Research About The Structure Design Method Of Machine Tool And Application In The Column Design

Static-dynamic optimization and light-weight design of the structure is a main way to achieve the high-speed and high-precision characteristics of modern CNC machine tool. Finite element analysis and structure optimization method has been widely used in machine tool structure design. Compared with the traditional design method for the machine tool structure, higher design efficiency and quality will be obtained while using the new design method based on the FEM analysis and structure optimization.This project is funded by the National Major Science and Technology Project 'high-grade CNC machine tools and basic manufacturing equipments'and National Technology Support Project. The project names are'digital design & software of machine tool oriented its static-dynamic-thermal characteristics'(NO.2009ZX04014-034),'One certain serial vertical turning-milling machining centers'(NO.2009ZX04001-031)and'series products development of high speed and multi-axis gantry machining center' (NO.2007BAF21B01). The design method of the CNC machine tool structure based on topology optimization has been discussed in this paper. And this design method has been successfully applied to the static-dynamic optimization and light-weight design of the moving column structure on a certain vertical turning-milling machining center. The concrete research works are focused on the following aspects:(1) The structure design method for the CNC machine tool is systematically discussed in this paper. The foundation of static-dynamic topology optimization is firstly studied. Considering both the typical load cases and the structural characteristics of the CNC machine tool, the design steps of the machine tool structure is put forward, which consists of physical model analysis, topology optimization conceptual model design and detailed performance design.(2) The structure types of the typical CNC machine tools and the loads distribution of the typical joint surfaces are studied, and then the parameter-driven mechanical model for the CNC machine tool structure is established. The relevant software is also developed to realize the digital solution of the FEA loads of the CNC machine tool structure while analyzing the structure physical model. (3) The above design method for machine tool structure is applied to design the column structure. In the physical model analyzing stage, the loads and boundary conditions of the column structure are obtained by using the software mentioned above. In the conceptual model design stage, the conceptual models of the column structure are established by variable density method in OptiStruct. In the optimization, topology optimization problems are carried out which based on different optimal objectives all subjected to volume constraint:the weighted structure compliance on multiple load cases, the first-order natural frequency and a multi-objective considering both the compliance and natural frequency. In the detailed design stage, a column structure is finally designed after three steps:column structure modeling based on the conceptual model, size design and technology improvement of the column structure.The stiffness and first-order natural frequency of the new design column structure improves 13.6% and 17.1% respectively and also with 9.7% mass reduction compared with the traditional design one. Results indicate that the design method discussed in this paper is efficient in the static-dynamic and light-weight design of the column structure. It also helps the enterprise solve the problem that the moving column structure is too heavy but without sufficient rigidity while researching and developing the vertical turning-milling machining center. As a result, the column structure designed in this paper is finally adopted and applied to production by the enterprise.