Some standard content:
Mechanical Industry Standard of the People's Republic of China
Cycloidal Pinwheel Reducer
Noise Measurement Method
1 Subject Content and Scope of Application
IB/T 7253
This standard specifies the test conditions, test instruments, measurement point locations and quantity, sound power level calculation, and test result determination for the noise impact power level of cycloidal pinwheel reducers (hereinafter referred to as reducers). This standard is applicable to the A-weighted power level of reducers measured at test sites that meet the requirements (i.e., environmental correction value K: less than or equal to 3dB). When required, the frequency band sound power level and directivity index can also be measured according to this standard. 2 Reference standards
G133241
GB3785
1/1 and 1/3 octave band filters for sound and vibration analysis-Electrical and acoustic properties and test methods of national level metersGR 3917
Scientific terms
G131027 Scientific quantities and units
JIC176 Test and verification procedures for sound level calibratorsJJG:188 Trial verification procedures for sound level meters
3 Test instruments
3.1 The test instruments shall be type 1 or type 0 sound level meters that comply with the provisions of 3785 and other test instruments with equivalent accuracy: When performing spectrum analysis, the 1/1 octave or 1/3 octave band filters used shall comply with the provisions of GB3241, and the test instruments shall be calibrated in accordance with the provisions of JIJG188 and JJC176.
3.2 Calibration of the shield before measurement
The instrument must be calibrated with a grade calibrator with an accuracy of not less than .5dB before and after the measurement. When the difference between the calibration before and after the measurement is greater than 1.013, the measurement is invalid.
4 Test requirements
4.1 Installation of reducer
The reducer should be firmly installed on a stable and reliable foundation to minimize the impact of the test environment. 4.1.1 Double-axis and double-coupling horizontal reducers should be installed horizontally on elastic pads for testing. 4.1.2 Double-axis vertical reducers should be changed to horizontal installation for testing, and elastic pads should be added between the bracket and the foundation. 4.1.3 Direct-connected reducers should be installed vertically on elastic pads for testing: 4.1.4 It is recommended to use 6~20mm thick rubber plates as elastic pads. 4.2 State of reducer during testbzxZ.net
The reducer should be tested in both forward and reverse directions under no-load and rated input speed operation. 4.3 Test room
This standard requires that the reflection of the room should not affect the readings of each measuring point by more than, that is, the environmental correction value K: less than or equal to 3 or: Approved by the Ministry of Machinery Industry of the People's Republic of China on July 18, 1994 and implemented on July 1, 1995
JB/T725394
less than or equal to 3dB octave, and the measurement results should be corrected according to 6.2. If the environmental correction value K is greater than 3, acoustic measures can be taken to improve the sound absorption of the room or select a suitable room. 4.4 Determination of the length 1, width 1 and height 1 of the reference body 4.4.1 The length 1 of the reference body of the double-axis horizontally installed reducer (see Figure 1) is the distance between the outermost plane of the flange at the output end of the reducer and the outermost plane of the input plate (or fan cover), the width 1 is the distance between the outer planes of the plates on both sides of the base, and the height 1 is the distance between the test plate (or the ground) and the highest point of the base (excluding the hanging screws). 4.4.2 The length 1 of the reference body of the direct-connected horizontally installed reducer (see Figure 2) is the distance between the outermost plane of the reducer output end and the top plane of the motor fan wing, the width 1 and the height 1 are the same as those in 4.4.1. 4.4.3 Double-shaft type support-mounted reducer (see Figure 3), the length and height of the base body are the same as those in 1.1, and the width is the outer diameter of the base support plane. 4.4.4 Vertical type vertically mounted reducer (see Figure 4). The length and width of the base body are both the outer diameter of the base support plane. The distance is the distance between the support plane and the top of the motor fan cover (the height of the bracket plus the thickness of the rubber pad). 4.5 Measuring surface and measuring distance The measuring surface is an equivalent rectangular envelope as shown in Figure 1. The maximum measuring distance is the upper (30 mm). 4.6 Measuring point matching cover JB/T7253 · Double-shaft type of step-up transmission The configuration of the measuring points of the horizontal reducer is in accordance with the provisions of Figure 1, and there are 4 measuring points. For the reducer with the center circle diameter of the needle teeth less than 33mm, the height H of the 1~3 measuring points is equal to 250mm. For the reducer with the center circle diameter of the needle teeth equal to and greater than 330mm, the height H of the 1~3 measuring points is equal to the center height of the reducer plus the thickness of the rubber pad. For the direct-connected horizontally installed reducer with a stage transmission, the configuration of the measuring points is in accordance with the provisions of Figure 2, and there are 5 measuring points. For the reducer with the center circle diameter of the needle teeth less than 330mm, the height H of the 1, 2, 3, and 5 measuring points is equal to 250mm. For the reducer with the center circle diameter of the needle teeth equal to and greater than 330mm, the height H of the 1, 2, 3, and 5 measuring points is equal to the center height of the reducer. Add the thickness of the rubber pad. · For double-shaft vertically mounted reducers with stage transmission, the configuration of the measuring points shall be in accordance with the provisions of Figure 3, with 4 measuring points. For reducers with a pinion center diameter of less than 330) mm, the height 11 of measuring points 1 to 3 is equal to 250 mm. For reducers with a pinion center circle diameter equal to and greater than 330) mm, the height 1 of measuring points 1 to 3 is equal to the center height 4 of the reducer. For direct-connected vertically mounted reducers with stage one, stage two, and stage three transmission, the configuration of the measuring points shall be in accordance with the provisions of Figure 4, with 5 measuring points, and the height of point 11 is equal to half of the distance between the support plane of the reducer base and the top plane of the motor fan cover plus the height of the bracket and the rubber pad.12
JB/T 7253-·94
For double-axis horizontal and vertical mounted reducers with two-stage and one-stage transmission, as well as direct-connected horizontal mounted reducers, the allocation of measuring points, the number of measuring points and the height of measuring points shall be based on the central circle diameter of the low-speed stage needle teeth in accordance with 1.6.11.6.2.4. .3 Execution, 4.7 The distance between each measuring point and the reflecting surface shall not be less than 1 (0 (mm, 5 Measurement steps
5.1 Measurement of A-weighted sound pressure level
At each measuring point, the microphone faces the reducer directly, and the reading of the sound level meter is the average value of the needle swing. The observation period shall not be less than 1 (5.2 Measurement of sound pressure level spectrum
In general, 1/1 octave measurement can meet the requirements. When there are special requirements, 1/3 octave measurement is used. The observation period for the frequency band with a center frequency greater than 1GHz shall not be less than 10: the observation period for the frequency band with a center frequency equal to and less than 160H shall not be less than 3055.3 Adjustment of microphone direction
When the microphone faces the airflow When the direction affects the measurement accuracy, the microphone should be moved to a position 45° to the airflow direction to configure the measuring point or add a standard windshield to the microphone. When testing outside the production plant. The wind speed should be less than 6m/$, and the sensor should be protected from wind and dew. 5.4 Background noise
After stopping the reducer, measure the background noise at each measuring point. The difference between the sound pressure level measured during the speed machine test and the background noise pressure level shall not be less than 6dB, otherwise measures should be taken to meet this requirement. The difference between the background noise measured before and after the test should not be greater than 1.B. Background noise correction K: Determined according to 6.1
5.5 Calculation of measurement surface area
The measurement surface area is calculated according to the following formula: S-4(uh: h+ru)
I., -+- cf
Wu Zhong: s
Measurement surface area, m\:
.Measurement distance. m
The length, width and height of the reference body, m,
Calculation of average sound pressure level and sound power level
Background noise correction K (dB)
When the difference between the sound pressure level measured during the reducer test and the background noise sound pressure level is less than 10d3, it should be corrected according to Table 1. Table 1 Background noise correction K
Difference between the sound pressure level and the glottal level of the back noise
Measurement invalid
(2)
6.2 Environmental correction K (dB)
IB/T72 53
When there are unnecessary reflections in the test environment, the measurement results must be corrected. The correction value K is determined according to Table 2. k: greater than 33 - measurement invalid
Correction value K when testing in a fire room or a soundproofing cabinet, equal to 0. Table 2 Environmental correction value K
Room decoration conditions
. The room has strong reflection (such as brick, stone or waxed floor
b. Between a and
C: The room wall has weak reflection (with sound-absorbing materials
Test room area,
rigid surface area m
6.3 Temperature positive correction (KB)
1(0125
150 200 30300
Under normal circumstances, temperature and air pressure have little effect on the measurement results. Replace the temperature at the time of measurement with the standard air pressure at the same time (take! "2: (standard air pressure at the time -100kPa).
When the difference is large, the correction amount should be calculated according to formula (5): K.—10 1g
Wu:?
Ambient temperature at the time of measurement·(;
Ambient air pressure at the time of measurement
K: When it is less than or equal to .5dB, it will be ignored. 6.4A weighted average pressure level calculation
Zp10 lg
Where: Za
A weighted average level dB (A):
273 +t
100000
A-weighted sound pressure level of the measuring point dBCA):
Background noise correction of the measuring point.lI3 (A):Environmental correction dB(A):
Temperature and pressure correction (A):
Total number of measuring points.
When the difference in pressure level of each measuring point is less than 53. The average level can be obtained by arithmetic mean: Lpa
(a-Ki)
Calculation of average sound pressure level in 6.5 frequency band
IB/T 7253--.94
T:=10 lg[
wherein: frequency band average active pressure level.dB
L. frequency band pressure level at the ·th measuring point B
K…frequency band background noise correction at the ·th measuring point, human…frequency band environment correction.d13
6.6A calculation of weighted sound power level
Iwa -- +10 Ig!
Wherein; Lwa
A-weighted sound power level.d(A):
A-weighted average sound level.dBA
Measured surface area.m:
Reference surface area, Im.
6.7 Calculation of frequency band sound power level
wr=—101g
Wherein: Iw.frequency band sound power level·d;
frequency band average sound pressure level.dB
Principles for judging test results
7.1 Evaluate the reducer noise with A-weighted sound power level. When testing the reducer, measure the positive and negative directions respectively. Sound power level, the larger value is the reducer noise level 7.2
8 Report content
The report should include the following contents:
a: Name, model, specification, rated power, rated speed, transmission ratio of the product under test: b. Production unit, production date, factory number of the product under test; c. Measurement basis; d. Acoustic environment: c. Measurement point layout: f. Test instrument name, model, accuracy, production unit: sales: test data and results; h. Test personnel and date, synthesis calculation method: Iw.
JB/T 7253.·94
Appendix A
Method of synthesizing A-weighted sound power level from 1/1 octave band or 1/3 octave band sound power level (supplement)
Lwa- lo lg
Sound power level of the 1st frequency band:
Count correction of the 1st frequency band
\When calculating with 1 octave band, 1Wu=7(, given by Table A1A1
1/1 octave band 1 center frequency/Hz
When using 1/3 octave band sound power level calculation, the above formula jm-21., is given in Table A2, Table A2
1/3 octave band center frequency/112
JB/T 725394
Continued Table A2
173 times the center frequency/H
Appendix B
Calculation of directivity index
(Supplement)
B1 The directivity index of the reducer can be measured in a free field environment (semi-elimination chamber) above a reflecting surface and calculated using B1:
L—L+3
Where:
Directivity index:
Sound pressure level measured on a certain side of the reducer measurement surface, dB;.
The average sound pressure level on the measurement surface d3.
Additional remarks:
This standard was proposed and managed by Tianjin Petrochemical General Machinery Research Institute. This standard was drafted by Tianjin Petrochemical Tongchuan Machinery Research Institute and Tianjin Reducer General Factory, and the main contributors to this standard were Zhang Jiliang and Gong Jingyu. (B1)
Additional Notes:
This standard was proposed and managed by Tianjin Petrochemical General Machinery Research Institute. This standard was drafted by Tianjin Petrochemical Tongchuan Machinery Research Institute and Tianjin Speed Reducer General Factory. The main drafters of this standard were Zhang Jiliang and Gong Jingyu. (B1)
Additional Notes:
This standard was proposed and managed by Tianjin Petrochemical General Machinery Research Institute. This standard was drafted by Tianjin Petrochemical Tongchuan Machinery Research Institute and Tianjin Speed Reducer General Factory. The main drafters of this standard were Zhang Jiliang and Gong Jingyu. (B1)
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