車削鈦合金之切屑控制探討

The Study of Chip Control in Turning Titanium Alloy

祝華杰(Huajie Zhu)

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(2017年)

https://doi.org/10.6342/NTU201703479

摘要

Ti-6Al-4V具有優異的物理和機械性質並具有生物相容性。隨著社會生產力的發展，鈦合金不僅僅應用於航空和軍事領域，正越來越多的應用在生活的各個方面。但是由於其特殊的材料特性使得其加工難度大，加工成本高。這其中鈦合金難斷屑的問題一直困擾業界，長而堅韌的切屑阻礙了加工效率的提高，影響工件的表面粗糙度，降低刀具的使用壽命。
本文旨在為Ti-6Al-4V的切屑控制找出合理的方案。首先對Ti-6Al-4V的切削力分別隨進給、切深、切速這三個切削參數進行討論，與切屑的形態進行比較；Ti-6Al-4V的切屑以螺旋狀(Helical)為主，最終在進給達到0.31mm/rev時，切屑有變為C型斷屑的趨勢。刀具適用的切削條件內，Ti-6Al-4V切屑與刀面的接觸距離不到1mm。根據本研究發現適當增大進給導致切屑流動角增大；適當減小車削速度導致上捲半徑減小，側捲半徑增大；適當減小車削深度導致上捲半徑減小，側捲半徑增大， 並搭配凹槽(Groove)型斷屑槽就有希望使得切屑被引導撞到刀腹面，進而在應力應變增大到極限值之後發生斷裂。本文還推導出了適用於金屬切削的斷屑準據，並用1045中碳鋼和304不鏽鋼初步驗證了其正確性。最後推導出要使得Ti-6Al-4V在小於0.2mm/rev的進給下斷屑，斷屑槽寬度要小於1.2mm，但是目前商用斷屑器的斷屑槽寬度都大於1.5mm。所以，干切削條件下Ti-6Al-4V，在刀具廠商推薦的切削範圍內，Ti-6Al-4V難以自行斷屑。

關鍵字

車削 ； Ti-6Al-4V ； 切屑控制 ； 斷屑槽

並列摘要

With the development of social productive forces, application of titanium alloys is not only confined to the field of aerospace and military, but also is increasingly being used in the production of all aspects of life. However, because of its unique material properties, we can not get better processing efficiency and lower processing costs. Among all these puzzles, the problem of chip control of Titanium alloys(Ti-6Al-4V) has been troubling the manufacturing industry. Long and tough chips hinder the improvement of processing efficiency, affecting the surface roughness of the workpiece, reducing tool life.
This research aims to find a reasonable solution for the chip control of Ti-6Al-4V. First, the cutting forces of Ti-6Al-4V were discussed with the three cutting parameters of feed, depth of cut and cutting speed respectively, comparing to the shape of the chips; Most of the chip shapes are helical. Finally, when the feed rate reaches 0.25mm/rev, chip has the tendency to become C-type breaking chip. the contact distance between the chip and tool face is less than 1mm in common turning conditions. We need to be reduced, to be increased, increase the chip flow angle appropriately and with the design of the Groove-type chip breaker at the same time to guide the chip collision to the flank face. According to this study found that increasing the feed rate appropriately causes increasing; decreasing the cutting speed appropriately causes decreasing, increasing; decreasing depth of cut appropriately causes decreasing, increasing, it is possible to guide the chip collision to the flank face. Finally, it is deduced that if Ti-6Al-4V chip breaks automatically under less than 0.2 mm / rev feed rate, we need the chip breaker width W less than 1.2mm, but the current commercial chip breaker chip breaker width is greater than 1.5mm. So, in dry cutting condition, in the cutting range recommended by the tool manufacturer, Ti-6Al-4V chip is difficult to break automatically.

並列關鍵字

lathe turning ； Ti-6Al-4V ； chip control ； chip breaker

參考文獻

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