There are dozens of fag imported bearings on the automobile, including almost all common bearing types in large and small, and the faults and damages of fag imported bearings are also common. As fag imported bearings are generally installed inside the mechanism, it is inconvenient to conduct visual inspection. We can only make a brief judgment according to the fault phenomenon, and then disassemble and inspect.
The correct use of fag imported bearings is a reliable guarantee to reduce bearing faults and prolong bearing life, including correct installation and reasonable lubrication.Analysis of common failures and precautions of IKO bearingAnalysis of common failures and precautions of IKO bearing
The following describes the use requirements, common faults and damages of fag imported bearings.
1、 Correct use of fag imported bearings
Disassembly and assembly of bearing
The bearing shall be cleaned before installation. During installation, special tools shall be used to press the auxiliary bearing straight and evenly. Do not knock with a hand hammer. In particular, it is forbidden to knock directly on the bearing. When the fit between the bearing race and the seat hole is loose, the seat hole shall be repaired or the bearing shall be replaced. Do not reluctantly use the method of pitting or padding copper skin on the bearing mating surface. Do not use a hammer to pull out the bearing when it is disassembled.
Bearing lubrication
There are two kinds of lubricants commonly used in fag imported bearings: lubricating oil and grease. When the circumferential speed of the shaft is less than 4-5m / s, or the parts on the vehicle that cannot be lubricated with lubricating oil, they shall be lubricated with grease. The advantage of grease lubrication is that the sealing structure is simple, the grease is not easy to lose, and it is not affected by temperature. Adding grease once can be used for a long time.Analysis of common failures and precautions of IKO bearingAnalysis of common failures and precautions of IKO bearing
Two problems should be paid attention to when using grease. One is to select the appropriate brand of grease according to the requirements of the automobile manual. For example, nano base grease should not be selected for automobile water pump bearing because of its poor water resistance. Second, the amount of lubricating grease added to the bearing should be appropriate. Analysis of common failures and precautions of IKO bearingAnalysis of common failures and precautions of IKO bearing
Generally, it is appropriate to fill only 1 / 2-L / 3 of the bearing cavity. Too much is not only useless, but also increases the running resistance of the bearing and heats it up. Special attention should be paid to the automobile hub bearing. It is necessary to advocate “empty hub lubrication”, that is, only apply an appropriate layer of grease on the bearing. Otherwise, it will not only waste and poor heat dissipation, but also overflow the grease by heating, which may affect the braking performance.Analysis of common failures and precautions of IKO bearingAnalysis of common failures and precautions of IKO bearing
The advantage of lubricating oil lubrication is that it has low friction resistance and can dissipate heat. It is mainly used for bearings with high speed and high working environment temperature. The brand of lubricating oil shall be selected according to the requirements of the vehicle manual, and shall be replaced in time after the vehicle maintenance cycle. Analysis of common failures and precautions of IKO bearingAnalysis of common failures and precautions of IKO bearing
After discharging the old oil, the mechanism shall be cleaned before adding new oil. The oil shall be added to the specified marking line or flush with the oil filler (depending on the specific structure and requirements of the vehicle), and no more oil shall be added. As the world’s IKO imported bearing, it is widely used. Each industry has different characteristics of damage.Analysis of common failures and precautions of IKO bearingAnalysis of common failures and precautions of IKO bearing
Mechanical damage
Mechanical damage of sliding bearing refers to the groove marks in different degrees on the alloy surface of bearing bush. In serious cases, metal peeling and large-area random scratch occur on the contact surface; Generally, contact surface damage and ablation exist at the same time. The main reason for the mechanical damage of IKO imported bearing is that the bearing surface is difficult to form oil film or the oil film is seriously damaged.
Bearing cavitation
Under the repeated action of cylinder pressure (impact load), the surface layer of sliding bearing will undergo plastic deformation and cold work hardening, lose the deformation ability locally, gradually form wrinkles and expand continuously, and then form cavities in the loaded surface layer with the falling off of wear debris. When the pitting is parallel to the interface, the pitting will expand gradually, and then the pitting will occur along the interface.Analysis of common failures and precautions of IKO bearingAnalysis of common failures and precautions of IKO bearing
The main reason for the cavitation of sliding bearing is that the sudden change of the cross section of structural elements such as oil groove and oil hole causes the strong disorder of oil flow, forming bubbles in the vacuum area with disordered oil flow, and then cavitation occurs due to the collapse of bubbles due to the increase of pressure. Cavitation usually occurs in the high load area of IKO inlet bearing, such as the lower bearing bush of crankshaft main bearing.Analysis of common failures and precautions of IKO bearingAnalysis of common failures and precautions of IKO bearing
fatigue pitting
Fatigue pitting corrosion of IKO imported bearing refers to the fatigue damage, fatigue pitting corrosion or fatigue falling off in the middle of the bearing due to overheating and excessive bearing clearance due to overload operation of the engine. This kind of damage is mostly caused by overload, excessive bearing clearance, or unclean lubricating oil and foreign matters mixed in it. Analysis of common failures and precautions of IKO bearingAnalysis of common failures and precautions of IKO bearing
Therefore, when using, attention should be paid to avoid bearing overload, and do not run at too low or too high speed; Adjust the engine to a stable state at idle speed; Ensure the normal bearing clearance and prevent the engine speed from being too high or too low; Check and adjust the working condition of the cooling system to ensure that the working temperature of the engine is appropriate.Analysis of common failures and precautions of IKO bearingAnalysis of common failures and precautions of IKO bearing
Bearing alloy corrosion
The corrosion area of IKO imported bearing alloy is generally that the lubricating oil is impure, and the chemical impurities (acid oxides, etc.) in the lubricating oil oxidize the bearing alloy to form acidic substances, causing part of the bearing alloy to fall off and form irregular small cracks or pits. The main causes of bearing alloy corrosion are improper selection of lubricating oil, poor corrosion resistance of bearing materials, or rough engine operation and high temperature.Analysis of common failures and precautions of IKO bearingAnalysis of common failures and precautions of IKO bearing
Bearing melting
There is a small convex metal surface between the journal and the bearing friction pair, which forms a local high temperature. In the case of insufficient lubrication and poor cooling, the bearing alloy will be blackened or partially burned. This fault is often caused by the tight fit between the journal and the imported IKO bearing; Insufficient lubricating oil pressure is also easy to burn the bearing.Analysis of common failures and precautions of IKO bearingAnalysis of common failures and precautions of IKO bearing
Outer circle of bearing
The outer circle of IKO imported bearing means that the bearing has relative rotation in the seat hole. After the bearing goes to the outer circle, it will not only affect the heat dissipation of the bearing, which is easy to ablate the alloy on the inner surface of the bearing, but also damage the back of the bearing and burn the bearing in serious cases. The main reason is that the bearing is too short, the tenon is damaged, and the processing or installation does not meet the specifications. Analysis of common failures and precautions of IKO bearingAnalysis of common failures and precautions of IKO bearing
Timken bearing is an important part of the rear axle drive wheel movement. Timken bearing is the main compound in the work, which can withstand bending and torque and absorb some impact loads at the same time. The axle integral carbon alloy quenched steel and induction heating hardening commonly used in quenching have a hardened layer depth of 4 – 6mm and a hardness of 50 ~ 55HRC. In the production of Timken bearings, it is found that Timken bearings are often burned out, which seriously affects the induction quenching quality of Timken bearings and parts. The test shows that the burned out area of Timken bearing is located in coil 225. Expand the regularity of fault characteristics of both sides near the construction site.Analysis of common failures and precautions of IKO bearingAnalysis of common failures and precautions of IKO bearing
Axle sensor heating, in addition to heating the workpiece, the main heat loss in three ways is the heat generated by the sensor.
Heat radiates all around. Guide the magnet and induction coil on the insulating paint and fiberglass cloth. This form of heat loss is less, heating is uniform, and has little effect on sensor burnout.
Heat of cooling water. This part of the heat dissipation cooling sensor enables the operation of induction heating. The study found that at 0-180 degrees, the intake of low water temperature indicates good heat exchange cooling water, smooth water and no water temperature; More than 180, Because of the length of the flow path, the rise of the water temperature and the rise of the water temperature, the heat exchange changes. Because the sensor can easily lead to the temperature rise of a station (such as 225. About the part), this is the main induction coil combustion.Analysis of common failures and precautions of IKO bearingAnalysis of common failures and precautions of IKO bearing
Induction coil of the heat transfer plate, part of the plate current density, large cross-section and low water temperature, in the area of the coil of the heat transfer plate. 0 to 90 degrees and 270 – 360 degrees are far away from the nearby induction coil plate, with good thermal conductivity; Far away from the plate, the thermal conductivity is poor. Analysis of common failures and precautions of IKO bearingAnalysis of common failures and precautions of IKO bearing
The induction coil of 90 to 270 pieces makes the temperature of the induction coil in this area easier to appear in this part, like burning the coil. The heat flow of the induction coil is compared in different parts. The thermal sensing circuit in the area near 225 degrees is stored, so there is a large difference between the combustion phenomenon of induction coil in this area.Analysis of common failures and precautions of IKO bearingAnalysis of common failures and precautions of IKO bearing
Analysis of common failures and precautions of IKO bearing
Contact fatigue failure refers to the failure caused by alternating stress on the working surface of IKO imported bearing. Contact fatigue spalling occurs on the working surface of IKO bearing, which is often accompanied by fatigue cracks. It first occurs from the large alternating shear stress below the contact surface, and then extends to the surface to form different spalling shapes, such as pitting or pitting spalling, which is called shallow spalling. Due to the gradual expansion of the spalling surface, it often expands to the deep layer, forming deep spalling. Deep spalling is the fatigue source of contact fatigue failure.Analysis of common failures and precautions of IKO bearingAnalysis of common failures and precautions of IKO bearing
Wear failure
Wear failure refers to the failure caused by the continuous wear of the metal on the working surface caused by the relative sliding friction between the surfaces. Continuous wear will cause IKO bearing parts to be gradually damaged, and eventually lead to the loss of dimensional accuracy of IKO bearing and other related problems.
Wear may affect the change of shape, the increase of fit clearance and the change of working surface morphology, may affect the lubricant or make it polluted to a certain extent, resulting in the complete loss of lubrication function, so that IKO bearing loses rotation accuracy and even can not operate normally. Wear failure is one of the common failure modes of various bearings. According to the wear form, it can be divided into common abrasive wear and adhesive wear.Analysis of common failures and precautions of IKO bearingAnalysis of common failures and precautions of IKO bearing
Abrasive wear refers to the wear caused by the relative movement of the contact surface due to the extrusion of foreign hard particles or hard foreign matters or wear debris on the metal surface between the working surfaces of IKO bearings, which often causes furrow like scratches on the working surfaces of IKO bearings. Hard particles or foreign matters may come from the inside of the host machine or from other adjacent parts of the host system, and are sent into the IKO bearing by the lubricating medium.Analysis of common failures and precautions of IKO bearingAnalysis of common failures and precautions of IKO bearing
IKO bearing accuracy error related knowledge. Adhesive wear refers to the uneven stress on the friction surface due to the micro bulge or foreign matter on the friction surface. When the lubrication conditions are seriously deteriorated, the local deformation and friction micro welding of the friction surface are easy to be caused due to the heat generated by local friction. In serious cases, the surface metal may be locally melted, and the force on the contact surface will tear the local friction welding point from the substrate and increase the plastic deformation. This cycle of adhesion tear adhesion constitutes adhesive wear. Generally speaking, slight adhesive wear is called scratch and severe adhesive wear is called bite.
Fracture failure
The main causes of IKO bearing fracture failure are defect and overload. When the external load exceeds the material strength limit and causes the part to break, it is called overload fracture. The main cause of overload is the sudden failure or improper installation of the host. Defects such as microcracks, shrinkage cavities, bubbles, large foreign objects, overheated tissue and local burns of bearing parts will also cause fracture at the defect during impact overload or violent vibration, which is called defect fracture.
It should be pointed out that in the manufacturing process of IKO bearing, the presence of the above defects can be correctly analyzed by instruments in the incoming re inspection of raw materials, quality control of forging and heat treatment and processing process control, and the control must be strengthened in the future. However, generally speaking, the fracture failure of IKO bearing is mostly overload failure.
Clearance change failure
During the operation of IKO bearing, due to the influence of external or internal factors, the original matching clearance is changed, the accuracy is reduced, and even “bite” is called clearance change failure. External factors such as excessive interference, improper installation, expansion caused by temperature rise, instantaneous overload, etc., and internal factors such as residual austenite and residual stress in an unstable state are the main reasons for the change and failure of clearance. Analysis of common failures and precautions of IKO bearingAnalysis of common failures and precautions of IKO bearing
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