It is not difficult to understand the characteristics of the seal, that is, to reasonably avoid leakage and environmental pollution. But how to reasonably guarantee this under special conditions is really another matter.

In order to successfully complete the seal in the hydraulic cylinder, it is necessary to balance the delicate relationship between the relevant elements, and this element compromises the actual effect of the seal in dynamic applications. They include: lubrication and mating surfaces, design elements-such as appearance, raw materials and processing technology, and environmental elements-such as working pressure, temperature, time, dynamic model and installation.

The first step to success

Mastering the effects of lubrication is the first step in achieving a successful seal in a dynamic system. A thoroughly lubricated system will cause oil leakage, but it will also reduce friction, thereby reducing seal damage. On the contrary, in the system lacking lubrication, the oil slick is reduced, but the friction and damage are relatively increased.

The second successful step

As the working pressure of the liquid increases, the sealing characteristics tend to be good. Since the working pressure of the system on the sealing surface is reduced radially, the seal is pressed more tightly into the trench, and the metal material surface of the seal and trench is more suitable. If the seal is properly designed, the sealing force and efficiency will increase as the working pressure of the system increases.

The third successful step

Sealing resistance is the third prerequisite. Seals in dynamic systems must be able to withstand the shear stress caused by the pressure difference between the working pressure side and the non-working pressure side of the seal. The shear stress will send the seal into the gap between the metal surfaces of adjacent trenches, and the seal material and geometry must be strong enough to resist damage.

1. Sealing ring of hydraulic cylinder

In light-load operation, individually sealed components cannot guarantee zero leakage and long service life. Since the hydraulic cylinder of the hydraulic cylinder is directly exposed to the external natural environment, it is particularly important to prevent leakage.

The solution is to connect the systems in series. Each sealing element in the system has its special function, and it is necessary to ensure the interaction between the components in order to produce a sealing system with excellent performance.

The figure shows the top view of reasonable sealing system of hydraulic cylinder (including wear-resistant ring series, vulcanized rubber force double-effect anti-fouling seal and single-effect O-ring force rod seal)

Tandem sealing system. Here are two key devices that are strongly recommend. The first is a unilateral PTFE sliding seal as the first seal, and a unilateral PTFE or polyurethane sliding seal as the second seal. According to the first seal, it can withstand a thin layer of slick oil, and it also has excellent pump suction capacity. Can achieve zero leakage, low friction, reduce damage. In addition, the above-described second seal has excellent sliding characteristics and greater wear resistance.

The second device is the BufferSeal, which has an integrated flat gasket and a U-ring of polyurethane material as a second seal. It is more cost-effective than the first one, and can achieve the high wear resistance or working pressure changes required by the system. The upgraded BufferSeal can also display the lubrication of the U-ring to prevent dry friction operation.

2. Anti-fouling seal of hydraulic cylinder

The most common cause of failure of seals and other components is environmental pollution from gear oil. It is recommended to use O-ring reaction force dust-proof ring and lip polyurethane dust-proof ring in the dynamic sealing system, which can be selected according to the type of air pollutants and the anti-friction and anti-creep conditions of each system.

The O-ring anti-force dust ring is made of PTFE or other thermosetting materials, and a tough O-ring is installed in the pipe trench. The O-ring can ensure sufficient working pressure between the sealing lip and the sliding surface, compensate for the deviation between the hydraulic cylinder and the guide sleeve, and can reasonably scrape off dust-even solid stains.

The lip-shaped polyurethane dust ring is superior to the traditional polyurethane elastomer dust ring. The design of the anti-fouling lip can reasonably remove stains and save the slick oil required for normal work. The inward sealing lip can be used for sealing under bottom pressure, and the static data seal is completed according to the tight axial force between the dust ring and the pipe groove. 3. Piston rod seal

The choice of piston rod seal should be based on its wear resistance, clearance extrusion, and gear oil compatibility, working temperature, sliding ability and installation difficulty level to choose. The mating surfaces are also an important consideration-the required limit values should be observed, as they can be very harmful to the life of the piston rod seal.

For dynamic piston rod systems, three types of double sliding seals are proposed: seals with modified PTFE or polyurethane material cross-sections, or PTFE sheet seals with integrated polyurethane elastomer components. The choice of seal depends on the material to be sealed and the desired frictional characteristics of the system.

⊙ PTFE sliding seals are ideal for low friction, no creep or large clearance applications.

PTFE sliding seals containing an integrated polyurethane elastomer component are ideal for applications where different substances need to be protected or where leakage is strictly controlled.

The polyurethane material sliding seal has high wear resistance, especially suitable for the occasion of serious leakage.

⊙ When series sealing needs to avoid leakage, unilateral sliding sealing or polyurethane U-ring can be added to one or both sides of the double sealing (pressure direction or change direction) to further avoid leakage and ensure separation from the material.