Multi-objective Optimization Design Of Vertical Machining Center

With the accelerated pace of global economy integration, manufacturing enterprises increasingly compete in performance, quality, lightweight, customization, cost and delivery time of products. How to quickly respond to the market in a relatively short period of time with products of higher performance and lower costs to dominate the market is a key for the enterprises to survive and develop. Manufacturings thus must implement various advanced design methods, manufacturing technology and equipments to optimize their product, to improve product performance, and to increase production efficiency while reduce costs.In the above context, this thesis presents a multi-variable, multi-discipline and multi-objective optimization method for design of CNC machining centers, with the objective of reducing the weights of machining centers under the constraints on their static and dynamic performance. The vertical machining center FWV-6A, a product of our enterprise partner, and its five major parts, namely the column, bed, slide table, headstock and worktable, are first studied with finite element analysis and modal testing to acquire their static and dynamic performance and weaknesses. The agreement between finite element analysis and modal test proves the accuracy of finite element model. Based on the finite element model, static analysis is then carried out to obtain the largest the deformation and stress of the five major parts of the machining center, as the basis of the structural topology optimization, reinforced ribs optimization and size optimization.Then, quality, natural frequency, or compliance of machining center is taken as the goal, the column framework is then designed by topology optimization, in order to achieve least materials (and hence the smallest least weight) with desired performance. Adaptive dynamic optimization method based on unit structure is used to design the reinforced rib structure which may play an important role in enhancing performance but reducing weight, of column, bed and slide table. The optimal sizes and thickness of structure are determined with response surface method. Finally, the static and dynamic performance of the optimized machining center consisting of the five optimized major parts is analyzed and compared with the original one. The results show that the presented optimization achieves weight reduction of 4.9% of the machining center with desired static and dynamic performance, and hence has good practicability in engineering.