Customized Linear bearings

Structural comparison and analysis of vibrating screen bearing and common bearing1 bearing design structure comparison of special vibration bearings: A. The diameter of the rolling body is increased, the length of the rolling body is increased.B. The cage is guided by the outer ring to reduce the force on the roller.C. Use an inner ring to guide the roller and improve the operation of the roller.1. Comparison of bearing design structureSpecial bearing for vibration:A. The diameter and length of the rolling element are increased. B. The cage is guided by the outer ring to reduce the force on the roller.C. Use an inner ring to guide the roller and improve the operation of the roller.D. Cellular roller bearing cage adopts integral structure, which greatly improves its strength. E. The outer diameter of the self-aligning bearing is designed with oil grooves and oil holes for a good lubrication effect.Common bearing:A. The diameter of the roller body and length of the roller body is small. Bearing B. Cage with a roller or inner ring guide. C. The cylindrical roller bearing cage adopts a rivet structure, which is easy to lose and drop the cover.D. The outer diameter of the self-aligning bearing has no oil groove and oil hole, resulting in a poor lubrication effect.2. Choose materialsSpecial bearing for vibration:A. The inner and outer rings and rolling bodies are made of vacuum degassing bearing steel with good fatigue resistance. B. The cage is made of aluminum, iron, and manganese bronze material with high strength, good elasticity, and better wear resistance.Common bearing:A. Common bearing steel is used for inner and outer rings and rollers.B. The cage is made of zinc brass with low strength and poor elasticity.3. Heat treatment modeBearing Special bearing for vibration of mining machinery bearing:A. The inner and outer ring adopts Bayer-Ma mixed quenching or Marstench quenching + high-temperature tempering, with uniform hardness and small internal stress; Good toughness, shock, and vibration resistance.B. Good stability when working within 150C temperature.Common bearing:The inner and outer ring adopts ordinary quenching mode, which has poor toughness, poor impact resistance and vibration performance of vibrating screen bearing, and poor thermal stability.4. Tolerance and manufacturing processSpecial bearing for vibration:A. Manufactured in strict accordance with the P6 precision standard, especially the tolerance of inner and outer diameter is very small.B. Size difference of rolling body ≤0.002.C. The cylindrical roller has a convex outer diameter to avoid stress concentration.D. Rolling surface superfine treatment, high finish.Common bearing:A. General PO class precision tolerance (part of P6 standard) manufacturing.B. Roller grouping ≤0.005.C. Cylindrical roller without convex practice.D. Some raceways are only polished and have a low finish.5. Internal clearanceSpecial bearing for vibration:The clearance is produced according to the requirements of vibration machinery, and the range is controlled within a small range with good consistency.Common bearing:The clearance is generally produced according to the standard group or C3 group, and the clearance of mining machinery bearings is either small, or the range is large and the dispersion is large.6. Usage effectSpecial bearing for vibration:Low noise, low-temperature rise, good stability, long service life, no early fatigue phenomenon.Common bearing:High noise, high-temperature rise, poor stability, short service life, early fatigue phenomenon.What are the actual differences between domestic bearings and imported bearings?The size deviation and rotational accuracy of domestic bearings are very close to those of imported bearings. However, there is still a certain gap in dispersion between bearings imported from Germany. Foreign countries have long started to study and use such fine rotation precision index as non-repeatable pulsation, but the research on this level is still blank in China. Two, in the rapid performance level of foreign brand products DMN value of 4 × 106 mm r/min, while the Chinese bearing is only 2 × 106 mm r/min.Three, in the vibration, abnormal sound, and abnormal sound level, Japan has launched silent and ultra-silent bearings, and the vibration extreme level of Chinese bearings is usually more than 10dB different from that of Japanese bearings. Four, in life and on the level in deep groove ball bearing, for example, foreign brand products usually accounting for the life of a life of more than 8 times, up to 30 times more 】 【 on sex for more than 98%, or pursue and host life 】 【 China bearing usually only for the life of a business accounting life of 3 to 5 times, on sex is approximately 96%.?At present, the bearing chemical industry in China has ranked third in the world in terms of the industrial economic scale, but there is still a considerable gap between China and the world's advanced level in terms of product accuracy and technical level. First, China's bearing industry manufacturing concentration is low. In the world's bearing sales of about $40 billion, the world's eight major multinational units account for 75%~80%. Two German units account for 90% of the country's total, five Japanese for 90%, and one American for 56%. And China's tile shaft and other 7 bearing enterprises with annual sales of more than 1 billion yuan, the sales volume only accounts for 28, 3% of the whole industry. China's bearing chemical production technology and process equipment technology development is slow, the CNC machining rate is low, the grinding automation level is low, the country only more than 200 automatic manufacturing lines. Most enterprises, especially the old state-owned enterprises as the main manufacturing force is still the old machinery. Advanced thermal treatment processes and equipment, which are critical to bearing life and reliability, such as adjusted vapor protection heating, double refining, bainite quenching, and other low coverage rates, have failed to make breakthroughs in many technical problems. The development of new kinds of bearing steel, the improvement of steel quality, the development of lubrication, cooling, cleaning, and abrasive tools, and other related technologies can not meet the needs of the improvement of the level and quality of bearing products. As a result, the process efficiency index is low, the homogeneity is poor, the product processing size dispersion is large, the product internal quality is not stable and affects the accuracy, performance, life, and reliability of the bearing. In recent years, the development of bearings in China has made continuous progress, slowly resulting in industrialization. At present, the world-bearing market in China is about 10%, and the sales volume occupies third place in the world. However, compared with the world's powerful countries in bearing chemical industry, there is still a certain gap between Chinese bearings. The primary manifestation is that the proportion of products with high technology, high precision, and high added value is low, and the stability of products needs to be further enhanced and improved.Three, low efficiency of China's bearing industry development and innovation because most of the enterprises in the innovation system of the construction and operation, development and innovation of investment and talent development level is still low, and industry service-oriented scientific research institutes to the enterprise, the state has no support for research in the general technology and industry, which weakened the ability for industry development. As a result, the industry is weak in basic theoretical research, weak in participation in the formulation of international standards, and less in original technologies and patented products. Now, our design and production technology is basically simulation, decades of consistent system. The low efficiency of product development is shown in that although the matching rate of domestic main engines meets 80%, the matching and repairing bearings of key main engines such as rapid railway passenger cars, middle and high-grade cars, accounting machines, air conditioners, and high level rolling mills are basically imported.

Rolling bearing is the most widely used in rotary machinery, and it is also one of the most easily damaged components. Many failures of rotating machinery are related to rolling bearings. The working quality of bearings has a great impact on the working state of machinery. The defects will lead to abnormal vibration and noise of equipment, and even damage the equipment in serious cases. Correct condition monitoring and diagnosis of rolling bearings is an important aspect of equipment optimization management and predictive maintenance in modern enterprises.The four stages of rolling bearing fault development:Corresponding to the structural composition of rolling bearings, rolling bearings have four kinds of failure frequencies: rolling bearing cage failure frequency, rolling bearing rolling body failure frequency, rolling bearing outer ring failure frequency, rolling bearing inner ring failure frequency. For calculating the bearing fault frequency, have a special mathematical formula, but in the practical work of calculation more troublesome, convenient method is to use special software, such as the United States with Rockwell automation software in this feature plug-in, as long as the input bearing model and the information such as the manufacturer, they can get the corresponding all kinds of bearing failure frequency.The first stage, that is, the budding stage when the bearing begins to fail when the temperature is normal, the noise is normal, the total vibration speed and the frequency spectrum are normal, but the total peak energy and the frequency spectrum have symptoms, reflecting the initial stage of bearing failure. At this time, the real bearing fault frequency appears in the ultrasonic section within the range of about 20-60kHz.In the second stage, the temperature is normal, the noise is slightly increased, and the total vibration velocity is slightly increased. The change of vibration spectrum is not obvious, but the peak energy is greatly increased, and the spectrum is more prominent. At this time, the bearing failure frequency appears in the range of about 500Hz-2KHz.In the third stage, when the temperature increases slightly, the noise can be heard, and the total vibration velocity increases greatly. In addition, the bearing fault frequency, its harmonics, and sidebands can be clearly seen in the vibration velocity spectrum. In addition, the noise horizon increases significantly in the vibration velocity spectrum, and the total peak energy becomes larger and the spectrum is more prominent than in the second stage. At this time, the bearing failure frequency appears in the range of about 0-1kHz.It is recommended to replace the bearing in the late stage of the third stage, then at this time, there should have been visible wear and other rolling bearing fault characteristics.In the fourth stage, the temperature increases significantly, the noise intensity changes significantly, the total vibration velocity and vibration displacement increase significantly, and the bearing fault frequency begins to disappear in the vibration velocity spectrum and is replaced by a larger random broadband high-frequency noise horizon. The total amount of peak energy increases rapidly and some unstable changes may occur. Bearings must not be allowed to operate in the fourth stage of failure development, otherwise, catastrophic damage may occur.According to the results of the study, in general, if the whole service life of the rolling bearing is then calculated from the time when the bearing is installed and put into use, in its former >;80% of the life period, the bearing is all normal. Then corresponding to the development of rolling bearing faults, the remaining life is 10% in the first stage.20%L10, the second stage is 5%-10%L10, the third stage is 1%-5% L10, and the fourth stage is about 1H or 1%L10.Therefore, when facing bearing problems in practical work, considering that the fourth stage of bearing fault development has unforeseeable sudden harm, it is recommended to replace bearings in the late stage of the third stage, which can not only avoid the expansion of the fault and the occurrence of more serious accidents but also try to ensure the service life of rolling bearings. And according to the bearing at this time has also appeared visible to the naked eyewear, parts damage, and other rolling bearing fault characteristics, more convincing. As for the identification of the late stage of bearing fault development, it is necessary to consider comprehensively according to the above theoretical characteristics combined with the actual temperature, noise, velocity spectrum, peak energy spectrum, the total trend of velocity, and peak energy, and practical experience.

1.Unilateral limit position of channel spalling offThe spalling at the limit position of the single side of the channel is mainly manifested in the serious spalling belt at the junction of the channel and the retaining edge. The reason is that the bearing is not installed in place or sudden axial overload in the process of operation. The countermeasures are to ensure that the bearing is installed in place or the outer ring fit of the free side bearing is changed to a clearance fit, in order to compensate the bearing when the bearing is overloaded. If it is impossible to ensure that the installation is in place, the oil film thickness of the lubricant can be increased (to improve the viscosity of the lubricant), or the load of the bearing can be reduced to reduce the direct contact of the bearing.2.The channel peels off symmetrically in the circumferential directionSymmetric peeling shows that the inner ring is peeling off the surrounding ring, while the outer ring is peeling off in a circumferential symmetrical position (that is, the short axis direction of the ellipse), which is mainly caused by the excessive ellipse of the bearing box hole. When the bearing is pressed into the bearing box hole with a larger ellipse, the outer ring of the bearing will produce an ellipse, and the clearance in the short axis direction will be significantly reduced or even negative. Bearing under the action of load, the inner ring rotation produces circumferential spalling marks, the outer ring only produces spalling marks in the symmetric position of the short axis direction, which is the main reason for the early trial sale of the bearing. The countermeasure is to improve the machining precision of the bearing box hole.3.The raceway is slanting offThe inclined peeling ring belt on the bearing working surface indicates that the bearing is working in an inclined state when the inclination Angle reachesPrecision, improve the use of conditions, and strengthen the quality control in the bearing manufacturing process.5.Cage fracture is an occasional abnormal failure mode. The reasons are mainly as follows: A.Abnormal load of the cage.Such as the installation does not reach the designated position, slope, etc of a large amount of interference of the clearance is reduced, increasing frictional heating, soften surface, the early abnormal spalling, along with the expansion of peeling, flaking, foreign body into the cage pocket hole lead to keep running block and generate additional load, aggravated the wear and tear in the cage, so with deterioration of the cycle, it may cause maintains a fracture.B.Poor lubrication mainly refers to the bearing running in a state of poor oil, easy to form adhesive wear, so that the working surface of the state of evil, adhesive wear produced tears easy to enter the cage, so that the cage produces abnormal load, may cause the cage fracture.C.The intrusion of foreign matter is a common mode of cage fracture failure. Due to the invasion of hard foreign bodies, the wear of the cage is aggravated and the abnormal additional load is produced, which may lead to the cage fracture.D.Creep phenomenon is also one of the causes of cage fracture. The so-called creep multi-finger ring sliding phenomenon, in the matchIn the case of insufficient interference of the joint plane, the load point moves to the surrounding direction due to sliding, resulting in the phenomenon that the position of the ring deviates from the relative axis or the outer shell to the circumferential direction. Once the creep occurs, the mating surface is significantly worn, and the wear powder may enter the bearing interior, forming the process of abnormal wear, raceway spalling, cage wear and additional load, and even may cause the rupture of the support.E.Cage fracture may be caused by cage material defects (such as cracks, large different metal inclusions, shrinkage holes, bubbles) and riveting defects (lack of nails, padded nails, or the gap between the two parts of the cage and serious riveting). Take measures to strictly control the manufacturing process.6.Card injuryThe so-called sticking injury is the surface damage caused by the summary of minor burns on the part of the sliding surface injury. Linear scars in the circumferential direction of the slide surface and rolling surface.The roller end face of the pendulum line scar, close to the roller end face of the axial torus wound. The main reasons for jamming are: excessive load, excessive preloading, poor lubrication, foreign body bite, the tilt of inner and outer rings, shaft deflection, shaft, bearing box accuracy is poor, etc. This can be solved by proper preloading, improved lubricants and lubrication methods, and improved accuracy of shafts and bearing boxes.7.Wear and tearWear failure refers to the relative sliding friction between the surfaces, resulting in continuous wear of metal on the working surface of the loss of efficiency. The main factors that cause wear failure are lubricant failure or lack of lubricant, the wrong lubrication mode, the grinding force into the bearing, and the load is too large. The solution can be improved by improving the lubricant or lubrication method, enhance the performance of the sealing mechanism, etc.8.scratchThe so-called abrasion is in the raceway surface and rolling surface, with the rolling body skid and oil film heat crack produced by the small burn of the summary and surface damage. Produces surface roughness with adhesion. The main causes of abrasion are high-speed light load, rapid acceleration and deceleration, improper lubricant, water intrusion, and so on. Solution: improve preloading, improve bearing clearance, use good oil film lubricant, improve lubrication method, improve the sealing device, etc.9.indentationBite into small metal powder and foreign bodies, etc. in the raceway surface or the rotary surface of the dent or due to the impact of installation, etc., in the rolling body spacing interval formed a concave surface (Brinell hardness indentation). Causing the main factors of indentation method and other methods to solve.11.Current corrosion (electric corrosion)The so-called electric erosion refers to the current in the rotating bearing ring and the contact part of the rolling body flow, through the thin lubricating oil film sparks, the surface of the local melting and concave-convex phenomenon. The main causes of current corrosion are the potential difference between the outer ring and the inner ring and the effect of static electricity. Solution: When setting the circuit, the current does not pass through the bearing to insulate the bearing, and the electrostatic grounding device is connected.12.The rust and corrosion of bearings include raceway, pit rust, comprehensive rust, and corrosion on the surface of the rolling body.The rust and corrosion of bearings will cause pit rust on the surface of the ring and rolling body, pear skin rust and pit rust with the same spacing of rolling body, and comprehensive rust and corrosion. There are many reasons for the rust and corrosion failure of rolling bearings. The main reasons are: the invasion of water or corrosive substances (paint, coal gas, etc.), improper lubricant; Due to the condensation of water vapor with water droplets, high temperature and wet stop, transportation over the course of poor rust prevention, storage state are not appropriate, use is not appropriate.The solutions are as follows: improve the sealing device, study the lubrication method, use effective anti-rust measures when to stop, improve the storage method, and pay attention to the use.3. In addition to the above common failure forms, there are many failure forms of rolling bearings in actual operation, which need to be further analyzed and studied.To sum up, from the common failure mechanism and failure mode of bearings, it can be seen that although rolling bearings are precise and reliable mechanical foundation parts, improper use will also cause early failure.Under normal circumstances, if the bearing can be used correctly, it can be used until the fatigue life. The early failure of bearings is mainly caused by the manufacturing accuracy, installation quality, use of strip, lubrication effect, invasion of external foreign matter, thermal influence and sudden failure of the main engine. Therefore, the correct and reasonable use of bearings is system engineering. In the application design, manufacturing, and installation process of bearings, corresponding measures can be taken to improve the service life of bearings and main engines effectively, which is the common responsibility of bearing manufacturing enterprises and customers.Radial clearance adjustment method for cylindrical roller bearingsThe composite radial load on the fixed load is exposed from the local ring raceway fixed ring and transmitted to the corresponding shaft or bearing local. This load is characterized by the fact that the radial load vector is relatively static in the composite and loop. Load bearing rings can be used relatively loosely.Rotating load is applied to the cylinder rotating along the circumferential direction of the synthetic radial load on the full cylindrical roller bearing ring, the rotation of various parts, such as a load of rotation, which is borne by the synthetic vector phase ring radial load rotation. The rotating load ring is closely matched, in special cases, the load, such as elected, is light or heavy at low speed under the load, only occasionally the ring, the bearing is made of hard material and the surface roughness is high, the rotating load bearing medium finger can also be used to be looser.Third load oscillation, the load or no load direction of synthetic direction uncertain load ring radial load, its characteristic is the synthetic ring radial load vector circle, in a certain region within the impact load, the vibration of the load, its direction is swinging, roll to bear a certain area, or acting on the bearing load, the load value change constantly. To bear the load swing, the outer ring, and shaft, bearing, the hole should be closely used.The commonly used methods for adjusting the radial clearance of full cylindrical roller bearings are as follows:1. The side clearance of cylindrical and elliptical bearing bushing can be adjusted by manual scraping or repairing and scraping after padded turning in the middle of the bearing.2. The top clearance of cylindrical and elliptical bearing bush can be adjusted by manual scraping or by adding a pad to the face of the bearing when the situation permits.3. In principle, scraping and adjusting the clearance of the bearing bush are not allowed for the multi-wedge fixed bearing bush. When the clearance is not suitable, a new tile should be replaced.4. Tilting bearing for the multi-oil wedge is not allowed to repair and scrape tile. When the gap is not suitable, the tile should be replaced. The thickness of the adjustable tile can be adjusted by adding stainless steel pad under the tile behind the adjusting block or thinning the adjusting block thickness method to adjust the amount of tile. Pay attention to the multi-wedge tilting bearing bush, the thickness error between the same group of tiles should be less than 0.01mm.

Under a certain load, the number of revolutions or hours experienced by the bearing before pitting is called the bearing life.The life of a rolling bearing is defined in revolutions (or hours of work at a certain speed) : the bearing within this life shall suffer initial fatigue damage (peeling or defect) on any bearing ring or rolling body.However, whether in laboratory tests or in actual use, it can be clearly seen that the actual life of the same bearing with the same appearance under the same working conditions is very different.In addition, there are several different definitions of bearing "life", one of which is the so-called "working life", which means that the actual life of a bearing can be achieved before the damage is caused by wear and tear. The damage is usually not caused by fatigue, but by wear, corrosion, sealing damage and other reasons.In order to determine the standard of bearing life, the bearing life is linked to reliability.Due to the difference in manufacturing accuracy and material uniformity, even if it is the same material and the same size, the same batch of bearings are used under the same working conditions, and their life length is not the same.If statistical life is taken as 1 unit, the longest relative life is 4 units, the shortest is 0.1-0.2 units, and the ratio of the longest to the shortest life is 20-40 times.90% of bearings do not produce pitting corrosion, and the number of revolutions or hours experienced is called the rated life of bearings.Main uses of angular contact ball bearingsSingle-row angular contact ball bearings can only bear axial loads in one direction.When this kind of bearing bears pure radial load, because the rolling body load line and radial load line of action are not in the same radial plane, the internal axial component force is generated, so it must be installed and used in pairs.Single row angular contact ball bearing is mainly used in machine tool spindle, high frequency motor, combustion turbine, centrifugal separator, small car front wheel, differential pinion shaft, booster pump, drilling platform, food machinery, dividing head, welding machine, low noise type cooling tower, mechanical and electrical equipment, coating equipment, machine tool slot plate, arc welding machineThe design of double row angular contact ball bearings is basically the same as that of single row angular contact ball bearings, but occupies only a smaller axial space.Double row angular contact ball bearings can bear radial load and axial load acting in two directions, it can limit the axial displacement of the shaft or shell bidirectional, the contact Angle is 30 degrees.High rigidity bearing configurations can be provided and can withstand overturning torque.Double row angular contact ball bearings can bear large radial loads, radial and axial combined loads and torque loads, which limit the axial displacement of both sides of the shaft.It is mainly used to limit the axial displacement of shaft and housing.Double row angular contact ball bearing is mainly used for oil pump, roots blower, air compressor, all kinds of transmission, fuel injection pump, printing machinery, planetary reducer, extraction equipment, cycloid reducer, food packaging machinery, electric welding machine, electric, square box, gravity type spray gun, wire stripping machine, axle shaft equipment, chemical machinery, testing analysis