Do you know the seal design of hydraulic support?

Seal design on the hydraulic, in fact, small series is not very clear, my company operates a series of hydraulic series also only understand the part, so Xiaobian today and everyone together to learn the knowledge of hydraulic, charging.

The most important seal of the hydraulic seal of the hydraulic support piston seal is the piston seal installed on the column, because its function is to maintain the chamber pressure of the supporting roof, and if the piston seal is damaged, the consequence may be disastrous. In the double telescopic column, the pressure of the emulsion can be as high as 60MPa or higher due to the area ratio of the inner and outer telescopic cylinders, and the lubrication performance of the emulsion is poor. Therefore, the main problem faced by the designer is that the seal is squeezed out and worn.

The hydraulic equipment relies on the liquid medium to transfer the power. The working pressure, speed and working environment of the equipment are restricted by the sealing of the medium. The sealing device is the main component of the equipment, and the reliability of the whole unit depends on the working capacity of the sealing device. The hydraulic support adopts 5% content emulsion medium, which has poor lubrication and corrosion resistance, so it is very difficult to overhaul in the well. Therefore, higher requirements for the applicability and reliability of the seal are put forward.

The test in the same test conditions specified, using extrusion type seal and lip seal, piston rod after high frequency quenching hard chrome plating, hardness HV800~1100, surface polishing Ra0.2~0.4. through 150 thousand reciprocating test, the conclusion is showed extrusion seal leakage and friction force is inversely related to the lip seal did not find what relationship leakage and friction of piston rod, the piston rod surface roughness than smooth surface wear caused by the more serious.

The damage is caused by the extrusion effect of high pressure and friction on the seal of the different, and double acting hydraulic cylinder usually where friction and pressure seal on the opposite direction, and support friction is generated by the pressure of the roof, so the direction of the pressure and friction forces, so to seal the anti collapse design put forward higher requirements.

Hydraulic seal is usually set anti extrusion ring, commonly used polymers (such as poly four argon, formaldehyde etc.) anti extrusion ring by ring thickness pressure F P pressure due to the sealing elastomer can flow, seal friction on the surface of the number is usually greater than 0.5, if the adhesive may be over 1). I contact length of contact length 1 is bigger than the thickness of the ring T, so it can be concluded that F and Fm are similar in magnitude, in the extrusion damage many occasions Fm friction may be greater than the extrusion pressure of F. caused by friction can be illustrated through the experiment.

Taking single hydraulic prop as an example, the static load test and reciprocating test are carried out according to the national standard. The test results show that the extrusion ring is seldom damaged when only static pressure is applied, but in operation, the friction force makes the sealing anti extrusion capacity drop greatly.

The wear of friction and wear seals is caused by a series of factors. In order to study the sealing performance changes caused by reciprocating wear, the international organization for standardization developed the 7 different laboratories in the world by the British fluid mechanics research council.