Research On Visual Acquisition And Processing Technology Of Spindle End Vibration Signal

The spindle is a symbol of the spinning industry.As a rotary body,it drives the yarn tube to rotate and completes the twisting and winding effect.Due to the problems of mass eccentricity and installation accuracy in the spindle structure,the spindle will produce vibration,noise and other phenomena,which will increase the wear of the spindle and greatly reduce the quality of the product.The detection of spindle amplitude is one of the links that the spindle needs to go through after the completion of production and processing.Only when the maximum amplitude of the spindle end meets the requirements,the spindle meets the standard and can be used.Aiming at the problem that the frame rate is limited when the industrial camera collects the spindle end vibration signal in the spindle vibration detection system studied by the research group,this paper proposes a spindle end amplitude detection method based on fast Fourier transform(FFT)interpolation.This method can reduce the detection error and the number of acquisition points without changing the frequency domain characteristics of the amplitude acquisition signal.Finally,it is proved by experiments that the digital interpolation method can significantly improve the detection accuracy of the maximum amplitude.The main contents of this paper are as follows :Firstly,the vibration characteristics of the spindle are analyzed,and the existence of free vibration,forced vibration,self-excited vibration and sub-harmonic vibration during the operation of the spindle is deeply analyzed.Using the transfer matrix method,the conical part of the spindle rod can be equivalent to a stepped shaft,the spindle plate is equivalent to a rigid part,and the spring support is equivalent to an elastic support.The simplified model of the spindle is obtained,and the first three natural frequencies are obtained by calculation.It provides a theoretical basis for avoiding resonance during operation and provides a basis for determining the acquisition parameters during vibration detection.Secondly,we studied the spectrum analysis method of vibration signal.The discrete Fourier transform method is used to obtain the frequency spectrum of spindle vibration signals.By analyzing three commonly used digital interpolation methods such as linear interpolation and comparing with the principle of FFT interpolation method,we use FFT interpolation method to interpolate the spindle vibration signal,which not only does not change the frequency domain characteristics,but also greatly reduces the detection error of the maximum amplitude of the spindle end face.Integrated the characteristics of using industrial camera to detect vibration signals and the principle of image smear,the method of determining interpolation factor is obtained.According to the textile industry standard and the acquisition characteristics of the system,the acquisition requirements and parameter setting methods of vibration signals are formulated.The main image processing algorithms for spindle vibration detection are introduced.The pixel points of the spindle end circle are obtained by Canny edge detection algorithm,and then the center of the spindle end circle is obtained by Ransac outlier removal algorithm and ellipse fitting algorithm,so as to obtain the amplitude of the spindle end.Finally,according to the overall framework of the system and the detection process,a system that can be used to detect the vibration of the spindle is built,including hardware and software.The hardware platform consists of a spindle drive unit,a vision machine,a camera unit,and a motion unit.The software interface includes the main interface,the new engineering interface,the parameter setting interface,the replacement spindle interface,the new recording interface,and the module design.After completing the whole system,the spindle vibration detection experiment is carried out.The experiment shows that the FFT interpolation method can significantly improve the detection accuracy,and the system error is controlled within 0.01 mm,and the expected results are obtained.