| With the rapid development of NC technology, CNC machine tools have been used in aerospace, engineering machinery, transportation and other fields widely. In order to match the production requirements of equipment manufacturing industry for geometric accuracy and surface quality, and enhance the competitiveness of enterprises in the market and meet the needs of production cost savings, and overcome shortcomings of bulky structure with the traditional experience and analogy design method of structural design, the static and dynamic characteristics of NC machine tools under the conditions, lightweight design for the key parts of machine tool becomes more and more important.In this thesis, a certain type gantry machining center crossbeam structure is taken as an example for the research of lightweight design based on the finite element analysis software ANSYS and sensitivity analysis method.Firstly, the gantry machining center machine of three-dimensional model has been established using three-dimensional Solidworks drawing software. The statics and the modal were analyzed with the help of finite element software for the crossbeam component. According to the results of the analysis, the crossbeam was determined as the next object toresearch by lightweight design.Secondly, the force and boundary conditions of crossbeam were analyzed, and the statics and modal characteristics were also analyzed with the help of finite element software. According to the actual force distribution of crossbeam, crossbeam structure force model was established. With the related parameters of gantry machining center and relevant knowledge of theoretical mechanics, the force of the crossbeam is calculated, and the total deformation, stress, the first six modal frequencies and mode of vibration of crossbeam structure were obtained by ANSYS software.Thirdly, the stiffened plate was changed by crossbeam lightweight design. On the basis of the original beam structure, combined with the common type of stiffened plate, the four different crossbeam structure schemes were designed, the statics and the modal were analyzed by using the finite element analysis software, and the maximum displacement deformation, stress, weight and the first six order modal frequency of four kinds of crossbeams were compared. At last, the V type plate crossbeam structure was conformed as the optimal scheme of the four schemes. Compared with the original structure, not only static and dynamic performance is significantly improved, but also the weight is reduced by 18 kg.And then, static and dynamic characteristics sensitivity analysis of key sizes of V type plate crossbeam were implemented based on ANSYS finite element software, lightweight crossbeam structure was designed using the extreme size adjusting method. The sensitivity analysis of the key sizes of crossbeam structure were analyzed, according to the results of the sensitivity analysis, the relative was obtained sensitivity of static and dynamic characteristics of crossbeam structural based on the least square method. Considering static and dynamic characteristics of the beam structure, was obtained a lightweight design structure of crossbeam using extreme size adjustment method. As a result, the weight of thecrossbeam structure is reduced by 152 kg, achieving a lightweight design beam structure. At last,the weight of crossbeam was reduced by 170 kg with the same conditions of static and dynamic characteristics, and the corresponding percentage decline is 3.6%.Finally, the lightweight crossbeam component is simulation analyzed on static deformation and experiment-tested. Compared with the experimental results, the reliability of crossbeam structure lightweight design is verified,which offers a feasible method for the light weight design of other machine tool parts. |
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