| Optical freeform surfaces are widely used in various industries due to their unique surface features and excellent performance.However,CNC machine tools for processing optical free-form surfaces have not been domestically produced,which has led to high production costs for various optical products..In order to break through this technical bastion,it is meaningful to develop optical free-form surface machining machines.In order to enable the developed CNC machine tool to produce optical free-form surfaces with surface surface accuracy,it is necessary to eliminate or compensate for all aspects of the machine tool.In this paper,the tool change error of a circular multi-station optical free-form surface machining machine is studied and analyzed,and a method for inposition detection identification and compensation of machine tool change error is designed,and the experimental verification is carried out on the machine tool.In order to solve the problem of machine tool change error identification and compensation,this paper firstly analyzes the tool change error and converts the tool change error into the position offset error of the tool tip.In order to analyze the influence of the position offset error of the tool tip,the ideal geometry of the machine tool fast machining servo machining system is carried out,and then the tool path modeling is carried out in MATLAB to predict the surface topography of the workpiece.Then,the tool change error identification and compensation method is designed by the influence of the offset of the tool tip position on the surface shape of the workpiece.The tool change error compensation verification model is established in MATLAB,and the compensation effect is good.In order to realize the in-position measurement of the surface shape error of the workpiece,this paper carried out the research of the machine tool measurement station and established the machine tool in-position measurement system.In order to make the in-situ measurement system have better measurement accuracy,the accuracy of the inposition measurement system is modeled,and the system error of the in-position measurement system,that is,the 13 geometric static errors are identified and compensated.In order to make the measurement more accurate,the comparison verification method is designed to measure the pre-measurement of the machine-in-place measurement system,as well as the measurement post-processing method such as the probe radius compensation,measurement data filtering processing and surface shape error evaluation.Finally,the measurement process planning is carried out for the overall measurement function of the measurement system,so that the in-position measurement system of the machine tool can perform fully automatic measurement.In order to verify the correctness and effectiveness of theoretical modeling and simulation,the paper has carried out the calibration of in-situ measurement system and the quantitative verification experiment of tool change error.Firstly,the in-position measurement system is coarsely adjusted to meet the requirements of the automatic measurement error identification of the ball.Then,the automatic measurement error identification experiment of the in-position measurement system is performed,which can better identify the geometric static error of the in-position measurement system.The deviation can be guaranteed to be within 15% in the secondary measurement.Then,using the standard plane and the standard concave spherical surface to perform the premeasurement measurement of the in-position measurement system based on the contrast verification method,it can not only verify that the identified geometric static error compensation effect is good,but also obtain the measurement uncertainty of the in-situ measurement system characteristic measurement.Finally,the trial processing experiment after the machine tool change was carried out,and the optical free-form surface that meets the requirements can be obtained through 5 times of "machining-measurementcompensation". |
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