In the field of modern industry, sealing should be considered in both the storage and transportation of fluid and the parts involving energy conversion. Sealing technology is not only widely used in traditional industries such as energy, chemical industry, and mechanical power, but also closely related to sealing technology in some cutting-edge equipment fields, such as aerospace. It is no exaggeration to say that small seals are filled with all fields of modern industry. All walks of life are inseparable from the application of sealing technology. Seals are important mechanical components. Seal failure will cause a waste of energy resources and cause serious safety accidents. Research shows that seal failure is an important cause of mechanical accidents. In the history of human aviation, the crash of the US space shuttle Challenger and the death of astronauts on the Russian Soyuz spacecraft are all disaster events caused by the failure of sealing materials. It can be seen that reliable sealing materials play a decisive role in the safety of equipment and personnel.
The main function of the seal is to prevent external impurities or air from entering the sealing mechanism and prevent the leakage of gas, oil, and other fluids in the sealing mechanism. With the progress of China’s industrial manufacturing capacity, under some harsh service conditions, traditional hemp and other materials can no longer produce a good sealing effect, while rubber has high strength and hardness after reinforcement. Its unique high elasticity enables rapid and powerful recovery of deformation under large deformation, and there are many kinds, which can meet the service conditions under different temperatures and different contact media, Therefore, rubber as a seal has been used for nearly a hundred years, and it is the most widely used sealing material. To ensure the reliability of the sealing mechanism, the rubber sealing material must meet several requirements; It has high strength and certain hardness; It has good elastic recovery ability and small compression set; Lo ng service life, strong aging resistance, and no embrittlement failure under low-temperature environment; For some sealing materials used in gas, liquid, and other environments, they must have good corrosion resistance to the transported or contacted fluid without premature failure or swelling.
1.1.2 Sealing mechanism of O-ring
O-ring is a common rubber sealing ring, which is widely used in various hydraulic or pneumatic systems under dynamic and static conditions. For such static sealing products, after putting them into the sealing groove, a certain compressive force should be applied on the contact surface under its elasticity О The O-ring will deform, so the seal itself is required to have a certain hardness to resist deformation. Generally, the initial compression is about 8% ~ 30%. When the pressure of the sealed medium is small, a good sealing effect can be achieved by relying on the elastic deformation of the rubber itself; However, when the pressure on one side of the sealing interface is large, The Custom Silicone Rubber O-ring will first move to the side with low pressure and deform itself to fill the gap between the contact surfaces to achieve better sealing. This kind of sealing is realized by changing the contact state of sealing products under the pressure of the fluid, which is also known as “self-sealing”.
Theoretically, at a fixed compression rate, as long as there is stress between the seal ring and the groove, a good seal can be achieved. Therefore, the rubber material with a certain hardness and a small compression set is an important condition to maintain the seal.
