Research On Measurement Theory Of Roundness Error Of Thin-walled Cylindrical Parts And Some Problems In Measurement Practice

With the development of modern industrial scale and the increasing production capacity of industrial products,thin-walled cylindrical parts have been widely used in many important national economic sectors.However,due to the unique off-line measurement characteristics of thin-walled cylindrical parts,the measurement results of thin-walled cylindrical parts often can't accurately reflect the true geometry of the workpiece being measured.Therefore,how to accurately and efficiently measure the roundness errors of thin-walled cylindrical parts under limited measurement conditions has become an important issue.The roundness error measurement of the notch circle is also a difficulty in the field of shape and position error measurement.Currently,there are fewer related papers on the measurement of the roundness error measurement of the notch circle.How to correctly evaluate the roundness error of the notched circle has become an important issue in the field of measurement.A large number of domestic and foreign related literatures show that the error separation technique can effectively eliminate the interference signals in the measurement signals and obtain accurate measurement results.Moreover,the error separation technique has appropriate requirements for measurement conditions and high work efficiency.This thesis focuses on the indexing methods of the roundness error separation technology.The main research contents of this thesis include:(1)Different roundness error evaluation methods are proposed for the complete circle and the notch circle respectively.The complete roundness error evaluation model was compared and analyzed.The comparative analysis results show that the model can correctly evaluate the roundness error of the complete circle.Based on the definition of profile error,a method for evaluating the roundness error of the notch circle is proposed.(2)Research on the two-step roundness error separation technique that is easy to implement,and analyze the influence of key parameters on the error separation results under different conditions.The simulation results show that the two-step error separation technique can completely separate the spindle rotation error in the measurement signal when the spindle rotation error is constant.The two-step error separation technique cannot completely separate the spindle rotation error in the measurement signal when the spindle rotation error is different.But the measurement accuracy can be improved by averaging multiple measurements.(3)The three-step transposition method is applied to the roundness error measurement of the notch circle,and the influence of related parameters on the error separation result under different conditions is analyzed.The simulation analysis results show that the three-step transposition method can obtain correct results when the spindle rotation error is constant.When the spindle rotation error is not the same during each index measurement,by adjusting the combination of related parameters,the three-step transposition method can still achieve satisfactory results.(4)The experiment on the measurability of the roundness error of thin-walled cylindrical parts is designed.The experimental results confirmed the off-line characteristics of thinwalled cylindrical parts.According to the off-line characteristics of thin-walled cylindrical parts,a digital filtering algorithm is proposed.The algorithm can weaken the interference signal in the measurement result and improve the continuity and effectiveness of the roundness error signal.(5)The evaluation strategies for the dimensional error and roundness error of thin-walled cylindrical parts are proposed.These solutions can reasonably evaluation the off-line measurement error of thin-walled cylindrical parts and properly evaluation the various errors of the parts.(6)Based on the requirements of the notch roundness error measurement experiment,the standard precision motion table and servo drive system commonly and the self-designed MCU-based data acquisition and control system are used to construct the measurement with high measurement accuracy.The experimental platform and the related construction techniques were explored and studied.(7)The three-step transposition roundness error experiment was carried out on the measuring bench.The correctness of the theoretical study was verified by comparing the calibration results with the tested parts on the Talyrond 385 roundness meter.