(1) Choice of vibration measurement method: planetary reducer
There are two ways to measure the vibration of the planetary reducer gear unit, one is to measure the vibration of the box and the other is to measure the vibration of the shaft.It is also often more effective to combine these two measurement methods to obtain the absolute movement of the shaft in the gear unit.
For planetary reducer gear units supported by rolling bearings, the radial clearance of the bearings is small, and the relative movement between the bearings and the box is also small, so the vibration measurement of the box should be used.For gear units supported by ordinary sliding bearings, shaft vibration measurement or box vibration measurement can be used.However, when the frequency is in the range of 0-500Hz, it is not easy to measure small vibrations due to the insensitivity of the box vibration measurement, and the shaft vibration measurement should be used.The vibration measurement of the box can obtain a wide frequency range and its dynamic characteristics, which can provide the necessary basis for the analysis of the meshing frequency of the gear teeth.
(2) Shaft vibration measurement:
The vibration displacement of the shaft shall be measured relative to the housing.A non-contact sensor should be used, and the sensor should be installed as close to the bearing as possible and fixed at a more rigid part of the box.Vibration in three mutually perpendicular directions of the shaft shall be measured, one of which shall be parallel to the axis.There must be an axial sensor on each shaft.The number of measuring points and the installation position shall be determined through negotiation between the user and the manufacturer.
(3) Vibration measurement of the box:
The vibration of the box should be measured at a more rigid part of the box (such as the bearing seat).Measurements should be made in three mutually perpendicular directions, two of which must lie in a plane perpendicular to the axis of rotation of the gear, preferably a horizontal or vertical plane.The number and installation position of sensors shall be determined through consultation between the user and the manufacturer.
Gear unit vibration measurements should be made during the factory run-in.The vibration measurement conditions stipulated in GB/T 6404.2-2005 are as follows.
Gear unit condition:
1. The gear device should run at the rated speed during the test. If the gear device is used in variable speed conditions, the test should be the arithmetic mean value within the speed range
at speed.
2. During the test, the gear device should run in the direction given by the design; if the gear device is reversible, the test should be carried out in both directions.
3. The gear device can be loaded or run without load during the test, which is agreed between the manufacturer and the user.
4. During the test, the lubrication of the gear unit and the temperature of the machine should meet the design requirements.
Acceptance value (grade):
(1) Evaluation curve
For the acceptance evaluation of a gear unit for a given application, the manufacturer and user negotiate to select the evaluation value in the figure, and compare it with the measurement value obtained by the measuring instrument selected by both parties.For acceptance, either one standard can be used uniformly for the entire gear unit, or individual rating standards can be used for each shaft or each measuring position.
When there is no measured frequency spectrum data or the data is incomplete, the following provisions may be used as the acceptance criteria for the total vibration level.
1. Take the rotational speed of the shaft as the nominal frequency, compare the maximum value of the unfiltered shaft displacement value with the value, and take the level not lower than the evaluation curve close to this value as the nominal vibration displacement level of the unfiltered shaft.
2. Compare the maximum value of the root mean square value of the unfiltered cabinet vibration velocity, and take the level of the evaluation curve that is not lower than and closest to this value as the unfiltered cabinet nominal vibration velocity level.
(2) Evaluation of axial displacement
Compare the shaft displacement spectrum measured by the 1'3-octave filter with , and take the level that contains and is closest to the evaluation level of the spectrum as the displacement evaluation level of the shaft, and take the level of all measured shafts of the gear device as The highest rating is used as the vibration level of the gear unit.
(3) Evaluation of planetary reducer box vibration
Compare the cabinet vibration velocity spectrum (root mean square value of velocity) measured by the 1/3 octave filter, and use the level that contains the evaluation curve closest to the spectrum as the evaluation of the cabinet vibration velocity at this place Level, take the highest evaluation level at all measurement positions of the gear unit as the vibration level of the gear unit.
