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標題: 加載軸向力對小彎徑金屬管迴轉彎曲製程研究
On Draw Bending Process of a Metal Tube in Small Bend Radius with Axial Load
作者: 謝武燈
Hsieh, Wu-Teng
關鍵字: Draw-Bending
Metal Tube
Metal Tube in Small Bend Radius
Axial Force
出版社: 機械工程學系
摘要: 產品的設計在現今科技發達的時代,輕薄及小型化成了設計的重要方向,因此金屬管要在不影響產品的應用功能及安全下的使用,減少使用的空間,所以小彎徑的彎管也變得日趨重要。小彎徑彎管的製程,在成形中會產生凹陷及管壁變薄等缺陷,將造成金屬管喪失應具備之主要功能。本研究將利用一般業界最常使用的迴轉彎曲法,建立一套可位移心軸及可加載軸向推力的彎管實驗機台,以了解心軸位置與進給方式以及加載軸向推力對於小彎徑彎管的影響,並針對不同的彎管速度及心軸與金屬管間潤滑對彎管的影響作相關之探討。 由實驗中證實,不同彎管速度對彎管並無影響,心軸與管壁間以滑脂潤滑可使心軸負荷降低,心軸位置對金屬管外側管壁的支撐改善了管壁的扁平化,而在心軸的進給方式上,深入金屬管內再微量後退可讓金屬管外側管壁的扁平化獲得比心軸定位的方式於斷面橢圓率有更好的改善,但心軸在到達定位後再微量前進則對斷面幾何反而造成外側管壁凹陷。因此,適當的心軸控制可以仰制金屬管外側管壁的扁平化,但也會對內側管壁造成曲率變大,使改善效果變得有限,心軸對回彈量的影響則是心軸越深入金屬管內可得到很小的回彈量。而加載軸向推力對小彎徑彎管於30°位置的橢圓率獲得更小,不但可以降低金屬管內側的扁平化程度,而使得斷面幾何更接近圓形,也可以改善因心軸造成內側管壁曲率變大而使橢圓率加大之不良影響,使金屬管有較佳斷面幾何。軸向推力越大回彈量越小,而心軸及軸向推力合併使用則可以得到更小的回彈量。因此,本研究所得的結果將有助於小彎徑於彎管工業上的應用,並提供業界有關於加載軸向推力可在小彎徑金屬管迴轉彎曲製程的改善成就。
Nowadays, becoming lighter and smaller is an important direction for product design. Metal tubes which are broadly used to transport the materials and energy should therefore diminish their application volume without any weakening their function and losing the safety. For this reason metal tubes bent into small radius becomes more and more significant. However, in processing metal tubes into small bend radius, some defects will exist, such as hollows on them or thinning on their outer walls. These defects might lose the function of metal tubes. Thus this research attempts to modify the draw bending process which is mostly applied in the industry to bend the metal tube into small radius, so that the defects might be eliminated. A test platform with a stroke controllable mandrel and a mechanism pushing metal tube in the axial direction was setup. The mandrel positioning, axial loading, and bending speed as well as lubricant status are therefore investigated experimentally in this research. The experiment results show that there is no significant difference found between various bending speeds. Regarding lubrication on the tube inner wall, a stick slip phenomenon can be found during tube bending, if no lubricant is applied. By positioning the mandrel firstly deeper beyond the bend center and then moving back during the bending process to its normal position, the hollowing on the tube can be reduced. However, if the mandrel moves deeper during the bending process from its normal position, the wall thickness can be conversely thinned. An axial loading imposed on the tube bending process can reduce the flattening of the bent tube. Superposing an axial loading on the tube bent with a mandrel can induce an excellent cross-section of the bent metal tube. The results obtained in this research regarding the mandrel positioning and the imposed axial loading can be offered for tube bending application industry to improve the tube bending process particularly into small bend radius.
Appears in Collections:機械工程學系所



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