Study On CNC Machine Error Modeling And Measurement System Based On Optical Freeform Surface

With the advances of modern technology, CNC machine tools have become themain equipment of modern processing technology. The machine tool precision isbecoming higher and higher to meet the requirements of precision components.Therefore, the error compensation for CNC machines have become an effectivemeans to improve the accuracy. As one of the main factors affecting the precision ofCNC machining, reducing geometric errors of CNC machining has significant impact.For five-axis CNC machine tools, the existing measurement methods are the use of alaser interferometer or ball-bars combination with other supporting devices. thesedetection methods are complicated and the cost is high. This paper makes full use ofthe advantages of optical freeform surface to simplify the system and improve systemperformance. A method of geometric error measurement based on an optical freeformsurface was proposed to evaluate the accuracy of CNC machine tools. The mainresearch works are as follows:1. Studied the principles of multi-body system modeling, and then used themethod to complete the modeling of five-axis CNC machine tool geometric error. Thefive-axis machine tool geometric error measurement path was planed, and finally thegeometric error measurement methods and device was developed.2. High efficiency, high precision, low cost and comprehensive measurement tothe geometric errors of five-axis machines was achieved compared to the currentmethods.3. Optimum optical freeform surface was designed to fit CNC geometric errormeasuring system features. The assessment of the optical freeform surface wasconducted. And the optical freeform surface was used as the reference conditions tocomplete the development of the measurement system.The optical freeform surface used as datum was designed. The experimentalplatform was built and the mathematical model of measurement system is established.Then, the system was calibrated and the accuracy was tested. Finally,three-dimensional displacement measurement experiments were carried out. Theaccuracy of the system is up to2.8μm. The results showed that the measurementsystem can be applied to CNC machine geometric errors measurement.