Electric Spindle Structure Analysis And Optimization Based On Goal-driven

The development of the latest achievements in the integrated application of modern CNC machine tools for mechanical design and manufacturing technology, computer technology, automatic control technology toward in high-speed, high-precision, complex, flexible, etc. The static and dynamic characteristics of the spindle system is one of the main reasons that affect the machining accuracy finite element analysis used in the design of electric spindle unit process, help to improve the efficiency and design level of the whole machine.In this paper, using the finite element analysis software Femap+NX Nastran and Matlab to analysis spindle system include:(1) According to the spindle system with bearing Model, theoretical calculations of the stiffness and damping of the spindle bearings, analysis of the relationship of the bearing preload force and bearing stiffness, draw the stiffness angular contact ball bearings with the preload change the law.(2) Finite element modeling of electric spindle, in the Femap+NX Nastran, analog spindle with beam elements, gets static stiffness of the spindle by static analysis.(3) Use of Matlab software, analysis dynamic characteristics of Spindle, obtained electric spindle first four modal frequencies and corresponding mode shapes, in further steps analysis model harmonic response of spindle, get the response curve of the of spindle front, center and back-end, summarized the relationship among spindle amplitude of response, natural frequencies and modes.(4) Used of the LMS test systems to do experiments validate the finite element model of the electro-spindle, Experimental results show that the electric spindle harmonic response curve trend consistent with the test results, the theoretical model simulation and experimental test from the first three natural frequency error is less than 9%, proves that the finite element modeling is essentially correct.(5) Calculated the critical speed of electric spindle system, in the original dynamics model added the centrifugal force and the gyroscopic torque generated by the spindle due to speed, analyzed the impact of centrifugal force and gyroscopic moment to the spindle critical speed solving, summarized the variation of natural frequency with the spindle speed.(6) Used the influence of the eccentric mass generated by the spindle, calculated the dynamic stiffness of the spindle system in various speed corresponding dynamic stiffness values, summarized the law of the spindle dynamic stiffness changing with the speed.(7) Optimized the design of the spindle, establish a finite element model of the spindle system parameters, take the Spindle volume as the objective function of optimize, take the length of each ladder section, the outer radius and the bearing span of the spindle as the design variables, take the deformation and the dynamic stiffness of the front spindle in the speed of common tasks as the state variables, optimized the design of the spindle system and weight loss of the spindle system, also has a good dynamic performance.