工具機主軸剛性提昇之研究

Promotion of Spindle Stiffness for Machine-Tool

張育哲(Yu-Che Chang)

指導教授 ： 林盛勇

國立虎尾科技大學/工程學院/機械與電腦輔助工程系碩士班/碩士(2014年)

摘要

隨著各產業的快速起飛及其產品的需求量持續提升，多數相關組件必須使用工具機製造，為了因應全球的競爭趨勢，加工製造勢必講求快速而有效率，使得工具機的需求量日益增加。由於高速主軸系統亦可說是工具機的心臟，高品質工具機需搭備高剛性及高性能之主軸，因高剛性主軸具備了良好的切削阻抗與切削穩定性的保持及滿足精密加工等須求，將有助於生產速率的提昇並有效地增進其附加價值。因此，主軸系統剛性提昇之設計與製造，以提高切削加工之精密度與穩定性，乃為精密主軸相關業者當前努力的方向與課題。
本文結合主軸設計輔助軟體，並搭配實務性的實驗驗證，發展高速主軸剛性提昇之設計技術建構。首先，檢視主軸剛性影響因子，試著去確立主軸剛性的主要影響因子，計有滾珠接觸角、軸承跨距、軸承預壓及軸承排列配置形式等設計參數並建立全因子組合。接著，使用主軸設計輔助軟體建構主軸模型，並求出每一設計參數組合之主軸剛性，同時估算熱源並以有限元素法從事主軸模態與軸承溫升模擬。以主軸剛性為目標函數，受制於軸承容許溫升的拘束條件要求，求取最佳或較佳主軸剛性的設計參數組合。然後依照所求得之最佳或較佳設計參數建構實體主軸，同時針對主軸系統執行靜剛性、動態特性(迴轉精度)及軸承運轉溫升監測等實驗。結果顯示，實驗與模擬有著相同的趨勢，影響主軸最主要因子為軸承接觸角、軸承跨距與排列型式；雖然軸承接觸角越大與軸承跨距越小其主軸剛性越好，但是運轉時產生的溫度會比原來的高；軸承排列形式為前後軸承數各為兩個為較佳之排列配置。

關鍵字

主軸剛性 ； 軸承 ； 預壓 ； 頻率響應 ； 工具機

並列摘要

As industries take off rapidly and the product demand amounts growing up continuously, most of the related parts and components in a product rely on machine-tool equipment to produce eagerly. In response to global competition, the machining and manufacturing should all be fast, effective and efficient, thus the needs of machine tools are augmented naturally day by day. A high-speed spindle system is the heart of a machine-tool and a high-quality machine-tool is always coupled with a spindle system that has high stiffness and better performance. Since high stiffness spindle system may provide the better abilities to withstand cutting-loading and to keep cutting stability that may satisfy the precision machining requirements, which can help production rate promotion and increase added value effectively. Therefore, the design and manufacturing of a spindle system with stiffness promotion for better machining precision and stability is one issue that the precision spindle makers have to deal with at the present time.
A spindle design-aided software and a practical execution of experimental verification are combined together to develop a design technique for a high-speed spindle stiffness promotion construction. First of all, check all possible influencing factors on spindle stiffness and try to ascertain those main influencing factors or design parameters such as span of bearings, ball bearing contact angle, bearing preload, and bearing arrangement and configuration type in a spindle system, etc. Next, the spindle design-aided software is utilized to construct the geometrical model of a spindle system and to determine the spindle stiffness for each combination of design parameters. At the same time, the FEM is applied to simulate the modal analysis and temperature rise in bearings while heat sources generated in a spindle system are estimated preliminarily. By selecting spindle stiffness as an objective function which is subjecting to a constraint of bearing allowable temperature rise and the better design parameters combinations can thus be determined for expected spindle stiffness. A solid spindle system was fabricated according to this better design parameter combination. Finally, experiments were carried out on these spindle systems for static stiffness measurements, and monitoring on dynamic characteristics (run-out) and temperature rise in the bearings during the run-in tests. The results obtained from the simulations exhibits the similar trends to those of experiments. The major factors affecting the spindle stiffness are ball bearing contact angle, span of bearings, and bearing arrangement and configuration type. The greater is the contact angle of bearing and the smaller is the bearing span, the higher is the spindle stiffness which the higher temperature rise accompanied in operations unfortunately. For the bearing arrangement and configuration type, a better arrangement is with two bearings at the front-end and two at the rear in this improved spindle system.

並列關鍵字

Spindle rigidity ； Bearing ； Preload ； Frequency Response ； Machine Tools

參考文獻

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