1. Find hydraulic faults according to the hydraulic system diagram

When analyzing and troubleshooting the hydraulic system diagram, the main method is to "grab both ends" - that is, grasp the power source (hydraulic pump) and the actuator (hydraulic cylinder, hydraulic motor), and then "connect the middle", that is, from the power source to the execution Pipes and control elements that pass between elements. When "catching both ends", it is necessary to analyze whether the fault lies in the hydraulic pump, hydraulic cylinder and hydraulic motor itself. In "connecting the middle", in addition to analyzing whether the fault lies in the hydraulic components on the connected line, special attention should also be paid to clarifying which control method the system adopts when transferring from one working state to another, and whether the control signal has any If there is a mistake, check the actual objects one by one, and pay attention to whether there is any wrong connection between the main oil circuits and between the main oil circuit and the control oil circuit, resulting in mutual interference. Wait.

2. Use cause and effect diagrams to find hydraulic faults

Using the causal diagram (also known as fishbone diagram) analysis method to analyze the failure of hydraulic equipment, it can not only find out the primary and secondary causes of the failure faster, but also accumulate experience in troubleshooting.

Cause-and-effect diagram analysis can be used to closely combine maintenance management with fault finding, so it is widely used.

3. Use ferrography technology to diagnose and monitor the fault of hydraulic system

Ferrography technology is based on the wear of mechanical friction pairs. With the help of a ferrograph, the wear particles and other pollution particles in the hydraulic oil are separated, and made into a ferrograph sheet, which is then placed in a ferrograph microscope or a scanning electron microscope. Under the observation, or deposited in the glass tube according to the size, the optical method is used for quantitative detection. Through the above analysis, important information about wear in the system can be accurately obtained. Based on this, the wear phenomenon is further studied, the wear state is monitored, the fault precursor is diagnosed, and finally the system failure forecast is made.

Ferrography technology can be effectively applied to the detection, monitoring, analysis of wear process and fault diagnosis of oil pollution in hydraulic systems of construction machinery, and has the advantages of being intuitive, accurate and rich in information. Therefore, he has become a powerful tool for the diagnostic analysis of hydraulic system failures in mechanical engineering.

4. Use the relevant analysis table of fault phenomenon and fault cause to find hydraulic faults

According to work practice, a table of correlations between failure phenomena and failure causes is summarized (or provided by the manufacturer), which can be used to find and deal with general hydraulic failures.

5. Use the self-diagnosis function of the equipment to find hydraulic faults

With the continuous development of electronic technology, in 2012, many large and medium-sized construction machinery adopted electronic computer control, through the interface circuit and sensing technology to carry out self-diagnosis of their hydraulic systems, and displayed on the fluorescent screen, users and maintenance personnel can Troubleshoot according to the content of the displayed failure.

6. Maintenance of hydraulic press Correct use of machinery and equipment, careful maintenance and strict implementation of safe operating procedures are necessary conditions to prolong the service life of equipment and ensure safe production. Therefore, operators should not only be familiar with the structure and performance of the machine, but also pay attention to the following points.

1. The debugging and maintenance of the hydraulic station requires professionals. When the hydraulic components are disassembled, the parts should be placed in a clean place. All sealed surfaces must be free of scratches.

2. Hydraulic oil is the energy transmission medium when the hydraulic station works. The quality, cleanliness and viscosity of the hydraulic oil play a dominant role in the life of the hydraulic pump, hydraulic valve and hydraulic cylinder. Therefore, great attention should be paid to the hydraulic oil when using the hydraulic station. quality and keep the hydraulic oil clean. The oil used in the hydraulic system must be strictly filtered, and an oil filter should be configured in the hydraulic system.

3. Under the condition of ensuring the normal operation of the system, the pressure of the hydraulic pump should be adjusted as low as possible, and the pressure of the back pressure valve should be adjusted as low as possible to reduce energy loss and heat generation.

4. In order to prevent dust and water from falling into the oil, the surroundings of the fuel tank should be kept clean and regular maintenance should be carried out.

5. The liquid level of the fuel tank should always be kept at a sufficient height, so that the oil in the system has sufficient circulating cooling conditions, and pay attention to keep the fuel tank, oil pipes and other equipment clean to facilitate heat dissipation. Generally, the oil temperature of 30℃-55℃ is the most suitable temperature for safe use, with the highest performance and longest life. When the oil temperature exceeds 60°C, its service life will be halved every time it rises by 8°C.

6. Try to prevent the pressure everywhere in the system from being lower than the atmospheric pressure. At the same time, a good sealing device should be used. When the seal fails, it should be replaced in time. Tighten regularly to prevent loosening. Prevent air from entering the hydraulic system and oil leakage.

7. For systems with water coolers, sufficient cooling water should be maintained and the pipelines should be unblocked. For systems with air coolers, ventilation should be maintained. Prevent oil temperature from being too high.

8. For systems with filters, the filter element should be cleaned or replaced regularly (about one month) to prevent clogging, and the oil temperature will rise too fast, which will cause the hydraulic components or oil pump to rupture in severe cases.

9. The working pressure of the system is to adjust the output pressure of the hydraulic pump through the pressure regulating valve. In general, the set pressure cannot exceed its original design rated pressure, otherwise it may cause damage to the hydraulic pump, hydraulic valve stuck or motor burnout and so on.

10. The letter codes of hydraulic valves and manifolds indicate that P is the pressure oil port, and T is the oil return port. A and B are the working oil ports connected to the actuator (hydraulic cylinder). X or K is the external control oil port of the hydraulic component, and Y or R is the external drain port of the hydraulic component.

11. In order to ensure the reliable operation of the press, it is recommended that the user must replace some components of the press after reaching the service life cycle. 12. Record the main problems that have been solved and unresolved in the maintenance into the file, as the data basis for the next maintenance or maintenance plan.