提昇超音波切骨手術的材料移除率方法之研究

Studies to Improve the Material Removal Rate in Ultrasonic Osteotomy

賴承佑(Cheng-Yu Lai)

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(2011年)

https://doi.org/10.6342/NTU.2011.02142

摘要

本研究目的為提升超音波骨刀的材料移除率，從切削理論得知材料移除率正比於切削功率，而與比切削能有反比關係。因此本研究將從刀具設計著手以減少比切削能，以及從減少摩擦能的方式來提昇刀具的切削功率，以獲得切削效率較現有市售來得優異的超音波骨刀頭。
刀具形狀分為齒數與每齒幾何形狀的變化，從齒數對材料移除率影響的探討知道，在1到5齒刀具的切削結果，以5齒刀具的材料移除率較高。而在鋸齒形狀的探討中，則利用田口式方法進行L9(33)的實驗，實驗結果得知鋸齒的Rake angle (θr)、Inclination angle (θi)和Chamfer angle (θc)對材料移除率都有顯著的影響，影響大小為θr>θc>θi。實驗結果顯示，齒數為5、θr= 0∘、θi =15∘和θc =40∘的刀具設計，可得到較現有超音波骨刀高的材料移除率。
在提升刀具切削功率方面，將相同外型的刀具搭配不同表面摩擦係數的薄膜鍍層，發現使用摩擦係數較低的刀具切削，摩擦耗能較少而切削功率提昇，使得材料移除率提昇，同時也因為摩擦耗能的減少而降低切削溫昇。在本研究中使用DLC薄膜與TiN薄膜鍍層，DLC薄膜的材料移除率較未鍍層增加11.4%，溫昇減少3.5℃；TiN薄膜的材料移除率較未鍍層增加3.4%，溫昇減少1.1℃，因DLC摩擦係數較TiN低，因此可得到較佳的效果。
根據本研究結果設計出新式超音波骨刀，採用齒數為5、θr= 0∘、θi =15∘和θc =40∘的齒型，而每齒的θi與θc方向交錯設計，並於外表鍍上DLC薄膜，預期材料移除率可達到0.49 mm3/s，較現有市售刀具0.13 mm3/s的材料移除率，增加3.8倍左右。

關鍵字

超音波切骨手術 ； 材料移除率 ； 切削功率 ； 比切削能 ； 刀具鍍層

並列摘要

The aim of this research is to increase the material removal rate (MRR) in ultrasonic osteotomy. According to the basic cutting theory, MRR can be increased by decreasing the specific cutting energy or by increasing the cutting power.
For the same work material, the specific cutting energy is mainly affected by the geometrical shape of the cutting tip, including the number of the teeth and the geometrical shape of the teeth. The Taguchi method was used to find the better geometrical shape of the cutting tip compared with the tips in clinical usage now. The highest MRR was found in this experiment for the 5 teeth cutting tip with 0∘rake angle、15 ∘inclination angle and 40∘chamfer angle of each tooth.
Three stainless steel cutting tips with different coefficients of friction were used in the experiment to increase cutting power, and thus MRR. They are uncoated, TiN-coated and DLC-coated, the coefficients of friction are about 0.5, 0.4 and 0.1 respectively. Under the mode of 50 the MRRs for the uncoated tip, TiN-coated tip, and DLC-coated tip are 0.149 mm3/s, 0.153 mm3/s and 0.165 mm3/s. Less power was consumed in overcoming the friction between the tip and side wall of the groove for the lower coefficient of friction cutting tip. This leads to a larger power left for cutting under the same power provided by the hand-piece. As a result MRR is higher.
In base of the experimental results above, a DLC-coated 5 teeth cutting tip with 0∘ rake angle、15∘inclination angle and 40∘chamfer angle of each tooth was proposed. The MRR of this cutting tip was expected to reach 0.49 mm3/s, which was 3.8 times larger than the tip in clinical usage now.

並列關鍵字

ultrasonic osteotomy ； material removal rate ； cutting power ； specific cutting energy ； coated cutting tips

參考文獻

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