I. Introduction of waterproof imported O ring
Taiwan Asahi Meike seal (XOK) suggested the necessity choice of waterproof imported O type ring, Taiwan imported O type seal ring: the essential characteristics of O type rubber sealing, refers to the good elasticity, good compression permanent deformation performance and good abrasion resistance, good heat resistance and not be resistant to liquids and gases the use of invasive, long service life etc.. However, because the material that meets all of these characteristics is not available for the time being, it is necessary to select different materials for use in accordance with their respective uses.
Two, waterproof imports, O ring groove design and physical properties
Taiwan Asahi Meike seal (XOK) supply in Shanghai imported waterproof O-ring is a compression type seal, when the sealed tank, the contact section under compressive stress and elastic deformation. The contact surface produces initial contact pressure Po. Even if there is no pressure or medium pressure is small, the sealing ring by the elastic force itself but also can realize sealing; when O-rings waterproof sealing ring, oil seal O-rings, the cavity filled with pressure medium, under pressure in the medium, the import O-ring bit shift, shift to low voltage side at the same time, the elastic deformation is increased further, filling and sealing clearance. At this point, the contact pressure used to seal the secondary coupling surface rises to Pm:
Pm=Po+Pp
In O, the contact pressure (0.1MPa) of Pp passes to the contact surface
Pp=K • P
K - O rubber seal pressure transfer coefficient, for rubber sealing O ring K=1;
P - the pressure of the sealed liquid (0.1MPa).
Thus greatly increasing the sealing effect. General K is more than 1, so Pm > P. Thus, as long as the rubber ring, O-rings sealing ring surface is smooth, there is the initial pressure, you can achieve no leakage of sealing. This depends on the pressure of the medium itself to change the contact state of the waterproof O - shaped sealing ring so that it can be sealed. It is called self - sealing.
Theoretically, the compression deformation of the waterproof O ring is even zero, and it can be sealed under the oil pressure. But considering the eccentricity, the O ring is generally compressed by 7% - 30% when it is loaded into the sealing groove. Static sealing takes larger compression ratio. The dynamic seal takes a smaller compression ratio. This is because the synthetic rubber at low temperature to be compressed, so static seal preload should consider its low-temperature shrinkage compensation.
Performance analysis of waterproof imported O ring for three and XOK:
Shanghai imported O ring compression, will produce contact stress on the contact surface, the contact stress and design pressure of Pw formula is satisfied, can be considered a good waterproof performance.
A = mPw, where m is the waterproof rubber seal coefficient, and waterproof rubber seal material, shape and surface condition of contact. The contact stress required for O ring, 0.1MPa, 0.15MPa and 0.2MPa hydraulic pressure is analyzed. In the actual project usually consider the safety factor of 3, and that M can satisfy the water tightness requirements 1.15. By calculation, the contact stresses required by 0.1MPa, 0.15MPa and 0.2MPa hydraulic pressure are 0.35MPa, 0.51MPa and 0.69MPa respectively. Three kinds of contact compression and finite element analysis of the stress when compared to the amount of compression 13mm, contact stress is greater than 0.1MPa the required contact stress, pressure can only withstand 0.1MPa; the amount of compression of 15mm, only 0.1MPa resistant to compression pressure; 18mm, water pressure can 0.2MPa resistant. In addition, the amount of compression is less than 20mm, a large piece of rubber compression stress is only 23kN/m, and combining the construction experience usually requires the value to 60kN/m, so the project can easily import three yuan O type ring groove or seam.
Three, waterproof import O ring, I produced the import O type sealing ring, the main material properties:
• three yuan ethylene propylene rubber (EPDM) - heat resistant, 150 degrees, chemical resistance, oil resistance.
• silicone material (SIL) - heat-resistant 250 degrees, resistant to oil in general, not wear-resistant.
Fluorine rubber (FKM) - heat-resistant 240 degrees, good oil resistance, wear resistance, chemical resistance.
• polyurethane (PU) - heat-resistant 120 degrees, oil resistance, wear resistance.
• polytetrafluoroethylene (PTFE) - heat-resistant 280 degrees, good resistance to oil (usually not made O ring).
- Dengqen rubber (NBR) - resistant 120 degrees, oil resistant, waterproof, high pressure oil. Is commonly used in the market O ring material.
The above is sealed by Taiwan Xu Meike (XOK) a brief account of the relevant import O - ring, Ningbo Business Department of waterproof O ring, O ring type imported from Taiwan