Development trend of special rubber sealing profil

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Development trend of special rubber sealing profiles for aviation

technical status of the industry

basic structure of profiles

special rubber sealing profiles for aviation have different shapes, which can be divided into compression seals and inflatable seals according to their sealing forms

compression rubber sealing belt uses the convex point of rubber section and the stress generated by the rebound of rubber compression to realize sealing, which is mainly used in the fields of large passenger aircraft and so on

advantages: it puts forward high requirements for the compression resilience of rubber materials. The section structure of its seal is diverse, which is only related to the door body required to be sealed, and has little correlation with other mechanisms of the aircraft, with strong relative independence

disadvantages: after long-term and repeated use, it will be affected by the stress relaxation caused by the aging of rubber materials, and the sealing effect will gradually deteriorate. At the same time, at low temperature, the problem of sealing leakage will occur due to the poor low-temperature resilience of rubber

the inflatable rubber sealing belt uses the hollow fully enclosed cavity to fill with gas, and realizes the contact sealing between the rubber surface and the door body through the expansion pressure generated by the gas. The sealing section is mainly a hollow fully enclosed closed structure, which is mainly used in fighter and other fields

the gap between the large sealing hatch and the hatch is subject to thermal expansion and cold contraction deformation due to the influence of processing and assembly accuracy, or the change of ambient temperature, resulting in the gap that needs to be sealed is also inconsistent, or it changes. Its change range is generally more than 3mm, or even more than 10mm. It is difficult to achieve the ideal sealing effect by using ordinary sealing strips. In this case, a sealing product that can change with the sealing gap is needed. Inflatable seal is a new technology successfully researched to meet this need

advantages: compared with the compressed rubber sealing belt, the requirements for the compression performance of the material itself are not so high. It mainly uses the filled gas pressure to adjust the sealing effect, supplement the stress relaxation of the rubber material due to long-term use, and achieve a consistent sealing effect. It will not appear at low temperature because of the poor low-temperature springback of the rubber. The relatively reliable sealing effect is high

disadvantages: due to the working characteristics of its inflatable seal, there are high requirements for the overall air tightness of the sealing belt. The defects of any small part of the sealing belt will cause gas leakage, resulting in the decline of the overall sealing efficiency, and even a major accident of sealing failure; It is highly related to other mechanisms of the aircraft and its maintenance is complex

profile design

the National Aviation record computer displays the pneumatic value. Most advanced enterprises have successfully promoted the application of cad/catia and other design software

the newly designed sealing profiles pay more attention to the functional requirements, changing from the previous sponge rubber sealing profiles and solid rubber sealing profiles to composite rubber sealing strips, involving a variety of rubbers. Its purpose is to promote the overall upgrading of China's new material industry, such as composite sealing profiles, metal skeleton and a variety of rubber composite sealing profiles, and rubber and plastic composite sealing profiles. In some newer model designs, new structural forms of composite rubber sealing profiles with variable cross-section structure and functional composite rubber sealing profiles have even appeared

through the introduction of proe/catia, the designed product parameters can be directly input to the CNC machining center for the design and processing of profile dies

profile molding processing

the molding processing of special rubber sealing profiles for aviation mainly has several major challenges, such as extensive use of materials, complex structure, molding difficulties and so on

the materials used in special rubber sealing profiles for aviation include sponge materials, pure rubber materials, composite rubber materials, metal rubber composites, and various material composites. The different shrinkage characteristics of different materials, the adhesion between interfaces, compatibility and other problems make the co molding of multi materials very difficult

from the use environment of special rubber sealing profiles for aviation, the profile section and overall size span are often designed to be large. The sealing profile of the hatch cover with a small section of 1mm and the sealing profile of the cargo hatch door with a large shape such as the boarding gate can often reach more than 10 meters; The section is simple, such as strip sealing profile, and complex, such as variable section sealing profile

in order to produce rubber sealing profiles with variable cross-section structure, some enterprises have introduced European patented molding technology and equipment. Its principle is mainly that the feeding end and cutting end jointly input signals to the microcomputer through the metal skeleton, the microcomputer output signals control the action of the cylinder at the die, and the variable cross-section sealing strip extrusion production is carried out from its moving multi flap die. Simple variable cross-section can also use mechanical methods or other automatic control methods to control the action of multi lobe die or cutting tool to complete the extrusion molding of variable cross-section profile

from the structure of the design of special rubber sealing profiles for aviation, many profiles are hollow and fully closed structures, and are compounded with fabric materials or metal skeleton materials, so it is very difficult to form. By adopting patented molding technology, some enterprises have realized the overall wrapping of the fabric on the outer fabric of the hollow fully closed structure. The fabric has no joints and laps, and the surface of the sealing profile is smooth and the size consistency is good

profile material

the rubber material used in China's aviation special rubber sealing profile has changed from nitrile rubber, which was widely used in the past, to silicone rubber, fluorosilicone rubber and functional rubber materials

among all kinds of sealing profiles used in China's aviation special rubber sealing profiles, the combination of nitrile rubber and neoprene is the most widely used. Although the blended rubber has good strength and excellent oil resistance, it is not resistant to sunlight. The processed rubber profile often cracks after being used in the flight environment for a period of time, and the service life and safety of the profile are greatly reduced

various aircraft newly designed by European and American countries mostly use silicone rubber as the main material of their special rubber sealing profiles for aviation. Silicone rubber has excellent temperature resistance and weather aging resistance, but it has low strength and does not have flame retardant requirements. In order to improve the strength and wear resistance of silicone rubber sealing profiles, they are often used in combination with fabric materials

most parts of aircraft have requirements for flame resistance. Silicone rubber needs to add various flame retardants when matching materials to make the processed sealing profiles meet the requirements for flame resistance. Flame retardants widely used in the past include aluminum hydroxide, decabromodiphenyl ether, etc. as an aftereffect flame retardant, aluminum hydroxide requires a large amount of filling to achieve a good flame retardant effect, which will seriously damage the mechanical properties of the filling materials. Decabromodiphenyl ether has excellent effect as halogen-containing flame retardant, but its toxic gas released during combustion is difficult to meet the current environmental protection requirements of the aviation industry

in order to meet various requirements, domestic enterprises use composite materials to improve the flame retardant performance of silicone rubber profiles, and achieve the dual requirements of high-efficiency flame retardant and environmental protection by using new and efficient platinum flame retardant. According to the literature, foreign countries have developed new reactive flame retardants, which can achieve the flame retardant effect through the chemical reaction during combustion with only a small amount

for the needs of aviation development, new special rubber sealing profiles for aviation even require special requirements such as electromagnetic shielding, ultra-high temperature resistance, heat conduction, ablation resistance, etc

airworthiness requirements

the use environment of special rubber sealing profiles for aviation determines their differences from other rubber sealing profiles, such as automotive sealing profiles, equipment sealing profiles and aerospace sealing profiles. Its high requirements for safety and repeated use determine the high and low resolution of the torque tester of Jinan new era Testing Instrument Co., Ltd. the resolution of the torque tester is an important indicator of the performance of the instrument, which determines that the special rubber sealing profile for aviation must meet various requirements of airworthiness

airworthiness requirements and airworthiness concepts have not been introduced into the previous special rubber sealing profiles for aviation from design to production and use. With the continuous progress of technology and people's understanding of themselves, people's requirements for the safety of aviation navigation continue to improve. Airworthiness requirements and airworthiness concepts are strictly required to be implemented in the product design and production process. Airworthiness simply means that all kinds of products must have various performance requirements suitable for aviation use. Take the special rubber sealing profile for aviation as an example. First, the functional design of the product during the design of the rubber sealing profile should meet the actual use environment. Second, the process design and control during the production of the rubber sealing profile must be effective and reasonable. The material, production process and product testing process must meet the requirements of various control documents. Finally, the tests of the products produced must meet the requirements of the flight environment. Considering the complexity of the flight environment of the aircraft, various tests must be carried out to ensure that the product can meet the design requirements and meet the actual use requirements of the aircraft

airworthiness requirements and airworthiness concepts abroad were established earlier. Special rubber sealing profiles for aviation used by various aircraft in Europe and the United States must be approved by the airworthiness Bureau before they can be finally installed for use. If domestic special rubber sealing profiles for aviation are to be exported, they must also be subject to various reviews by the airworthiness Bureau. At present, some domestic manufacturers of special rubber sealing profiles for aviation have begun to introduce the concept of airworthiness. From the design and production of sealing profiles to the test process, they are carried out in strict accordance with the requirements of the airworthiness bureau to ensure that the products produced can meet the airworthiness requirements

technical gap at home and abroad

material research

domestic materials are slowly updated, and there is an urgent need to develop some new functional materials with advanced special properties; Lack of serialization and generalization of research and development work; Due to the lack of research funds, affected by the demand and short research cycle, some only solved the problem of whether the products are available or not, did not carry out in-depth and systematic basic material research, and the research on the standardization and serialization of materials is relatively weak. The research and development of materials in foreign advanced countries has become standardized and serialized. The upgrading of sealing materials follows the needs of mechanical equipment, and even drives the development of equipment

product design

most advanced domestic enterprises have successfully promoted and applied design software such as proe/catia. Professional design software is used to comprehensively design the sealing structure design, section selection, three-dimensional dimension and use shape simulation of different profiles according to the application position and use condition requirements of different profiles

however, our experience in profile design is limited, and most of them focus on applied research, lacking basic research on the correlation between material properties and product structural parameters, between product structural parameters, and between structure and service conditions. The design of profile products often cannot meet the use requirements at one time

finished product performance test and evaluation

finished product performance test is an important means to evaluate the rationality of formula, product structure parameter design and finished product performance. Due to the limitations of technology and capital, China's rubber products industry has not put the finished product performance test in its due position, making it far behind developed countries in R & D capacity and technological innovation. In recent years, there are many supporting research and development of various models in China, but there is a lack of means and equipment to test the product performance of special rubber sealing profiles for aviation, and only some products or samples can be carried out

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