立式切削中心機之熱影響精度問題改善研究

Abstract

摘要 就現今工具機業而言，由於NC化及自動化的演進，對立式切削中心機精度的穩定性要求日益嚴苛。如何降低由溫升熱變形所引起之加工誤差乃成為立式切削中心機製造廠必須面對的重要課題。尤其當立式切削中心機朝向高速化發展後所產生的熱變形必定會更明顯。本研究將針對進給系統相關元件及機械結構補償方式，建立最佳化設計，提高及穩定立式切削中心機加工精度。 在進給系統方面，本研究對於滾珠導螺桿施以適當的拉應力，並量測滾珠導螺桿因受熱所產生之熱位移，另外在實驗方面將軸座加以冷卻及變更進給回饋系統方式，並再相互搭配運用，且選擇其最佳組合，實驗結果顯式定位誤差由原先約70μm改善至約15μm。 最後本研究針對立式切削中心機，在不同的主軸轉速與環境溫度之下，量測主軸與立式切削中心機結構的溫升熱變形，檢討立式切削中心機主軸轉速所產生的熱與環境溫度的變異，並且建立溫度與熱誤差之關係的補償數學模型，由實機線上補償驗證，顯式機體之定位誤差由原先約100μm改善至約15μm。

ABSTRACT In recent years, the developement of machine tools seems moving toward NC and automation , The accuracy of vertical machine center thus becomes more and more important. Heat induced structural deformation causes machining error, reduces machine accuracy. These problems are one of the major task that the machine manufacturer has to face. Especially when machining speed becomes more and more fast, thermal deformation will no doubt increases. In the study, the focus was set at feeding system and machine structure compensation. In feeding system, a pre-tensions were applied to ball screws, their thermal deformations were measured. On the other hand, cooling was introduced to reduce the heat produced at bearing seat, and the deformation at the feeding system were measured again, and if was found that positioning accuracy improved for 70μm to 15μm. Finally, the heat induced deformation of the machine were measured at various main spindle revolution and ambient temperature. A compensation unit developed from above experiments was added to the machine, and if was found that the positioning of the machine accuracy improved from 100μm to 15μm.