An Optimization Analysis of Cooling Channel Design in a CNC Lathe Spindle System

臥式車床主軸頭熱變形模擬與冷卻流道優化分析

楊智凱(Chih-Kai Yang) ； 李明蒼(Ming-Tsang Lee)

《中國機械工程學刊》 40卷3期 (2019/06) Pp. 231-238

摘要

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.

關鍵字

machine tools ； thermal error ； spindle ； multiphysics analysis ； Taguchi method

並列摘要

本研究探討一典型臥式車床主軸系統熱傳現象以及散熱流道設計。首先根據臥式車床主軸在運轉的情況之下所產生的熱源，運用有限元素分析軟體，進行車床主軸系統的熱流固耦合熱傳模擬，探討這些熱源在車床主軸系統所產生的溫升與熱變形的現象，以及對整體車床主軸系統結構熱變位之影響。原本的主軸套管並無散熱流道的設計，所以本研究接著以模擬模型於主軸套管上設計內部往復式散熱流道，希望利用油冷機將冷卻液注入散熱流道進而適當地控制主軸頭結構溫度的變化與改善熱變形。本研究所探討的散熱流道設計參數為流道孔徑、流道數量與質量流率，依據田口法配對出9組不同的流道設計參數，接著使用有限元素分析軟體進行溫升與熱變形分析模擬。經由分析結果得知有流道設計的套管熱變形明顯減少；並且根據模擬結果的統計與分析，得知熱變位最小的設計參數，以及討論在運用田口法進行冷卻流道模擬實驗規劃與優化分析時應選擇的適當參數。本研究成果與研究方法可作為工具機主軸冷卻系統設計建模分析與優化的參考。