Use and maintenance of four-column hydraulic press

1. Mechanical operation should be gentle and smooth. Mechanical operation should avoid roughness, otherwise it will inevitably generate impact loads, causing frequent mechanical failures and greatly shortening the service life. The impact load generated during operation will cause early wear, fracture and crushing of mechanical structural parts, and on the other hand, it will generate impact pressure in the hydraulic system. The impact pressure will damage the hydraulic components, premature failure of the oil seal and the compression joint of the high-pressure oil pipe joint and the hose, oil leakage or pipe burst, and frequent operation of the overflow valve and oil temperature rise. Our unit once purchased a new UH171 front shovel excavator. During operation, the bucket door oil pipe would leak oil or burst every 4 to 6 days. The oil pipe is a pure imported product and has no quality problems after inspection. Through on-site observation, it was found that the bucket door was opened and closed when it hit the limit block and door frame. To effectively avoid the generation of impact loads: the operating procedures must be strictly followed; the hydraulic valve cannot be opened and closed too violently or too quickly; avoid causing the working device components to move to the extreme position to cause strong impact; hydraulic equipment without impact function cannot use the working device (such as the bucket of the excavator) to violently impact the working object to achieve the purpose of crushing. There is another issue worth noting: the operator should remain stable. Because the free clearance of each equipment's operating system is different, the degree of wear of the connection parts is different, so the clearance is also different, and the output of the engine and hydraulic system is also different. These factors give the equipment its personality. Only when the operator who uses the equipment carefully explores and corrects his own operating actions to adapt to the personality of the equipment, and after long-term operation, can he develop good operating habits that conform to the personality of the equipment. The general machinery industry adheres to the system of fixed people and fixed machines, which is also one of the factors.

2. Pay attention to cavitation and overflow noise

Always pay attention to the sound of the hydraulic pump and overflow valve during operation. If the hydraulic pump has "cavitation" noise, it cannot be eliminated after exhaust. The cause should be found out and the fault should be eliminated before use. If an actuator moves slowly when there is no load and is accompanied by the overflow sound of the overflow valve, it should be stopped immediately for maintenance.

3. Strictly implement the handover system

When the handover driver parks the machine, it is necessary to ensure the safety of the successor driver during inspection and check the accurate oil level. Whether the system is leaking, whether the connection is loose, whether the piston rod and hydraulic hose are damaged, whether the low-pressure oil inlet pipe of the hydraulic pump is connected reliably, whether the oil level in the tank is correct, etc. are the key points of the hydraulic system inspection by the successor driver. The normal pressure oil tank should also check and clean the oil tank vent to keep it unobstructed to prevent the pores from being blocked and causing a vacuum in the oil tank, which will make it difficult for the hydraulic oil pump to absorb oil and cause damage.

4. Maintain a suitable oil temperature

The operating temperature of the hydraulic system is generally controlled between 30 and 80°C (dangerous temperature ≥100°C).

Too high oil temperature in the hydraulic system will lead to: reduced oil viscosity, easy to cause leakage, reduced efficiency; reduced lubricating oil film strength, accelerated mechanical wear; generation of carbides and sludge; oil oxidation accelerates oil quality deterioration; premature aging of oil seals and high-pressure hoses, etc. To avoid excessive temperature: do not overload for a long time; pay attention to the radiator fins not being contaminated by oil to prevent dust adhesion from affecting the heat dissipation effect; maintain sufficient oil volume to facilitate oil circulation and heat dissipation; do not work all day in hot summer, and avoid high temperature at noon. When the oil temperature is too low, the oil viscosity is high, the fluidity is poor, the resistance is large, and the working efficiency is low; when the oil temperature is below 20℃, sharp turns are prone to damage hydraulic motors, valves, pipes, etc. At this time, warm-up operation is required, start the engine, idle at no load for 3 to 5 minutes, increase the engine speed with medium-speed throttle, operate the handle to make any action of the working device (such as excavator bucket) to the extreme position, and keep it for 3 to 5 minutes to allow the hydraulic oil to heat up through overflow. If the oil temperature is lower, it is necessary to increase the warm-up operation time appropriately.

5. Control of hydraulic oil tank air pressure and oil volume

The pressure tank air pressure should be paid attention to at all times during work, and its pressure must be kept within the range specified in the random "Instruction Manual". If the pressure is too low, the oil pump will be damaged due to insufficient oil suction. If the pressure is too high, the hydraulic system will leak oil, which may cause the low-pressure oil circuit to burst. For equipment that has been repaired and changed oil, after exhausting the air in the system, check the oil level according to the "Instruction Manual" that comes with it, stop the machine on a flat place, check the oil level again after the engine is turned off for 15 minutes, and replenish it if necessary.

6. Other precautions

During operation, prevent flying stones from hitting hydraulic cylinders, piston rods, hydraulic oil pipes and other components. If there are small scratches on the piston rod, use an oil stone to grind the edges around the small spots in time to prevent damage to the sealing device of the piston rod. It can continue to be used without oil leakage. For equipment that has been shut down for more than 24 hours, oil should be added to the hydraulic pump before starting to prevent damage to the hydraulic pump due to dry grinding.

7. Precautions for regular maintenance

At present, some engineering machinery hydraulic systems are equipped with intelligent devices, which have warning functions for certain hidden dangers in the hydraulic system, but their monitoring range and degree are limited. Therefore, the inspection and maintenance of the hydraulic system should combine the monitoring results of the intelligent device with regular inspection and maintenance.

Dongguan Shengshi Weiye Machinery Technology Co.The main equipment produced are: Liquid Die Forging Machine, low-pressure Casting Machine, Gravity Casting Machine, cold forging machine, hot forging machine, etc