Abstract
In this study the heat transfer phenomena, thermal deformation and the design of cooling channels for a standard Computer Numerical Control (CNC) lathe spindle system were conducted numerically. The heat sources taken into consideration include the rotary hydraulic cylinder, the bearings and the spindle pulley. Discussions and conclusions are based on numerical simulations of temperature variations and structural thermal displacement. To reduce the degree of thermal deformation a system of cooling channels was designed for the spindle and tested numerically. Design parameters investigated of the cooling channels were the diameter of the channels (6, 8 and 10mm), the number of channels (4, 6 and 8) and the coolant mass flowrate (0.085, 0.113 and 0.142 kg/s). The Taguchi method was used with simulations of nine sets of combinations of these parameters. The numerical results showed that the best cooling channel design among the aforementioned design parameters has 8 channels, 8mm in diameter and a mass flowrate of 0.085 kg/s. It was also noticed that, when optimizing the cooling system with design parameters comprising the geometrical dimensions of the channel and the coolant flow rate, extra attentions should be taken to assure the independency between these design factors, especially on the flowrate of the coolant to the other design parameters. The method and the results of this study provide a useful reference for the design and optimization of cooling channels for spindle systems in machine tools.