Process characteristics for judging the vibration of imported bearings and the temperature of imported bearings

First, the vibration of imported bearings

The vibration of the imported bearing is very sensitive to the damage of the imported bearing. For example, peeling, indentation, rust, crack, wear, etc. will be reflected in the vibration measurement of the imported bearing. Therefore, by using a special bearing vibration measuring device (frequency analyzer, etc.) The magnitude of the vibration is measured, and the specific situation of the abnormality cannot be inferred by the frequency division. The measured values ​​vary depending on the conditions of use of the bearing or the mounting position of the sensor. Therefore, it is necessary to analyze and compare the measured values ​​of each machine in advance to determine the judgment standard.

Second, the temperature of the imported bearings

The temperature of the imported bearing is generally estimated by the temperature outside the bearing. If the oil hole can directly measure the temperature of the outer ring of the imported bearing, it is more suitable.

Usually, the temperature of the imported bearing rises slowly as the bearing starts to run, and reaches a steady state after 1-2 hours. The normal temperature of the imported bearings varies with the heat capacity, heat dissipation, speed and load of the machine. If the lubrication and installation parts are suitable, the temperature of the imported bearings will rise sharply, and abnormal high temperature will occur. At this time, it is necessary to stop the operation and take necessary precautions.

The thermal sensor can be used to monitor the working temperature of the imported bearing at any time, and automatically alarm or stop the occurrence of the burning shaft accident when the temperature exceeds the specified value.

The use of high temperatures often indicates that the bearing is in an abnormal condition. High temperatures are also detrimental to the lubricants of imported bearings. Sometimes bearing overheating can be attributed to the lubricant of the bearing. Long-term continuous rotation of the bearing at temperatures above 125 °C will reduce bearing life. Causes of high temperature imported bearings include: insufficient lubrication or excessive lubrication, lubricants. Containing impurities, excessive load, loss of imported bearings, insufficient clearance, and high friction caused by oil seals.

Therefore, it is necessary to continuously monitor the temperature of the imported bearings, whether it is measuring the bearing itself or other important parts. If the operating conditions are the same, any temperature change can indicate that a fault has occurred.

The periodic measurement of the temperature of the imported bearing can be carried out by means of a thermometer, such as a digital thermometer, which can accurately measure the temperature of the imported bearing and display it in °C or Fahrenheit.

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Common quality defects of KOYO imported bearing parts after heat treatment

Common quality defects of KOYO imported bearing parts after heat treatment include: quenching microstructure superheat, underheating, quenching crack, insufficient hardness, heat treatment variant, surface decarburization, soft point.

Overheat

Overheating of the microstructure after quenching can be observed from the rough mouth of KOYO imported bearing parts.

However, in order to correctly judge the degree of overheating, it is necessary to observe the microstructure. If coarse needle-shaped martensite appears in the quenched structure of gcr15 steel, it is quenched and superheated. The formation may be caused by excessive heating of the quenching heating temperature or the heating temperature is too long; or it may be due to the serious banding of the original structure, forming a local martensite needle-like coarse in the low carbon zone between the two zones. Cause local overheating. The retained austenite increases in the superheated structure, and the dimensional stability decreases. Due to the overheating of the quenched structure, the crystal of the steel is coarse, which leads to a decrease in the toughness of the part and a decrease in the impact resistance. The life of the KOYO bearing is also reduced. Excessive heat can even cause quenching cracks.

2. Underheat

Low quenching temperature or poor cooling will produce a tortite structure exceeding the standard in the microstructure, called underheated structure, which will reduce the hardness and sharply reduce the wear resistance, affecting the life of KOYO bearings.

3. Quenching crack

The crack formed by KOYO imported bearing parts due to internal stress during quenching and cooling is called quenching crack. The causes of such cracks are: the heating temperature is too high due to quenching or the cooling is too fast. The thermal stress and the mass of the metal change the tissue stress greater than the fracture strength of the steel; the original defects of the working surface (such as micro cracks or scratches on the surface) or internal defects of the steel (such as slag inclusions, severe non-metallic inclusions) , white spots, shrinkage holes, etc.) stress concentration during quenching; severe surface decarburization and carbide segregation; insufficient firepower or timely tempering after quenching; excessive cold stress caused by previous processes, forged folding, deep Turning tool marks, sharp edges and corners of oil hooks.

4. Heat treatment deformation

KOYO imported bearing parts have thermal stress and tissue stress during heat treatment. These internal stresses can be superimposed or partially canceled. It is complex and variable because it can follow heating temperature, heating speed, cooling method, cooling rate, The shape and size of the part change, so heat treatment deformation is inevitable. Knowing and mastering the changing laws can make the deformation of KOYO imported bearing parts (such as ellipse of the sleeve, large size increase, etc.) in a controllable range, which is conducive to the production. Of course, mechanical collisions during heat treatment can also cause deformation of the part, but this deformation can be reduced and avoided with improved operation.

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