipment of parts to be treated must be fully considered. Excellent quenching oil is made of refined base oil with high thermal stability (generally paraffin base) and various additives that can improve service performance and service life. Difference between dynamic load rating and static load rating of SKF Bearing
For rolling IKO bearing parts, during quenching and cooling, the transformation of pearlite type shall be prevented to avoid opaque quenching or local defects such as troostite and soft spots. Therefore, the cooling rate of quenching oil should be greater than the critical cooling rate of IKO bearing steel.
However, the cooling speed should not be too large, so as not to cause large internal stress, resulting in cracking and excessive quenching deformation. Difference between dynamic load rating and static load rating of SKF Bearing
According to the C curve, the austenite transformation temperature of gcr15iko bearing steel is about 650 ℃ and 450 ℃. Before this temperature, it must be cooled quickly, but at the later temperature, it can be cooled slowly, especially between the starting point of martensite transformation MS and MF.
Slow cooling can reduce deformation and cracks, but it can not be too slow. Otherwise, the stable aging of austenite is easy to cause the increase of residual austenite.
Therefore, the cooling rate can be higher than the critical cooling rate at 650 ℃ and 450 ℃, and the oil with slow cooling rate after this temperature is quenching oil Under normal conditions, it is difficult to determine the critical cooling rate of steel under various conditions due to different field conditions
However, in the field, the change trend of critical cooling rate can be judged according to the factors affecting the critical cooling rate, and the quenching oil can be selected accordingly If the quenching temperature is high, the holding time is long, and the original structure is fine, the critical cooling speed will be smaller, which is the quenching oil with small cooling capacity.Difference between dynamic load rating and static load rating of SKF Bearing
For IKO bearing rings with large wall thickness, if sufficient hardening layer is obtained, the quenching oil should have a faster cooling rate. For thin-walled IKO bearing rings, the quenching oil should have a slower cooling rate. For parts with complex shapes, quenching oil with short steam film stage and fast cooling speed should be selected.Difference between dynamic load rating and static load rating of SKF Bearing
For IKO bearing rings requiring small deformation, graded quenching oil shall be selected. If the grading temperature of IKO bearing steel ring is above MS point, the cooling speed reaches the critical cooling speed.Difference between dynamic load rating and static load rating of SKF Bearing