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研究生:賴永中
研究生(外文):Lie, Yeong-Jong
論文名稱:改良式三維金屬切削預測模式分析
論文名稱(外文):An Improved Analytical Pridiction of Three Dimensional Cutting Process
指導教授:劉思正劉思正引用關係
指導教授(外文):Lui Si-Zong
學位類別:碩士
校院名稱:國立屏東技術學院
系所名稱:機械工程技術研究所
學門:工程學門
學類:機械工程學類
論文種類:學術論文
論文出版年:1996
畢業學年度:84
語文別:中文
論文頁數:99
中文關鍵詞:有限元素法無限元素法最小平方法
外文關鍵詞:finite elementinfinite elementleast square method
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本研究主要的目的在增加對三維金屬切削中切削力量系統基礎理論的瞭
解,基於此並導出切削力量的預測模式。

本研究主要分二種分析方式來進行。在第一部份的研究分析中,著重於藉
由刀具不同的幾何形狀及一連串不同切削條件的實驗中,改善前人所推導
之數學公式,以建立一個改良式三維金屬切削的力量預測實驗模式。這個
模式含括了生產線上大部份實際的切削過程,刀具複雜的幾何形狀也包括
在此模式中。以S15C機械構造用碳鋼為工件(被切材料),並採用碳化物(
Tungsten Carbide)為刀具來作切削實驗,是因為這二種材料已被產業界
廣泛使用。又因為要配合動力器與車床,實驗中所採用的刀具係參考CNS
國家標準規格來設計,並以左手方向來進刀。配合不同切削參數(進給、
切深角度)等,並以Kistler動力器來量測切削分力。這些量測所得資料,
經由最小平方法導出材料參數,再建立力量預測模式。以FORTRAN 77撰寫
電腦程式來描述此預測模式,並用以預測不同切削條件之切削力量系統。
從實驗與預測所得的結果也順帶地討論影響切削特性的各種切削條件。

其次則討論切削溫度的分佈。在此部份的研究中,著重於改善現有以有限
元素法(finite element)來模擬三維金屬切削的數值分析模式。由於此熱
偶合切削模式非常鄰近刀尖部份,刀具邊界溫度的設定非常重要,必須反
應相當距離遠的刀具實際邊界溫度,無限元素(infinite element)可達到
此目的。由於mapped infinite element可立即與現有程式的有限元素相
結合,程式稍作修改,即可應用到模式中以改善切削溫度分佈預測值。此
改良之數值分析模式可預測溫度分佈同時也預測切削力量。溫度與力量的
預測值,則與前人切削實驗結果來互相驗證。
在經驗預測模式中,採用有圓鼻之刀具(round tool),若圓鼻半徑趨近於
零成尖銳刀具(sharp tool),會造成預測值的發散。此時可改採數值分析
模式來預測切削力量,以解決上述問題。此二種力量預測模式所預測力量
之力量系統均與實驗值互相驗証,驗証結果相當符合,証明本研究採用的
方法是可行的。

關鍵字:有限元素法 無限元素法

最小平方法



The objective of this research is to gain more fundamental
understanding cutting forces system in the three-dimensional
metal cutting, and from that understanding develop a predictive
model of tool cutting forces.

Two major analysis were conducted in this work. In the first, an
improved three-dimensional empirical model base on various tool
geometries and a series of comprehensive cutting experiments is
developed. This model covered most practical metal cutting
operations in the production line. The complexity of geometric
shape of tool is also included. Experimental cutting tests were
performed using S15C mild steel as workplace, and Tungsten
Carbide as tool. Due to the limitation of the lathe, a self-
designed left-hand tool was used throughout experiments.
Cutting, feed, radial components of the tool force were
measured. Base on least-square method, all measured data were
applied to find material constants for the mathematical model.
This model can then be used to predict cutting forces over a
wide range of cutting conditions. A computer code written in
FORTRAN 77 was developed for this purpose. The effect of
cutting conditions on cutting performance was also evaluated.

The second analysis focused on the temperature distribution
along tool boundary. An existing three-dimensional analytical
model based on the Eulerian finite element method is modified.
In this thermal-coupled model, special boundary condition was
treated with so-called infinite element for the tool boundary at
a great distance form the cutting edge. The mapped infinite
element was selected in this model for its simplicity and ease
in programming. The numerical model showed to be capable of
predicting tool cutting forces as well as temperature
distributions. The predicted forces and temperature were
compared with previous cutting experiments using a high speed
steel(HSS-T15)tool to cut aluminum alloy(Al 6061-T6).

It should be pointed out that a round tool was used in the
empirical model and a sharp tool was used in the numerical
model. Predicted cutting forces form both empirical and
numerical model were compared with experimental results. Good
correction was found between the measured and predicted results.
Predicted temperature results showed that the infinite element
provide a simple yet more accurate method to calculate the
unbound tool temerature.

Keywords:finite element infinite element

least square method



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