Как обслуживать и управлять гидравлической системой экструзионного пресса
Large aluminum extrusion presses can be used to produce high-specification aluminum extrusion products such as industrial profiles, rail transit profiles and large radiators.
It can be used in aerospace, rail transit, automobiles, ships, construction, machinery manufacturing, electronic power and other fields. In the working process of large aluminum extrusion press, to ensure the working accuracy and high performance, the premise is to have a certain degree of stability. Once the stability of the extruder fails to meet the production standards, the quality of the products produced will be greatly compromised. And enterprises will also suffer huge economic losses.
一. Common problems of hydraulic system of large aluminum extrusion press and their solutions
(一) Pipe leakage:
The welding position of the pipe and the flange is most likely to cause pipe leakage. In addition, the pipe flange installation surface and screw position are also extremely likely to cause pipe leakage.
The occurrence of pipe leakage is mainly caused by the loosening of the screw and pipe joints caused by long-term operation. At the same time, after the flange mounting surface seal is aging, the sealing ring will be damaged.
Improper welding caused pores and cracks, and leakage occurred. In addition, the use time was too long, the safety awareness was not strong, and timely maintenance was not carried out, which caused the situation to expand and eventually cause leakage. We can eliminate pipe vibration and improve stability by adding pipe clamps and brackets.
If the welding operation is not standardized, there are pores or cracks, we can polish in the original position, and after the debris is removed, we can weld again.
(二) Oil leakage in the cylinder:
1. The occurrence rate of oil cylinder leakage is relatively high. Due to the long-term working condition, it will inevitably cause a large amount of abrasive particles. At the same time, because the exposed position of the piston rod is exposed to the air for a long time, it is inevitable that there will be a large amount of dust and aluminum powder attached.
In such situations, a dust ring is usually used to scrape out. However, in view of the effect of the dust ring, it is difficult to completely scrape off, so that the piston rod seal is damaged, which in turn causes leakage. Therefore, two treatment methods are usually adopted for oil cylinder leakage: First, clean the oil cylinder and replace the seals; Second, confirm whether the surface layer of the piston rod is worn or not,
2. The axis of the cylinder is not parallel to the guide rail, and the error exceeds the standard range: 0.04-0.08mm/m. In turn, the end cover fixing bolts were loosened and the seal failed. Then we need to maintain parallelism and control the error within the standard range.
3. The seal is broken and the oil leakage occurs due to the back pressure and the pressure setting is too high. In turn, the seal is exposed to excessive pressure and the seal is broken. This requires resetting the hydraulic system pressure and testing the hydraulic control valve components.
4. The seals are severely worn and fail because the hydraulic oil is severely polluted and produces a lot of impurities. When the oil temperature is at a high temperature for a long time, the hydraulic oil is gradually oxidized, resulting in the production of colloidal deposits. When the oil temperature is in a low temperature state for a long time, the elasticity of the seal will be lost. The aging of the seal is caused by the accumulation of a large amount of oil residue.
Then we need to strengthen the management of hydraulic oil and strictly control the intrusion of pollution sources; Confirm the working condition of the cooling system of hydraulic equipment and ensure its normal operation. The most suitable temperature is 30-45℃.
5. When the appropriate seal is not selected for sealing treatment, when selecting the seal. In order to take into account the material, model and roughness of the seal, oil leakage occurs. Therefore, when selecting seals, carefully identify the characteristics of the seals and select the corresponding reasonable seals.
(三) Leakage of control valve components:
Internal leakage is the most common in leakage of control valve components. The root cause of internal leakage is the large accumulation of hydraulic impurities, which in turn blocks the control valve components; In addition, excessive wear of the valve core and improper closing can cause leakage.
Excessive pressure will cause hydraulic clamping of the spool, which will also cause leakage. It is recommended to clean the control valve repeatedly after disassembling, or to polish the control valve components. In order to improve its accuracy and restore it to its original appearance.
(四) Solenoid valve failure: Solenoid valve failure can be divided into the following types:
1. The spool does not move: (1) Electromagnet failure, combined with vibration and magnetic field detection, it can be seen that the spool does not move; (2) The valve core is clamped, the oil changes, and the return spring is faulty. After vibration detection, the valve core stuck failure can be seen;
2. Large pressure loss: (1) The flow is too large and the size is wrong, which can be seen by joint inspection of vibration and magnetic field; (2) The spool does not move in place, and the spool jamming fault can be seen through vibration detection;
3. Magnetic flux leakage: Defects appear on the surface of the electromagnetic coil, which can be seen by magnetic field detection.
4. Shock (vibration): The spool closing speed is too fast, and the screws are loose, which can be seen by vibration detection.
In view of the causes of the above problems, take corresponding measures to solve the problem.
二. Maintenance and management of hydraulic system of large aluminum extrusion press
(一) Draw up daily maintenance plan
(1) For some equipment exposed to the air for a long time, clean it regularly to keep the exposed parts of the equipment clean and free of impurities;
(2) Keep the operating environment clean and tidy to avoid the intrusion of dust and debris and pollute the hydraulic system;
(3) Carry out patrol inspections at any time where the oil leakage rate is relatively high, and once found, take corresponding measures to solve them immediately;
(4) Standardize the inspection process. Delineate the inspection route and the highest part of the oil spill point. After a certain stage of the inspection work is completed, it shall be handed over with the staff of the next stage, and the work progress of the previous stage shall be explained in detail;
(5) Record the original operating status in detail. Understanding the normal working conditions of the hydraulic system can help to discover and solve problems in time during the inspection process, improve work efficiency, and avoid safety risks.
(二) Develop a regular maintenance and inspection system and schedule a date to calibrate various instruments of the hydraulic system. Ensure that the meter is working properly and has a high degree of accuracy.
At the same time, the hydraulic system should be pressure tested to set a reasonable pressure value to maintain normal temperature. In order to avoid pressure imbalance, the temperature is too low or too high, resulting in leakage. Regularly clean and replace the filter element to determine the composition of debris and hydraulic oil pollution.
Confirm the degree of wear and wear of the hydraulic system, and sample and test the hydraulic oil of the extruder every three months. Check hydraulic oil viscosity, acid value, moisture, particles and other items so that reasonable measures can be taken to solve them.
Through analysis, it can be confirmed that the hydraulic system leakage of the aluminum extrusion press is mainly caused by the lack of stability of the hydraulic system. So we have to take corresponding measures.
However, solutions are always attributable to remedial measures, and cannot have a preventive effect.
Therefore, it is of great significance to take necessary hydraulic system maintenance and management in daily work.
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