Online Monitoring Technology For Geometric Accuracy Of CNC Machine Tool Foundation Parts

In the process of using machine tools,because of the influence of various internal and external factors,the basic large parts of machine tool will be deformed over time,causing the static geometric accuracy of the machine tool to be worse,which directly affects the machining precision of the machine tool itself.With the improvement of accuracy requirement of CNC machine tools,the maintenance of geometric accuracy of machine tool foundation is becoming more and more important.The most important thing to analyze the geometric accuracy of machine tool foundation is to get the deformation field of machine tool foundation.At present,there are few researches on the deformation field on machine tool foundation,and there are few researches on the long-term deformation monitoring of machine tool foundation.Therefore,this paper studies the deformation monitoring technology based on the large basic parts of machine tools.By studying the deformation of the large basic parts of machine tool by the distributed strain method,the change of geometric precision of large basic parts of the machine tool is studied.The main work includes the following aspects:In this paper,the traditional detection methods of machine tool geometric accuracy are analyzed,and the development of the distributed strain monitoring system in str uctural deformation monitoring is introduced.The processing method and deformation calculation algorithm for distributed strain monitoring data are summarized,and then the distributed strain monitoring technology is applied to the deformation monitoring of large basic parts of CNC machine tool.The basic principle and the sensing characteristic of the resistance strain sensor are expounded,and the measuring circuit of resistance strain gauge and the working principle of rectangular rosette are introduced.By using the method of plane bending hypothesis and polynomial fitting,the deformation of three basic parts of machine tool column,bed body and saddle are analyzed.The relationship model of the deformation of distributed strain and three basic parts is established.The straightness error of each base part is calculated through the endpoint connection method.The column,bed and saddle of vertical machining center KVC850 M are taken as research objects.A wireless strain monitoring system is built to monitor the basic parts of machine tools in real time,and the layout of measuring points,temperature compensation and collection frequency are carried out on the surface of basic parts of each machine tool.The real-time strain monitoring of machine tool base parts is realized.In order to solve the problem of high frequency noise and abnormal point in the long term monitoring data,the wavelet decomposition and reconstruction method is used to denoise the variable data,and the denoising results of different decomposition levels of different wavelets are compared and analyzed.The pre-processing of strain monitoring data for machine tool base parts is realized.The straightness error of KVC850 M axis in vertical machining center is detected by laser interferometer.The feasibility and correctness of the method are verified by comparing the results of the geometric model and the error results of each month’s straightness,and the geometric precision monitoring of the machine bed base parts based on the distributed strain is realized and the base of the machine tool is used as the base of the machine tool.A new method for geometric accuracy monitoring of large parts is provided.