| Linear structured light 3D detection technology is widely used in various fields of industry and science because of its advantages of non-damage,high efficiency,and high precision.In order to realize the high precision 3D measurement of the tooth profile of small modulus gear,a highresolution thin line structured light telecentric measurement system with large FOV(field of view),WD(working distance)and measuring range is proposed.Firstly,according to the principle of optical triangulation,various optical path parameters were determined based on the application background of small module gear tooth profile measurement.From the purpose of coordinating optical resolution and DOF(depth of field),the optimal Angle of two light paths construction was demonstrated.The importance of light strip with minimal projection width to improve the measurement resolution and accuracy was discussed.The approximation model of light strip width variation with the change of projection distance and the pixel resolution equation of depth were established,and the feasibility of designing and machining high precision optical slit was demonstrated through investigation.According to the above theoretical analysis and demonstration,the components selection and construction of light path were completed.Secondly,completed the system evaluation.A high-precision resolution test target was used for lens magnification detection,three edge detection programs and two different light intensities were used for comparison experiments.The results show that the lens magnification is close to the nominal value.The DOF and the ultimate resolution of the lens were obtained by testing the gray contrast and its variation generated by object distance change of the target element in the image plane.The certain height difference was determined by the combination of standard gauge blocks,and then it was measured by different field regions.The average depth and fluctuation range of per pixel of the system were obtained,so it was inferred that imaging distortion had little influence on depth measurement.By changing the relative distance between the measured surface and the measuring system,the different widths of projection fringes were obtained,so that the depth measuring range of the system,the minimum width of the projection fringe and its edge mass were determined.By using standard gauge blocks and first grade flat crystal,1μm height difference was acquired,and it can be accurately identified by the system.Finally,completed the system calibration and application.The theoretical model of system calibration was established,and the actual calibration equations were obtained according to the system parameters detected.The system was applied to the surface profile measurement experiment of vertical milling roughness samples ▽5 ～ ▽7,the measured surface profile and roughness evaluation parameters were obtained.It is indicated that the results measured by the system are consistent with the profilometer.The system was applied to the measurement experiment of involute artifact.The measuring stripe center was extracted by adaptive threshold segmentation algorithm.The deviation of the measured results from the theoretical involute tooth profile was 2μm.Based on the experimental results,the source of measurement errors were analyzed,and the improvement scheme was given.The thin line structured light measurement system created in this design has the advantages of fine projection fringes,high optical resolution,powerful discernibility,large measuring range and working distance,and wide application range.It can realize the high-precision measurement of involute tooth profile,and the system whole meets the design requirements. |
PDF Full Text Request