熱塑性塑膠聚醚醚酮 (PEEK,polyetheretherketone)具備低線性熱膨脹係數、以及高熱變形或軟化溫度之特性,經常被選擇做為工程結構板材。然而,由於塑膠的延展特性,加工容易變形,切削製程有一定的困難度。
文獻中,許多學者指出「主軸轉速」與「進給率」為影響鑽削製程的重要參數,本研究進行PEEK塑膠板之鑽削實驗,設置力感測器與加速度計量測三軸向切削力與加速度,依實驗方法分析鑽削參數對兩項加工特性之水準效應;並藉由頻譜分析軟體執行時域與頻域分析,觀察切削狀態。分析案例有二:∅2、∅6 mm,各執行18組參數實驗,討論出最佳參數水準組合。最後,執行風冷驗證實驗,觀察鑽削溫度與軸向推力之關聯性。
參數實驗的結果顯示:兩個分析案例的最佳參數水準組合皆是以低主軸轉數搭配小刀具進給率,它們可使切削推力與加工系統的加速度變化量為最小,保持穩定的加工特性。
The thermoplastic of polyetheretherketone, PEEK, has excellent characteristics of low coefficient of linear thermal expansion and high soften temperature or thermal deformation, which is selected as an engineering material for structural plate frequently. However, due to the ductility of plastics, deformations are occurred easily in machining. It is difficulty in cutting processes certainly.
In literatures, several scholars indicated that the spindle revolution and tool feed rate are two important parameters in drilling process. This study performed drilling experiments of an engineering plastic plate. A force sensor and an accelerometer were installed for measuring the tri-axial cutting force and acceleration. The level effects of the drilling parameters analyzed on the two cutting characteristics were evaluated based on the experimental method, and executed the frequency spectrum analyses of time domain and frequency domain to observe machining states. Two cases of ∅2 and ∅6 in diameter were discussed, and eighteen parametrical experiments were carried out to derive the optimal parameter level set. Final, verification experiments with air cooling were performed to observe the correlation between the drilling temperature and the axial thrust force.
Results of the parametric experiments showed that the optimal parameter level sets were to select a lower spindle revolution coupled with a smaller tool feed rate in the two cases. In which, they can result in a smaller thrust force in drilling and a lower acceleration variation of the operation system, and keep stable machining characteristics.