超音波輔助沖壓加工之應用-剪切、引伸與等通彎角擠製;The application of press forming with ultrasonic vibration-shear, deep drawing and equal-channel angle extrusion

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Title:	超音波輔助沖壓加工之應用-剪切、引伸與等通彎角擠製;The application of press forming with ultrasonic vibration-shear, deep drawing and equal-channel angle extrusion
Authors:	朱祖孝;Chu,Tsu-Hsiao
Contributors:	機械工程學系
Keywords:	超音波振動;剪切;引伸;等通彎角擠製;ultrasonic vibration;shear;deep drawing;equal-channal angle extrusion
Date:	2015-07-29
Issue Date:	2015-09-23 14:53:42 (UTC+8)
Publisher:	國立中央大學
Abstract:	本論文之目的在於研究超音波振動於金屬成形加工之效應。研究中主要以超音波振動輔助沖切、引伸與等通彎角擠製等三種製程為主，探討模具與工件之加工特性並進行試驗，分析比較超音波振動所產生的影響。本論文研究分為四個主題，包括超音波振動實驗設備的設計製作、超音波振動輔助沖切模具設計、振動輔助引伸模具設計與超音波振動輔助等通彎角擠製模具設計與其試驗。研究中，首先利用有限元素法配合超音波加工理論，針對超音波輔助沖切、引伸與等通彎角擠製等實驗所需的模具進行設計並成功應用於相關試驗。於超音波輔助沖切研究中，以模具間隙、沖壓速度與進料角度等三因子的不同水準進行實驗設計，配合反應曲面法(Response Surface Methodology, RSM)規畫傳統沖切與超音波輔助沖切兩大組試驗來討論，結果顯示超音波由於動態振動的特性，於低間隙、沖壓速度慢與高進料角時，越能減少毛邊的生成。其次，配合伺服沖床(Servo press)可調式加工曲線，結合沖壓速度與振動振幅等三因子的不同水準進行實驗設計，以反應曲面法探討超音波振動對引伸加工的效應，其結果顯示，配合適當之加工曲線與超音波振幅能夠降低沖頭之成形負荷與成形過程之摩擦力，並增加材料在引伸過程中之成形極限，於引伸加工製程中加載超音波振動所產生的動態摩擦應力的特性，為改善產品品質及提升加工經濟效益的主因。最後，探討超音波輔助等通彎角擠製(ECAE)之影響，其結果顯示超音波加載於ECAE製程，最大成形力負荷隨著超音波振幅增加而減少，有利於模具與沖頭的使用；試片的硬度隨著振幅增加也隨之增加，顯示於ECAE製程中的確能強化材料的機械強度；試片的表面粗糙度隨振幅提升而下降，顯示超音波振動能使界面的潤滑劑有更好的分布與作用，改善摩擦條件。然而，利用有限元素模擬分析的結果，得知當擠製速度大於特定臨界抽拉速度時，前述超音波振動作用的摩擦效應將幾乎完全消失。本論文針對超音波加工模具設計、超音波輔助沖切、引伸與等通彎角擠製等製程分別進行了研究與分析，並藉由實驗之結果了解不同加工製程之特性，期能夠以此結果供日後研究超音波輔助加工之參考。 ;The purpose of this paper is to investigate the effect of ultrasonic vibration to the process of metal forming. The three main processes in the investigation are the shear with ultrasonic vibration, the deep drawing with ultrasonic vibration and equal-channel angle extrusion with ultrasonic vibration to study the characteristics between mold and workpiece and to analyze the influence of ultrasonic vibration. The paper is divided into four themes, including the design of test equipment with ultrasonic vibration, the design of shearing mold with ultrasonic vibration and the design of ECAE mold with ultrasonic vibration. Using finite element method with ultrasonic processing theory to mold design for the shear with ultrasonic vibration, the deep drawing with ultrasonic vibration and ECAE with ultrasonic vibration are successfully applied to the relevant tests. First, In the investigation of the shear with ultrasonic vibration, the die clearance, the shearing speed and the feeding angle are the three factors with different levels in experiment design. The traditional shearing process and shearing process with ultrasonic vibration are two groups into discussion with RSM(Response surface methodology, RSM). The results showed that low die clearance and high feeding angle can reduce burr formation more due to the characteristics of dynamic vibration. Secondly, with adjustable working curve in servo press combined with punch speed and vibration amplitude are the three factors with different levels. The RSM is used to investigate the effect on the deep drawing process with ultrasonic vibration. The results showed that the punch load and the friction force could be reduced with the appropriate process of ultrasonic amplitude and working curve. It also can increase the material limitation in the deep drawing process. The characteristic of the dynamic frictional stress with ultrasonic vibration is the main reason to improve the product quality and enhance the economic process. Finally, the influence of ECAE with ultrasonic vibration is discussed. The results showed that the maximum load decreased with the increasing ultrasonic amplitude in favor of using the punch. The hardness of workpiece can also increase with the increasing ultrasonic amplitude. The manufacturing process is shown in ECAE can indeed strengthen the mechanical strength of the material. The surface roughness of the workpiece can be reduced with the increasing ultrasonic amplitude. It showed that the lubricant in the interface can get better distribution and effect to improve the conditions of friction. However, when speed is greater than a certain critical drawing speed, the friction effect of ultrasonic vibration will almost completely disappear in the use of finite element method to analyze the result. The paper is investigated in the mold design with ultrasonic vibration, the shear with ultrasonic vibration, the deep drawing with ultrasonic vibration and ECAE with ultrasonic vibration. The paper can also understand the characteristics of different working process as a result of possible reference for future study of the ultrasonic assisted forming.
Appears in Collections:	[Graduate Institute of Mechanical Engineering] Electronic Thesis & Dissertation

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