| Large-scale roller is one of most widely used elements in manufacturing equipment,its roundness,cylindricity and straightness of generatrix affect the surface quality of products.Coordinate measuring machine and roundness measuring equipment are the most useful equipments for measuring cylindrical form errors.Due to measured object is big and heavy,in-situ measurement(in production and application)is a good measuring strategy.How to improve accuracy of the in-situ measuring the form errors of large-scale roller,and how to avoid or reduce the influence coming from in-situ error motions of the spindle and straightness deviations of the probe carriage,are the most remarkable issues in measurement of large-scale cylinder.In-situ measurement of cylindrical form errors involves two essential issues: the cylindrical profile measurement and reconstruction,as well as the form errors evaluation.The multi-probe error separation techniques(EST)integrates multi-probe roundness error separation and multi-probe straightness error separation to realize total harmonic separation during measuring the cylindrical form,and then,reconstructs the cylindrical profile which conforms to mathematic definition,so as to high-accuracy data are provide for evaluating cylindrical forms.A mathematic model of the 4-probe cylindricity EST has been established,the radius deviation and roundness of cross-sectional profile are determined by 3-probe roundness EST,as well as the differential vector of the least squares centers(LSC)in two adjacent cross-sectional profiles is extracted in the thesis.The vector of LSC in each cross-sectional profile is obtained by accumulation.A cylindrical profile reconstructed based on the spatial curved median line,which is fitted with the vectors of LSC of cross-sectional profile.The 4-probe cylindricity EST not only can extract the vector of LSC center but also solve the harmonic suppression problem,and it has a quite strong anti-interference capability.The methods of evaluating cylindrical form errors based on the envelope principle has been studied in the thesis,and a new algorithm,mesh searching method,has been conducted which can evaluate roundness,cylindricity and straightness of generatrix errors under the envelope principle.It is proved that the results of evaluated cylindrical form errors conform to the respective geometrical judging criteria.The thesis also has demonstrated the good consistency of spatial curved median line profiles and generatrix profiles in the repeatable experiments,which prove that 4-probe cylindricity EST has a great anti-interference capability.Based on the studies,respective software were completed by MATALAB and VS2010,which realize the functions of separation,reconstruction and form errors evaluation. |
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