Fact nearly one thousand services for the construction machinery industry in China rubber seals manufacturers, but with better production conditions and technological capabilities of enterprises, only 40 more than the current Chinese construction machinery industry had been introduced in developed countries, a large number of host design and manufacturing techniques, and gradually adopted the international advanced sealing system design concept and application of the sealing device technology. However, due to the constraints of the seals domestic industrial and manufacturing standards, NSK bearings mechanical seal technology level still lags behind the international advanced level of about 20-25 years. Host no leakage of normal working hours only 400 h, less than the international advanced level of 1/10.
Application Status: domestic sealed product variety and quality are still unable to meet the introduction of advanced manufacturing technology development and supporting the needs of the construction machinery.
But in practice there are still many drawbacks exist. The main reason is too weak industrial base, the quality and variety of raw materials is not satisfactory, management is not standardized. Which has strong technical capabilities, enterprises only 7-8 sets of advanced equipment (in military seal products produced by the Professional Institute is not listed). Nevertheless, the production of sealing products in terms of quality and service life is still with foreign advanced level more or less the gap. Engineering machinery and high-pressure hydraulic components industry after the introduction of world-renowned manufacturers such as Linde, Carter, Komatsu, ZF word, Rexroth and other manufacturing technology, the domestic sealed SKF bearings product variety and quality can not meet the introduction of advanced manufacturing technology product development and supporting a case in point. Second, demand rather dump truck lifting device with a small cross-section U-shaped ring (AU), due to the poor quality of domestic sealing products, OEMs and users of procurement to foreign companies.
Problem: the quality of the seals and sealing systems design and application level to be improved.
A. Seal product quality
20 years, the joint efforts of domestic scientific and technical personnel, the establishment of a complete integration with ISO/TC131/SC7 various seals install cavity national standards system. Also established the standards of international standards and various types of seals seals - Dimensions, seal performance and seal the appearance of quality, seal packaging, storage, transportation and other seals National Standards System. Thus, INA bearings facilitate the design and selection of construction machinery and other medium and high pressure hydraulic machinery sealing system seals. Gap especially in the hydraulic pump, hydraulic motor and gearbox rotary oil seals and hydraulic cylinder reciprocating seal the product quality is the worst. Oil seal life ZL50C loader drive axle wheel side, the author has done a an installed comparison test, developed by a unit with Vice lip skeleton oil seal, installed after the road test, only 50 km started to leak, capacity assessment of a foreign company BABSL oil seal, the use of the past three years, yet leak. Another example: engineering machinery hydraulic cylinders move the quality of the sealing elements, the level of foreign meet 5000 for hours without leakage, while the domestic seal life in general for their 1/10, some even less than 100 hours of work.
Two. Sealing system design and application level
The sealing system design and application level is dependent on seal products, research capacity, mainly in three aspects.
(1) rotary dynamic sealing system
Still a large number of ordinary standard type oil seal, NTN Bearing pressure rotary seals can only provide pressure for l-3 MPa pressure type oil seal, while the international advanced level of 10 MPa. Acting hydraulic return oil seal applications in engineering and mechanical rotary seals has not been universal.
(2) hydraulic cylinder reciprocating dynamic sealing system
Most of the domestic construction machinery hydraulic cylinder moving sealing system design is still U-shaped ring as the primary seal. Interim design and production of construction machinery hydraulic cylinder dynamic sealing system in the 1990s, began to use the coaxial sealing components and composite design of the U-shaped ring. Commonly used in the seasonal international component (or components), the hydraulic cylinder piston seal assembly with support ring combination, the production process is more complex, the current is stuck in small batch production stage, the quality is less stable.
(3) Static Seals Static Seals, despite the elimination of asbestos and plant fiber sealing products, liquid gasket to use of polymer materials is not yet popular. Domestic use such products still Loctite NACHI bearing all kinds of sealant products. Less domestic liquid sealant for hydraulic system piping connections anaerobic adhesive products brand, and the coating process and quality of performance there are some gaps.
Outlook: China sealed-for-surgery research and medical seals manufacturing industry will face the grim task of engineering Peter mechanical and other medium and high pressure hydraulic machinery industry.
High pressure hydraulic technology development needs, will be a highly intensive, large-scale, low-power, high efficiency, the operating system with the introduction of international advanced technology and manufacturing technology and the development trend of the economy after 2000, U-introduction of advanced technologies based on Chinese construction machinery industry will have a larger development. Hydraulic system pressure and the system's advanced, reliable work. @ The probe. Will promote speaking sealing system design and development of manufacturing technology of sealing elements, therefore, the grim task of sealing technology research and seals manufacturing industry will face the machinery and other works in the high-pressure hydraulic machinery industry. It can be expected, when the sealing industrial system will no longer be a high energy consumption, low efficiency, the heterogeneous structure of small-scale peasant-style business model. By then, the main varieties of Chinese seals will be 60% to the level of quality in the International 80 late in the early 1990s, another 15% of the product variety of the contemporary level of quality of the international seal products. Chinese construction machinery and high-pressure hydraulic machinery sealing system design and application level will reach the mid-1990s of the international technical standards.
Background information: four stages of the Chinese engineering mechanical seal technology
Rubber seals seal for the application of the main construction machinery technology development process can be divided into four stages.
A. The initial stage (1960 - 1970)
This period, Chinese construction machinery products hydraulic system pressure is roughly as 12-14 MPa. The sealing system seals: 0-shaped rubber seals (NBR); the Hulled a leather rotary oil seal; corrugated steel skin 10 cork 10 metal spring face seal; asbestos packing; asbestos 10 rubber gasket; V ring (leather 10 phenolic ten bakelite); V-ring (NBR ten folders fabric]: the case of gasket.
(2) start-up phase (1971 - 1980)
During this period the production of construction machinery IKO bearing the main hydraulic system working pressure of roughly 14 - 3.5 MPa. Sealing system used in seals, rubber seals, mainly out of the leather, asbestos fibers and corrugated steel skin 10 cork face seal. The main types of D as follows: 0-ring (NBR, FKM); the crawler D chassis with floating seal (metal ring dry 0 chart); package skeleton rotary oil seal Chuan the BR D FKM, ZACM). Hydraulic and pneumatic reciprocating motion seals D 0-ring (NBR, FKM); U-shaped density D shot ring (NBR, AU, BU): V-ring (NBR 10 folders of fabric); cup-shaped ring ( NBR ten folders fabric).
Over the past 10 years, to adapt, such as construction machinery, forging machinery, such as the former Ministry of Machinery set up seven specialized rubber and plastic seals manufacturing plant. In addition, to promote the development of sealing technology, was formed in 1975 and 1979, the National Hydraulic, pneumatic Standardization Technical Committee 'hydraulic, pneumatic Standardization Technical Committee rubber seal Standardization Technical Committee (with the old ISO/TCI3 / SC7 corresponding) as well as friction Society of fluid sealing at the Technical Committee.
3. The consolidation and development phase (1981-1990)
Working pressure of the hydraulic system of the domestic construction machinery products reached 16 - 40MPa, the sealing system uses a sealed form is still the rubber sealing products mainly. The main types are: O-ring (NBR, FKM); crawler chassis with floating seals (O - Figure 11 metal rings); lubricated sealed tracked within the skeleton and the outer skeleton of sealed components (NBR + AU): rotation oil Health 10 ( NBR, FKM, ACM, EPDM); combination gasket (NBR + metal); hydraulic cylinder piston and rod density. Sealed coaxial seal assembly (PTFE + NBR); the axis of rotation with hydraulic return oil seal (of NBR, FKM, ACM); and the working pressure for 1 - 3 MPa pressure rotary oil seal (NBR, FKM); KOYO, bearing two-way media rotary oil seal (NBR, FKM), liquid O pressure cylinder piston with a support ring double-acting reciprocating D dynamic sealing components (NBR + PTFE + POM), and so on.
4. High-speed development stage (after 1991)
Construction machinery and other medium and high pressure hydraulic industry has introduced a large number of manufacturing technology, to promote the pace of foreign sealed businesses to enter the Chinese seals market. The entry of foreign capital and technology to improve the overall level of the sealing industry in China.
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