It is mainly divided into two forms, one is the inner diameter * wire diameter, the other is the outer diameter * wire diameter. At present, it is widely used abroad and at home to express inner diameter * linear diameter. For example, American Standard as568 and Japanese standard g / P are all represented by inner diameter * wire diameter. And GB / t342.1-1982 is also the inner diameter D1 * wire diameter D2. For example, the O-ring 25 * 1.8 means that the inner diameter of the sealing ring is 25 mm, and the sectional diameter of the rubber ring is 1.8 mm.
A. O-ring: rubber O-ring of various materials, mainly including NBR, HNBR, FKM / Viton, EPDM, ffkm, SIL, PU, Cr, PTFE, etc;
B. Ed ring, star ring, rubber ball, rubber flat gasket, retaining ring, combined gasket, pneumatic seal and non-standard rubber miscellaneous parts;
C. Oil cylinder: TC framework oil seal is the main oil seal in stock, and other oil seals are also produced, such as Y-ring, U-ring, V-type combination, stefeng, gley ring, dust-proof ring, water seal, etc;
3 How to match the hardness and pressure of O-ring correctly
The hardness to be selected is positively related to the pressure. In other words, the greater the pressure, the greater the hardness of O-ring. In general, the conventional hardness of NBR, EPDM and SIL is 70 degrees, while that of FKM / Viton is 75 degrees. We know that the O-ring is sealed by elastic deformation which produces a return force. Therefore, if the pressure is not large, it is better to choose the one with lower hardness as far as possible, because the resilience with lower hardness is better, and the sealing is better. In this case, can we make the hardness 35 or lower? Of course not. Because we have to consider the difficulty and cost of processing. Generally, the processing range of hardness is 40-90 degrees of shore hardness. The corresponding pressure range is 0 ~ 35MPa. If the pressure is greater, it will be used together with the retaining ring. The retaining ring is divided into two types: type A (incision type: the angle between the incision and the side is 22 degrees) and type B (closed type). At present, polytetrafluoroethylene retaining ring (PTFE) is widely used, which belongs to A-type retaining ring.