The Thermal Error Analysis And Compensation Techniques For Spindle System Of SV-48 Vertical Machining Center

High precision is the ever pursuing goal of manufacturing industry and machine tool bears the important mission of processing sophisticated components. Even though the machine tool has made a big improvement, from simple hardware control to computer system control, from single axis to nine axis linkage and from common machine tool to machining center, its machining accuracy still can’t meet the machining requirements. Research indicates that one of the key factors that limit the machine tool’s machining accuracy is the thermal error, especially in the precision machining, thermal error has become the main error source.Machine Tool Thermal Error Compensation Technology possesses the merits of real-time compensation, low cost of compensation and high compensation efficiency,which has become the key research aspect in the field of thermal error compensation in recent years. The research object of this thesis is the spindle of SV-48 vertical machining center. Meanwhile, combining with the implementation process of machine tool thermal error compensation technology, the author has conducted a series of researches, which are as following:(1) It explores the research background and significance of Machine Tool Thermal Error Compensation Technology, summarizes its research achievements and problems at home and abroad and finally establishes the research target and content.(2) Through analyzing the heat transfer and finite element theory, this thesis introduces three kinds of hear transfer methods and conduction process and also elaborates several common thermal load expression ways in the analysis of thermal characteristics for machine tool.(3) Combining the structural characteristics of the spindle of SV-48 vertical machining center, the thesis analyzes the spindle’s heat source distribution, thermal transfer mechanism and heat transfer process and quantifies the spindle’s heat source and heat transfer quantity. Based on the heat transfer and finite element theory, the author establishes the spindle’s finite element model. Under the normal conditions, byusing the ANSYS Workbench software, the author has carried on the analysis of transient thermo-structure coupling and got the results of the spindle’s temperature change curve, thermal displacement curve, temperature field cloud picture and thermal displacement cloud picture. What’s more, the author makes a further study of the influence of broach mechanism on the spindle’s thermal deformation.(4) The author has placed the temperature sensor and displacement sensor on the spindle in simulation state and got a series of temperature simulation data and Z-direction thermal displacement simulation data. By combining the methods of SOM Neural Network Clustering Algorithm and multiple correlation coefficient optimization, the author has finally decided three groups’ optimal temperature variables, and optimized the location of sensors.(5) In the end,The author also explores the structural characteristics of the fuzzy neural network, establishes the thermal error compensation model based on Takagi-Sugeno’s a learning algorithm of fuzzy neural network, and simulates the model by programing the MATLAB program. The simulation result shows that this model has a relatively higher quality of robustness, achieving the aim of this research.