This standard specifies the method of measuring the sound pressure level on the measuring surface of an imaginary envelope machine tool in an acoustic test environment with a free field above a reflecting plane, and calculating the sound power level. The data obtained are used to evaluate and compare the sound power level of machine tool noise. The measurement method in this standard is determined according to the acoustic test environment and measurement requirements. The measurement methods are divided into engineering method, quasi-engineering method and simple method. The engineering method and quasi-engineering method are applicable to various machine tools that radiate steady-state, non-steady-state broadband noise or narrowband noise, but not to machine tools that radiate pulse noise and linear scales exceeding 15m. The simple method is applicable to machine tools that radiate broadband, narrowband, discrete frequency and other steady-state noise. In addition to burst sounds with a repetition rate of less than 5 per second, it is also applicable to machine tools that radiate non-steady-state noise. There is no restriction on the volume of the machine tool to be tested. For machine tools with extra-large sizes, the part with the main noise source is selected for measurement. GB/T 4215-1984 Determination of sound power level of noise in metal cutting machine tools GB/T4215-1984 standard download decompression password: www.bzxz.net

1 Introduction
National Standard of the People's Republic of China
Determination of sound power levels of metal cutting machine tools
Determinati on of sound power levels of metal seen by metal cutting machine tools UDC 534.885
GB4215-84
1.1 This standard specifies the method of calculating the sound power level by measuring the sound pressure level on the measuring surface of an imaginary envelope machine tool in an acoustic test environment with a free field above a reflecting plane. The data obtained are used to evaluate and compare the sound power level of machine tool noise. 1.2 The measurement method in this standard is determined according to the acoustic test environment and measurement requirements. The measurement methods are divided into engineering method, quasi-engineering method and simple method. The engineering method and engineering method are applicable to various types of machine tools that radiate steady-state, non-steady-state broadband noise or narrowband noise, but are not applicable to machine tools that radiate pulse noise and have a linear scale of more than 15m. The simple method is applicable to machine tools that radiate broadband, narrowband, discrete frequency and other steady-state noises. In addition to the sound with a repetition rate of less than 5 per second, it is also applicable to machine tools that radiate non-steady-state noises. There is no limit on the volume of the machine tool to be tested. For machine tools with extra-large sizes, the part with the main noise source is selected for measurement. 1.8 This standard is formulated with reference to the national standards GB3767-83 "Determination of sound power level of noise source - engineering method and quasi-engineering method" and GB376883 "Determination of sound power level of noise source - simple method".
The names and symbols of terms, quantities and units used in this standard are in accordance with the provisions of national standards on acoustics such as GB3947-83 "Terms of Acoustics" and GB3102.7-82 "Quantities and Units of Acoustics". Measurement items and measurement errors
2.1 Engineering method
2.1.1 Measurement items: A sound power level and frequency band sound power level. When there is a special need, other weighted sound power levels can be selected. 2.1.2 Measurement error, the standard deviation of the sound power level A is not greater than 2dB: the standard deviation of the sound power level of 1/1 octave band and 1/3 octave band is not greater than the requirements in Table 1. Table 1 Error of sound power level in frequency band
Center frequency of 1/1 octave band
250—500
1000--4000
Center frequency of 1/3 octave band
100—160
200 630
800 —5000wwW.bzxz.Net
630010000
Note: ① The measurement error here refers to the cumulative standard deviation caused by various attenuation factors. ② The standard deviation of the sound power level in the frequency band below 63Hz is about 5dB. 2.2 Quasi-engineering method
2.2.1 Measurement item: A sound power level.
Published by the National Bureau of Standards on August 24, 1984
Implemented on January 1, 1986
GB4215-84
2.2.2 Measurement error: standard deviation is not more than 3dB. 2.3 Simple method
2.3.1 Measurement item: A sound power level.
2.3.2 Measurement error: for machine tools that radiate noise with uniform spectral density, the standard deviation is not more than 4dB; for machine tools that radiate noise with discrete frequencies, the standard deviation is not more than 5dB; when comparing machine tools of the same type and specification in the same test environment, the standard deviation is less than 3dB.
8 Acoustic environment
3.1 The acoustic environment that meets this standard is: a room with a free field above a reflecting plane or a flat outdoor square with a hard reflecting surface. The size of the reflective surface should be at least 1/2 larger than the size of the projection of the measuring surface on each side, 1 is the wavelength corresponding to the lowest measured frequency (m).
3.2 Generally, the environmental correction value K, or A/S [A is the room sound absorption (m2), S is the surface area of ​​the measuring fish (m2)] is used to measure the degree to which the test environment meets the test requirements. When the test environment meets K, <2.2, or 4/S>6, the engineering method is used! a.
When the test environment meets 2.2
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