Research On Measuring Methods Of The Geometric Errors And Surface Roughness Based On The Laser Range Sensor

Geometric errors and surface roughness of parts are two main indexes for evaluating machining accuracy.They directly affect the assembly and positioning accuracy of parts,and then affect the overall performance and service life of mechanical equipment.With the rapid development of modern industry,the precise measurement of geometric error and surface roughness of mechanical parts becomes more and more important.Geometric error detection method has always been a research hotspot of scholars at home and abroad,and according to the change of testing object and using environment,the configuration of testing system is constantly improved to meet the requirements of different industrial fields.The objective of this paper is to measure the geometric shape and surface roughness of workpiece in the process of mechanical manufacturing and assembly,with the high precision laser displacement sensor as the tool,research work has been carried out on the detection methods of straightness,flatness of parts,shape and position errors and roughness of turning parts,The main research contents are as follows.(1)Two-dimensional and three-dimensional W-M functions in fractal theory are used to establish rough surface models of workpieces.The corresponding relationship between fractal dimension and scale coefficient and surface roughness Ra is proved by numerical calculation,that is,the larger the fractal dimension is,the smoother the surface is,the larger the scale coefficient is,and the rougher the surface is,and the statistical characteristic parameters of different rough surfaces are given;Finally,the simulation analysis of milling plane and turning cylindrical surface is carried out,and the flatness and roundness errors are calculated by using the minimum enveloping area method.The corresponding relationship between fractal parameters and flatness and roundness errors is found out.(2)Based on the corresponding relationship between fractal parameters and flatness,a three-dimensional model of rough plane is established.An algorithm for extracting normal plane projection ripple of rough plane and a method for evaluating plane straightness by using normal plane projection ripple are presented;Based on the test results of three-contact straight line planar linearity detection mechanism,an algorithm for reconstructing normal planar projection corrugated lines is proposed,the accuracy of the algorithm is evaluated by numerical simulation reconstruction algorithm and plane straightness.(3)Considering the synchronous and asynchronous rotation errors of turning spindle,the surface roughness generated during turning process is described by fractal function,and the geometric shape model of workpiece section is established;Through numerical simulation,the effects of synchronous and asynchronous errors of spindle rotation and fractal parameters on the roughness and roundness errors of workpiece sections are simulated respectively;Then,according to the position relationship between tool and workpiece in turning process,a method of detecting synchronous and asynchronous errors of spindle and roundness errors of workpiece cross-section by using laser ranging sensor is proposed,which is verified by numerical simulation.(4)The errors of the above flatness detection and the shape and position error detection of turning workpiece are analyzed.The influence of measurement principle error,flatness detection mechanism manufacturing and assembly error and sensor installation position error on the test results is analyzed,and the corresponding methods and control indicators to ensure the detection accuracy are proposed.