| Recent years as CNC machine tool is developed in high speed, high accuracy and high efficiency direction, dynamic characteristic of CNC machine tool has been becoming increasingly demanding, linear rolling guide(LRG) with excellent characteristic has been widely used. Accurate dynamic model is the foundation of dynamic analysis and dynamic design of the machine tool, while the key factor of establishing an accurate dynamic model of the machine tool is the treatment of the joint surface. Linear rolling guide is the commonly used function part of modern CNC machine tool, its dynamic characteristic has great influence on the dynamic characteristic of the machine tool.CAKxxx CNC machine tool and SNS35LR LRG produced by THK in Japan are research objects in this paper. Influence of the LRG joint on dynamic characteristic of machine tool is analyzed using both theory and test method, then structural improvement and optimization on the main components of the machine tool is also made.The main contents of this paper is as following:(1) Research methods and status on guide joint, research purpose, significance and status of the dynamic analysis and dynamic design of machine tool are summarized. Research method combined with theoretical research, dynamic test and finite element analysis is proposed.(2) Contact analysis on SNS35LR LRG produced by THK is made, and normal and tangential stiffness is obtained.(3) Dynamic theoretical model and finite element model(FEM) of LRG joint are established. Calculation of theoretical model, modal and harmonic response analysis of FEM are made. Accuracy of the theoretical model and FEM is verified by the dynamic test of the LRG. (4) FEM of machine tool with and without LRG joint are established and dynamic characteristic analysis is made. The first5-order natural frequency and vibration modes are obtained in both cases. Comparison shows that LRG joint has significant influence on the dynamic characteristic of machine tool.(5) Dynamic test is made on prototype of the CAK×××CNC machine tool, its parameters of each modal and dynamic stiffness are obtained, great influence of LRG joint on the dynamic characteristic of machine tool is verified, which offers foundation for accurate modeling and dynamic design of machine tool.(6) Static and dyanmic analysis on the machine tool bed and spindle box is made. Weak links of these components are found. Structural improvement and optimization on these components are made to furthermore improve the characteristic of the machine tool. |
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