Car seals are widely used in doors, body, engine compartment and luggage compartment and other parts, with waterproof, sealing, sound insulation and noise reduction and other important role. The car open and closed parts in the process of relative movement trend, so the open and closed parts of the seals become the hardest hit in the seal noise problem, the common open and closed parts of the seals include door frame seals, door seals and luggage compartment seals, etc.
The door frame seal is installed on the side panel stop, and after the door is closed, the upper frame of the body presses the sealing strip bubble tube surface to form a seal. In the process of driving, the sealing strip bubble tube surface and the upper frame of the body relative movement, while the door frame strip "U" type slot firmly fixed in the body on the side surround, to maintain relative static. It is concluded that the noise of the sealing strip is mainly the frictional noise between the body sheet metal and the sealing strip.
The energy generated by friction work, part of the internal energy loss by the rubber material, part of the conversion into heat energy, and part of the conversion into sound energy. When the energy accumulation to a certain extent, the conversion rate of thermal energy can not meet the energy conversion, there is an instantaneous release of energy, thus forming noise.
From the analysis of the seal assembly environment, when the vehicle is moving, the body produces vibration, the seal in contact with the body and the body sheet metal produces relative displacement, the two produce friction between them.
Initially, we hear a small sound, with the passage of time, mutual friction of the object surface collision, because the collision between molecules is extremely frequent, and the direction is random, in the movement, the movement of molecules may migrate kinetic energy to the interior of the object, so that the internal molecules of the object collide with each other, so that the internal molecular movement intensifies, resulting in the whole object becomes hot. After the object becomes hot, it objectively causes an increase in the coefficient of friction, and the increase in the coefficient of friction, which leads to a significant increase in the total energy, thus increasing the chance of the appearance of high frequency noise.
In addition, the sliding speed has an important influence on the friction coefficient and the generation and evolution of high-frequency noise. Increasing with the sliding speed not only increases the volume, but also leads to an increase in the variation of the friction coefficient, thus increasing the chance of forming high-frequency noise. Friction coefficient on the sliding speed changes show a certain threshold sex, and a large friction coefficient is more likely to produce high-frequency noise. And when the relative rate is greater than a certain value, the coefficient of friction and wear are rapidly declining, S increase in speed than the rate of reduction in the coefficient of friction μ, which explains why in the relatively gentle road, we can not hear the noise.
The above analysis from the friction force work, friction coefficient and noise, sliding speed and volume, reduce the friction coefficient and reduce the sliding speed can effectively control the odds of noise generation and volume of the foreign noise source. If you need to reduce the sound energy, then you can increase the internal energy consumption of the rubber itself or increase the heat energy, but the increase in friction heat, resulting in an increase in the coefficient of friction μ, the chance of high-frequency noise increases, so it is best to reduce the noise from increasing the internal energy consumption of the material.
To reduce reverberation, on the one hand, reduce the source of reverberation, on the other hand, increase the acoustic propagation loss. Reduce the source of noise, mainly from the reduction of friction coefficient and reduce the sliding speed of two aspects; increase the acoustic propagation loss can start from the rubber itself, the choice of rubber materials and matching agent with high internal consumption, or the use of covering materials to change the acoustic propagation channel to improve energy loss.
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