GB/T 23281-2009Metal forming machinery -- Noise measurement method of sound pressure levels (English PDF)

5.1 Overview

This standard applies to the environment in accordance with 5.2 and the background noise is corrected according to 5.3.

5.2 Applicable criteria for test environment

The environmental correction value K2A of the test environment (as defined in GB/T 23282-2009 Measurement Method for Noise Sound Power Level of Forging Machinery) is used to characterize the degree to which the test environment deviates from the ideal, free field condition, the environmental correction value K2A should not exceed 7dB.

5.3 Background noise correction criteria

At the microphone position, the background noise measured as the weighted sound pressure level (including wind noise at the microphone) should be at least lower than the measured mechanical sound level 3dB (preferably lower than 10dB), the background noise correction value is calculated according to formula (1).

K1 = -10lg1-10-0.1delta() L (1) where.

deltaL---The difference in sound pressure level measured at the specified position when the forging machine under test is opened and closed, the unit is decibel (dB).

Note. If deltaL>10dB, K1A=0 is specified; if deltaL3dB), the measurement is invalid; K1A for each microphone position should be determined.

5.4 Environmental conditions during measurement

5.4.1 Indoor test environment

5.4.1.1 The ratio of the equivalent sound absorption area A of the test house to the measurement surface area S should be greater than or equal to 1, that is, A/S>=1 (when A/S=1 Environmental correction value K2A=7dB).

5.4.1.2 Objects that interfere with the sound field should be as far away as possible from the forging machine to be measured, at least outside the measurement surface.

5.4.1.3 The reflecting surface (ground) should be larger than the projection of the measuring surface on the reflecting surface (ground).

5.4.1.4 The ground on which the machine is installed is preferably concrete or asphalt poured.

5.4.2 Outdoor test environment

5.4.2.1 Outdoor measurement should be carried out on open, flat and hard ground, but not on sand, snow or grass.

5.4.2.2 The wind speed should be less than 6m/s during measurement. When the wind speed is greater than 1m/s, a windshield should be added to the microphone.

5.4.2.3 The measurement shall not be carried out under severe weather conditions such as rain and snow.

5.5 Local environment correction value

Appendix A gives the determination of the local environment correction value K3, K3 considers the impact of reflected sound on the emission sound pressure level at the designated location. A-weighted

When the local environment correction value K3A should not exceed 2.5dB.

Note. If the limit of 2.5dB is exceeded, the accuracy of the results will be reduced.

GB/T 23281-2009

8.1 Overview

This chapter specifies the relevant installation and operating conditions. For the forging machinery to be tested, if there is a noise test procedure, the relevant Regulation. Noise test procedures for forging machinery should detail their installation, placement, and operating conditions.

For large equipment, the installation and operation of the parts, components, auxiliary equipment, power source, etc. of the machine should be determined.

8.2 The position of the forging machine to be tested the forging machine under test should be installed on a reflective surface according to normal use conditions, and should be kept away from any walls, ceilings or other reflections.

shot surface.

8.3 Installation of forging machinery during measurement

In many cases, the noise emission at the specified location of the forging machine under test is related to the installation conditions. When the forging machinery meets the specified installation conditions , this condition should be used whenever possible.

If the specified installation conditions are not available or these conditions cannot be used for the test, the machine radiation caused by the installation used for the test should be avoided Changes in noise, and take measures to reduce the radiated noise generated by equipment installation.

8.3.1 During the measurement, the installation and fixing state of the forging machine to be tested should generally be consistent with the stipulations in the product manual, and the distance from the wall should be shall not be less than 2m.

8.3.2 During the measurement, all the safety devices, noise reduction and sound insulation devices, etc. supplied randomly shall be installed on the forging machinery.

8.3.3 All auxiliary equipment required for the work of the forging machine under test but not part of the sound source shall be located outside the test environment. Otherwise, auxiliary Auxiliary equipment shall be included in the reference body and its working conditions shall be expressed in the test report.

8.4 Operation of the forging machinery during the test

8.4.1 During the measurement, the auxiliary device of the forging machine under test shall act together with the main engine.

8.4.2 During the measurement, the forging machine shall be in no-load continuous operation (driving the working mechanism to operate) or in a single stroke.

8.4.3 Forging machines with adjustable stroke and speed shall be measured at the maximum stroke and maximum speed.

8.4.4 The noise of the tested forging machinery shall be measured according to the test procedure.

9.1 Steady-state noise

When the tested forging machine is in the specified action specification, it is the radiated "steady-state noise" [that is, the frequency weighting of the sound level meter is used at the observation time "A", when the time-weighted characteristic is "slow", the fluctuation of the indication value is less than ±3dB (A) noise], the observation time shall not be less than 15s, and the reading is Take the average value of the maximum and minimum indications of the sound level meter during the observation time.

9.2 Unsteady Noise

When the tested forging machine is in the specified action specification, it is the radiated "unsteady noise" (that is, the sound pressure level changes significantly during the observation time) noise, that is, when the frequency-weighted "A" and "slow" time-weighted characteristics of the sound level meter are used, the fluctuation of the indication value is greater than ±3dB) , measure with an integrating sound level meter. Periodically changing non-stationary noise can also be measured by the "slow" time-weighted characteristic of the sound level meter.

The sound pressure level and duration of each cycle were recorded to calculate the average value of one cycle.

GB/T 23281-2009