What are the maintenance and repair of the spring machine hydraulic system?

The hydraulic spring machine uses a spring as an energy storage component and a hydraulic oil as a transmission carrier. It has the advantages of small size, high reliability, low noise, convenient installation and flexible operation in the work. For the hydraulic system, maintenance is required from the following aspects:

1. Select the right hydraulic oil.

Hydraulic oil plays the role of transmitting pressure, lubricating, cooling and sealing in the hydraulic system. Improper selection of hydraulic oil is the main reason for the early failure and the decrease of durability of the hydraulic system. The hydraulic oil should be selected in accordance with the brand specified in the instruction manual; when special circumstances require the use of alternative oil, it should try to choose an alternative oil with the same performance as the original brand.

2. Prevent solid impurities from entering the hydraulic system.

Clean hydraulic oil is the life of the hydraulic system. If solid impurities invade, it will cause problems such as oil passage clogging of precision instruments. General solid impurities invade the hydraulic system through the following methods: the hydraulic system is unclean; the refueling tools are unclean; the refueling and repair and maintenance are not careful; the hydraulic components are chipped. You can prevent solid impurities from entering the system in the following ways:

（1） When refueling

The hydraulic oil must be filtered and filled, and the refueling tools should be cleaned reliably. In order to increase the refueling speed, the filter at the fuel filler of the fuel tank cannot be removed. Staff members should use clean gloves and work clothes to prevent solid and fiber impurities from falling into the oil.

（2）During maintenance

Remove the fuel tank fuel filler cap, filter cover, detection hole, hydraulic oil pipe and other parts, so as to avoid the dust when the system oil duct is exposed, the disassembled parts must be cleaned thoroughly before opening. For example, when removing the fuel filler cap of the hydraulic oil tank, first remove the dust around the fuel tank cap. After loosening the fuel tank cap, remove the debris remaining at the joints (do not rinse with water to prevent water from penetrating into the fuel tank), and confirm the cleaning before opening the fuel tank cap. If you need to use a wiping material and a hammer, you should choose a wiping material that does not lose fiber impurities and a special hammer with rubber on the hitting surface. The hydraulic components and hydraulic hoses should be carefully cleaned and blown dry with high pressure air for assembly. Use a well-packed genuine filter element (the inner packaging is damaged, although the filter element is intact, it may not be clean). Clean the filter at the same time when changing the oil. Before installing the filter element, carefully clean the dirt on the bottom of the filter case with a wiping material.

3. Cleaning of hydraulic system.

The cleaning oil must use the same hydraulic oil as the system used. The oil temperature is between 45 and 80 ° C. Use a large flow to remove impurities from the system as much as possible. The hydraulic system should be repeatedly cleaned more than three times. After each cleaning, release all of the system while the oil is hot. After cleaning, clean the filter and replace the new filter element with new oil.

4. Prevent air from entering the hydraulic system.

At normal pressure and temperature, the hydraulic oil contains a certain amount of air. When the pressure is reduced, the air will escape from the hydraulic oil, and bubbles will rupture and erode the hydraulic components to generate noise, which will reduce the working efficiency of the hydraulic system. The following points should be noticed to prevent air intrusion:

（1） After maintenance and oil change, the air in the system must be purged according to the provisions of the “Instruction Manual” for normal operation.

（2） The suction pipe opening of the hydraulic oil pump must not expose the oil surface, and the suction pipe must be well sealed.

（3） The seal of the oil pump drive shaft should be good. Pay attention to the use of genuine "double-lip" oil seals when replacing the oil seals there. Do not use "single-lip" oil seals, because "single-lip" oil seals can only seal oil in one direction , does not have the function of sealing gas.

5. Prevent water from entering the hydraulic system.

Excessive moisture in the oil will rust the hydraulic components, emulsify the oil, deteriorate the strength of the lubricant film, and accelerate mechanical wear. In addition to preventing water intrusion during maintenance, it is also necessary to pay attention to the cap when the oil storage tank is not in use, and it is best to place it upside down; oil with large water content must be filtered several times, and the filter paper to be dried should be replaced every time. When there is no special instrument for testing, the oil can be dripped on the hot iron plate, and there is no steam coming out and burning immediately before filling.

6. Precautions during operation.

The mechanical operation should be gentle and smooth, and rough operation of machinery should be avoided. Otherwise, shock loads will inevitably occur, causing frequent mechanical failures and greatly shortening the service life.  The impact load generated during operation, on the one hand, causes early wear, fracture, and fragmentation of mechanical structural parts, on the one hand, it generates impact pressure in the hydraulic system, and the impact pressure can cause damage to hydraulic components, oil seals, and high-pressure tubing joints and hoses. Premature failure Oil leakage or burst pipe, overflow valve frequent action Oil temperature rises.

7. The key to preventive maintenance is to strengthen daily maintenance. 
The main maintenance tasks are as follows:

(1) Daily inspection

Its main items include hydraulic systems, sliding lubrication systems, cooling systems, and pneumatic systems. Daily inspection is based on the normal conditions of each system.

(2) Weekly inspection

Its main items include machine tool parts and sliding lubrication systems. They should be properly inspected weekly, especially the machine tool parts must be cleaned of iron debris and external debris.

(3) Monthly inspection

Mainly check the power supply and air dryer. The power supply voltage is rated at 180V-220V and frequency 50Hz under normal conditions. If there is any abnormality, measure and adjust it. The air dryer should be disassembled once a month, and then cleaned and assembled.

(4) Quarterly inspection

The quarterly inspection should mainly be performed from three aspects: the machine bed, the hydraulic system, and the sliding lubrication system. For example, when inspecting the machine tool bed, it mainly depends on whether the accuracy of the machine tool and the level of the machine tool meet the requirements in the manual. If there is a problem, you should contact the mechanical engineer immediately. When inspecting the hydraulic system and the spindle lubrication system, if there is a problem, the new oil 60L and 20L should be replaced and cleaned.

(5) After half a year's inspection, the hydraulic system and sliding lubrication system of the machine tool should be inspected. If something goes wrong, you should replace with new oil and then clean it.

After comprehensively familiarizing and mastering the knowledge of preventive maintenance, it is necessary to have a deeper understanding and necessary grasp of the causes and treatment of abnormal phenomena in the oil pressure system. For example, when the fuel pump does not inject fuel, the pressure is abnormal, and noise occurs, you should know what the main reasons are and what the corresponding solutions are. The causes and treatment of abnormal phenomena in the oil pressure system should be understood from three aspects:

① Oil pump does not inject fuel

The main reasons may be the low liquid level in the fuel tank, the reverse rotation of the oil pump, the speed is too low, the oil viscosity is too high, the oil temperature is low, the filter is clogged, the volume of the suction pipe is too large, the intake air is drawn in at the oil inlet. For the damaged part, there are corresponding solutions to the main reasons, such as filling up with oil, confirming the label, and changing it when the oil pump is reversed.

② Stress is abnormal

That is, the pressure is too high or too low. The main reasons are also various, such as improper pressure setting, poor operation of the pressure regulating valve coil, abnormal pressure gauges, and leaks in the hydraulic system. The corresponding solutions include dismantling and cleaning according to the prescribed pressure settings, changing a normal pressure gauge, and checking each system in turn.

③ Noisy

Noise is mainly caused by oil pumps and valves. When the valve is noisy, the reason is that the flow rate exceeds the rated standard, and the flow rate should be adjusted appropriately; when the oil pump is noisy, the reason and the corresponding solutions are also multifaceted, such as high oil viscosity and low oil temperature to raise the oil temperature; when there are air bubbles in the oil, the air in the system should be released.

8. Troubleshooting for possible problems in the maintenance of the hydraulic system:

It is more economical to perform regular maintenance and maintenance inspections of the hydraulic system than to perform repairs after a failure. It is recommended that after a certain period of work, the system is subjected to periodic preventive maintenance and regular replacement of important sealing materials. To prevent omissions, maintenance procedures are recommended in accordance with the direction of oil flow:

Fuel tank: The oil level must be correct, the oil must be of the specified type and have a corresponding viscosity. For large systems, regular oil sample analysis can be performed to confirm whether the oil can continue to be used.

Suction pipe: Damage and severe bending must be checked. It will reduce the diameter of the oil pipe and become a noise source. Oil pump: Check the shaft seal and other oil leakage. Pressure oil pipe: Different oil circuits at the pressure end should be checked one by one along the direction of oil flow, and there should be no leakage. Control part: mainly check the leakage situation at the valve interface. Oil return pipe and oil filter: They should be checked for leaks. The filters must be checked. If there is no pollution indication, the filters must be taken out and checked for cleaning or replacement. Actuator: Check for leaks. Accessories: check the work. Electrical section: Periodically check the connection of the motor wiring section. The hydraulic oil should be replaced once after three months of initial use, and then every six months to ensure the normal operation of the system. During the operation of the hydraulic system, the oil filter blockage should be checked at any time and the filter element should be cleaned or replaced in time. The hydraulic system should always be provided with wearing parts and spare parts in order to deal with the failure in time. When the indoor oil temperature does not reach 25 ° C in winter, it is not allowed to start the sequential operation. When the oil temperature in summer is higher than 60 ° C, pay attention to the working condition of the system and notify the maintenance person to handle it. For equipment that has been stopped for more than four hours, the pump should be run for five minutes at no load before starting the actuator. The interlocking device of the electronic control system cannot be arbitrarily adjusted, the position of each limit stop is damaged or arbitrarily moved. When the hydraulic system fails, unauthorized movement is not allowed, and the maintenance department should be immediately notified to analyze the cause and eliminate it. Check the components and accessories of the hydraulic system regularly.

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