The Lightweight Design For Tool Bracket Of The Direct-drive Spindle Head Of The Milling-turning Center

The milling & lathing compound machining center is a medium and high-end machine tool featuring high precision,high efficiency,and high speed.As the core functional unit of the milling & lathing compound machining center,the performance of the direct-drive turntable power turret directly affects the geometric accuracy,processing quality and efficiency of the machine tool.The tool bracket is the most worth optimizing design structure in direct-drive turntable power turret components,because other major components such as spindle motor and torque motor both are standard parts purchased from outside.This work was funded by the project of the development of a sub-project vertical milling & lathing compound machining center(Project No.: 2010ZX04001-032)in the National Science and Technology Major Project of the “High-end CNC Machine Tools and Basic Manufacturing Equipment” in 2010.In this work,the lightweight design for the tool bracket was conducted,combining with the methods of topology optimization and static and dynamic finite element analysis.Firstly,the finite element model of the tool bracket was established,and its static and dynamic analysis was analyzed to obtain the basic design parameters.Secondly,the topology optimization method was used to optimal design of the structure,and the design proposal of the new tool bracket was obtained.The results show that the static and dynamic characteristics of the optimized tool bracket have no significant change,but the quality is reduced by 22%,which achieves the optimization goal.The main contents of this thesis are as follows:(1)The 3D model of the tool bracket was established using Solidworks software,and then its static characteristics were analyzed by ANSYS Workbench14.0software.The maximum deformation and maximum stress at different swing angles were also obtained,and the limiting conditions were determined.(2)The modal analysis of the tool bracket was performed,the first six order natural frequencies were obtained and the vibration modes of each order were analyzed.Based on the modal analysis,the harmonic response analysis of the tool bracket was carried out to obtain the amplitude-frequency characteristic curve under the excitation force.(3)The topology optimization of the tool bracket was conducted and a new topology structure was obtained,which provided a design reference for the optimaldesign of the tool bracket.(4)A new tool bracket model was established and static and its static and dynamic characteristics were analyzed.If the result was not satisfactory,modify the model until it meets the design requirements.Finally,an optimized new model of the tool bracket was obtained.