The Research On Squareness Of Complex-curved-surface Profilometer

The arbitrariness of the form,the complexity of geometric shape and the difficulty of the mathematical expression are the characteristics of the complex curved surface.The great challenges are brought to the measurement and evaluation of the surface by the characteristics.In order to get the better metrical performance,the accuracy of the geometric error measurement on profilometer needs to satisfy with the level of the corresponding accuracy.For the ultra-precision profilometer which is used to measure the complex curved surface,the squareness is important to improve the accuracy of the profilometer,and is accurately measured and controlled.However,the accuracy of traditional metrical method of squareness is limited by two disadvantages: The first one is the finite accuracy of the standard parts such as the square and optical square brick.The standard parts are difficult to process and high cost.The second one is that the sub-arcsecond accuracy of the angle of the standard parts used for large travel measurement is difficult to reach.The limitations will bring the lower metrical accuracy of squareness and the difficulties to compensate.The influences of the squareness on the working performance of the profilometer have been researched,the results show the squareness of the three axes must be reached at the accuracy for meeting the measurement uncertainty of the profilometer.Therefore,the squareness of the complex-curved-surface profilometer is measured by the method based on error separation.According to analysis,the metrical accuracy of the squareness is not limited by the standard part.The metrical result of the squareness between the X and Y axis of the profilometer is got,the uncertainty of result is the sub-arcsecond level.The main work of this paper are:1.Study on the effect of squareness on measurement of the profilometer.The effect of squareness on the measurement of the profilometer is great.The results show that the effects of the squareness between the three axes are linear.The squareness between the three axes must be reached the accuracy for meeting the measurement uncertainty of the profilometer.2.Study on the principle based on the error separation.The metrical principle of squareness based on error separation is introduced in details and the metrical model of the profilometer is built well.The problems that affect the accuracy of the squareness are found and solved by the simulation experiment and the practical measurement.Therefore,the accuracy is improved.3.Study on the application of the method based on error separation.The squareness of the Coordinate Measuring Machine(CMM)and the ultra-precision machine in the lab are measured based on the principle of the error separation.The measurement is foundation of experiment carried on profilometer for insurance the right of the principle.The squareness of the profilometer and the uncertainty of the squareness measurement are got.It is found that the accuracy of the squareness of the standard parts method are smaller than the accuracy of the error separation measurement.However,due to the factors such as the precision of measuring equipment and standard parts.4.Study on the error of the metrical process.With the change of the accuracy of the angle ? and the faces of the brick,the accuracy of the method based on error separation has been researched.The experimental results show the squareness are keeping same with the changes of the angle ? and the Peak Value(PV)of the surface.Hence,the conclusion that the accuracy of the method is not limited by the standard parts is proved.Through the simulation experiment and the geometrical analysis of the spatial position between the measurement lines and the planes,the error analysis of the error separation method for the measurement of the squareness is carried out,and the sum of the four items of error on the measurement error of the squareness is got.