Study On Reliability Optimization Design For Double-Axis CNC Machine Tool

As the mainstream processing equipment of modern manufacturing, the quantity and performance level of CNC machine tool reflects a country’s overall manufacturing capacity. At present, there is a big gap between the level of domestic CNC machine tool on technology and developed countries. The performance level can barely meet the growing demand, especially in accuracy and reliability of the machine. Meanwhile, traditional methods, which usually use a larger safety factor and ignore the influence of uncertain factors such as machining errors, are used in the machine optimization design process. These may cause waste of resources and the reliability of machine tool is not protected. Therefore, studying on reliability is required in optimization design of machine tool, so the performance is guaranteed.The double-axis CNC machine tool for bearing ring is used as study object. Aiming at the heavy weight of the machine tool, reliability optimization design for key components is completed with the objective of minimum weight of the machine tool, based on reliability optimization method. The main contents are as follows:(1) The objects for reliability optimization design are determined based on the analysis of problems in reliability optimization design of the machine tool. Then optimization modeling methods are researched and solution strategy for reliability optimization design of double-axis CNC machine tool is carried out.(2) The double-axis CNC machine has two spindles. Finite element analysis is carried out for both spindles after the study on the force of spindle assembly and sub spindle assembly for different conditions. Then stress and deformation contours of headstock and sub headstock are obtained after the study of their static and dynamic characteristics. Their safety is also studied. This is the basis for optimization.(3) The heat-structural coupled finite element model is established to analyzed temperature distribution of headstock and sub headstock. Validate the model by experiment. Mathematical model for reliability optimization design is established with the integration of Isight to study on the influence of design variables on headstock and sub headstock performance, with the minimum weight of headstock and sub headstock as design objective. Then implement optimization design of headstock and sub headstock based on the reliability. The weight of the headstock and sub headstock decreases and the reliability is improved after the optimization design. (4) Dynamic characteristics of the machine tool bed is researched. Optimal constraints are determined based on the researched result. The influence of the design variable is analyzed after the establishment of mathematical model for reliability optimization design of the machine tool bed with the integration of Pro/E、ANSYS and Isight. Expected result is concluded after the optimization with multi-island genetic algorithm.The weight of the double-axis CNC machine tool decreases after the optimization design for key components and the reliability of key components improved to varying degrees. The optimization result of the article provides a theoretical basis for the improvement of structure of the machine tool.