Study On The Redesign Method Of Five-axis Gantry Machining Center Based On Stiffness Mathing

Taking the five-axis gantry machining center as an example,the finite element static analysis and modal analysis of the machining center were carried out to study the stiffness matching of the main components.And taking the beam of a waste machine tool as an example,a new machine tool was designed based on the stiffness matching theory of machine tool.The main contents of this project are as follows:(1)The CAD/CAE model of the five-axis gantry machining center's sliding plate was established.Through modal test and finite element analysis,the accuracy of the model was verified by comparing the test results with the finite element calculation results,and the CAD/CAE model of the whole machine center was established by the same method.(2)The definition of static stiffness matching was put forward:when the stiffness of one component is increased or decreased in a certain direction,the stiffness change of the modified machine tool is more than 50%relative to the stiffness of the original machine tool in this direction,it can be argued that the stiffness of this component in this direction is not matched.We made the static analysis of the machine tool,followed by raising and lowering the static stiffness of the pillar,slide plate,beam,ram and saddle,and compared the results with the static analysis results of the original machine.The static stiffness matching of components was summed up,and the optimization design method of machining center based on the static stiffness matching was put forward.(3)The definition of dynamic stiffness matching was put forward:when the stiffness of one component is increased or decreased,the natural frequency change of the modified machine tool is more than 50%relative to the natural frequency of the original machine tool in the same type of vibration,it can be argued that the stiffness of this component in this order is not matched.We made the modal analysis of the machine tool,followed by raising and lowering the dynamic stiffness of the pillar,slide plate,beam,ram and saddle,and compared the results with the modal analysis results of the original machine.The dynamic stiffness matching of components was summed up,and the optimization design method of machining center based on the dynamic stiffness matching was put forward.(4)Through the method of sensitivity analysis,the beam structure was optimized and its static stiffness and dynamic stiffness were improved.The static stiffness of the optimized machine in the three directions of X,Y and Z were increased by 3.3%,0.46%and 4.33%,and the natural frequencies of several orders which had great influence on the dynamic performance of the whole machine increased by 1.44%,0.43%and 0.065%.Static and dynamic performance were improved,which verified that the optimization method of machining center based on stiffness matching proposed in this paper was effective and reliable.(5)Based on the beam of a waste machine tool,the structure of ram,slide plate and pillar were designed respectively through the optimization design method based on stiffness matching,realizing the redesign of the new machine tool.After the redesign,the static stiffness of the new machine tool increased by 4.76%,10.07%and 18.28%in X,Y and Z directions respectively.The natural frequencies of several orders which had great influence on the dynamic performance of the whole machine increased by 4.51%,17.33%,5.10%and 5.97%.The static and dynamic performances were greatly improved.The introduction of artificial granite had saved the cost of manufacturing,reduced the emission of pollution,while realizing the green design idea.The stiffness matching theory proposed in this paper is very important for the structural optimization design of this type of gantry machining center and lays the foundation for further research on such and other types of machine tools.