With the unremitting pursuit of higher quality of life, science and technology have been developing rapidly. For mechanical engineering sealing technology, it is developing in the direction of green and intelligence; To meet the requirements of green manufacturing, energy conservation and environmental protection and long life , high reliability, and micro / zero leakage of mechanical equipment under extreme environment / harsh working conditions, the performance requirements of polymer sealing materials are also higher and higher, which will face more arduous challenges for China’s polymer material industry, which is already in the backward stage. However, in any case, understanding the development trend and requirements of relevant materials is conducive to promoting the development of relevant industries in China, mainly including the following aspects:
(1) High and low temperature range
On the lunar surface, the temperature is as low as – 160 ~ – 180 ℃ at night and 130 ~ 160 ℃ during the day, and the temperature difference is as high as 340 ℃. Therefore, high requirements are put forward for the high and low temperature resistance and ultra wide temperature range of polymer sealing materials.
(2) High speed and high pressure
The hydraulic system is developed to 80000 R / min and 105 MPa, and the deep well pressure can reach 140 MPa. Polymer sealing materials are required to have excellent pressure resistance, extrusion resistance, low friction and wear performance and compression permanent deformation resistance.
(3) Complex media environment
The wide application of new fuel oil, new lubricating oil, and various additives that have a strong corrosive effect on polymer materials in automotive engines and hydraulic systems, as well as the complex medium environment of multi-media hydraulic and pneumatic components for deep good drilling , metallurgy, chemical industry, and petroleum, all put forward higher requirements for the medium resistance characteristics of polymer sealing materials: Chang and others use different fillers to fill and modify nitrile rubber, A series of Sealing Composites with better coolant resistance were obtained. Xu Yuduo and others used blending to modify nitrile rubber to improve the ozone and oil resistance of silicone seals. Taking the oil seal as an example, the actual working medium environment is complex. In addition to modifying the base material, to improve the sealing retention ability of the oil seal, rubber and plastic seals such as metal skeleton oil seals and cloth clamp oil seals have been d developed based on the all-rubber material oil seal. At the same time, the installation of a spring can improve the sealing force, which can compensate for the wear of the end face of the friction pair and reduce the leakage rate.
Rubber and plastic seal inspection
At present, rubber and plastic sealing products are developing in the direction of “high-end, extreme, high requirements and long life”. To ensure the quality of rubber and plastic sealing products, more perfect inspection and testing are needed.
Rubber and plastic sealing inspection and testing technology include sealing material performance testing, product appearance dimension analysis, and testing, sealing performance analysis and testing, etc. The material performance test is an important means to evaluate the formula of sealing materials. Modern analytical instruments are used to comprehensively evaluate the sealing materials scientifically and reasonably by testing material composition, physical and chemical properties, and mechanical properties. However, the material performance cannot directly determine the sealing performance, so a product-level performance test must be carried out. Product appearance dimension analysis and test are the simplest means of preliminary screening of sealing rings. It is divided into the appearance analysis of working face and nonworking face, and the measurement of macro dimension by contact or non-contact method based on national standards or industry standards. Sealing performance analy sis and test, including product functional test, simulated life test, field installation test, etc., are mainly used for sealing structure selection, design, production, and sampling test of manufacturers. The functional test includes testing the shaft holding force, mouth opening force, compressive stress relaxation, static torque, etc. For the life test of the sealing ring, because the field test is difficult, time-consuming, and expensive, the commonly used method is the simulated life test to observe, analyze and compare the quality and working life of the sealing ring in a short time. The installation test is the final application assessment of the seal delivered after passing all the above tests, which is generally completed by the seal user.
In the future, rubber and plastic seal detection technology will mainly develop in the direction of full life cycle and more accurate data:
(1) Joint test under multiple working conditions: in the actual service process, rubber and plastic sealing products are under the joint action of the working medium, grinding surface, and whole machine environment, and will also be affected by many uncontrollable factors such as friction heat, mechanical vibration, and eccentric inclination. The working environment is very complex, and corresponding to rubber and plastic sealing used in an extreme environment or severe working conditions, this influence will be amplified, This results in significant differences between the actual service performance and the test results. Therefore, the joint testing of rubber and plastic seals under multiple working conditions is the development direction to ensure the service performance of products and improve the detection accuracy and reliability in the future.
(2) Dynamic monitoring of service process: in the service process of rubber plastic seal, under the joint influence of complex factors such as medium, friction and temperature, macro/microstructure, physicochemical properties, and other parameters change from time to time, and some unpredictable external shocks will also have an unpredictable impact on the sealing system in service. Under the action of this sudden impact, the rubber plastic seal may have special deformation or deformation, resulting in the reduction of service life and potential safety hazards. Therefore, for rubber and plastic seals with special working conditions or high safety levels, dynamic monitoring during service is required to ensure the safety and stability of rubber and plastic seal products.
Large rubber and plastic seals for high-end equipment such as large water turbine units, wind turbine spindles, shield machines and die forging presses. Due to the large size of this type of product, compared with traditional small parts and unique processing characteristics, it is necessary to study its processing equipment and process accordingly. Taking the manufacturing process of a large O-shaped silicone seal rings as an example, to solve the problems of poor material homogeneity and difficult precision processing, the current domestic scheme is to install a heating device directly on the rubber mold, which is both vulcanization medium and heat source. This way greatly improves the product quality. Saint Gobain high-performance plastics The company in France adopts the method of welding and extruding peek bars to prepare large-diameter thermoplastic seals.
With the accelerated development of the new generation of technological revolution, the era of a new generation of information technology represented by automation, informatization, and intelligence has come. The accelerated application of the new generation of information technology in the traditional rubber and plastic sealing industry has become a trend. The application of digital intelligent manufacturing technology has appeared in some rubber and plastic sealing enterprises. Practice shows that emerging technologies can greatly improve product quality, reliability and production efficiency.