臺灣博碩士論文加值系統

厚板件如筆電轉軸摩擦片，在彎曲後常在彎曲部外側發生裂紋，隨著彎曲半徑越小裂紋越明顯，影響產品外觀、機械強度及製造良率，其原因在於彎曲部外側的過度拉伸，超出材料本身所能承受之最大抗拉強度所致。在執行某壁櫥家具零件產學案時，發現滾輪成形長條形軌道工件時，常因為道次過多，所累積的殘留應力不易預測，往往造成彎曲精度不佳，由於滾壓道次過多，滾輪修正困難，因此嘗試對板料進行預壓成形，以補償滾壓彎曲精度不佳的缺陷。
本研究針對三個彎曲成形實務問題進行個案研究：案例一為厚板彎曲破裂之改善分析，使用 DEFORM 有限元素軟體，進行 2D 之平面應變案例分析，並提出改良型模具方案，以降低破壞值且避免彎曲部外側之過度拉伸。案例二為薄板彎曲回彈之改善分析，針對案例一的破壞分析進行延伸研究，透過降低胚料厚度與加大彎曲半徑來放大觀察回彈之改善程度，使用 DynaForm 軟體分析此種二道次彎曲的改善方案，可降低回彈量的程度。案例三為預壓工序對 U 型彎曲之回彈補償分析，以單道次的 U 型彎曲，來簡化滾輪成形長條形軌道工件之特徵彎曲造型，本研究提出在滾輪成形前，對板料進行壓印及浮壓前加工，來達到預先補償回彈量或前彈量，針對厚度 1 mm 之 AA6016 鋁合金與 SGC 340 熱浸鍍鋅鋼兩種不同材質板材，以 DEFORM 有限元素分析軟體進行 2D 平面應變之有限元素模擬分析，分別對彎曲內部上中下 It、Itm、Im、Imb、Ib，與彎曲外部上中下 Ot、Otm、Om、Omb、Om 共 10個不同位置，探討胚料 U 型彎曲部的前壓印及浮壓加工對回彈量的影響，並搭配試驗模具以驗證模擬之準確性。研究結果如下：

I. 案例一：厚板彎曲破裂之改善分析
(1) 彎曲模擬分析顯示，單道次彎曲所造成之拉伸應力因集中於彎曲部外側，故造成較高之破壞值，隨著彎曲半徑增加，則破壞值隨之降低；改良型彎曲法則是透過類似鍛造擠壓之加工方式，使彎曲所產生之應力均勻分散於彎曲部外側，可有效降低破壞值。
II. 案例二：薄板彎曲回彈之改善分析
(1) 彎曲模擬中顯示，單道次彎曲因彎曲量大，故相對回彈量大；改良型彎曲法分為二道次，具有重複定寸之效果及減少該道次彎曲量，達到降低回彈量的效果。
(2) 壓料力對回彈影響之模擬分析顯示，搭配適當的壓料力組合可降低回彈量。
III. 案例三：預壓工序對 U 型彎曲之回彈補償分析與實驗驗證
(1) U 型彎曲模擬中顯示，浮壓於內側能使回彈量增加，外側則減少回彈量；壓印於內側與外側則均可使回彈量增加。但因受極大變形，殘留應力局部片斷化，回彈量僅能以大方向判斷。

Thick plate parts such as the friction plate of the notebook hinge often have cracks on the outside of the bent part after bending. The cracks become more obvious with the smaller the bending radius, which affects the appearance, mechanical strength and manufacturing yield of the product. The reason is the excessive outside of the bent part. Stretching is caused by exceeding the maximum tensile strength that the material itself can withstand. When implementing a production-academic project of a certain closet furniture part, it is found that when the rollers are forming long rail workpieces, the accumulated residual stress is often difficult to predict due to too many passes, which often results in poor bending accuracy. Due to the excessive rolling passes, the rollers It is difficult to correct, so try to pre-coining the sheet to compensate for the defects of poor rolling and bending accuracy.
This research conducts case studies on three practical problems in bending forming: Case 1 is the improvement analysis of bending and cracking of thick plates, using DEFORM finite element software to conduct 2D plane strain case analysis, and propose an improved mold solution to reduce the damage value and avoid excessive stretching on the outside of the bend. Case 2 is the improvement analysis of the bending spring-back of the thin plate. An extended study was conducted on the failure analysis of Case 1. The improvement of spring-back was observed by reducing the thickness of the blank and increasing the bending radius. The DynaForm software was used to analyze this two-pass bending. The improvement plan can reduce the degree of rebound. Case 3 is the spring-back compensation analysis of U-shaped bending in the pre-coining process. A single-pass U-shaped bending is used to simplify the characteristic bending model of roller forming long rail workpieces. This research proposes that before the roller forming, the sheet metal Pre-coining for embossing and floating pressure to achieve pre-coining spring-back or front spring. For AA6016 aluminum alloy and SGC 340 hot-dip galvanized steel plates with a thickness of 1 mm, the 2D plane strain is limited by DEFORM finite element analysis software Element simulation analysis, respectively, on the inner top, middle and bottom It、Itm、Im、Imb、Ib of the bend, and the outer top, middle and bottom Ot、Otm、Om、Omb、Om, respectively, 10 different positions, to explore the U-shaped bending part of the blank The impact of front imprinting and floating pressure processing on the spring-back, and the test mold is used to verify the accuracy of the simulation. The results of the study are as follows:

I. Case 1: Analysis of improvement of bending and cracking of thick plates
(1) The bending simulation analysis shows that the tensile stress caused by single-pass bending is concentrated on the outside of the bend, which results in a higher damage value. As the bending radius increases, the damage value decreases; improved bending law Through a processing method similar to forging and extrusion, the stress generated by bending is evenly dispersed on the outside of the bending part, which can effectively reduce the damage value.
II. Case 2: Analysis of improving the spring-back of thin plate bending
(1) The bending simulation shows that the single-pass bending has a large amount of bending, so the relative spring-back is large; the improved bending method is divided into two passes, which has the effect of repeated sizing and reduces the bending amount of this pass to reduce The effect of rebound volume.
(2) The simulation analysis of the impact of the pressing force on the spring-back shows that the amount of spring-back can be reduced with a proper combination of the pressing force.
III. Case 3: Analysis and experimental verification of spring-back compensation for U-shaped bending in pre-coining process
(1) U-shaped bending simulation shows that floating pressure on the inner side can increase the amount of rebound, while the outer side reduces the amount of rebound; imprinting on the inner and outer sides can increase the amount of rebound. However, due to the extreme deformation, the residual stress is locally fragmented, and the amount of spring-back can only be judged in the general direction.

摘要 ................................................................................................................................. iv
ABSTRACT ................................................................................................................... vi
致謝 ............................................................................................................................... viii
目錄 ................................................................................................................................. ix
圖目錄 ............................................................................................................................ xii
表目錄 ........................................................................................................................... xiv
一、緒論 ......................................................................................................................... 15
1.1 前言 .................................................................................................................. 15
1.2 文獻回顧 .......................................................................................................... 16
1.3 研究動機與目的 .............................................................................................. 21
1.4 論文架構 .......................................................................................................... 22
二、基礎理論 ................................................................................................................. 24
2.1 沖壓成形 .......................................................................................................... 24
2.1.1 沖壓成形之優點 ..................................................................................... 24
2.1.2 沖壓成形之缺點 ..................................................................................... 24
2.1.3 沖壓成形之種類 ..................................................................................... 24
2.2 彎曲成形 .......................................................................................................... 28
2.2.1 簡介 ......................................................................................................... 28
2.2.2 彎曲定義 ................................................................................................. 29
2.3 沖床類別 .......................................................................................................... 30
2.4 回彈(spring-back) ............................................................................................. 31
2.4.1 影響回彈的條件 ..................................................................................... 31
2.4.2 改善回彈量之方案 ................................................................................. 32
2.5 彎曲破裂 .......................................................................................................... 33
2.6 有限元素分析軟體 .......................................................................................... 34
2.6.1 DEFORM 軟體簡介 ................................................................................ 34
2.6.2 DynaForm軟體簡介 ............................................................................... 35
2.6.3 顯性與隱性算法 ..................................................................................... 35
三、研究方法 ................................................................................................................. 36
3.1 材料參數 .......................................................................................................... 38
3.1.1 AA6016鋁合金 ....................................................................................... 38
3.1.2 SGC 340低碳鋼 ..................................................................................... 39
3.2 案例一厚板彎曲破壞改善分析之模擬參數 .................................................. 40
3.2.1 L型-單道次彎曲 .................................................................................... 40
3.2.2 L型-改良型彎曲 .................................................................................... 42
3.2.3 V 型-單道次彎曲 .................................................................................... 44
3.2.4 V 型-改良型彎曲 .................................................................................... 46
3.3 案例二薄板彎曲回彈改善分析之模擬參數 .................................................. 48
3.3.1 L型-單道次彎曲 .................................................................................... 48
3.3.2 L型-改良型彎曲 .................................................................................... 50
3.3.3 V 型-單道次彎曲 .................................................................................... 52
3.3.4 V 型-改良型彎曲 .................................................................................... 54
3.3.5 壓料力對V 型彎曲回彈之影響 ............................................................ 56
3.4 案例三預壓對彎曲回彈影響改善分析之模擬參數 ...................................... 57
3.4.1 壓印與浮壓成形 ..................................................................................... 57
3.4.2 U 型彎曲成形 ......................................................................................... 59
3.5 回彈鎖點 .......................................................................................................... 61
3.6 回彈量測 .......................................................................................................... 62
3.7 有限元素分析設定 .......................................................................................... 63
3.7.1 DEFORM ................................................................................................. 63
3.7.2 DynaForm ................................................................................................ 63
3.8 實驗設備 .......................................................................................................... 64
3.9 案例三之實驗方法 ......................................................................................... 66
3.9.1 案例三之模具設計 ................................................................................. 66
3.9.2 案例三之實驗流程 ................................................................................. 67
3.10 案例三之實驗步驟 ........................................................................................ 68
3.10.1 壓印與浮壓 ........................................................................................... 68
3.10.2 彎曲成形 ............................................................................................... 68
3.10.3 回彈量測 ............................................................................................... 69
四、結果與討論 ............................................................................................................. 71
4.1 案例一厚板彎曲破壞改善分析之模擬結果 ................................................. 71
4.1.1 L型-單道次彎曲 .................................................................................... 71
4.1.2 L型-改良型彎曲 .................................................................................... 72
4.1.3 V 型-單道次彎曲 .................................................................................... 73
4.1.4 V 型-改良型彎曲 .................................................................................... 74
4.2 案例二薄板彎曲回彈改善分析之模擬結果 .................................................. 75
4.2.1 L型-單道次彎曲 .................................................................................... 75
4.2.2 L型-改良型彎曲 .................................................................................... 76
4.2.3 V 型-單道次彎曲 .................................................................................... 77
4.2.4 V 型-改良型彎曲 .................................................................................... 78
4.2.5 壓料力對V 型彎曲回彈之影響 ............................................................ 79
4.3 案例三預壓工序對板材彎曲回彈影響改善分析之模擬結果 ...................... 80
4.3.1 壓印於彎曲部內側 ................................................................................. 80
4.3.2 壓印於彎曲部外側 ................................................................................. 81
4.3.3 浮壓於彎曲部內側 ................................................................................. 82
4.3.4 浮壓於彎曲部外側 ................................................................................. 83
4.4 案例三實驗結果 .............................................................................................. 84
4.4.1 壓印於彎曲部內側 ................................................................................ 84
4.4.2 壓印於彎曲部外側 ................................................................................ 84
4.4.3 浮壓於彎曲部內側 ................................................................................ 85
4.4.4 浮壓於彎曲部內側 ................................................................................ 85
4.5 彎曲成形之回彈分析統整 .............................................................................. 86
五、結論 ......................................................................................................................... 87
5.1 結論 .................................................................................................................. 87
5.2 未來展望 .......................................................................................................... 89
參考文獻 ......................................................................................................................... 90
附錄 ................................................................................................................................ 92

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