Evaluation And Measure Of Cylindrical Error

Evaluation of cylindrical error is one of basic elements for measuring shape error. As an indispensable evaluating indicator of evaluating columniform parts error, it plays a very important role in the fields of machinery manufacturing, aerospace and automation control, etc. Today, as one measurement equipment, three coordinates measuring machine is wildly applied to the manufacture. However, it still has not formed an unified evaluation method using the coordinate measuring machines to evaluate shape error elements of rotating cylinder, and these limit the implementation and application of coordinate measurement method of cylindrical error in the Cartesian coordinates.Based on the comprehensive study of evaluation pattern of cylindrical error, in the precision measurement fields, this paper uses the space geometry and the graphics features to resolve some interrelated issues of measuring and evaluating cylindrical error in the Cartesian coordinate system, and makes some progress. Moreover, regards geometrical relationship of space structure, mathematical simulation modeling, character analysis of intersection chords and measurement applications as the major research objects in this paper. The cylindrical error evaluation method charactering as maximum intersecting chord is proposed. The specific areas of research are as follows:1. Mathematical evaluation model of cylindrical error in the Cartesian coordinates is established. Logical mathematical evaluation model of cylindrical error is established in Cartesian coordinates, which is based on section sampling method. A mathematical algorithm of constructing the least square section contour line using conic quadratic is researched, and obtains the solution about how to find the centre of the section. To establish a simulation model of cylindrical central axis and to make the transformed mathematical model more suitable to the computer's data processing.2. Evaluation method of section error. Aiming at the identification of section centre, the section centre searching method by geometrical symmetry relation of secation contour line characters is brought. Through the specialties chords, the movement regularity of characteristic points of inscribed & circumscribed circle is found, so making use of the restriction direction can control movement range of inscribed & circumscribed circle, so as to define the section center efficiently and accurately.3. Section evaluation methods of the cylindrical error evaluation model. After establishing intersecting chord model, this paper uses the projection datum to construct MCC, MIC and MZC valuation model, and expounds the three evaluation methods based on intersecting chord model in detail. By comparing and analyzing the three structures of evaluation methods, achieves the attempt using MCC & MIC to build MZC. Efficient and accurate searching section centre for the purpose of evaluating error.4. Discussion and analysis of evaluation. After data acquisition and data analysis, Summarizes and generalizes some problems consisted in cylindrical error evaluation. Sampling points of the section and the cross-section sampling points volume are studied and discussed, and studies presence issues in the course of computation and evaluation.Intersecting chord relation can search the center of evaluation section accurately and rapidly by distinguish virtual centre on perpendicular bisector of maximum chord, and avoids calculating searching step and direction. The results and data prove that the algorithm mentioned above have higher computing speed and evaluating precision, it realizes that three coordinates measuring machine and other measuring appliances can evaluate cylindrical shape error by means of the coordinates sampling datum.