For this reason, it is necessary to constantly adjust the degree of compaction of the filler so that the lubricant in the filler is squeezed out after a period of running, and then the lubricant is squeezed to compensate for the compressive force relaxation caused by the volume change of the filler.
Packing seals define packing seals, also known as Gland Packings seals, commonly known as packings. Packing seal is the oldest kind of sealing structure. In ancient Chinese water lifting machinery, the method of stuffing cotton was used to block the leakage. The steam engine that appeared in the world first adopted this type of sealing. The production and development of oil and gas exploration technology in the 19th century has led to new developments in filler-sealed materials. In the 20th century, packing seals were favored by many industrial sectors because of their relatively simple structure, low price, and wide range of sources.
Packing seals are mainly used for dynamic sealing of process machines and moving parts of machinery in the machinery industry, such as centrifugal pumps, compressors, vacuum pumps, mixers, shaft seals and reciprocating pumps for reactors, plungers or piston rods for reciprocating compressors. And the seal packing seal principle between the valve stem of the spiral motion valve and the fixed body. After the filler is loaded into the packing cavity, it is axially compressed by the gland. When the shaft and the packing have relative motion, due to the plasticity of the packing, It produces radial forces and is in intimate contact with the shaft. At the same time, the lubricant impregnated in the filler is extruded to form an oil film between the contact faces. Since the contact state is not particularly uniform, the "boundary lubrication" state occurs at the contact portion, which is called "bearing effect"; while the uncontacted recess forms a small oil groove, and has a thick oil film, and the contact portion and the non-contact portion do not form a The regular labyrinth acts to prevent leakage of the liquid flow, which is called the “maze effectâ€. This is the mechanism of packing sealing. Obviously, a good seal is to maintain the "bearing effect" and "maze effect." That is to say, to maintain good lubrication and proper compression. If the lubrication is poor, or if it is too tight, the oil film will be interrupted, causing dry friction between the packing and the shaft, which will eventually lead to burnt shaft and severe wear.
For this reason, it is necessary to constantly adjust the degree of compaction of the filler so that the lubricant in the filler is squeezed out after a period of running, and then the lubricant is squeezed to compensate for the compressive force relaxation caused by the volume change of the filler. Obviously, this often squeezes the filler, which will eventually deplete the impregnant, so regular replacement of the filler is necessary. In addition, in order to maintain the liquid film and carry away the frictional heat, it is also necessary to intentionally allow a small amount of leakage at the filler.
The packing sealing material has a certain plasticity. Under the action of the pressing force, a certain radial force can be generated and closely contact with the shaft.
2 has sufficient chemical stability. Without contaminating the medium, the filler is not swollen by the medium, the impregnating agent in the filler is not dissolved by the medium, and the filler itself does not corrode the sealing surface.
3 self-lubricating performance is good. Wear resistance and friction coefficient are small.
There is a small amount of eccentricity in the 4 axes, and the packing should have sufficient floating elasticity.
5 Easy to manufacture and easy to load.
Http://news.chinawj.com.cn Editor: (Hardware Business Network Information Center) http://news.chinawj.com.cn
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