棒材旋鍛成形之有限元素分析

FE Analysis of Rotary Swaging of Rods

黃國鈞(Guo-Jun Huang)

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(2009年)

摘要

棒材在旋鍛縮徑成形時，旋鍛模塊受到主軸旋轉帶動而對工件造成切方向作用力，進而形成螺旋流線之成形缺陷，本研究藉由DEFORM 3D有限元素軟體來模擬棒材旋鍛成形，探討面積縮減率、旋鍛模傾角、摩擦因子與胚料直徑等參數，對於棒材在旋鍛過程中所形成螺旋流線、等效應變分佈與多餘變形因子之影響。
研究後有以下結論: 棒材旋鍛成形後呈現螺旋流線之成形缺陷，增加面積縮率、減少傾角與增加摩擦因子，都會造成旋鍛模的切向作用力加大，因此工件的扭轉角度也愈大，其中尤其以面積縮率的影響最明顯。在相同成形條件下工件外徑為0.1與1 mm的扭轉角相當接近，而在外徑10 mm的扭轉角則明顯較低，顯示棒徑愈小，表面力作用的效應則更明顯，旋鍛後愈容易造成工件表面等效應變的增加，此效應類似以較大摩擦因子的條件進行旋鍛，間接驗證微旋鍛情形下，表面作用力會較顯著。
藉由多餘變形因子來定量分析圓棒旋鍛之變形不均程度，結果顯示面積縮率較小、眼模半角較大、摩擦因子較大與外徑較小時，變形不均程度較大。較奇特的現象是在面積縮率較小的旋鍛條件下，模具對工件的作用較不易達到軸心部，再加上旋鍛是以漸增方式成形，因此在工件軸心之等效應變會略小於均勻變形之應變值，但是在表面之應變值仍高，因此多餘變形因子仍較高，因此旋鍛製程的最終變形不均程度仍高。

關鍵字

旋鍛 ； 金屬成形 ； 有限元素法

並列摘要

In sinking rods with rotary swaging, spiral defect would occur because the workpiece is subjected to tangential force caused by the swaging dies driven by spindle motor. This work investigates the effect with the aid of FEM software DEFORM 3D. The influence of reduction of area, die inclination angle, friction factor, and workpiece diameter on the formation of spiral defect, distribution of effective strain, and redundant deformation factor was analyzed.
The results showed that spiral became significant with increasing reduction, decreasing die angle or increasing friction factor. The effect of reduction of area was most influential. Under the same forming conditions, the twist of diameters 0.1 and 1 mm were similar, while that of diameter of 10 mm was smaller. This indicated the effect of surface force became more influential and caused the increase in effective strain near workpiece’s surface with small sized workpiece. The effect was also similar to rotary swaging with high friction. Therefore a deduction could be made that surface force became influential in micro rotary swaging.
Redundant deformation factor was used to evaluate the level of deformation inhomogeneity. The results showed that inhomogenity increased with decreasing reduction, increasing die angle and friction factor, and decreasing workpiece diameter. A peculiar phenomenon would occur in rotary swaging with smaller reduction. The effective strain was smaller than the homogeneous strain at workpiece center, while greater than that of drawn rod on the surface. This was due to the swaging die only acted on the surface and less effectively at center, under the increment forming operation. The resultant redundant deformation factor was still greater with rotary swaging because surface strain was still higher than that of drawn rod.

並列關鍵字

rotary swaging ； metal forming ； finite element method

參考文獻

參考文獻

[1] 中華民國發明專利公報第200711672 號，「醫療用導引線和其製造方法AMEDICAL GUIDE WIRE AND A METHOD OF MAKING THE SAME」發明人：日本ASAHI INTECC，加藤富久。

[2] “2008 台灣精微製造技術研發成果發表會?，金屬工業研究發展中心，97年12 月19 日，台中市。

[3] P. Amborn, S.K. Ghosh, I.K. Leadbetter, Modern Side-Shafts for Passenger Cars: Manufacturing Processes II- Monobloc Tube Shafts, Journal of Materials Processing Technology 63 (1997) 225-232.

[4] 李榮顯、李驊登、王凱弘、陳興時、高景海，“電腦模擬在鈦合金四面精鍛製程設計之應用?，鍛造，第7 卷第4 期，1998 年11 月，pp. 21-38。