Seal editing
This entry is reviewed by the "Science China" encyclopedia science entry compilation and application work project.
Seals are materials or parts that prevent fluid or solid particles from leaking between adjacent joint surfaces and prevent external impurities such as dust and moisture from invading the parts inside the machine equipment. The storage room temperature of the seals is below 30 ° C to avoid high temperature aging of the seals.
Chinese name seals to prevent fluid or solid particles leakage of solid parts of the material or parts classification shaft with sealing, dust seal
catalogue
1 Development
2 Use Classification
3 Storage
4 Use Points
5 Influencing Factors
6 Precautions
7 Common Names
8 Industry status
Development editor
Although the rubber seal is small, its role makes it become the basic parts and accessories in the main industries of the national economy such as national defense, chemical industry, petroleum, coal, transportation and machinery manufacturing, and occupies a very important position in the development of the national economy. In recent years, with the rapid growth of the economy, the rubber seal manufacturing industry has maintained double-digit growth. Data show that in 2011, China's rubber and plastic seal manufacturing industry scale (above enterprises (according to the National Bureau of Statistics statistics caliber, sales revenue of more than 20 million yuan) to achieve a total industrial output value of 10 billion, an increase of more than 20%. At present, China's rubber and plastic seal manufacturing industry scale (annual income of 20 million yuan) more than 150 enterprises, the domestic rubber seal industry generally presents a small enterprise scale, low technical level of development situation. From the perspective of enterprise economic type, private and foreign-funded enterprises account for more than 95%, which is the main economic type of the industry; At the same time, enterprises are basically concentrated in the East China region, from the number of enterprises, sales revenue and asset scale, East China has occupied a considerable share, and the market concentration is high. [1]
Use category editing
1. Classification by function: divided into shaft seal, hole seal, dust seal, guide ring, fixed seal, rotary seal; 2. According to material classification: divided into butyl cyanide rubber, EPDM rubber, fluorine rubber, silicone, fluorine silicone rubber, nylon, polyurethane, engineering plastics, etc. [1]
Storage editing
1. The storage room temperature of the seals is below 30 ° C to avoid high temperature aging of the seals; 2. Seals must be stored in sealed packages to avoid contact with moisture or dust in the air; 3. The seals must avoid strong light exposure to avoid the seals being eroded or prematurely aged by ozone in the air. The performance factors of various seals are different, such as mechanical seals (packing seals, etc.) affecting factors are temperature, medium, wear, pressure and so on. [1]
Use point editing
(1) Select the appropriate seal material and hydraulic oil, as well as the adaptability to the working temperature and the compatibility of the oil. (2) The geometric position accuracy (concentricity) of the sliding parts relative to the seals is high and the material is good (such as hard chrome plating) and the surface roughness is finer to extend the service life. ① The oil seal used for hydraulic pump and motor journal not only requires the roughness of the sliding surface to be within Ra 0.25m, but also requires hard chrome plating on its surface. In specific use, the radial spring force on the lip of the oil seal needs to be adjusted appropriately according to the specific situation to make it moderately elastic, and an installation sleeve or thin gasket is also used to protect the seal ring during installation. To avoid lip roll, distortion, resulting in the spring slip out. The commonly used rolling processing method on the inner surface of the hydraulic cylinder not only improves the surface roughness, but also makes the surface cold hardening treatment, which is conducive to extending the service life of the sealing ring. In addition, the pressure used, the length and type of sliding surface also have a great impact on the service life. Therefore, the "final inspection" time should be determined according to these conditions. ③ The sealing surface is required to be in good lubrication condition and prevent dirt from invading. The use of an oil of the required cleaning grade and the correct installation method are also necessary conditions. [1]
Influence factor editing
Hydraulic seals play a vital role in the integrity of hydraulic pneumatic components, if a hydraulic pneumatic component product seal is not up to standard, then the hydraulic pneumatic component product is not a good product. There are many factors that affect seals. First of all, the pressure is an important reason for the quality of the seal, the level of pressure, the length of the pressure cycle change, the seal damage (such as extrusion) has a great impact. The higher the pressure, the greater the impact of other factors on the performance of the seal, such as temperature, speed, material of the seal, the clearance between the piston and the cylinder, the clearance between the piston and the cylinder head. Another is the temperature and friction, and it is difficult to describe the use temperature and the use temperature of a sealing material, because it is the result of a series of factors. For the piston and piston rod operating temperatures are different, they should be selected differently. There is also a seal product surface roughness, surface characteristics, pressure, medium, temperature, seal material, seal type and speed of movement are all factors that affect seals. The last is the surface treatment, experience has shown that the characteristics of the cylinder piston and piston rod surface have a very large impact on the life of the seal. Surface characteristics are often defined by the value of surface roughness RA, which is the arithmetic mean of the absolute value of the surface shape deviating from the center line. However, these values do not fully represent the impact of the surface condition on the seal, because even under the same roughness, different surface shape characteristics can lead to different degrees of seal wear. [1]
Note edit
1. Please read the product description of each series before designing the groove, and make it clear that the product uses a whole groove or a separate groove; The process of installing seals should pay attention to avoid sharp edges, holes with seals into the overall slot must be equipped with installation tools; Designers should consider the grooves dimensional accuracy, surface roughness, extrusion clearance and other parameters, please refer to the product instructions, drawings and size table. 2. Before installing the seals, ensure that there are no impurities and cracks in the sealing grooves, and apply operating oil on the surface of the sealing grooves and seals respectively; Install seals gradually in sequence; Avoid sharp edges during installation, straighten seals to avoid distortion and skew; If the slot is separate, tighten the gland. [1]
Common name editing
Sealing ring, packing, mechanical seal, oil seal, water seal, packing, sealing gasket, sealant, soft packing, hydraulic seals, pneumatic seals, etc. [1]
Industry status editor
In recent years, the production and quality of rubber sealing products in China has gradually entered a new stage and a new period. However, only these are far from being able to meet the needs of other industries for the development of various types of rubber sealing products standardization and serialization, especially compared with the international advanced countries, our products in terms of product quality, or in terms of product varieties, there is a considerable gap. In this issue, the 100 forum focused on the concept of sealing science, research content and research significance, summarized the status quo of rubber and plastic sealing, mechanical sealing and packing sealing technology, analyzed the gap between China and the world's advanced sealing technology in the research level and new product development ability, and put forward some suggestions on the focus of China's future sealing field research. [1]
The overall competitiveness of China's sealing industry is not strong, as we all know, in our country, the sealing industry can be said to be the smallest industry, but the product can be used with large industry. Whether aviation, navigation, petroleum, chemical industry, or machinery, power generation, metallurgy, mining, etc., can not be separated from the seal. In short, where organic, pump, pipe, valve, all rely on seals. So although the industry is small, it involves a wide range of areas. In recent years, with the development of the economy, the development of the sealing industry is also rapid. However, unlike other industries, although the sealing industry is developing fast, the sealing enterprises are changing slowly. For example, in the late 1970s and early 1980s, only a few manufacturers in Jiang, Zhejiang, Lu, and whether it is coastal, inland, or the south, the north, everywhere can be seen seal factories, the entire sealing industry has been from the previous several, the development of 300, the speed of development can be said to be very fast. However, in terms of individual enterprises, many enterprises have not changed much, the scale of production is roundabout, and some even regress, scientific and technological power is not only not a large increase, but it is weakening, many manufacturers are still holding on to the "four old", that is, old products, old technology, old equipment, old scale. Of course, there are some companies that have the ability to imitate some products, but there are not many companies in the entire industry that have the ability to independently develop new products. In terms of products, the vast majority of manufacturers are still some winding gaskets, packing rings, packing and high-strength gaskets and other old products. Slightly new polytetrafluoroethylene products, in technology and quality are greatly behind foreign countries, such as polytetrafluoroethylene packing, expanded polytetrafluoroethylene tape. Looking around, there are few new products. In terms of technical strength, the proportion of scientific and technological personnel in most enterprises is small, and many enterprises lack technical personnel from genuine courses, and technical strength is weak, so enterprises lack the corresponding development and transformation ability. Since the establishment of the EU, the strength brought by the union has prompted the EU to improve and establish a new European seal quality standard, replacing the previous series of standards developed by the American Fluid Association. Leakage rates appear and are highlighted in the new European seal quality standard. The leakage rate of our products is generally 10-1mg/s, and in Europe, high-strength graphite composite panels with leakage rates of 10-4mg/s have appeared! In terms of equipment, the vast majority of enterprises have only a few old knitting machines, a few earthen winding machines, simple punching machines and shearing machines, etc., relying on the ability of old workers to organize production; The equipment of many manufacturers is in a state of unsaturated production tasks for a long time. In terms of quality management, the vast majority of enterprises rely on the proficiency of operators to do a good job of products, and do not produce in accordance with standardized process standards, but also necessary management means. Although many manufacturers have obtained ISO9000 series certification, their internal process documents, quality control plans or operation guidance documents and equipment management documents are often empty and weak, and the international level is far from it. In terms of scale, the vast majority of enterprises have sales below 5 million yuan, a small number of 10 million, and a handful of more than 10 million. Frankly speaking, a large part of the sales of many manufacturers is outsourced procurement parts, and the proportion of real production is not very high. Therefore, it is difficult for many small enterprises to compete with some famous foreign companies and manufacturers. [1]
In summary, the competitiveness of our sealing industry is weak, but this refers to some small enterprises, and we also have some strong companies or factories. Although there are several famous large enterprises abroad, there are also more small enterprises, and many commercial companies specializing in sealing business buy products from China and sell them in their own countries or other countries, so the advantages and disadvantages of the entire international counterparts are different. In terms of advantages, we have advantages in three main aspects: raw material advantages Whether asbestos, graphite and other non-metallic materials, we are a large producer, many countries lack this resource. At present, seals are still labor-intensive products, and China's manufacturing costs are low (United States: operators $1500 / person/month; Japan: Young workers 200,000 yuan/person/month, older than 300,000 yen; We are more than 1000 yuan/person/month), 60% of the current seal competition depends on the price factor. In the domestic market, the host matching (OEM form) this phenomenon has been obvious, and the international market is even more so. With the further deepening and improvement of domestic reform. The role of price factors in the maintenance market is becoming more and more obvious. At present, the marketing of seals in the domestic market mainly relies on interpersonal relationships, unique time and people, and we have many advantages under the same quality conditions in the domestic market. From the perspective of market competition, with these three advantages, you can embark on the road to competition. [1]
Conversely, the disadvantages may be even greater
The first is technological backwardness. On the one hand, in order to adapt to the higher and higher requirements of human environmental protection, ISO14000 standards have begun to be paid attention to by Chinese enterprises, and people's requirements for sealing are becoming stricter. Just as the entry of a large number of joint ventures has brought new quality requirements, new environmental concepts. On the other hand, the new standard objectively brings about the redistribution of the market. The new and more stringent quality standards will become the biggest obstacle to the export of sealed products in China; And it has become a killer for foreign enterprises to enter the Chinese market. Companies that do not pay attention to technological progress will be eliminated in the next five years. And the subject of technology is human. As far as the status quo is concerned, the sealing industry is relatively loose, the individual scale is small, so the ability of hiding dragons and crouching tigers is small, and the overall quality of enterprise employees is low. In addition, there may be a need for correct business philosophy. Capitalism has been around for more than 200 years, and many of our peers, or competitors, have experienced the continuation of four generations, and have long since gotten rid of the psychology of seeking wealth from poverty to prosperity, and have moved toward a mature mindset of doing markets, doing management, doing brands, and doing culture. And our enterprises, the reason why there are so many repeated establishment at this stage is that many people are eager to get rich while taking advantage of the various irregular status quo in the reform process. This is a very natural alternating process, and capitalist countries have also experienced such a process. But what we have in front of us is how to accelerate the evolution from a rush for wealth and entrepreneurship to a mature business culture. On this basis, it is not difficult to see all kinds of drawbacks in the behavior of our enterprises. Lack of cooperation and competition, resulting in a decline in the market, is the first major problem in management. In fact, blindly lowering the price, blindly pursuing orders, the result will be the destruction of the market. The market is not a cake, but a field, need to pay, need to cultivate, need to love, there will be harvest, will be long. In terms of quality awareness, after-sales service, product packaging, equipment investment and other aspects of the ISO9000 standard, each enterprise naturally has its own evaluation. Although there are "three points of technology, seven points of management" management problems, as long as there is confidence or easy to improve.
