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Over the years, Langfang Bokai Sealing Material Factory has accumulated rich experience in production management, and has worked closely with many research institutes in the domestic machinery industry to challenge first-class R&D and commercial platforms, making the management system more perfect and employee-conscious. Gradually improve, the product structure is more reasonable, thus forming a young and efficient, fast-output elite team. First-class technology, first-class equipment, to provide you with first-class products.
First, the sealing principle of packing packing
The sealing principle of packing packing depends mainly on the maze effect and the bearing effect.
Labyrinth effect: the shaft is very uneven on the microscopic surface, and the packing can only partially fit, but the part is not in contact, so there is a slight gap between the packing and the shaft, like a labyrinth, with a pressure medium in the gap. It is throttled several times to achieve the seal.
Bearing effect: There is a thin liquid film between the packing and the shaft, so that the packing and shaft are similar to the sliding bearing, which plays a certain lubrication role, thus avoiding excessive wear of the packing and shaft.
Second, the packing material requirements for the material
Due to the temperature, pressure, PH of the sealed medium, as well as the line speed, surface roughness, coaxiality, run-off, eccentricity, etc. of the equipment, the packing material is required to have the following characteristics:
1, there is a certain elastoplasticity 2, chemical stability 3, impermeability 4, self-lubricating 5, temperature resistance 6, easy disassembly and assembly 7, simple manufacturing, low price.
The properties of the above materials directly affect the sealing performance and service life of the packing, and the materials that can fully meet all the above properties are few. Therefore, obtaining high-quality sealing materials and improving the material properties have always been the focus of research in the field of sealing.
Third, the form and characteristics of packing
With the continuous emergence of production processes, the form of packing of packing is gradually diversified. Depending on the conditions of use and the environment, different forms of preparation have a direct impact on the performance and service life of the seal. The main types of packing used for packing and packing are: braid braiding, sheath braiding, threading, and sandwich preparation. The layout and characteristics of the packing are as follows:
1, hair braid
The bun weaving is woven on two tracks with eight spindles. There is no core in the middle and the middle. The braided product has a square cross section. It is characterized by loose packing, but it has a certain compensation effect on the vibration and eccentricity of the shaft. Used for small-section fillers, but the size of the section will be large, the appearance of the filler will be rough, the structure will be loose, and the compactness will be poor.
2, the layer weave
The sleeve weaving is woven on the two tracks with 8, 12, 16, 24, 36, 48, 60 and other spindles. The cover layer is determined according to the packing specifications. Generally, the layer is woven 1~4 layers, and there is no core in the middle. The compactness is good and the sealing property is strong. However, since it is a jacket layer, there is no fiber connection between the layers and it is easy to delaminate, so it is mostly used for static sealing or low speed equipment.
3, sandwich weaving
The sandwich is made of rubber or metal as the core, the fiber is outside, and one layer is woven. The number of layers is determined according to the needs. It is similar to the sleeve weaving. The sandwich woven has better compactness, high strength, good bending performance and sealing. The property is good, but like the jacket structure, the surface layer is easy to fall off after being worn, and is generally used for pumps and valves, and is rarely used for reciprocating equipment.
4, through the heart
The core weaving is made of 8, 12, 16, 24, 36, 48, 60 and other spindles on three or four tracks. The section is square, the surface is flat, the elasticity and wear resistance are good, the strength is high, and the density is high. The property is good, the contact surface with the shaft is larger and more uniform than the hairpin type, and the gap between the fibers is small, so the sealing property is good, the whole filler is not loose after the surface layer is worn, and the service life is long, which is a relatively advanced braided structure.
When the packing is selected, the braiding form of the packing should be selected according to the specific working conditions of the equipment, so that the packing can exert the sealing performance as it should.
Fourth, the classification, composition and application of packing
Due to the different working conditions, the types of packing are also very diverse. In order to better distinguish and select the packing, we usually divide the packing according to the material of the main sealing material of the packing of the packing:
1. Natural fiber packing
Natural fiber mainly consists of natural cotton, hemp, wool and other packings for sealing substrates.
2, mineral fiber packing
Mineral fiber packings mainly include asbestos packing
3. Synthetic fiber packing
Synthetic fiber packings mainly include: graphite packing, carbon fiber packing, polytetrafluoroethylene packing, Kevlar packing, acrylic sandwich type silicone fiber packing, etc.
4, ceramic and metal fiber packing
Ceramic and metal fiber packings mainly include: silicon carbide packing, boron carbide packing, medium alkali glass fiber packing, etc. Since a single fiber material has more or less the disadvantages of some materials, a single fiber is used. To braid the packing, it is easy to cause leakage due to the gap between the packing fibers. At the same time, some fibers have poor self-lubrication and large friction coefficient, so some lubricants, fillers and special additives should be impregnated. To improve the compactness and lubricity of the filler, such as mineral oil mixed with graphite powder or molybdenum disulfide grease, as well as talcum powder, mica, glycerin, vegetable oil, etc., as well as impregnated polytetrafluoroethylene dispersion emulsion, and An appropriate amount of a surfactant, a dispersing agent, and the like are added to the emulsion. Special additives usually have zinc particles, barriers, molybdenum-based corrosion inhibitors, etc., to reduce corrosion of the packing by the packing.
With the development of science and technology, the application of nanotechnology is more and more extensive. Nanotechnology mainly discovers some hidden characteristics inherent in materials. Some features can reduce or eliminate some of the disadvantages of materials in this province, and play the role of the material itself. Some excellent features. In the sealing industry, the research and development of sealing materials has always been the industry's cutting-edge technology field. Through the long-term cooperation of well-known nano research institutions at home and abroad, the nano packing series has been successfully developed, and the invention patents have been applied to the State Intellectual Property Office. At the same time, it has also opened up a new field of packing application, which has improved the spanning technology of packing packing. Its application has significantly improved the sealing performance and service life of the equipment, and brought considerable economic benefits to users.
5. Performance indicators of packing materials
The material properties of the packing material directly affect the sealing and service life of the packing, and have the following indicators:
1. Compression ratio: the ratio of the thickness of the material to the initial thickness when loading, the rebound rate: the ratio of the rebound amount of the solid material when unloading and the amount of compression during loading. 3. Wear resistance: the surface of the two materials Degree of loss caused by relative motion 4, self-lubricating property: the property of the material itself has lubricity 5. Stress relaxation rate: percentage of stress attenuation under stress relaxation state 6. heat loss: after the substance is burned within the specified time within the specified temperature Loss of mass 7. Loss of acid: Percentage of mass lost after treatment of the material in the acid solution of the specified operating procedure. 8. Loss of alkali: Percentage of mass lost after treatment of the material in an alkaline solution of the specified operating procedure
We will uphold the enterprise spirit of “pragmatic, strict, honest and innovative†and abide by the core business philosophy of “winning by quality, mutual benefit and mutual benefitâ€, and we will provide excellent products and services to our customers wholeheartedly! Each material has a strict regulation for each performance indicator country or industry, thus ensuring the quality of the packing can be guaranteed.
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