超音波振動輔助高速銑削 Inconel 718之研究

The Study of Ultrasonic Vibration Assisted High-speed Milling Inconel 718

邱子瑜(Tzu-Yu Chiu)

指導教授 ： 廖運炫

國立臺灣大學/工學院/機械工程學研究所/碩士(2022年)

https://doi.org/10.6342/NTU202203035

摘要

Inconel 718是在高溫下依舊能保持良好機械性質的鎳基超合金，近年來多做為航太零件的材料。但因為材料具有低熱傳導率及易加工硬化等特性，切削時的高切削溫度、切削力使切削速度無法提升、刀具快速磨耗，造成加工效率跟加工品質皆無法有效提升，而過去多應用不同冷卻方法或改變刀具材料來解決上述所產生之問題。本研究希望利用縱扭超音波振動輔助銑削(LTUVM)以達到提升Inconel 718切削速度之目的，並進一步由刀尖軌跡方程式探討縱向超音波振動輔助銑削(LUVM)及縱扭超音波振動輔助銑削(LTUVM)之間的差異，從中了解LTUVM中扭轉振動的作用機制，以及不同加工方法下的表面粗糙度、切削力、刀具磨耗量隨切削速度變化之關係。
通過扭轉方向之刀尖軌跡模擬分析，在低切削速度時，刀尖會有往進給方向前進之後退運動發生，導致刀腹擠壓、摩擦到未切削工件表面。若提高切削速度其後退運動將明顯減小直至消失。
實驗結果顯示，不論LUVM、LTUVM皆表明超音波加工能使表面粗糙度降低，而隨著速度的提高表面粗糙度值越低，其中LTUVM更具優勢。通過切削力及刀腹平均磨耗量之結果能證明模擬之推論。和CM相比施加超音波皆能使切削合力下降；在低切削速度時，因LTUVM中扭轉造成之後退運動擠壓到未切削工件的影響，LUVM會得到較低之切削力值；若提高切削速度使後退運動逐漸消失，LTUVM的表現則皆會優於LUVM，切削速度56m/min時，和LUVM相比可以再減少5.18%的切削力；切削速度84m/min時，則可以減少4.36%的切削力。刀腹平均磨耗量的變化趨勢和切削力相同，也顯示在較高的速度下，LTUVM會有更好的效果；而切削速度提高至84m/min時，不論何種加工方法皆發現到刀具材料有剝落之行為發生。以上結果及趨勢皆表明，利用LTUVM來提高切削速度之想法為可行，且在切削速度為56m/min會有最佳的效果。

關鍵字

超音波振動輔助 ； Inconel 718 ； 縱扭超音波振動 ； 縱向超音波振動

並列摘要

Inconel 718 is a nickel-based alloy, which can maintain excellent mechanical properties at high temperature. However, due to its low conductivity and easy work hardening properties, the high cutting temperature during cutting process makes it difficult to rise the cutting speed, and the cutting tool also wears rapidly. These problems result in the processing efficiency and quality both cannot be improved. In the past, several studies applied different cooling methods or changed the tool material to solve the problems. This study intended to achieve the purpose of rising the cutting speed of milling Inconel 718 by longitudinal-torsional ultrasonic vibration assisted milling(LTUVM), and further investigated the difference between longitudinal ultrasonic vibration assisted milling(LUVM) and LTUVM from the tool-tip trajectory equation to understand the mechanism of torsional vibration in LTUVM, and the relationship between surface roughness, cutting force, and tool wear with cutting speed under different processing methods.
The simulation analysis of the tool-tip trajectory in the torsional direction found that it had a backward movement at lower speed with moving forward in the feed direction, causing the tool flank squeeze and rub against the surface of the uncut workpiece. If increasing the speed, the separation motion will gradually reduced until it disappears. The results showed that both LUVM and LTUVM could reduce the surface roughness, and the value became lower as the speed increased. The simulation result could be proved by the cutting force and the average tool flank wear. Compared with CM, applying ultrasonic could reduce the cutting force; LUVM got lower force at lower speed due to the torsional backward motion in LTUVM, as the speed increased, LTUVM had a better performance. The force could be reduced by 5.18% compared with LUVM at 56m/min, and be reduced by 4.36% at 84m/min. The trend of the average tool wear was the same as the cutting force, also showed that LTUVM got a better effect at higher speed. However, the tool material had flaking behavior at 84m/min in every processing methods. The results and trends all showed that the idea of using LTUVM to rise the cutting speed is feasible, especially at 56m/min.

並列關鍵字

Ultrasonic Vibration Assisted Machining(UVM) ； Inconel 718 ； Longitudional Vibration ； Longitudinal-Torsional Vibration

參考文獻

[1] E. O. Ezugwu, J. Bonney, and Y. Yamane, “An overview of the machinability of aeroengine alloys,” Journal of Materials Processing Technology, vol. 134, no. 2, pp. 233-253, 2003.

[2] G. Mahalle, O. Salunke, N. Kotkunde, A. K. Gupta, and S. K. Singh, “Neural network modeling for anisotropic mechanical properties and work hardening behaviorof Inconel 718 alloy at elevated temperatures,” Journal of Materials Research and Technology-Jmr T, vol. 8, no. 2, pp. 2130-2140, 2019.

[3] N. Khanna, P. S. Shah, C. Agrawal, F. Pusavec, and H. Hegab, “Inconel 718 machining performance evaluation using indigenously developed hybrid machining facilities: experimental investigation and sustainability assessment,” International Journal of Advanced Manufacturing Technology, vol. 106, no. 11-12, pp. 4987-4999, 2020.

[4] E. O. Ezugwu, Z. M. Wang, and A. R. Machado, “The machinability of nickel-based alloys: a review,” Journal of Materials Processing Technology, vol. 86, no. 1-3, pp. 1-16, 1999.

[5] T. Ramkumar, M. Selvakumar, P. Narayanasamy, A. A. Begam, P. Mathavan, and A. A. Raj, “Studies on the structural property, mechanical relationships and corrosion behaviour of Inconel 718 and SS 316L dissimilar joints by TIG welding without using activated flux,” Journal of Manufacturing Processes, vol. 30, pp. 290-298, 2017.