Research On Noise Analysis And Control Of Pineapple Leaf Fiber Extractor

Pineapple leaf fiber extractor is the key equipment of fiber processing. The working principle is that the leaf is stroke and scraped and vibrated by the blades on a roller with a very high rotation, which have a certain clearance with the stationary concave board. When the leaf has been destroyed and fresh is got rid of, the fiber is obtained. Because the blade roller has a 2470r/min rotation, the fiber extractor gives a loud noise with 93.7 dB (A) .To prevent this noise does harm to the operator or to the environment and satisfy requirements of the according regulations, analysis on and control the noise of the fiber extractor is needed.In this research, a sound level meter type 2260 made by B&K Corp. and a sound analyzing software BZ7210 version 2.0 based on Fast Fourier Transform technology are used for noise signals collection and data processing. The testing methods and results dealing with are according to China national standard 《 GB 3796-1996 Acoustics-Determination of sound power levels of noise sources using sound pressure-survey method using enveloping measurement surface over a reflecting plane》 .Noise sources of the extractor includes of mechanical noise sources and aerodynamic noise sources. The mechanical noise sources contain of the noise from vibration of the blade roller , the roller cover , the bearings and the noise of the electric motor. The aerodynamic noise sources contain of gyrating noise and blade-vortex noise. Through frequency calculation , spectrum analysis and vibration test of the tow parts made of steel sheet which have a big areas, it is concluded that the aerodynamic noises are the major factor to the noise of extractor, and the blade-vortex noise generated by the blade leading edge are the most important contribution to the aerodynamic noise. The frequency range of extractor noise is from 63Hz TO 16,000Hz, and the major noise peak values are in the range of 315~3,150Hz. The highest noise peak value's central frequency is 1600Hz, which is thought to be related to the blade-vortex noise. The second highest noise peak value's central frequency is 400Hz and 1000Hz, and 400Hz is thought to be related to the gyrating noise. It is show that the sound level are increasing 3~5 dB(A) when the rotation of the blade roller increase every 300r/min from 900 r/min to 2100r/min in different rotation test.Different combination of the three parts are used in order to analyze the influence to...