Latest large slewing bearings

According to the ISO grading standard, it is divided into: P0, P6, P5, P4, P2. The grades increase in turn, of which P0 is ordinary precision, and other grades are precision grades, which are so-called precision bearings. The precision grades and material properties of precision bearings are different. It is more beneficial than ordinary bearings. Based on the analysis of precision bearings, Zhonghua Bearing Network will tell you the difference between precision bearings and ordinary bearings, the use requirements of precision bearings, and how WXING bearings are precise and reliable?The difference between precision bearings and ordinary bearings:1. The size requirements are different, and the dimensional deviation (inner diameter, outer diameter, ellipse, etc.) of products with high precision grades is smaller than the required value of products with low precision grades;2. The required value of rotation accuracy is different. The rotation accuracy (inner radial runout, outer radial runout, end-to-raceway runout, etc.) of products with high precision grades is stricter than that required by products with lower precision grades;3. The required values of surface shape and surface quality are different. The surface shape and surface quality of products with high precision grades (surface roughness of raceways or channels, circular deviation, groove shape deviation, etc.) are lower than those with low precision grades. The value required by the product must be strict;4. The material properties of products with particularly high precision grades are more favorable than those of products with general precision grades.In general, the requirements of precision bearings for accessories:1. The roundness of the shaft and seat hole and the verticality of the shoulder should be required according to the corresponding precision of the bearing.2. It is necessary to accurately calculate the interference fit of the rotating ferrule and the appropriate fit of the fixed ferrule.The amount of interference of the rotating ring should be as small as possible. As long as the influence of thermal expansion at the working temperature and the influence of centrifugal force at the highest speed are ensured, it will not cause creep or sliding of the tight fit surface. According to the size of the working load and the size of the bearing, the fixed ring selects a very small clearance fit or interference fit. Too loose or too tight is not conducive to maintaining the original and accurate shape.3. If the bearing is operated at high speed and the working temperature is high, special attention should be paid to the fit of the rotating ferrule not being too loose to prevent eccentric vibration, and the fit of the fixed ferrule to avoid gaps to prevent the ferrule from being under load. Deforms and excites vibrations.4. The condition for adopting a small interference fit for the fixed ring is that both sides of the mating surface have high shape accuracy and small roughness, otherwise it will make installation difficult and disassembly more difficult. In addition, the influence of the thermal elongation of the spindle needs to be considered.5. The main shaft using paired double angular contact ball bearings is mostly light-loaded. If the fit interference is too large, the internal axial preload will be significantly larger, causing adverse effects. The main shaft using double-row short cylindrical roller bearings and the main shaft of tapered roller bearings have relatively large loads, so the fit interference is also relatively large.NSK has developed countless new types of bearings to meet the needs of users all over the world, and has made great contributions to industrial development and technological progress. At the same time, relying on its technical advantages in precision machining, WXING continues to develop high-end, precision and cutting-edge products such as auto parts and precision mechanical components, and actively develops diversified operations in the fields of electronic applications.WXING bearing research and development technology:4. Analysis technologyNSK's analysis technology, which contributes to the design and development of high-function and high-reliability products, and the construction of efficient production systems, is advancing towards sophistication. In addition, for tests that require high precision and tests that are difficult to evaluate, WXING realizes the method of virtual tests with computer simulation experiments, and promotes the improvement of product development speed by further improving the level of analysis technology.How does WXING bearing achieve precision and reliability?Home appliances such as refrigerators and washing machines, automobiles, airplanes, large-scale industrial machinery, space stations, and many other things used in the world are equipped with bearings. With the slogan of "beautiful and infinite operation and control", WXING provides various products such as auto parts and precision machinery products to the world in addition to various bearings. Based on the technology honed in the field of bearings, WXING is pursuing the possibility of development in various technical fields. WXING bearings are durable and have a wide variety of bearings that can achieve long life even under harsh working conditions such as mines and engineering sites.As one of the important components to ensure the safe operation of railways, bearings for railway trains must have extremely high reliability.1. Tribological technologyCompared with the automatic design of supporting rotary motion and reciprocating motion, lubrication is required to improve its high-speed, quiet sound, load resistance, and durability. nsk uses high-level lubricating technology in the design of grease and solid lubricants, surface processing research, etc., and plays a playful role in products.2. Material technologyIn order to improve product function and durability, as well as the low production efficiency of industrial offices and high schools, nsk focuses on material cost, heat treatment, design performance and analysis and evaluation, and actively strives to improve material technology. The honed material technology is effectively used for high longevity and high reliability for various purposes such as trains and industrial machinery.3. Mechatronics TechnologyNSK's unique mechatronics technology, which combines mechanical elements and electronic elements, is effectively applied to high-function motors, control technology, induction technology, high heat resistance, high density, high reliability mounting technology, and biomedical micro-electromechanical systems. systems technology etc.

The bearing cage has a great influence on the performance and life of the rolling bearing, and the selection of its material is particularly important. The cage material should have the characteristics of high mechanical strength, good wear resistance, impact load resistance and good dimensional stability.Bearing cages are generally divided into stamping cages and solid cages.The stamped cages for small and medium bearings generally use high-quality carbon structural steel strips or steel plates, such as 08 or 10 steel. According to different purposes, there are also brass and stainless steel plates.Large-scale bearings and bearings with small production batches generally use mechanism-based solid cages, and materials include brass, bronze, aluminum alloy and structural carbon steel.Precision angular contact ball bearing cages are usually manufactured using phenolic laminated cloth tubes.In recent years, my country has developed engineering plastic cages. The typical material is glass fiber reinforced polyamide 66 (GRPA66-25), and the working temperature is -30~+120°C. This material is light in weight, low in density, friction-resistant, corrosion-resistant, good in elasticity, good in sliding property, easy to direct injection molding, low in manufacturing cost, and has been used to manufacture cages of various bearings.

Under certain special operating conditions, bearings can obtain a longer life than traditional calculations, especially under light load conditions. These special operating conditions are when the rolling surfaces (rails and rolling elements) are effectively separated by a lubricating oil film and limit the possible surface damage caused by contamination. In fact, under ideal conditions, so-called permanent bearing life is possible.1. Be careful when using and installingStrong stamping is not allowed, direct hammering on the bearing is not allowed, and pressure transmission through rolling elements is not allowed.2. Use appropriate and accurate installation toolsTry to use special tools and try to avoid things like cloth and short fibers.3. Try to keep the bearing and its surrounding environment cleanEven if the invisible dust enters the bearing, it will increase the wear, vibration and noise of the bearing.4. Prevent the corrosion of bearingsWhen taking the bearing directly by hand, it is necessary to fully wash off the sweat on the hands and apply high-quality mineral oil before handling. In the rainy season and summer, special attention should be paid to anti-rust.Rolling bearings are precision components and must be used with corresponding care. No matter how high-performance bearings are used, if they are not used properly, the expected high performance will not be obtained. Precautions for the use of bearings are as follows.(1) Keep the bearing and its surroundings clean.Even small dust, invisible to the eyes, can have a bad effect on bearings. Therefore, keep the surrounding clean so that dust does not invade the bearing.(2) Use with caution.If a bearing is subjected to a strong impact during use, scratches and indentations may occur, which may cause accidents. In severe cases, it will crack and break, so be careful.(3) Use appropriate operating tools.Avoid substituting existing tools, use the right tools.(4) Pay attention to the corrosion of the bearing.Sweat from hands when handling bearings can be the cause of rust. Pay attention to operate with clean hands, it is best to wear gloves as much as possible.

1. Poor lubrication (accounting for about 50%)     According to the survey, poor lubrication is one of the main reasons for the premature damage of imported bearings. The main reasons include: improper selection of lubricant or lubricating oil, not filling lubricant or lubricating oil in time; not filling lubricant or lubricating oil in place; and so on.Suggestion: Choose the correct lubricant or lubricating oil, use the correct lubrication and filling method, and maintain the bearing regularly.     2. Improper installation (about 16%)1. Use brute force during installation. Hitting the imported bearing directly with a hammer will cause the most damage to the bearing; it is the main cause of deformation.2. The installation is not in place, the installation is deviated or not installed in the bearing position, resulting in too small bearing clearance. The inner and outer rings are not at the same rotation center, resulting in non-concentricity.     Suggestion: choose appropriate or professional bearing installation tools, and use special instruments to detect after installation.     3. Fatigue (about 34%)      Common causes of fatigue damage may be: long-term overloading of bearings; failure to maintain in time, or improper maintenance; equipment aging, etc.     4. Pollution (about 14%)Pollution will also lead to premature damage to imported bearings. Pollution refers to the entry of dust, metal filings, etc. into the bearing. The main reasons include: opening the bearing package prematurely before use, causing pollution; the working environment is not clean during installation, causing pollution; impurities enter the NTN bearing and cannot work normally.    The length of service life of the bearing is generally affected by the two factors of material and process.    The material of the bearing determines the service life of the bearing to a large extent. The metallurgical quality of the bearing used to be the main reason for the early failure of the rolling bearing. The impact of bearing material on service life has been greatly improved in metallurgical technology, and after the emergence of bearing steel and other materials, it has been greatly improved.    In the failure analysis of bearings, the proportion of bearing failures caused by raw materials has dropped significantly, but materials are still an important cause of bearing failures, and are the main constraints on bearing service life.The manufacturing process of bearings is complicated, and the finished product can only be obtained after many processes. Among them, the technical capabilities and completion quality of forging, heat treatment, turning and grinding processes will affect the service life and application effect of bearings, especially heat treatment and The grinding process is the direct cause of many bearing failures and needs to be highly valued by manufacturers.    After the bearing is installed, in order to check whether the installation is correct, it is necessary to carry out a running inspection. Small machinery can be rotated by hand to determine whether the rotation is smooth. The inspection items include poor operation caused by foreign objects, scars, and indentations, unstable torque due to poor installation and poor processing of the mounting seat, excessive torque caused by too small clearance, installation errors, and seal friction, etc. wait. If there is no abnormality, the power operation can be started.    Large machines cannot be rotated by hand, so cut off the power immediately after starting without load, run the machine idly, check whether there is vibration, noise, whether there is contact with the rotating parts, etc. After confirming that there is no abnormality, enter the power operation.Power operation starts from no-load and low speed, and gradually increases to the rated operation of the predetermined premise. The inspection items during the test run are whether there is abnormal sound, temperature change of NTN bearing, leakage or discoloration of lubricant, etc. If an abnormality is found, stop the operation immediately, check the machine, and remove the bearing for inspection if necessary.    The bearing temperature can usually be inferred from the external temperature of the bearing seat. However, it is more accurate to directly measure the temperature of the outer ring of the bearing by using the oil hole. The bearing temperature gradually rises from the start of operation, and usually stabilizes after 1 to 2 hours. If the bearing is installed poorly, the temperature will rise sharply, resulting in abnormally high temperature. The reasons are, for example, too much lubricant, too small bearing clearance, poor installation, excessive friction of the sealing device, etc. In the case of high-speed rotation, the wrong choice of bearing structure and lubrication method is also the reason.    The rotation sound of bearings is checked with a stethoscope, etc., and there are strong metal noises, abnormal sounds, and irregular sounds, which indicate abnormalities. The reasons are poor lubrication, poor precision of the shaft or bearing seat, bearing damage, foreign matter ingress, etc.