Static And Dynamic Analysis Of Feeding Mechanism Of High Speed Vertical Machining Center

With the continuous improvement of modern manufacturing technology, CNC machine tools are developing toward in the direction of high speed, high precision, high efficiency and high automation, which require the static and dynamic characteristics of the machine tool more and more high. There are many factors that affect the performance of machine tools, and the static and dynamic characteristics are one of the key factors, so it has important theoretical and practical significance to study the static and dynamic characteristics of CNC machine tools.This topic study on a certain model of high speed vertical machining center, the following research work was carried out on the static and dynamic characteristics of each part of the longitudinal feed mechanism through combination of theory and finite element analysis.(1) According to the given technical parameters, the type selection and structure design are carried out on several major components of longitudinal feeding mechanism, including ball screw nut pair, rolling guide rail vice, feeding mechanism base, and 3D modeling by using Solid Works software. Considering the influence of the ball screw axial deformation, contact deformation of ball and screw nut and axial deformation of support bearing on the stiffness of ball screw's axial transmission, the theoretical formulas are derived for the three mentioned above by using Hertz contact theory, and then analyzed by finite element software. It is concluded that the improved methods to the axial stiffness of the ball screw nut.Then, the six different supporting modes of nut's different working position of at left end, middle and right end when fixed at both ends and one fixed one supported, for which the modal analysis and harmonic response analysis of ball screw nut are separately carried out. The correctness of the type selection is verified, and the frequency of the dynamic load in the actual working condition should be avoided is obtained, providing theoretical basis for future design.(2) The finite element model of rolling linear guide rail vice is established considering the influence of the rolling ball in the linear guide, and the static analysis and modal analysis are carried out to verify the correctness of type selection.(3) Five different arrangements of ribs of feed mechanism base are designed according to the structural characteristics of the base of the feeding mechanism combined with design experience, then the static analysis and modal analysis are carried out combined with the operating characteristics, finally the final design scheme is determined.(4) Considering the influence of the bolted joints surface, bearing joints surface, and the ball scew joints surface, the model of the whole longitudinal feed mechanism were simplified, and the static analysis and modal analysis are carried out under the actual working conditions. The X, Y, Z direction stiffness and the weak link in the joints surface are obtained, which find out the direction of improving its dynamic characteristics.