Measurement Of Gear Body Vibration Signals And Its Application In Fault Diagnosis

The gear transmission system as an essential transmission mechanism in the mechanical equipment has been applied widely to the mechanical device in various trades of industry, agriculture, national defense, spaceflight as well as communications and transport. However, the gear transmission system easy to be damaged and present breakdown and gear is also the mechanical part which is damaged easiest because of its complex structure, poor working conditions and other reason .Therefore, it is important how to defect the fault of geared system as possible to make the repair schedule reasonably and economically and to avoid the body hurt and device damage.Operator hopes that the information on initial fault can be obtained as early as possible during operating device .But the vibration motivation from initial fault is much weaker than normal vibration motivation. The path of vibration spread is complicated. Useful information of measurement noises after the frequency components of the gear vibration through the stronger interring noise and the nonlinearity of vibration spread. But present information-process technology of mechanical fault diagnosis is only suitable to distributing fault of gear (e.g. severe surface wear), not to initial fault and local fault of gear. This brought great difficulties to diagnose the early fault of gear.This article discussed the influence of the path of vibration signal spread on the gear fault diagnosis by comparing analysis results between the transfer function from the point near the meshing point to the testing point near the meshing point of the gear body and that from the point near the meshing point to the testing point of the gearbox respectively. This article discovered that the vibration signals of gear body with high sensitivity than gearbox for the gear fault by comparing the vibration signal of gear body and gearbox at the same time .We can test the vibration signal of gear body by installing symmetrically two accelerometers that have same characteristic on the gear face. The meshing time of crack tooth is shorter than the normal tooth by analyzing time-domain signal of the failure gear .Round body vibration signal in time and frequency analysis and the continuous wavelet function and Hilbert-Huang function can be found the failure characteristics of the tooth root crack when the body vibration signal was applied to the local fault diagnosis of gear.Studies have shown that:(1) We found that gear vibration signal in the transmission process will be filtered, attenuation or amplification by analyzing the system intrinsic mode from the pulse frequency response function.(2) Round body vibration signals can directly reflect the actual state of gear vibration. Measurement interference is small measuring accuracy Round body vibration of gear vibration signals reflecting the causes of vibration is no influence from transmission path, that will not reduce the useful frequency components and will not increase frequency components.. (3)Results show that round body vibration signal can sensor the gear failure,Using round body gear vibration signals easier to detect the early failure.