KOYO bearing failure cause analysis inspection method

According to the import of grinding badness layer of bearings working surface formation mechanism, the main factors influencing the grinding metamorphic layer is a function of grinding and grinding force. Here we analyse about bearing failure reason. 1. KOYO bearing grinding heat in KOYO bearing grinding, grinding wheel and workpiece contact zone, consume large amounts of energy, to produce a large number of grinding heat, local transient high temperature caused by grinding area. On the basis of the theory of linear motion heat source heat transfer formula derivation, calculation or by the method of infrared ray and measured experiment under the condition of instantaneous temperature thermocouple method, can be found in 0. 1 to 0. The grinding area within 001 ms instantaneous temperature up to 1000 ~ 1500 ℃. The instantaneous high temperature, which would have made certain depth on the surface of the work surface to produce high temperature oxidation, amorphous group, high temperature tempering, secondary hardening, and even burn cracking and other changes. ( 1) Surface under the action of transient high temperature oxide layer of the surface of the steel and the oxygen in the air, rises into extremely thin ( 20～30nm） The iron oxide thin layer. It is worth noting that the oxide layer thickness and surface grinding metamorphic layer is the total thickness test results in corresponding relation. This shows that the thickness of oxide layer, is directly related to the grinding process is an important symbol of grinding quality. ( 2) Amorphous layer organization grinding the instantaneous high temperature makes the workpiece surface reach a molten state, molten metal molecular flow is evenly coated to the work surface, and the matrix metal cooling at breakneck speed, formed a very thin layer of amorphous tissue layers. It has high hardness and toughness, but it is only about 10 nm, it is easy to be removed in the precision grinding processing. ( 3) High temperature tempering instantaneous high temperature can make the surface layer of grinding zone certain depth ( 10 ~ 100海里) Be heated to a temperature higher than the workpiece temperature tempering heat. In the absence of austenitizing temperature reached, with the improvement of heated temperature, the surface will produce one by one and heating temperature corresponding to the organization transformation, or high temperature tempering tempering hardness. The higher the heating temperature and hardness of the decline is more severe. ( 4) Transient high temperature quenching layer when the grinding area on the second floor heat the workpiece surface layer to the austenitizing temperature ( Ac1） Above, the layer of austenitizing group in the subsequent cooling process, the quenching into martensite structure anew. Where the secondary hardening burns of workpiece, the second time hardening layer must be under very low temperature tempering hardness layer. ( 5) Grinding crack two quenching burns will make workpiece surface layer stress changes. Secondary hardening zone is in compression state, the high temperature materials back to the fire area underneath there are the largest tensile stress, this is the place where the most likely to occur crack core. Crack is the most easily spread along the original austenite grain boundary. Serious burns can lead to crack of the grinding surface ( Formed a crack) Artifacts caused by scrapping. A, KOYO bearings rolling sound the sound device is adopted to the size of the rolling sound of bearing in operation and the quality inspection, bearing even with slight stripping damage, such as would an exception and irregular, and with the sound of the measuring device can distinguish. Second, the bearing vibration is sensitive to bearing damage, such as peeling, indentation, rust, crack and wear will be reflected in the bearing vibration measurement, therefore, through the use of special bearing vibration tester ( Frequency analyzer, etc. ) Can measure the size of the vibration, through frequency analysis cannot deduce the abnormal situation. Measured values of bearing or sensor installation position and different using conditions, thus requiring prior to each machine is analyzed by the measured value of the determined after judgment standard. Three, the temperature of the bearing, generally have a bearing on the surface of the outdoor temperature can be predicted, if using the oil hole can directly measure temperature of bearing outer ring, is more appropriate. Usually, the temperature of the bearing with operation began to slowly rise, 1 - After 2 hours to reach steady state. The normal temperature of bearing for machine heat capacity, heat dissipating capacity, rotational speed and load. If the appropriate lubrication, installation department, the bearing temperature will rise sharply, appear unusually high temperature, must stop at this moment, take the necessary precautions. Using thermal device can monitor the bearing temperature at any time, and realize e. automatic alarm when the temperature is more than the household or stop to prevent the shaft accidents. Four, lubrication on the fatigue life of rolling bearing, friction and wear, temperature rise, vibration and so on have important influence, not the normal lubrication, bearing cannot work. Analyze the failure reasons of KOYO bearing show that about 40% of the bearing damage is related to bad lubrication. Therefore, good lubrication of the bearing is an effective measure to reduce the bearing friction and wear.