Three methods to distinguish the quality of ina universal joint bearing and their application selection
Three methods to distinguish the quality of ina universal joint bearing and their application selection
2022年4月7日
Solutions to common faults of ina stainless steel bearing
2022年4月7日

Methods and diagnostic techniques for identifying whether ina non-standard bearings can be reused

  • INA Bearing Vibration Diagnosis Technology includes signal acquisition, signal processing and fault identification.
  • The vibration generated by signal acquisition rolling bearing includes low-frequency vibration below 1kHz and high-frequency vibration of thousands of Hz or even tens of thousands of Hz.

Methods and diagnostic techniques for identifying whether ina non-standard bearings can be reused

  • Therefore, the acceleration sensor or speed sensor is commonly used for vibration signal acquisition. The selection principle is as follows to ensure that the weight of the sensor itself is at least 1 / 10 of the effective weight of the tested system.
  • The test frequency range shall be within the linear frequency range of the selected sensor.
  • The large vibration level tested shall not exceed 1 / 3 of the allowable impact speed of the sensor. Generally, low sensitivity sensors are used for large vibration levels, and high sensitivity sensors are used for small vibration levels.
  • The sensor signal processing suitable for the corresponding environment shall be selected. The output signal of the sensor contains rich vibration waveforms representing the working conditions of INA Bearing, as well as various noises.
  • The function of signal processing is to separate the required characteristic parameters and their curves from the signal output by the sensor.
  • The analysis of vibration signal is mainly divided into time domain analysis and frequency domain analysis. Time domain analysis is in two forms: amplitude domain and TDOA domain. The transformation between time domain and frequency domain is realized by technology.
Methods and diagnostic techniques for identifying whether ina non-standard bearings can be reused
  • However, if ina bearing has the following defects, it can no longer be used, and a new non-standard bearing should be replaced immediately. The details are as follows:
  •  There are cracks or notches on any one of the inner ring, outer ring, rolling element and cage of the bearing;
  • Any one of the bearing rings and rolling elements is broken;
  • The raceway surface, retaining edge and rolling element of the bearing are significantly jammed;
  • The cage of the bearing is significantly worn, or the rivet is significantly loose;
  • There is rust and damage on the raceway surface and rolling element of the bearing;
  • There are serious indentations and scratches on the raceway surface and rolling element of the bearing;
  • The inner ring inner diameter surface or outer ring outer diameter surface of the bearing has obvious creep;
  •  Discoloration caused by heat is obvious.
  • Therefore, in case of the above situation of INA Bearing, please do not continue to use it and replace it with a new non-standard bearing immediately. Avoid unnecessary accidents.
  • After the ina bearing is installed, in order to check whether the installation is correct, the operation inspection shall be carried out. Small machinery can be rotated by hand to confirm whether it rotates smoothly. Methods and diagnostic techniques for identifying whether ina non-standard bearings can be reused
  • The inspection items include poor operation caused by foreign matters, scars and indentation, unstable torque caused by poor installation and poor processing of mounting base, excessive torque caused by too small clearance, installation error and sealing friction, etc. If there is no abnormality, the power operation can be started.Methods and diagnostic techniques for identifying whether ina non-standard bearings can be reused
  • Power operation, starting from no-load and low speed, slowly increase to the rated operation under the specified conditions. During the test run, the inspection items are whether there is abnormal sound, non-standard bearing temperature change, lubricant leakage or discoloration, etc. Methods and diagnostic techniques for identifying whether ina non-standard bearings can be reused
  • If any abnormality is found, stop the operation immediately, check the machinery, and remove the INA Bearing for inspection if necessary.cMethods and diagnostic techniques for identifying whether ina non-standard bearings can be reused
  • Selection and control of shaft and bearing housing tolerance: the bearing shall rotate flexibly without blocking feeling after being pressed into the bearing. If there is obvious inflexible rotation, it indicates that the size of the shaft is too large and the tolerance should be reduced.Methods and diagnostic techniques for identifying whether ina non-standard bearings can be reused
  •  If the non-standard bearing has an obvious “rusty” feeling after being pressed into the bearing by hand, it may be that the tolerance of the bearing is too large or the roundness of the bearing is not good. Methods and diagnostic techniques for identifying whether ina non-standard bearings can be reused
  • Therefore, when controlling the tolerance of shaft and bearing chamber, it is also necessary to control the roundness. At present, many domestic manufacturers only control the tolerance, not the roundness.Methods and diagnostic techniques for identifying whether ina non-standard bearings can be reused
Methods and diagnostic techniques for identifying whether ina non-standard bearings can be reused
  •  Assembly method of bearing: because the bearing is a high-precision product, if it is improperly assembled, it is easy to damage the non-standard bearing channel, resulting in the damage of INA Bearing. The bearing shall be equipped with a special mold during assembly, which cannot be knocked at will.Methods and diagnostic techniques for identifying whether ina non-standard bearings can be reused
  •  When pressing the shaft, only the small ring can be stressed, and when pressing the large ring, only the large ring can be stressed. Air pressure or hydraulic pressure is required during assembly. Methods and diagnostic techniques for identifying whether ina non-standard bearings can be reused
  • During press assembly, the upper and lower touch shall be outside the horizontal state. If there is inclination, the bearing channel will be damaged due to stress and the bearing will produce conduction sound.Methods and diagnostic techniques for identifying whether ina non-standard bearings can be reused
  •  Prevention of assembly foreign matters: when the non-standard bearing is installed on the rotor for dynamic balance, it is easy to put the iron filings generated during dynamic balance into the bearing, so the dynamic balance is carried out before installing the bearing. Methods and diagnostic techniques for identifying whether ina non-standard bearings can be reused
  • In order to facilitate assembly, some manufacturers apply some oil or grease in the bearing chamber for lubrication effect during assembly, but it is often difficult for operators to control the amount. If there is a large amount of oil or grease in the bearing chamber, it is easy to enter the INA Bearing along the shaft when the bearing rotates. Methods and diagnostic techniques for identifying whether ina non-standard bearings can be reused
  • The bearing chamber shall not be coated with oil or grease. If it must be coated, it shall be controlled and there shall be no accumulation in the bearing chamber.Methods and diagnostic techniques for identifying whether ina non-standard bearings can be reused
  • Prevention of paint rust: paint rust is often found in sealed motors. The sound of the motor is very good during assembly, but after being put in the warehouse for some time, the abnormal noise of the motor becomes very large, and there is serious rust when removing non-standard bearings. In the past, many manufacturers thought it was the bearing problem. Methods and diagnostic techniques for identifying whether ina non-standard bearings can be reused
  • After our continuous publicity, now the motor factory has realized that the main problem is the insulating paint. This problem is mainly because the acid substances volatilized from the insulating paint form corrosive substances at a certain temperature and humidity, which corrodes the bearing channel and leads to the damage of INA Bearing.Methods and diagnostic techniques for identifying whether ina non-standard bearings can be reused
  •  At present, the problem can only be to select good insulating paint and assemble after drying and ventilation for a period of time.Methods and diagnostic techniques for identifying whether ina non-standard bearings can be reused
  • The service life of ina bearing is closely related to manufacturing, assembly and use. It must be done well in each link in order to make the non-standard bearing in the running state, so as to prolong the service life of the bearing.
Methods and diagnostic techniques for identifying whether ina non-standard bearings can be reused
  • Size limitations. Generally, the space where ina bearings can be installed is limited. In most cases, the shaft diameter (or bearing inner diameter) is limited by mechanical design or other design. Therefore, the selection of bearing type and size is determined according to the inner diameter of universal joint bearing. Therefore, the main dimension tables of standard bearings are compiled according to the inner diameter dimensions of international standards.
  • There are many sizes and forms of scale bearings. Scale bearings are used in the design of mechanical devices. The nature, size and direction of the load of bearings and the load imposed on bearings are changeable. In general, the rated base load is shown on the dimension table. 
  • However, axial load and radial load are also important factors in selecting suitable bearings. When the size of the ball and needle roller bearing is commensurate, the needle roller bearing usually has high load capacity and bears large vibration and impact load.
  • The speed and allowable speed are determined according to the type, size, accuracy, cage type, load, lubrication mode, cooling mode and other factors of INA Bearing. The table of universal joint bearing lists the allowable speed of scale precision bearing under oil lubrication and grease lubrication.
  •  In general, deep groove ball bearings, self-aligning ball bearings and cylindrical roller bearings are all suitable for high-speed operation.Methods and diagnostic techniques for identifying whether ina non-standard bearings can be reused
  • Feel the bearing quality through the surface
  • The customer said that as long as the surface of the universal joint is bright, it is wrong. The brightness of the bearing surface should be a kind of dark brightness. The reason for this dark brightness is whether the steel used by the bearing meets the standard, its grinding process and the cutting fluid used, mainly the first two items.
Methods and diagnostic techniques for identifying whether ina non-standard bearings can be reused