Rubber and plastic seals are an important basic component of mechanical products, and their manufacturing accuracy requirements are high. With the rapid growth of my country's automobile manufacturing and automobile ownership, seal products require high-precision technology and equipment both in structure and material. support. In recent years, some enterprises in the professional production of seals in my country have adapted to the market positioning, adjusted their industrial structure and product structure in time, and developed rapidly. While rapidly increasing the output value, a large investment has also been made in the production and testing experimental equipment.
Figure 1: DF sealing ring in metallurgical industry
Domestic and foreign technology development trends
◆Development trend of rubber and plastic sealing materials
Research on the formulation and processing technology of special rubber and plastic materials such as nitrile, hydrogenated nitrile, fluorine rubber, acrylate rubber, and polytetrafluoroethylene commonly used in rubber and plastic seals. Improving the applicability and utilization rate of materials is still the focus of work. The application of nanomaterials will improve the mechanical properties and special functions of rubber and plastic materials. One of the first four national standards for nanomaterials promulgated and implemented by the National Standardization Committee on April 1 this year is the "nano-zinc oxide" standard for rubber.
Special engineering elastomers have replaced low-performance oil-resistant rubber; surface treatment of rubber bright surfaces; modification of rubber and plastic materials and application of liquid rubber materials through nanotechnology have made some progress in recent years. Especially the recent application of some new materials has greatly promoted the rubber and plastic sealing technology.
The relatively weak thermoplastic elastomer (TPE) used in seals in my country has the physical properties of vulcanized rubber and the processability of thermoplastic resins. The molding process does not require vulcanization, so it is used as the third-generation rubber. Among the main varieties, TPO, TPV, and TPU have been widely used in the world: the application of TPV in automobiles has an average annual growth rate of 15%. Generally, it is a fully cross-linked compound of EPDN and PP, which combines high tensile strength, oil resistance, heat resistance, etc. It can withstand 150 ℃ hot oil conditions for a long time, and can be used to replace EPDM in the production of automotive seals and other products; TPO is currently mostly composed of EPDM and polyethylene components, and the production process has a mechanical blending method and dynamic vulcanization. in TPO produced by dynamic vulcanization. The rubber component is as high as 60-70%, and the wear resistance, ozone resistance, high tear strength, small compression deformation, and comprehensive performance are better than EPDM vulcanized rubber.
The United States, Western Europe and Asia are continuing to build TPO production facilities; TPU has both excellent plastic processing properties and rubber physical properties, and its wear resistance, low temperature resistance, radiation resistance are excellent. , daily necessities, military materials and other industries have made great progress. TPU can be widely used in automobile shock pads, bushings, bearing bushes, bushings, airbags and other parts.
◆New materials introduced by domestic and foreign companies
1. Perfluoroelastomer FFKM
High temperature resistance (250℃～320℃), gas resistance and strong chemical corrosion resistance, good elasticity, low compression set, good elasticity, etc., suitable for some very harsh working conditions. It is used in chemical, food, printing, semiconductor and other industries. Launched by Parker, Evco and others.
2. Fluoroplastic coated rubber products
Fluoroplastic varieties such as FEP (fluorinated propylene) and PFA (perfluorinated compound) are coated with rubber O-rings and rubber gaskets (such as plate heat exchanger seals) to improve the resistance of rubber products to media (solvent, strong acid, strong alkali) ), launched by Shanghai Yigang, EVCO, Fluorten and other companies.
3. Unique polyurethane material
PU 92 AU 21100 has good lubricity, and its ultra-low temperature resistance reaches 20K (-253 ℃), and it can withstand ultra-low temperature conditions. Simrit exclusive.
4. Polytetrafluoroethylene (PTFE) compounding and modification
In order to overcome the shortcomings of PTFE such as cold fluidity and poor thermal conductivity, and reduce product wear, PTFE material is used as the matrix and carbon fiber, polyimide (PI), polyetheretherketone (PEEK), polyphenylene sulfide (PPS) and other materials are used. Composite, develop oil-free lubricating seals (piston ring, guide ring, packing ring), which are widely used in medium and high pressure oil-free lubricating compressors. This type of seal developed by Guangyan Sealing is used in many well-known compressors in China.
The application of expanded polytetrafluoroethylene, expanded polytetrafluoroethylene is a tough, porous, and highly fibrous new material formed by stretching and puffing, which not only maintains the unique chemical stability of polytetrafluoroethylene itself , extremely low friction coefficient, wide operating temperature, and its microfiber internal structure makes its products have unimaginable toughness.
◆New product structure
In recent years, with people's attention to sealing technology, new sealing structures are emerging constantly, which can meet the domestic market demand in terms of technical level, quality level and cost performance and push them to the international market.
1. New oil seal: The oil seal is equipped with a sensor for testing the leakage of the seal (rotary seal), which can be used for online state detection of equipment leakage. It is exclusively introduced by Simrit;
2. Evd sealing system: After the oil cylinder seal is worn and deformed, a special device is used to adjust the internal pressure of the seal (elastomer) to eliminate leakage, and it is used for equipment with very high reliability requirements (such as servo oil cylinder, water conservancy oil cylinder) . Launched by Hunger Corporation;
3. The spindle with the new SETCO AirShieldTM seal integrates the advantages of friction seal and labyrinth seal. Compressed air is tangentially fed into the circulation groove of the fixed front bearing seat, forming a closed labyrinth together with the main shaft. Air flows around the main shaft in the groove. The vortex-like motion creates uniform pressure, dissipating airflow with an even flow. Combined with the flexible sealing lip, the leakage air will blow the dirt away from the main shaft, mainly the bearing;
4. Structural innovation of PTFE seals: PTFE seals have derived many new structures, which are used in reciprocating seals, rotary seals, static seals, such as AQ seals, PTFE-V-rings, pan-plug seals and other sealing systems. seal.
◆New development of manufacturing equipment and testing instruments
The production equipment and testing technology of seals are developing in the direction of automation, low cost and high reliability.
The rubber compound mixing equipment is equipped with an internal mixer system with automatic batching and automatic control of the mixing process, which can effectively achieve energy saving and high efficiency, reduce environmental pollution, and at the same time produce high-quality compounding compounds. In order to improve the effectiveness and efficiency of internal mixing, manufacturers' research focuses on the shape of the rotor of the internal mixer. Japan's Kobe Steel Works and Farrell have developed 4WH rotors and ST rotor mixers respectively, while the GK-E rotor developed by Japan's Mitsubishi Heavy Industries focuses on production efficiency.
In terms of molding technology, high-efficiency, advanced and high-quality rubber injection molding processing technology is widely used abroad. The screw reciprocating injection machine for small products and the screw plunger injection machine for large-scale products can effectively improve the appearance quality and performance of seals and save raw materials. Paker Company produces O-rings, and uses an injection machine to make products with small flash edges. With the three processes of liquid nitrogen freezing trimming, plastic pellet trimming and water stone washing, the appearance of the product has reached a very high level.
In terms of vulcanization process equipment, many domestic manufacturers of seals are currently equipped with vacuum flatbed machines and injection machines, and ordinary flatbed vulcanizers are also heated by circulating oil to ensure process stability.
The Austrian company Aikonomos has made a big breakthrough in the traditional production of sealing rings. The company's machining equipment for producing seals can produce seals by machining, which is suitable for the production of seals of various materials, and its market share is expanding year by year.
At the same time, the manufacturer also attaches great importance to the secondary development of the design software, and has a good ability to analyze the processing fluidity of the mold cavity material. The precision of the CNC equipment mold has been widely used in the processing and manufacturing, and the apparent quality has reached a very high level. It has greatly promoted the technological development of my country's rubber and plastic sealing industry.
In terms of inspection technology, the latest development is the use of optical systems. For example, companies such as Freudenbezy use the third-generation new optical system developed by KMK, which completely replaces manual inspection and successfully integrates the quality inspection of seals into the production process. This image processing system achieves extremely high inspection speed and inspection accuracy, and can detect the smallest defects on the surface of seals, such as cracks, air bubbles, impurities and slip lines.
Domestic seal companies have also introduced oil seal detection devices that measure oil seal lip tension as the main basis, and gas-sensing detectors (Italy) that measure oil seal lip sealing performance by detecting changes in air pressure. It has a high detection rate and can be detected every hour. 1200-1800 oil seals.
CNC machine tools have been widely used in processing and manufacturing, and professional mold manufacturing companies have basically achieved full CNC. The precision and apparent quality of the mold have reached a very high level. At present, many domestic rubber and plastic seal companies are equipped with CNC machining equipment, and have accumulated a lot of experience in mold design and processing application of CAD/CAM.
Figure 2: Various sealing products
Suggestions for the development of the sealing industry
The machinery industry develops seven major equipment manufacturing fields, including basic equipment, energy equipment, transportation equipment, raw material industrial equipment, modern agricultural equipment, environmental protection equipment, green manufacturing technology and equipment, and strengthens research on basic processes and common technologies. Micro-nano manufacturing technology is the starting point, implement the scientific development concept of green manufacturing, expand and extend the connotation of services, and make the manufacturing industry move towards advanced. In order to adapt to the development goals of the machinery industry, the development of enterprises in the rubber and plastic seal industry should focus on brand awareness, environmental protection awareness and standardization. Strengthen the research and development of products with independent intellectual property rights, and promote the progress of common technologies in the industry.
◆Creating a national brand and promoting advanced services
At present, our industry is still dominated by ordinary structural products with a large quantity and a wide range, and there is a high degree of homogeneity. In terms of brand creation, we do not have a well-known brand like "Parker", "Busak+Shamban", or even a national famous trademark. Without a strong brand effect, it is difficult for users to distinguish the quality level of each company's products. Therefore, when choosing similar products, price is often the main selection factor, which leads to mutual suppression within our industry and a vicious circle of smaller and smaller profit margins.
◆Strengthen the application of green manufacturing technology
Green manufacturing technology is the technical basis for the implementation of ISO14001; adopt green design technology; adopt clean energy to eliminate or reduce harmful emissions; adopt energy-saving technology to improve energy utilization; adopt precision molding technology to improve material utilization; non-toxic and low-toxic technology Materials and processes to minimize harmful emissions; low-vibration, low-noise, low-radiation process equipment; waste recycling;
◆Standardization system construction
The construction of a standardized system is an important part of the production, operation and management of an enterprise, a necessary condition for organizing modern socialized large-scale production, and a prerequisite for realizing specialized production. Raw materials and energy consumption are important guarantees for stabilizing and improving product quality, the basis for realizing scientific and modern management, an important way for continuous improvement, and an important measure to ensure production safety and strengthen environmental management. Information technology, to achieve technological progress.
◆Accelerate specialized and characteristic production
At present, most of my country's rubber and plastic sealing enterprises focus on grasping immediate benefits. As long as the customer needs it, no matter the scale or the amount of income, we will do it if we have work and business. As for the division of labor in the industry, its own characteristics and specialties, they often don't care much. It has formed a similar industry environment for hundreds of factories, with low-level repetition, without prominent competitive advantages, and it is difficult to form the best economic benefit model. It restricts the development of enterprises and industries and is not conducive to long-term development. Therefore, while seeking current economic benefits, enterprises must take a long-term view and accelerate the realization of specialized and characteristic production.
◆Perfect technology research platform
The Chinese government attaches great importance to and encourages the construction of technology research platforms, because all new technologies that develop rapidly rely on technology research platforms to play a huge role. This is still relatively weak in basic industries. my country's rubber and plastic seals have established a standardization committee and a hydraulic and pneumatic seals industry association. They have not yet established a national rubber and plastic seal engineering technology research and development center and its technological innovation system. The lack of industry technology platforms makes many OEMs unable to find technical support in time.
All in all, with the rapid development of my country's machinery industry, especially the development of the automobile industry and electronic communication industry, my country's rubber and plastic seal industry has an irreplaceable practical significance and far-reaching connotation of industry development.
Under the new international environment, the global rubber and plastic seal product manufacturing base will continue to shift to my country. my country's rubber and plastic seal industry will also usher in a period of leap-forward development, and will certainly make greater contributions to the development of my country's new industrialization.