Experimental Modal Analysis On Precision Machine Tool

High-precision and high-efficiency are the long-term development direction of CNC machine tools. Among them, improving machining accuracy of CNC machine tools is the universal demand of modern manufacturing industry. High-precision and high-efficiency are not only major technical indicators of CNC machine tools, but also the main goal of machine tool manufacturers and users. Improving the kinetic characteristics, especially the cutting stability and vibration resistance is the main way to attain this aim. The main mean for obtaining the kinetic characteristics of products is kinetic analysis, which plays a very important role in products design and improvement. Specially, experimental modal analysis is an effective way to solve such engineering problems.CY-HTC4050μ, a high-precision CNC lathe produced by an enterprise in YunNan, is the research object of this thesis. Its main structural characteristics embodied in its granite 45°oblique style bed. How to assess dynamic characteristics of this new structure, experimental modal analysis method is a choice under current conditions. The main work has been done as follow:1. Hammer testing is conducted on the lathe in Y and Z directions under typical state. Then, modal parameters, such as modal frequency, damping ratio and mode of vibration have been identified by parameter identification method in frequency domain, and the experimental modal has been established.2. The experimental modal has been verified by modal verification methods.3. Based on the sensitivity analysis of frequency to quality, parameter modification on two response points are carried out.Conclusions are as follow:1. The inherent characteristic analysis shows that the joints of the lathe bed and other components have bigger vibration response.2. From the view of improving the spindle speed (bigger than the maximum speed at present), the judgment of the weak mode and the main vibration component of the lathe can provide a basis for the improvement of the lathe.Test and analysis results proved that the analysis of such complex structure by experimental modal analysis method is a new attempt of theoretical methods and test technologies.