Clarifying the typical faults of hydraulic rotary actuators is the basis for carrying out fault early warning work, which mainly includes four categories: leakage, seal damage, cylinder block and swing rod wear, and abnormal system pressure. At present, the core implementation path of hydraulic rotary actuator fault early warning revolves around "monitoring-collection-analysis-early warning". Through five core technologies including vibration monitoring, pressure and flow monitoring, temperature monitoring, intelligent diagnosis algorithm and oil analysis, early fault signals can be accurately captured, providing solid data support for subsequent early warning and maintenance.

In the core composition of modern mechanical equipment, the hydraulic system occupies an irreplaceable position. As the core executive component of this system, the hydraulic rotary actuator's operating status directly determines the equipment's work efficiency, stability, and operational safety. With the continuous advancement of the wave of industrial automation and intelligence, the fault early warning technology for hydraulic rotary actuators has attracted increasing attention from the industry. It has become a key support for avoiding equipment failures and ensuring production continuity, and its development level has also become one of the important indicators to measure the intelligence level of industrial equipment.
I. Analysis of Typical Faults of Hydraulic Rotary Actuators
Hydraulic rotary actuators are prone to various faults due to wear, medium changes, assembly deviations and other factors when operating under long-term high load and complex working conditions. Clarifying the fault types is the basis for effective early warning work. The main common faults are divided into the following categories:
•Leakage fault: It is divided into internal leakage and external leakage. Internal leakage will directly reduce the output efficiency of the hydraulic rotary actuator, damage the stability of the swing action, and affect the equipment operation accuracy; external leakage will cause system pressure loss, which not only wastes oil but also may lead to potential safety hazards in equipment operation.
•Seal damage: As a key sealing component of the hydraulic rotary actuator, the sealing ring is prone to aging, wear, deformation and other problems due to long-term oil erosion, friction loss and temperature changes, which in turn leads to oil leakage and increases the frequency and cost of equipment maintenance.
•Cylinder block and swing rod wear: Friction generated by long-term reciprocating swing, foreign body intrusion, etc., will cause scratches and wear on the inner wall of the cylinder block, and bending, rust and other problems on the swing rod, which directly affect the motion accuracy and service life of the hydraulic rotary actuator, and may even lead to jamming failure of the hydraulic rotary actuator in severe cases.
•Abnormal system pressure: When the load of the hydraulic rotary actuator exceeds the rated range, the control valve fails or the oil circuit is blocked, it will lead to excessive or insufficient system pressure, damage the balance of the hydraulic system, affect the normal operation of the hydraulic rotary actuator, and even cause damage to related components.
II. Core Implementation Path of Fault Early Warning Technology
The core logic of the hydraulic rotary actuator fault early warning technology is "monitoring-collection-analysis-early warning". It obtains operating data through various sensors and combines intelligent algorithms for analysis to identify potential faults in advance. The main core technical means are as follows:
(I) Vibration Monitoring Technology
Vibration sensors are installed on the cylinder block, swing mechanism and key connection parts of the system of the hydraulic rotary actuator to capture the vibration signals during operation in real time. Through signal processing methods such as frequency domain analysis, time domain analysis and wavelet transform, the abnormal characteristics in the signals are extracted, which can identify potential faults such as bearing wear, swing mechanism jamming and cylinder block loosening in advance. It is one of the most widely used early warning methods at present.
(II) Pressure and Flow Monitoring Technology
Pressure and flow are the core parameters reflecting the operating status of the hydraulic rotary actuator. By installing pressure sensors and flow sensors at key nodes of the oil circuit, the pressure changes and oil flow fluctuations of the hydraulic rotary actuator during operation are monitored in real time, which can quickly identify problems such as oil leakage, oil circuit blockage and abnormal load, and provide direct data support for fault early warning.
(III) Temperature Monitoring Technology
The temperature change of hydraulic oil is closely related to the internal friction of the hydraulic rotary actuator, oil quality, system heat dissipation, etc. Temperature abnormality is usually an early signal of failure. Real-time monitoring of oil and cylinder block temperature through temperature sensors can early warn of system damage caused by excessive friction, oil deterioration and poor heat dissipation, and avoid further expansion of faults.
(IV) Intelligent Diagnosis Algorithm
Relying on the development of machine learning and artificial intelligence technology, the multi-dimensional monitoring data such as vibration, pressure, flow and temperature are integrated and analyzed. Through algorithms such as Support Vector Machine (SVM), neural network and deep learning, a fault pattern recognition model is established to realize accurate judgment of fault type, severity and development trend, which greatly improves the accuracy and timeliness of early warning.
(V) Oil Analysis Technology
Monitoring indicators such as metal particle content, pollutant concentration, viscosity and water content in hydraulic oil through professional equipment can indirectly reflect the wear of the internal cylinder block and swing rod of the hydraulic rotary actuator and the degree of oil deterioration, make up for the limitations of surface monitoring, and provide an important supplement for internal fault early warning.
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