Research And Optimized Design On Fan Impeller Dynamic Balance Testing System

Fan impeller is an important part of the fan.If the impeller is imbalance, it will produce severe vibration. Light and large noise which can cause the retaining bolt, equipment damage or casualties.The dynamic balance of fan impeller is very important, After balancing,it operates smoothly and the vibration is very small.The equipment of dynamic balance test is of high precision. Detection systems involvs so many disciplines and fields, including mechanical, electrical, digital signal processing, etc. Some years ago, foreign technology has maintained a monopoly.Recent years, some independent research and development of the domestic detection equipment gradually appear in our country.but the detection accuracy, repeatability, detection principleand test time are still relatively backward than foreign products, so detection also has very big development space in data processing method, etc.On the actual project basis, this paper developed a set including industrial PC, embedded controller and signal transfer plate.The programming of upper machine is based on. NET c#.The main work includes the following:Primarily establishs the system dynamics model.The model concluds the dynamic equations of the system.According to the different application situation, two calibration methods have been realized.One is for the sake of easy to operate-permanent calibration. Another is for the sake of high precision and simplified calculation process-using the influence coefficient method of calibration.Permanent calibration model and the calculating model of influence coefficient method are deduced.Because of interference, the process of calibration will appear abnormal data which cause the K value of calibration errors. If K value is error,Subsequent calculation will be all mistake.For this kind of situation, the K coefficient of least squares calibration method is proposed to improve the K series precision calibration and can have more stable and accurate test results.Data processing includs signal filtering and the phase and amplitude estimate of the filtered signal. Using the method of window function method to design FIR filter has chosen the black window whose sidelobe is smaller.Comparing the filtering effect of the blackman window filter and ordinary narrow-band pass filter, it can be easyly found that the effect of blackman filter is more good and blackman filter is more easy to implement.After the sensor signal filtered,the effect of phase and amplitude extracted by Fourier fitting is better than the effect using DFT and butterfly FFT method.PC communicates with AD card by PCI interface and communicates with embedded controller by serial port.Embedded controller can measure the rotate speed. Designed the control sample start-stop logic circuit and the PCB of front-end filtering of hardware circuit.For operator convenience, the test results will be sent to mobile phones through the wifi module.Operator can act accord to the test results.WiFi module USES the USR-WIFI232-A. The data transmission between STM32 and Android is through WiFi module.The development of Android data displaying program which involvs the wi-fi module data reading and displaying is based on eclipse platform.Fan impeller dynamic balance testing equipment is vital for fan production enterprises, and the data processing algorithm involved in this detection system can be applied to detection of other fields at the same time.So the research of this thesis has very important practical and theory significance.