Machining dexterity model-based comparison of kinematic chains for five-axis machine tools with different configurations

Five-axis machine tools are widely used for machining complex curved surfaces. Different configurations of five-axis machine tools can have significant kinematic performance differences when machining the same curved surface. Current research on tool axis vector optimization is usually limited to machine tools with a specific configuration, and comparisons of kinematic chain performance between machine tools with different configurations are lacking and insufficient. In order to quantify the dexterity differences during tool axis optimization, a novel machining dexterity model is proposed to compare the kinematic chains for five-axis machine tools with three different configurations. The machining dexterity model of five-axis machine tools mainly includes the Main Dexterity, the Regional Dexterity, and the Fine-tuning Dexterity. The Main Dexterity is calculated through the dexterity index to comprehensively evaluate the adjustability of five-axis machine tools during whole tool axis vector optimization; The Regional Dexterity is calculated through the dexterity cone to evaluate the corresponding changes in the adjustability of each motion axis under different regional adjustment requirements; The Fine-tuning Dexterity is calculated through the motion axis sensitivity to evaluate the adjustment accuracy of the motion axis during tool-orientation fine-tuning. The simulation and comparison are performed between three typical configurations of five-axis machine tools: spindle-tilting, spindle-table-tilting, and table-tilting (Type I, Type II, and Type III). Quantitative calculations and comparisons have been validated by the same case of tool axis vector optimization, and the results show that the proposed machining dexterity model can effectively and systematically evaluate the dexterity performance of five-axis machine tools.