Research Of The Mechanical Part Roundness Error And Cylindricity Error Based On The Image Measurement Technology

With the development of computer technology and photo electricity, a new inspection technology based on computer visual has been presented. Using CCD and computer to collecting image measuring roundness and cylindricity error by automation and non-touching. By comparing measuring and analyzing precision, it proves that the measurement has high precision, simple structure and practical value.With the rapid development of mechanism and computer ,more and more accurate round and cylindrical part is being required. At the same time, more accurate measurement of roundness and cylindricity is being desired. Most of traditional measuring methods are low level of automation and low efficiency, especially can't satisfy the demand of measuring of multi-Parametric. So developing a fast, high accuracy and low cost measuring system is very significance.The non-contact measurement principle making use of image measurement technology is introduced. The main measurement approaches include the image preprocessing, edge detection, system calibration and calculation of roundness and cylindricity, etc.The components of the system, the key technology and the actual measuring experiment are explained. The reason of the error margin creation is analyzed. The results of the practical measurement show that this method is correct and feasible. There are introducted by this paper studying according to chapter in below. Chapter one—Introduction. In the base of plentiful abroad and domestic information on computer visual inspection technique, this chapter discussed simply development process of computer vision. We also summarized abroad and domestic research actuality and trends of computer vision inspection technique. We introduced the application results of computer vision inspection technique. Instruments for roundness error inspection were introduced, and the theories and characteristics of contact and no contact in Section for roundness in last decade were also introduced. The trend of roundness inspection was given. In the paper, the image measure's value of theory and practice based on computer vision is emphasized. And main technique is clarified. At last we made primary study contents of this paper clearly.Chapter two—The inspection system of hardware. In this chapter, the character and advantage of computer visual inspection were analyzed. And the structure of computer visual inspection system was discussed. In the end, the general principles of choosing hardware of computer visual inspection system was given and the necessity of studying computer visual inspection is emphasized.Chapter three—The edge detection of the image. The edge of image is important to both image division and measurement. Meanwhile, edge measurement is the main technology in non-contact measurement. It's result has directly impacted on precision. This chapter adopted rough edge detection, together with precise edge detection to process the image. Firstly, we searched the rough edge by a new edge thinning method based on sobel operator. The location precision attained pixel level. For attaining a higher precision in searching the rough edge, we made use of sub pixel arithmetic -- cubic spline function interpolation. It breaks the restrict of the CCD camera physics resolution, and makes the edge location precision attained sub pixel level.Chapter four—The measuring methods of the roundness and cylindricity error. A new non-contact measurement system of the roundness errors based on CCD image was presented, which is more precise. And this new method is also suitable even if the little error assumption or little departure assumption is not fulfilled. We established a logical and reasonable mathematics model on roundness errors. We also solving the error value. Then we analyzed this new method of roundness assessment with the least square solutions. We provided an ideal computing method for the evaluation of cylindricity error value which based on the research and study of the Error Separation Technique. It can advance the machining precision and measurement precision of the cylindricity error. Under the same measure situation, we discussed the number of measuring points influence on the measuring precision.Chapter five—Analyze the error of measure. This chapter analyzed the error of measure, specially the error of the angle, the error from calibration, the error of algorithm and random error. Then the results made by this system and universal tool microscopy are compared. The results of experiment indicated that this measuring system can satisfy the demand of measuring accuracy and have high low efficiency and low cost.Chapter six—Conclusion and expectation. This chapter is the summary of the whole dissertation, and the main research achievement and innovative discover are expatiated. At last, we gave some advice for future study.