The working principle of the hydraulic cylinder of the four-column hydraulic press

Fulfillment arrangements in the hydraulic system. Generally, it is composed of a cylinder, a cylinder rod (piston rod) and a seal. The inside of the cylinder is divided into two parts by the piston, and an oil hole is separated. Because the compression ratio of the liquid is very small, when one of the oil holes enters oil, the piston will be pushed to make the other oil hole discharge oil, and the piston drives the piston rod to extend (retract), and vice versa. Dongguan Hydraulic Press manufacturers analyze the operating principle of hydraulic cylinders of hydraulic presses.

The working principle of hydraulic cylinder

Let me talk about its 5 most basic components:

  • 1-Cylinder tube and cylinder head
  • 2- Piston and piston rod
  • 3- Sealing equipment
  • 4-Buffering equipment
  • 5-Exhaust equipment.

The operating principle of each cylinder is almost the same. Take a manual jack as an example. The jack is actually the simplest cylinder. Manually pressurize the stalk (hydraulic manual pump) to make the hydraulic oil enter the cylinder through a one-way valve. At this time, the hydraulic oil that enters the cylinder cannot be reversed because of the single valve, and the cylinder rod is forced upward, and then the hydraulic oil is continuously applied during workmanship. Continue to enter the hydraulic cylinder, and continue to rise like this. When you want to fall, open the hydraulic valve to make the hydraulic oil return to the tank. This is the simplest operating principle. The others are improved on this basis. The cylinder and the oil cylinder The principle is basically the same.
According to the structure of common hydraulic cylinders, it can be divided into four types: 1 piston type 2 plunger type 3 telescopic type 4 swing type
The advantages and disadvantages of cylinders and cylinders

Because the operating pressure of the pneumatic system is generally in the range of 0.2-1.0Mpa, the cylinder cannot be used as a high-power power element. Hydraulic cylinders can be used as components with relatively large power, using hydraulic systems
From the point of view of the medium, air can be used inexhaustibly, without cost and supply difficulties. The used gas is directly discharged into the atmosphere, which is convenient to handle and will not pollute. The hydraulic oil is the opposite.

The air viscosity is small, the resistance is less than the hydraulic oil

But the compression rate of air is much higher than that of hydraulic oil, so its operation stability and response are far behind.
Hydraulic cylinder is the most important performance element in the hydraulic system. It transforms hydraulic energy into mechanical energy and cooperates with various transmission arrangements to complete various mechanical movements. The hydraulic cylinder has the characteristics of simple structure, large output force, stable and reliable function, convenient operation and maintenance, and wide use scale.

cylinder processing

oil cylinder is the traditional processing method of the most important part of construction machinery.

broaching cylinder block-fine boring cylinder block-grinding cylinder block. Choosing the rolling method to broach the cylinder block-fine boring cylinder block-rolling cylinder block, the process is three parts, but the time comparison: grinding the cylinder block 1 meter about 1-2 days, rolling the cylinder block 1 meter is about 10-30 minutes. Investment cf.

grinder or quilting machine (tens of thousands-several million), rolling knife (1,000-tens of thousands). After rolling, the surface roughness of the hole is reduced from Ra3.2~6.3μm before rolling to Ra0.4~0.8μm, the surface hardness of the hole increases by about 30%, and the fatigue strength of the inner and outer surface of the cylinder increases by 25%. If the service life of the oil cylinder only considers the influence of the cylinder barrel, it will be increased by 2 to 3 times, and the power of the boring and rolling process will be increased by about 3 times compared with that of the grinding process. The above data clarifies that the rolling process is efficient and can greatly improve the appearance quality of the cylinder.

Hydraulic cylinder rolling processing compares the characteristics of the oil cylinder after rolling

There are no sharp small edges on the outside, and long-term movement conflicts will not damage the sealing ring or seals. This is particularly important in the hydraulic industry.
The principle of rolling processing

It is a pressure finishing process, which uses the cold plastic characteristics of metal at room temperature, and uses rolling tools to exert a certain pressure on the surface of the workpiece, so that the surface metal of the workpiece can undergo plastic activity and fill it into the original residual valley. , And the roughness value of the workpiece surface is reduced. Because the rolled surface metal is plastically deformed, the surface layer is arranged cold hardened and the crystal grains become finer, forming a dense fiber shape, and forming a residual stress layer, which improves the hardness and strength, and then improves the wear resistance and corrosion resistance of the surface of the workpiece. Sexuality and cooperation. Rolling is a non-cutting plastic processing method.

Without cutting skills, it is safe and convenient, and it can accurately control the precision. Several advantages:

  • 1. Improve the surface roughness, which can basically reach Ra≤0.08μm.
  • 2. Correct the roundness, the ovality can be ≤0.01mm.
  • 3. Improve the surface hardness, eliminate the force deformation, and increase the hardness by HV≥4°
  • 4. There is a residual stress layer after processing, which improves the fatigue strength by 30%.
  • 5. Improve the quality of cooperation, reduce wear and extend the service life of parts, but the processing costs of parts are reduced.

The oil cylinder is the most important part of construction machinery. The traditional processing method is: broaching the cylinder-fine boring the cylinder-grinding the cylinder. The rolling method used is: broaching cylinder block-fine boring cylinder block-rolling cylinder block, the process is three parts, but the time comparison: grinding the cylinder block 1 meter about 1-2 days, rolling It takes about 10-30 minutes for a cylinder to be 1 meter. Investment comparison: grinder or quilting machine (tens of thousands-millions), rolling knife (1,000-tens of thousands). After rolling, the surface roughness of the hole is reduced from Ra3.2~6.3μm before rolling to Ra0.4~0.8μm, the surface hardness of the hole increases by about 30%, and the fatigue strength of the inner and outer surface of the cylinder increases by 25%. If the service life of the oil cylinder only considers the influence of the cylinder barrel, it will be increased by 2 to 3 times, and the power of the boring and rolling process will be increased by about 3 times compared with that of the grinding process. The above data clarifies that the rolling process is efficient and can greatly improve the appearance quality of the cylinder.

After the cylinder is rolled, there is no sharp and small edge on the outside, and the long-term movement conflict will not damage the sealing ring or the seal. This is particularly important in the hydraulic industry.

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