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Technical application and development prospect of domestic seals in the construction machinery industry

technical application and development prospect of domestic seals in the construction machinery industry

China Construction machinery information

Guide: at present, China's construction machinery industry has introduced a large number of host machine design and manufacturing technologies from developed countries, and gradually adopted international advanced sealing system design concepts and sealing device application technologies. However, due to the restriction of domestic seal industrial manufacturing level, the application level of construction machinery seal technology still lags behind China

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 internationally advanced sealing system design concept and sealing device application technology. However, due to the restriction of domestic seal industrial manufacturing level, the application level of construction machinery seal technology still lags behind the international advanced level for about years. The normal working hours of the host without leakage are only about 400H, less than 1/10 of the international advanced level

application status "no name" series: the product variety and quality of domestic seals still cannot meet the development and supporting needs of construction machinery with advanced manufacturing technology

in fact, there are nearly 1000 rubber and plastic seal production enterprises serving the construction machinery industry in China, but there are only more than 40 enterprises with good production conditions and technical capabilities, including strong technical capabilities There are only enterprises with complete sets of advanced equipment (excluding professional research institutes engaged in the production of military sealing products). Nevertheless, the quality and service life of the sealing products produced by these enterprises are still more or less behind the advanced level of foreign countries. After introducing the manufacturing technology of world-famous manufacturers such as Linde, Carter, Komatsu, caiezi, Rexroth, etc. into the construction machinery and medium and high pressure hydraulic parts industry, the product variety and quality of domestic seals can not meet the development and supporting needs of products with advanced manufacturing technology is an example. Secondly, McEuen also imagined that the small section U-shaped seal ring (AU) for the lifting device of the dump truck with a large demand. Due to the poor quality of domestic sealing products, the main engine manufacturers and users purchased from foreign companies

existing problems: the quality of seal products and the design and application level of sealing system need to be improved

1 Over the past 20 years, with the joint efforts of domestic scientific and technological personnel, a complete national standard system for various seal installation cavities in line with iso/tc131/sc7 has been established. At the same time, it has also established a national standard system for seals in line with international standards for all kinds of seals, including seal size series, seal performance indicators, seal appearance quality, seal packaging, storage, transportation, etc. Thus, it is convenient for the design and selection of seals for sealing systems of construction machinery and other medium and high pressure hydraulic machinery products. But there are still many disadvantages in practice. The main reasons are that the industrial foundation is too weak, the quality and variety of raw materials are not satisfactory, and the management work is not standardized. In particular, the product quality of rotary oil seals and reciprocating seals of hydraulic cylinders for hydraulic pumps, hydraulic motors and gearboxes is the worst. In view of the service life of the wheel side oil seal of the drive axle of the ZL50C loader, the author once conducted an installation comparison test. The oil seal with the inner framework of the auxiliary lip developed by a domestic unit began to leak after being installed on the road for only 50km. At the same time, the babsl oil seal of a foreign company that was installed and evaluated has not leaked for nearly 3 years. Another example: the quality of dynamic sealing elements of hydraulic cylinders of construction machinery can meet the foreign level of 5000 working hours without leakage, while the service life of domestic seals is generally 1/10 of that, and some are even less than 100 working hours of material properties

2. The 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 seal system

at present, ordinary standard oil seals are widely used. For rotary seal devices with pressure requirements, only pressure resistant oil seals with pressure of 1-3mpa can be provided, while the international advanced level is 10MPa. The application of hydraulic return oil seal has not been popularized in the rotary sealing device of construction machinery

(2) reciprocating dynamic sealing system of hydraulic cylinder

at present, the design of dynamic sealing system of hydraulic cylinder of most domestic construction machinery still adopts U-shaped seal, which makes it the preferred material for clothing manufacturers; In the field of fashion, the use of a general coat as the main use of the seal ring as the main seal. The dynamic sealing system of hydraulic cylinder 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. The manufacturing process of the 5-component (or 3-component) hydraulic cylinder piston combined seal assembly with backup ring, which is widely used internationally, is relatively complex. At present, the domestic production is still in the stage of small batch production, and the quality stability is poor

(3) static sealing system in the static sealing system, although asbestos and plant fiber sealing products are eliminated, the use of polymer liquid gaskets is not yet popular

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