中間縮徑微旋鍛成形之有限元素分析

FE Analysis of Micro Rotary Plunge-Swaging

林均治(Jun-Zhi Lin)

指導教授 ： 林恆勝

國立虎尾科技大學/工程學院/創意工程與精密科技研究所/碩士(2010年)

摘要

線材在中間縮徑旋鍛成形時，模具凸模圓角與工件最先接觸，且因旋鍛模塊易受到主軸旋轉帶動而對工件造成切方向的作用力，容易增加等效應變與扭轉角，在模具圓角過大時容易造成胚料呈現多邊形的情形，過小則會有咬料的情況發生；而一般旋鍛所探討的大多為進料式旋鍛的端部縮徑，本文主要以中間縮徑旋鍛透過DEFORM 3D有限元素法分析線材旋鍛成形，並且針對在不同模塊數的條件下，所搭配不同的模具傾角、模具圓角、摩擦因子等參數，探討在旋鍛過程中對等效應變、扭轉與模具負荷之影響。
研究結果有以下結論：中間旋鍛時模塊受到主軸旋轉帶動下，對工件產生表面壓力與切向摩擦力，且在中間旋鍛時由於模具凸模部分與工件最先接觸，因此若搭配不當的模具片數與模具圓角時，容易造成等效應變與扭轉角過大的情形，研究結果為四片式模具搭配模具傾角12.5°、圓角0.04 mm時為最佳成形製程參數。
從模擬結果可得知等效應變與扭轉角是有正相關的趨勢，因此也間接驗證在各不同模具片數下，有最佳成形模具圓角設計值，此現象類似於抽製，有最佳眼模半角，使得負荷最低。
在三組不同模具片數比較下，四片式模具所受徑向負荷與軸向負荷皆為最低，並且模具對於工件成形所需的步數最少，因此四片式模具對於在中間縮徑旋鍛成形時最為穩健且成形性最好。

關鍵字

微旋鍛 ； 中間縮徑旋鍛 ； 有限元素法 ； 金屬成形

並列摘要

The fillet of the convex die makes first contact with workpiece in the plunge-swaging process. The swaging dies are driven by a spindle and are liable to cause tangential deformation and twist on the workpiece. The workpiece would appear polygon-shape with a large fillet whereas forming defect would occur with a sharp fillet. Up to now broad reports can be found regarding the feed-in swaging process, while scarce resources are reported for the plunge-swaging process. This work aims to analyze the plunge-swaging process of wire via finite element software DEFORM 3D. Under the three die configurations, namely two-, three- and four-piece, the effects of die inclination angle, fillet radius and friction factor on effective strain, twist and forming load are investigated.
The results show that the optimum forming condition was achieved with die inclination angle 12.5° and fillet radius 0.04 mm under the four-piece die configuration. The simulation shows that inclination angle has to be maximal in order to reduce the flow resistance toward the axial direction to reduce the effective strain and twist on the workpiece. The effective strain is also directly related to the twist. There exists an optimum fillet radius which the lowest strain and twist level can be obtained, which is a similar analogy that the lowest load can be achieved in drawing with the optimum die angle in the drawing process.
Among the two-, three, and four-piece die configurations, both the radial and axial forming loads are the lowest in forming with the four-piece die configuration. The required forming stroke is minimal as well. Therefore, four-piece die configuration becomes the optimum choice in plunge-swaging.

並列關鍵字

micro rotary swaging ； plunge swaging ； finite element method ； metal forming

參考文獻

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