Research Of Surface Roughness Measurement System Based On Laser Scattering

The roughness value refers to the micro-geometric structural characteristics of peaks and valleys and intervals of the surface of the object.It is closely related to the quality and service life of mechanical parts.With the development of science and technology and the improvement of industrial requirements,there is an increasing need for quantitative analysis and monitoring of surface roughness values of objects.Roughness measurement methods are mainly divided into contact measurement and non-contact measurement,in which the stylus contact measurement method is widely used,but the measurement speed is slow and it is easy to cause destructive scratches on the measured surface,so it is not suitable for the application environment of online measurement and automatic monitoring under specific conditions.In order to meet the needs of users,this thesis chooses a non-contact measurement method.Common non-contact roughness measurements are: electron microscope method,optical stylus method,optical interference method,optical speckle method,light scattering method,optical sensors method and so on.According to the target roughness range and measurement accuracy requirements of the measured object,this thesis chooses a laser scattering-based measurement scheme,performs theoretical analysis and experimental verification,designs the optical path and software,achieve the measurement of metal and insulation surface roughness values.The specific research contents are as follows:(1)Introduce the research background and current situation of the surface roughness measurement system,and determine the non-contact measurement scheme according to the measurement objectives and requirements;(2)By comparing and analyzing several common measurement methods,propose a non-contact measurement scheme for laser scattering-based method.The theoretical analysis illustrates the principle of surface roughness measurement by laser scattering,by metal experimental measurement,it is proved that there is a monotonic relationship between some characteristic parameters of the scattered light spot and the roughness value,and the feasibility of the scheme is verified;(3)Design the specific optical path structure of the system,select appropriate optical devices,complete the optical path structure packaging and design a mechanical structure to ensure the stability of the measurement system;(4)Use MATLAB to design GUI interface to realize the function of human-computer interaction,complete the computer’s call to industrial camera,then complete the fitting between characteristic parameters and roughness value through digital image processing and calculation;(5)Through the measurement of several metal materials and insulation surfaces,compared with the results obtained by the stylus contact measurement,the relative error is less than 8%,which can realize the one-button roughness measurement and display of different materials.