Research On Wheel Axle Microscratch Detection System Based On White Light Confocal

The depth of scratches on railway locomotive wheel axles that exceed the specified range can increase the potential for safety accidents.The conventional micro scratch detection process is complex,and the equipment and personnel required are relatively professional.Nowadays,the frequency and accuracy of detecting micro scratches on wheel axles are increasing,and traditional detection methods are no longer applicable.Therefore,this paper proposes a method for detecting micro scratches on locomotive wheel axles based on the white light confocal principle,which can achieve high-precision and high-efficiency measurement.The research content and results of this article are as follows:1)Aiming at the needs of locomotive wheel axle scratch detection,a wheel axle scratch detection scheme based on Y-type optical fiber confocal structure was proposed.The detection system consists of a white light source,a dispersive objective lens optical system,a spectral measurement system,a computer,and a displacement measurement platform.The working principle of the system is as follows: The broad spectrum light emitted by the LED white light source enters the dispersion objective lens through a Y-type optical fiber and generates axial dispersion.The light encodes the axial position of the detection surface and then reflects into the optical fiber and spectral measurement instrument to complete the identification of the reflected light wavelength.The computer completes the determination of the axial position of the detection surface through measurement data collection and processing.The electric displacement measurement platform drives the dispersion objective lens to scan the locomotive wheel axle,Through real-time position measurement,the detection effect of the scratch contour is achieved,and the scratch depth measurement is completed.2)According to the detection scheme,the white light confocal optical system was designed and simulated.Firstly,a dispersion objective lens capable of producing axial linear dispersion was designed,with a measurement range of 1.025 mm,a working spectral range of 400 to 700 nm,and a lens RMS radius of less than 1.2μm.The dispersion linearity determination coefficient R2 is 0.9972,which has the advantages of high linearity and short optical cylinder length.The lens has a yield of 80% within processing and assembly tolerances.Secondly,based on the axial displacement resolution relationship of the confocal system,the optical system of the spectrometer was simulated,and a crossed C-T structure optical system of the spectrometer was designed,which can resolve wavelengths of 0.3 nm.Finally,the dispersion objective is connected to the spectrometer,and the resolution,fiber coupling efficiency,and energy loss of the white light confocal optical system are analyzed and verified.The optical system design is reasonable and meets the measurement requirements.3)The development of an experimental prototype of a white light confocal scratch measurement system has been completed.The hardware system of the experimental prototype is composed of a dispersion objective lens,a magnetic V-shaped seat,an electric displacement slider,and an integrated equipment box.The software system is based on the Winform platform in Visual Studio software,and is jointly programmed with C # and Matlab,enabling dynamic detection of scratches.The processing methods of scratch detection signals were studied.Aiming at the characteristics of wheel axle scratches,light intensity compensation and curved surface compensation methods were proposed,and the dispersion position and wavelength were calibrated.The scratch detection experiment was completed.The measurement error is within 1% of the range,with good repeatability,which meets the design expectations.The overall portability of the system is high,and it can adapt to the needs of wheel axle scratch detection under various links.