1 Gear vibration signal extraction The detection of rotating machinery faults such as bearings and gears generally uses vibration. The operating state of the time domain signal characteristic parameters and spectrum analysis is judged. The bearing and the gear are mounted on the same shaft. There is only one measuring point when detecting, and the vibrations of both are collected together to form signal interference. In order to detect the vibration of the gear separately, it is necessary to eliminate the vibration signal of the bearing as much as possible.
The vibration of the bearing is high frequency vibration, generally above 4000 Hz.
When the rotational speed of the wheelset is 400r/min, the bearing vibration signal is below 8000Hz, so the cutoff frequency of the signal when detecting the bearing is set at 8000Hz.
The vibration of the gear is mainly reflected in its meshing frequency. The calculation formula of the meshing frequency is as follows:
Fm=frN
Where Fm is the meshing frequency; fr is the frequency of the axis; N is the number of gear teeth.
When the top wheel of the locomotive is detected, the wheelset speed is 400r/min, and the gear ratio of the DF4B cargo locomotive is 6314 (the number of teeth of the large gear is 63, the number of teeth of the motor shaft pinion is 14), so the meshing frequency Fm=(400/60)63 =420Hz; DF8B's gear ratio is 7717, its meshing frequency Fm=(400/60)77=513Hz.
Therefore, when detecting the gear separately, the cutoff frequency should include both the gear vibration and the vibration of the bearing. Considering the frequency multiplication of the meshing frequency, the cutoff frequency is 34 times the meshing frequency, so the cutoff frequency of the gear vibration signal is collected. Set at 2000Hz, the interference of bearing vibration can be eliminated.
2 gear failure type and diagnosis 2.1 excessive tooth surface wear or gap excessive gear normal vibration meshing frequency amplitude is small, such as. After a long period of use, the gear will excessively wear the tooth surface, causing the backlash to be too large, and the additional impact force will increase when meshing. Reflected on the vibration signal is the amplitude of each harmonic of the meshing frequency increases, especially the higher harmonic amplitude increases, such as. Collect signals, do spectrum analysis, observe the peak value of the meshing frequency, and compare with the normal value to determine whether excessive wear is observed.
2.2 Tooth deformation, pitting, root crack and broken gear are rotated once a week. The load on the tooth surface defect (one tooth or several teeth) fluctuates smoothly once, and the degree of failure is small, forming a modulated wave in the vibration signal. ,Such as. The signal is collected, and the spectral analysis is performed centering on the meshing frequency. It can be seen that the side frequency centered on the meshing frequency exists, for example.
2.3 Large flakes of the tooth surface This type of fault causes a large shock vibration, which has a significant impact in the time domain signal, such as. Every one revolution of the gear, there is vibration, so the frequency of the shaft and the frequency multiplication form a distinct peak.
3 successful cases (1) 1141 locomotive overhaul (1)
It is shown in the spectrum that there is a side frequency at the meshing frequency at the frequency of the frequency division, and the amplitude is higher, for example. Therefore, it is judged that the gear is early failure.
No. 1141 locomotive maintenance parameters locomotive number model fault axis position repair speed / (r! min-1) detection date 1141DF4BD1 gear box small 13802009-08-03 disintegration found: the repair of the gear tooth gap is large, wear is serious, The gear meshing sound is loud.
(2) locomotive maintenance of No. 33 (2) to refine the 8 times spectrum with the meshing frequency as the center, and the spectrum display peak value is 6.5 Hz wheel-to-axis frequency conversion and multiplication, for example. The abnormal sound is large during the collection process, so it is judged that the large gear is faulty.
No. 33 locomotive maintenance parameters locomotive number model fault axis position repair speed / (r! min-1) detection date 33DF8BD2 gear box small 34002010-01-15 gear vibration refinement spectrum diagram body found: output end gear large area stripping .
4 End the use of advanced testing equipment In the detection of the locomotive running part, the prevention of the failure of the axle box bearing and the traction motor bearing is the focus of the work. When the test data is obviously abnormal and the data shows that the bearing has no problem, further analysis is needed. Through research, it is found that the failure probability of the traction gear failure is large. Therefore, some methods for judging the gear failure are summarized for this situation, and the driving safety is further ensured in practice.
Hydrofoil surfboard is like a hydrofoil boat where there is a wing-like structure underwater that, at speed, lifts the hull above water.The aluminium design is affordable, robust and stable.
This technology has entered the world of Stand Up Paddle boarding with the hydrofoil. The foil insert into the fin box of the bottom of the board, and once you hit a certain speed, either on a wave, from paddling, or once enough wind gets trapped under your board, the foil will lift the board and the rider above the water, providing the rider with a flying sensation.
Foil For Surfboard Sup,Carbon Fiber Hydrofoil,Hydrofoil Carbon Foil,Carbon Hydrofoil Surfboard,Carbon Hydrofoil Board,Hydrofoil Surfboard Foils
Huizhou City Melors Plastic Products Co., Limited , https://www.foamexpert.net