In modern industrial production, rolling bearings are the core components of rotating machinery, and their health status directly affects the stable operation and production efficiency of the equipment. Once the bearing malfunctions, it can lead to increased equipment vibration and noise, and in severe cases, cause unplanned shutdowns, resulting in huge economic losses.

Therefore, timely and accurate fault diagnosis of rolling bearings is crucial.

The traditional "observation, listening, questioning, and cutting" inspection method is no longer able to meet the high requirements of modern industry for equipment reliability. Nowadays, experienced equipment maintenance engineers are like "miracle doctors" in factories, relying on a series of precision diagnostic instruments to "diagnose the pulse" of equipment and achieve the transformation from passive maintenance to predictive maintenance. This article will deeply analyze the three core "miracle tools" in rolling bearing fault diagnosis - portable vibration analyzer, impact pulse/resonance demodulator, and online monitoring system, and combine them with practical application scenarios to explain their working principles and diagnostic value.

Stethoscope "- portable vibration analyzer: precise positioning of the fault source vibration is a direct reflection of the operating status of mechanical equipment. When the inner and outer rings, rolling elements, or cage of a rolling bearing are damaged by wear, peeling, or cracking, periodic impact forces will be generated during operation, thereby triggering specific vibration signals. A portable vibration analyzer is like

The "stethoscope" of the "divine doctor" can capture and analyze these weak vibration signals, accurately locate the source of the fault.

Working Principle

The vibration analyzer collects the vibration signal of the bearing seat through an acceleration sensor and converts the time-domain signal into a frequency-domain spectrum using fast Fourier transform technology. On the spectrogram, different types of bearing faults exhibit unique "fault characteristic frequencies"

Outer ring fault characteristic frequency: When the outer ring raceway is damaged, the rolling element will produce an impact every time it passes through the damaged point, and its frequency is related to the geometric dimensions, speed, and contact angle of the bearing.

Inner ring fault characteristic frequency: The impact frequency generated by inner ring damage also follows a specific formula, but due to the rotation of the inner ring with the shaft, there are usually sidebands with rotation frequency intervals next to the fault frequency, which is an important indicator for identifying inner ring faults.

Characteristic frequency of rolling element failure: Damage to the rolling element itself (such as pitting and cracks) will produce vibration components related to its rotational frequency.

Characteristic frequency of cage failure: The wear or deformation of the cage can cause low-frequency vibrations related to its rotational frequency.

By comparing the peak frequency in the measured spectrum with the theoretically calculated characteristic frequency, engineers can accurately determine which component of the bearing has a problem. For example, in the machining center of a certain automotive parts enterprise, the spindle vibration was abnormal. Through vibration spectrum analysis, it was found that the 2-fold rotation frequency component was too high, and the misalignment problem caused by loose coupling bolts was ultimately located. After recalibration, the vibration amplitude decreased significantly.

Application advantages

The portable vibration analyzer is flexible to operate and suitable for rapid on-site diagnosis. It can not only detect obvious faults that have already occurred, but also observe changes in vibration amplitude through trend analysis, predict the development trend of faults, and provide a basis for maintenance decisions.

2、 Microscope - Impact pulse analyzer/resonance demodulator: Insight into early micro damage

The fatigue failure of bearings often begins with tiny pitting or cracks on the surface of the raceway. In the early stages of the malfunction, the impact energy generated by these minor damages is very weak and easily overwhelmed by background noise, making it difficult to detect through conventional vibration analysis. At this point, it is necessary for the "miracle doctor" to use a more precise "microscope"

Shock pulse analyzer or resonance demodulator.

Working Principle

Both impulse pulse method and resonance demodulation technology belong to high-frequency vibration detection technology. Their commonality is their focus on capturing high-frequency stress waves (also known as acoustic emission signals) generated by small defects inside the bearing.

The impact pulse method utilizes the transient impact force generated when the bearing damage point comes into contact with the rolling element, which excites the natural frequency of the bearing and sensor system. The instrument evaluates the degree of damage and lubrication status of the bearing by measuring the amplitude and frequency of the impact pulse. LR value and HR value are commonly used evaluation indicators, with LR value reflecting the lubrication status and HR value reflecting the degree of damage.

Resonance demodulation technology: This technology first extracts high-frequency resonance signals containing fault information through bandpass filters, and then performs envelope demodulation on them to convert high-frequency modulated signals into low-frequency envelope signals. By performing spectral analysis on this envelope signal, the fault characteristic frequency of the bearing can be clearly seen, even if the fault characteristics in the original vibration signal are very weak.

These two technologies are extremely sensitive to early failures and can issue warnings before visible damage to the bearings appears. For example, in a certain heavy machinery factory, by combining vibration analysis with impact pulse technology, the "inner ring peeling precursor" of three motor bearings was identified 15 days in advance, avoiding catastrophic failures and reducing the maintenance cost of a single unit from 50000 yuan to 8000 yuan.

Application advantages

The microscope like insight makes it an ideal tool for achieving early warning and evaluating lubrication status. It can help companies upgrade their maintenance strategies from "regular maintenance" to "predictive maintenance", maximizing equipment lifespan and reducing maintenance costs.