Research On The Measurement Technique Of The Geometric Features Of The Stepped Plane Of Large Vertical Axis

With the continuous improvement of industrial demand and the continuous upgrading of processing technology,the shape of mechanical parts is becoming more and more complex.Represented by rotary parts,its geometric characteristics show a complicated trend,extending from single layer to multi-layer.Observed from the perspective of vertical axis of rotation,there are multiple types of geometric dimensions at each layer,and the traditional measurement means can hardly meet the measurement needs.In recent years,the workpiece geometric feature quantity visual detection method has developed rapidly,and has been widely used in the automatic production line,has gradually become an indispensable part of industrial production.In the field of high-precision visual detection,the parts with a diameter of 400 mm studied in this paper are generally considered to be of large size compared with the aperture of optical lens.Meanwhile,the variation of the measured height range of 500 mm also presents many difficulties for measurement.Based on the above background,this paper studies the measurement technology of the geometric feature quantity of the stepped plane of large vertical axis.The main work is as follows:(1)The structural characteristics of the vertical step surface workpiece are analyzed,and the round holes of each step surface are measured by visual detection method.The workpiece measurement system suitable for measuring height of 500 mm and field of view range of400mm*400mm is designed,and the image acquisition unit hardware analysis and selection and software planning.(2)A variety of filtering algorithms and edge extraction algorithms are analyzed.Aiming at the single section geometry measurement,the image processing method is studied,the median filter,Gaussian filter and guided filter are processed,and the processing effect is compared,and the filtering method suitable for the measurement system is obtained.At the same time,the effect of pixel level edge detection and subpixel level edge detection is compared,the appropriate edge extraction method is selected,and the weighted least square method is used to fit the circle.(3)The fixed focus adjustment method and object distance elevation measurement method are studied to measure different step surfaces with object distance parameter changes.In order to provide quantitative basis for measurement requirements of different precision levels,the imaging difference of circular hole dimensions of the same size in different step surfaces was analyzed and the accuracy difference of geometric dimensions detected by two measurement methods was studied.At the same time,the error caused by lens distortion is analyzed,the distortion parameters are corrected by calibration plate,and the feasibility of the method is verified by repeated measurement.In industrial measurement,the two measuring methods studied in this paper can be reasonably selected according to the measurement efficiency and the difference of the height of the measured step surface,so as to realize the geometric measurement of multiple step surfaces with the priority of efficiency or precision.(4)The influence of the incline Angle between the workpiece axis and the base surface on the measurement results was analyzed,and the axis was corrected for eccentricity and incline,and the simulation experiment was established to correct the position of the workpiece for repeated testing.The results showed that in different step surfaces and in the same image,the circular hole of the same size showed a state of near larger and far smaller with the change of object distance.By using this method,the measurement error of two circular holes can be less than 20μm.