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Research on Speed Detection Method of Bearing Rolling Element Based on Weak Magnetic Detection Technology

2020-09-30 13:33

Skidding is a common failure form during the operation of high-speed light-load bearings, that is, under the influence of inertial force, the rolling element cannot roll normally under the drive of the inner ring, and the linear velocity of the two contact points is different, resulting in the rolling element Scragging occurs between the ring raceway. Its main manifestation is that the speed of the cage decreases due to the decrease of the speed of the rolling element, so it is also calledCage slipping. Once the slip occurs, it will cause the contact surface scratch, serious will lead to scratch parts of the surface spalling and other failure forms, the stable operation of the bearing has a great threat.


At present, a large number of experimental studies have been carried out on the monitoring of cage slip at home and abroad. Document [5] uses electromagnetic induction probe to obtain pulse signal to measure the speed of the cage; Document [6-7] uses magnetic sensor to record the rivet passing situation of the cage, so as to obtain the speed of the cage; Document [8-10] preforms reflective marks on the cage, and realizes the measurement of the speed of the cage by counting the reflected pulse optical signal or laser signal; document [11] uses photoelectric sensor and grating combination to measure the rotation speed of bearing inner ring, cage and rolling body; Document [12] preforms acceleration sensor with grooves on the outer surface of outer ring, and calculates the rotation speed of rolling body by recording the stress signal generated by each passing of rolling body.


AlthoughThe above detection method and test systemIt provides an effective method for laboratory cage slip research,There are still some limitations in the monitoring of cage slip in the actual use of bearings..electromagnetic induction methodThe rolling body needs to be magnetized, and at high speeds,The magnetic field will aggregate wear debris in the bearing and aggravate the bearing wear[13];Optical sensors and fiber optic measurements require the installation of test devices at the end of the bearing, while the high-temperature lubricant mist environment severely restricts the accuracy of monitoring.[14];Photoelectric and grating combined sensors require high installation space and are difficult to operate in practical engineering applications.;The acceleration sensor needs to modify the bearing structure and destroy the bearing ring.[12]. Therefore, the above test method is difficult to be applied in engineering due to the particularity of the bearing structure, the working space and the working environment.


To sum up, a kindSpeed Detection Method of Bearing Rolling Element Based on Weak Magnetic Detection Technology,Without destroying the bearing structure and the magnetized rolling body is not disturbed by the oil mist in the bearing cavity, the rolling body speed can be measured by detecting the weak magnetic field information of the rolling body and extracting the characteristic frequency of the rolling body rotation under the condition of the outer ring of the bearing.

Measuring principle

Measured speed of cagenmThrough the measured frequencyfmCalculated, the measurement principle of weak magnetic detection technology is shown in Figure 1, each rolling body has a certain strength of weak magnetic field, when the rolling body through the weak magnetic detection sensor, its weak magnetic field in each.φThe radian produces an alternating excitation signal, which is identified by a weak magnetic detector and its frequency information is extracted and calculated by a specific detection circuit to obtain the measured Establish a test platform, through test analysis, it is concluded thatConclusion


The theoretical analysis and the test results of the actual rolling element speed of the bearing show that the weak magnetic signal detection technology can provide a new and effective measurement method for the detection of the rolling element speed of the bearing.


1) The weak magnetic signal sensor can detect the speed of the rolling element when the bearing ring is blocked, and the detection result is not affected by the measurement distance and has high accuracy;


2) When the test distance is small, the ferrule affects the signal strength detected by the weak magnetic detection sensor to a certain extent; with the increase of the test distance, the signal strength gradually decreases, and the influence of the ferrule on the detection result becomes smaller; in a wide test distance range, the magnetic field change can still be effectively measured.


3) The magnetic field changes caused by the rolling body in the rotation process are affected by the speed to a certain extent, and the intensity of the identified pulse weak magnetic signal decreases with the increase of the speed, but does not affect the identification of the signal characteristic frequency.