Sealing device introduction

Sealing ring O-ring mounting groove, in addition to rectangular, but also V-shaped, dovetail-shaped, semi-circular, triangular and other practical applications can refer to the relevant manuals and national standards.

3. Lip seals Lip seals can be classified into Y-shaped, V-shaped, U-shaped, L-shaped, etc., depending on the shape of the section. Its working principle is shown in Figure 6-8. The hydraulic pressure presses both lips h1 of the seal ring against the surfaces of the two parts forming the gap. This sealing function is characterized by the ability to automatically adjust the sealing performance as the operating pressure changes. The higher the pressure, the tighter the pressure on the lip and the better the tightness. When the pressure decreases, the degree of pressure on the lip also decreases. This reduces frictional resistance and power consumption. In addition, it automatically compensates for the wear of the lip and maintains the sealing performance without degradation.

How lip seals work Small Y seals Currently, the so-called small Y seal shown in Figures 6-9 is commonly used in hydraulic cylinders as a seal for pistons and piston rods. Figure 6-10 (a) shows the shaft seal ring, and Figure 6-10 (b) shows the hole seal ring. This small Y-shaped seal is characterized by a large ratio of the width and height of the section, increasing the width of the bottom support and avoiding the flipping and twisting of the seal caused by friction.

Sealing devices are also used in high pressure and extra high pressure (pressures greater than 25 MPa) V-rings. The shape of the V-rings is: it is pressed from a multi-layer rubberized fabric, usually consisting of a pressure ring, a seal ring and a support ring. When used together, the rings can be used together to ensure good sealing. When the pressure is higher, the number of intermediate sealing rings can be increased. Such sealing rings are pre-pressed during installation, so the frictional resistance is large.

The lip seal should be installed so that its lip is open to the pressure oil, so that the lips open and they are tightly attached to the surface of the machine.

4. Assembled seals With the increasing application of hydraulic technology, the requirements for seals are getting higher and higher, and ordinary seals alone can not meet the sealing performance, especially the service life and reliability requirements. Therefore, a combined sealing device composed of two or more elements including a seal ring was researched and developed.

Pressure; reciprocating seal, the speed up to 15m / s; reciprocating swing and spiral motion seal, the speed up to 5m / s. The advantages of rectangular slip ring combination seal is that the anti roll ability is slightly poor, alternating between high and low pressure Occasionally work leaks easily. Figure 6-11(b) shows the combined seal of the shaft consisting of the support ring 2 and the O-ring 1. Since the seal between the support ring and the member to be sealed 3 is a wire seal, its working principle is similar to the lip seal. The support ring uses a specially treated compound, which has excellent wear resistance, low friction, and shape retention. There is no “crawling” phenomenon that rubber seals can easily produce at low speeds. Working pressure up to 80MPa.

The combined sealing device can not only be reliable in operation, but also has low friction and stability due to the full use of the advantages of the rubber seal ring and the slip ring (support ring), and the service life is nearly 100 times longer than the ordinary rubber seal, and is widely used in engineering. . ?

5. Rotary Shaft Sealing Devices There are many types of rotary shaft sealing devices. Figure 6-12 shows a rotary shaft seal ring made of oil-resistant rubber. The internal ring is supported by a right-angled annular iron skeleton. The inner edge is surrounded by a coil spring and the inner edge is tightened on the shaft for sealing. This seal ring is mainly used as the seal of the extending shaft of the hydraulic pump, hydraulic motor and rotary hydraulic cylinder to prevent the oil from leaking to the outside of the housing. Its working pressure is generally not more than 0.1 MPa, and the maximum allowable line speed is 4 ~ 8m/s, must work with lubrication.