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How to solve the problem of high oil temperature in hydraulic system of hydraulic press machine?
Apr 12, 2018

More than 70% of the hydraulic system fault is caused by hydraulic medium (mainly hydraulic oil). In addition to the reasons for the contamination of the medium, high hydraulic oil temperature is also one of the important reasons that affect the normal operation of the hydraulic press system. The normal working temperature of the hydraulic press system is 30 - 50 degrees, the highest temperature does not exceed 70 degrees, the lowest is not less than 15 degrees. What is the effect of high oil temperature on the function of hydraulic press system? What are the causes of high oil temperature and how to prevent it?

The composition and basic operation principle of the 1. hydraulic press system

A complete hydraulic system consists of the following parts: power components, performance components, control elements, auxiliary components and hydraulic oil; the effect of the power components (oil pumps in the system) is to convert the mechanical energy of the motor into the pressure energy of the liquid and supply the power to the whole hydraulic system. The effect of performing components, such as hydraulic cylinders and hydraulic motors, is to transform the pressure energy of liquid into mechanical energy and drive the load to reciprocate straight or reverse. Control components (i.e. all kinds of hydraulic valves) control and regulate the pressure, flow and direction of liquid in the hydraulic press system. Auxiliary components include fuel tank, oil filter, cooler, heater, pressure gauge, oil level and oil temperature gauge. Hydraulic oil is the medium for transmitting energy in the hydraulic press system.

2., the influence of too high hydraulic oil temperature on the hydraulic press system.

The high oil temperature of the hydraulic press can cause the bad consequences of the viscosity of the hydraulic oil attack, the attack of the cavitation and the acceleration of the aging of the oil, so that the smooth deterioration between the moving parts of the system, the aggravation of the wear and the deterioration of the wear, the failure of the hydraulic components or the death of the card; together, the seal will accelerate the aging and lose the elasticity, and the light makes the system leaking and grim. There will be a system shutdown.

The effect of 2.1 on the viscosity of hydraulic oil

In general industry, the working pressure of the hydraulic press system is below 20MPA. Under this pressure, the influence of pressure factors on the viscosity of hydraulic oil can be ignored, and the influence of temperature on viscosity is considered first. When the temperature rises, the cohesion of oil molecules decreases and its viscosity decreases. The influence of the viscosity of hydraulic oil viscosity on the composition of the system is the addition of leakage. It is known from the leakage principle of the hydraulic oil slit that the amount of leakage is proportional to the reciprocal of the viscosity of the hydraulic oil, the temperature rises, and the amount of leakage is multiplied.

2.2 more simple attacks of cavitation

Under the condition of temperature rising, the air separation pressure and the full vapor pressure of hydraulic oil will increase, which will make the cavitation phenomenon easier.  For example, when a general hydraulic pump works, it will happen when the vacuum level is 0.5MPA. The cavitation erosion from the cavitation can severely damage the surface of the damage element (especially the power element), thus greatly shortens the life of the components, and reduces the operation power of the whole hydraulic system, such as the oil absorption capacity of the hydraulic pump and the decline of the volume power. 2.3 speed up the aging of hydraulic oil

The oxidation reaction is the primary cause of the aging of hydraulic oil, and the relationship between the oxidation reaction and the oil temperature is very close. The test shows that when the oil temperature reaches the temperature zone (55 - 60 C), the oxidation reaction of the hydraulic oil is doubled and the life of the oil is 50% when the temperature of the oil reaches the temperature of 10. After the pollution of hydraulic oil, the wear and tear between components will be accelerated, resulting in a vicious circle.

Analysis of the cause of high oil temperature in the 3. hydraulic press system

According to the operation principle of the hydraulic system, there are two parts of the heat in the system: one is the fuel pump that converts the mechanical energy to the pressure energy, the other is the control element and the fulfilling element that converts the pressure energy into the mechanical energy; the two parts will attack the heat in the normal operation state, and these heat are from the body. The cooling system of the system is cooled. Therefore, when one or several operations of these components are abnormal, the oil temperature of the system will increase.

3.1 cooling system presents a fault

Generally, a large hydraulic system is equipped with cooling system, and most of them will use water cooling. Its basic principle is to use low temperature water and high temperature hydraulic oil to heat exchange, to keep the heat of the attack in the hydraulic system and keep the temperature of the hydraulic system in a relatively stable range.