At present, China's construction machinery industry has introduced a large number of host design and manufacturing technologies from developed countries, and gradually adopted the international advanced sealing system design concept and sealing device application technology. However, due to the constraints of the domestic seal industry manufacturing level, the application level of construction machinery seal technology is still lagging behind the international advanced level of about 20-25 years, and the normal working hours of the host without leakage are only about 400h, which is less than 1/10 of the international advanced level.
Application status: The product variety and quality of domestic seals are still unable to meet the development and supporting needs of construction machinery with the introduction of advanced manufacturing technology.
In fact, there are nearly a thousand rubber and plastic seal manufacturers serving the construction machinery industry in China, but there are only more than 40 companies with better production conditions and technical capabilities. Among them, there are strong technical capabilities and companies with complete sets of advanced equipment. Only 7-8 (professional research institutes engaged in the production of military sealing products are not included). Nevertheless, the sealing products produced by these companies still have more or less gaps with foreign advanced levels in terms of quality and service life. After the construction machinery and medium and high pressure hydraulic parts industry has introduced the manufacturing technology of world-renowned manufacturers such as Linde, Carter, Komatsu, Caiai, Rexroth, etc., the variety and quality of domestic seals cannot meet the development and matching needs of products with the introduction of advanced manufacturing technology is an example. Secondly, the demand for a large dump truck lifting device with a small section U-shaped sealing ring (AU), due to the poor quality of domestic sealing products, the host plant and users are to foreign companies to purchase.
Problems: The quality of seal products and the design and application of sealing systems need to be improved
1. Seal product quality
In the past 20 years, through the joint efforts of domestic scientific research and technical personnel, a complete national standard system for the installation of various types of seals in line with ISO/TC131/SC7. At the same time, it has also established a national standard system for seals, such as seal size series, seal performance index, seal appearance quality, seal packaging, storage and transportation, which are in line with all kinds of international standards for seals. Thus, it facilitates the design and selection of seals for sealing systems of engineering machinery and other high-pressure hydraulic machinery products. But there are still many ills in the actual operation. The main reasons are that the industrial foundation is too weak, the quality and variety of raw materials are not satisfactory, and the management is not standardized. The gap is especially in the hydraulic pump, hydraulic motor and gearbox with rotary oil seal and hydraulic cylinder reciprocating dynamic seal product quality is the most. According to the service life of the wheel rim oil seal of the drive axle of ZL50C loader, the author has done an installation comparison test. The oil seal with auxiliary lip inner skeleton developed by a domestic unit began to leak only 50km after being installed in the road surface test. At the same time, the BABSL oil seal of a foreign company that was installed for examination has not leaked for nearly 3 years. Another example is: the quality of hydraulic cylinder dynamic sealing elements of construction machinery can meet the requirements of 5000 working hours without leakage, while the service life of domestic seals is generally 1/10 of that, and some even less than 100 working hours.
2. Design and application level of sealing system
The design and application level of sealing system depends on the development ability of sealing products, mainly in three aspects.
(1) Rotary dynamic sealing system
At present, a large number of standard oil seals are still used. For rotary sealing devices with pressure requirements, pressure-resistant oil seals with pressure-resistant l-3MPa can only be provided, while the international advanced level is 10MPa. The application of dynamic hydraulic return oil seal has not been popularized in the rotary seal device of construction machinery.
(2) Hydraulic cylinder reciprocating dynamic sealing system
At present, most of the domestic engineering machinery hydraulic cylinder dynamic sealing system design still uses U-ring as the main seal. The hydraulic cylinder dynamic sealing system of construction machinery designed and produced in the mid-1990s began to adopt the composite design of coaxial sealing components and U-shaped sealing rings. When the international commonly used 5-component (or 3-component) hydraulic cylinder piston with support ring combination seal assembly, the production process is more complex, the current domestic is still stuck in the stage of small batch production, quality stability is poor.
(3) Static sealing system In the static sealing system, although the asbestos and plant fiber sealing products are canceled, the use of liquid gaskets made of polymer materials is not yet popular. At present, such products in domestic use are still mainly produced by Loctite Company. There are few brands of domestic liquid sealant and anaerobic adhesive used for hydraulic system piping connection, and there is a certain gap in coating process and quality performance.
Outlook: China's seal replacement research and medical seal manufacturing industry will face severe issues raised by engineering machinery and other medium and high pressure hydraulic machinery industries.
With the introduction of international advanced technology and manufacturing technology and the development trend of the national economy after 2000, China's construction machinery industry based on the introduction of advanced technology will have a greater development. The working pressure of the hydraulic system of construction machinery is advanced and reliable. @'s probe height. It is bound to promote the development of sealing system design and sealing element manufacturing technology. Therefore, the scientific research of sealing technology and sealing element manufacturing industry in China will face the serious issues raised by construction machinery and other medium and high pressure hydraulic machinery industries. It can be predicted that China's sealed industrial system will no longer be a small-scale peasant economic business model with high energy consumption, low efficiency and complex structure, but will be a highly intensive, large-scale, low energy consumption and high efficiency management system. At that time, 60% of the main varieties of Chinese seals will reach the international quality level in the late 1980 s and early 1990 s, and another 15% of the product varieties will reach the contemporary quality level of international seal products. The design and application level of the sealing system of China's construction machinery and medium and high pressure hydraulic machinery products will reach the international technical level in the mid-1990s.
Background information: Four stages of the application of China's construction machinery seal technology
The development process of engineering machinery seal technology with rubber and plastic seals as the main application can be roughly divided into four stages.
1. Initial stage (1960-1970)
During this period, the working pressure of the hydraulic system of Chinese construction machinery products is roughly 12-14MPa. The seals used in the sealing system include: 0-shaped rubber sealing ring (NBR); Iron shell-cowhide rotating oil seal; End face seal of corrugated steel skin ten cork ten metal springs; Asbestos packing; Asbestos ten rubber sealing gaskets; V-shaped sealing ring (cowhide ten phenolic and ten bakelite);V-shaped sealing ring (NBR ten clamp fabric]: soft will belong to sealing gasket, etc.
2. Start-up phase (1971-1980)
The working pressure of the hydraulic system of the main products of Chinese construction machinery produced during this period is approximately 14-3.5MPa. The seals used in the sealing system are mainly rubber and plastic seals, eliminating the end face seals of cowhide, asbestos fiber and corrugated steel skin ten cork. The main type D is: 0-shaped sealing ring (NBR, FKM); Floating oil seal for crawler D chassis (metal ring dry O-shaped figure);D includes skeleton rotating oil seal Sichuan BR, FKM, ZACM). Hydraulic and pneumatic reciprocating seals D have O-ring seals (NBR, FKM);U-shaped dense D-shaped injection ring (NBR, AU, BU):V-shaped sealing ring (NBR ten clamp fabric); Cup-shaped sealing ring (NBR ten clamp fabric), etc.
In the past 10 years, in order to meet the development needs of medium and high pressure hydraulic technology, such as construction machinery and forging machinery, seven professional rubber and plastic seal production plants have been set up by the original machinery department. In addition, in order to promote the development of China's sealing technology, the "National Hydraulic and Pneumatic Standardization Technical Committee I and the" National Hydraulic and Pneumatic Standardization Technical Committee Rubber and Plastic Seal Standardization Sub-Technical Committee "(corresponding to the old ISO/TCI3/SC7) and the Fluid Seal Sub-Technical Committee of the Friction Society were established in 1975 and 1979.
3. Consolidation and development phase (1981-1990)
The working pressure of the hydraulic system of the main products of domestic construction machinery has reached 16-40MPa, and the sealing system is still dominated by rubber and plastic sealing products. The main types are: O-ring seals (NBR, FKM); Floating oil seal for crawler chassis (O-shaped figure 10 metal ring); Sealing assembly for lubricating and sealing crawler (NBR AU): rotating oil generation 10 (NBR, FKM, ACM, EPDM) for inner and outer frames; Combined sealing gasket (NBR metal); Hydraulic cylinder piston and piston rod are tight. Coaxial seal assembly (PTFE NBR) for sealing; dynamic hydraulic return oil seal (NBR, FKM, ACM) for rotating shaft; pressure-resistant rotary oil seal (NBR, FKM) with working pressure of 1?3MPa; bidirectional medium rotary oil seal (NBR, FKM), double-acting reciprocating D-dynamic seal assembly with supporting ring for hydraulic O pressure cylinder piston (NBR PTFE POM), etc.
4. High-speed development stage (after 1991)
Construction machinery and other medium and high-pressure hydraulic industries have introduced a large number of product manufacturing technologies, which has promoted the pace of foreign seal merchants entering the Chinese seal market. The entry of foreign capital and technology has improved the overall level of China's sealing industry.
If you are interested in our products or have any questions, please feel free to contact us and we will reply you within 24 hours.
