Research On The Method Of Determining The Optimal Measurement Zone Of CNC Machine Tool On-machine Measurement System

Measurement accuracy is an important performance indicator of CNC machine tool on-machine measurement system as measurement equipment.In addition to the existing error prevention method and error compensation method to improve measurement accuracy of CNC machine tool on-machine measurement system,placing the workpiece to be measured in its optimal measurement area can further improve its measurement accuracy.However,the existing scientific research results lack the research on the optimal measurement zone of the CNC machine tool on-machine measurement system,so this paper has conducted research on the optimal measurement zone of the CNC machine tool on-machine measurement system.This paper taked the CNC machine tool on-machine measurement system composed of Shenyang Machine Tool VMC850E vertical machining center and Renishaw Primo system as the research object.The 15 individual error curves of the CNC machine tool on-machine measurement system were measured by Renishaw XL-80 dual-frequency laser interferometer,and the comprehensive error of CNC machine tool on-machine measurement system were measured by Renishaw's QC-20 ballbar,and the error of verticality between the three axes of X,Y and Z were obtained through error separation.The mathematical models of 15 single-term errors was established by GA-BP algorithm,and a space measurement error model of the on-machine measurement system was established.A large number of sampling points were selected in the overall measurement space using a suitable point distribution method,and the distribution of measurement errors in the measurement space of the CNC machine tool on-machine measurement system at different measurement speeds was simulated by MATLAB.Based on this,the influence of the measurement speed on its measurement error was analyzed,and the existence of the optimal measurement zone was verified by the measurement error distribution diagram.In order to quantify the optimal measurement zone of the CNC machine tool on-machine measurement system,the target model of the optimal measurement zone of CNC machine tool on-machine measurement system was first established,and the optimal measurement zone was successfully solved by the improved FOA algorithm.The basic FOA algorithm was improved,the information of historical optimal individuals and population centroids was added to the population update process,the cooperation and information sharing among drosophila individuals was increased.At the same time,the individuals of fruit fly in each iteration were directly used as the taste concentration determination value S(i),so that the candidate solution can cover the entire domain as much as possible,and its global optimization ability and algorithm stability were improved.Experiments were carried out to compare the optimized results of the improved FO A algorithm and various optimization algorithms.Experimental results show that the improved FOA algorithm is superior to several other algorithms in terms of convergence speed and algorithm stability.In this paper,the CNC machine tool on-machine measurement system was composed of Shenyang Machine Tool VMC850E vertical machining center and Renishaw Primo system.The length of standard gauge blocks at different positions in the specified measurement space was measured by the CNC machine tool on-machine measurement system,and the measurement errors of different measurement positions was obtained,the verification experiment of the optimal measurement zone was carried out.From the experimental results and simulation results,it can be known that the measurement error distribution law in the specified measurement space obtained by actual measurement is generally consistent with the measurement error distribution law in the specified measurement space obtained by simulation.And the optimal measurement zone in the specified measurement space obtained by using the improved FOA algorithm is approximately the same as the optimal measurement zone obtained from the analysis of the measurement error data obtained from the actual measurement.The validity and accuracy of the method proposed in this paper for the optimal measurement zone is verified.