In our daily equipment manufacturing and production process, we will encounter parts that need to be sealed. So which parts need to be sealed? In fact, there are quite a few. As long as pneumatic or hydraulic fluids are involved in the movement of the mechanism, they basically need to be sealed. One is to maintain pressure, and the other is to prevent leakage.
In the sealing process, we often use parts specially used for sealing, which are named O-rings because of their appearance. O-rings are named after their annular shape and circular cross-section. This shape It is conducive to compression and easy to assemble, but its production process must follow certain principles. It is a mainstream product for sealing materials.
When making seals, the compression rate parameter is usually taken into consideration. This parameter determines the size of the relatively reserved sealing space, which is the placement groove of the sealing ring. If this is not grasped well, it will be made. The sealing ring cannot achieve a leak-free seal, and it may not fit in after it is made. If it cannot fit in, it can be easily solved. It can be improved by heating. If it cannot seal, it can only be redone.
Another factor to consider is that the contact surface of the sealing ring should be maximized as much as possible. The larger the area, the better the sealing performance. However, if the area is large, there will be installation problems. In addition, the friction force ( What we are talking about here is dynamic sealing) should be reduced as much as possible. Excessive friction will directly lead to permanent deformation of the seal, making it difficult to continue to use it.
It can be seen from the factors that affect the sealing effect mentioned above that there are self-contradictory problems among these factors. A large compression ratio can obtain larger contact pressure and contact area, but it will also There is an excessive compression ratio, which causes the sliding friction to increase even more, and natural permanent deformation is unavoidable. If the compression ratio is too small, it may be due to the coaxiality of the sealing groove (this is for the piston of the cylinder). Errors and shrinkage errors of the sealing ring during the manufacturing process eventually make it difficult to install, or the sealing function cannot be achieved even after installation, causing leakage.
Therefore, when we make seal rings and choose materials, the compression rate becomes the primary consideration. In addition, we weigh several other factors. From a general condition, the compression rate of static seals is greater than that of dynamic seals, but Its extreme value should be less than 30% (it has a lot to do with the rubber material). Otherwise, the compressive stress will cause the entire sealing ring to relax significantly, and permanent deformation will occur, making it difficult to meet the use requirements. Under high temperature conditions, it appears Especially serious. The compression rate of the
sealing ring can also be effectively controlled during the actual manufacturing process. When making the forming mold, the size of the mold can be scaled accordingly. Of course, the prerequisite is to first determine the compression rate of the material. Please confirm clearly, this general material will have corresponding instructions.
When making a sealing ring, first make a mold. The mold is usually a profiling. In order to make the sealing ring beautiful in appearance, it is usually made directly on CNC, and the mold is made like a plastic mold. The mold is made smooth and flat, and It is necessary to analyze the process of mold parting, mold closing, and drafting. Non-standard products are fine, but batch products need to be more careful.
can be made by high-temperature injection or extrusion. The manufacturing process is not much different from that of plastic. I won’t go into details here. However, it is necessary to popularize the knowledge about non-standard and non-batch production. Usually one or two Even if there are a dozen or so, the mold still needs to be made, but the forming method does not use high-temperature extrusion and injection, but uses glue and mixed coagulant at room temperature, pours it into the mold, then closes the mold, waits for about 24 hours, and then Open the mold and it's basically done.
Friends, have you learned it?
