巻号一覧
58 巻, 2 号
選択された号の論文の6件中1～6を表示しています
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研究論文
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畑中 伸夫, 飯塚 高志, 高倉 章雄原稿種別: 研究論文
2008 年 58 巻 2 号 p. 47-53
発行日: 2008/02/29
公開日: 2008/03/30
ジャーナル フリーBulging process is suitable to produce cups with wide flange because of keeping the contour shape of blank sheet unchanged. On the other hand, it is difficult to form tall cups by conventional bulging because, at punch shoulder, thickness of metal sheet becomes much smaller than other portions and it results in a quick breakage there. When the way to decrease the thickness of a sheet metal during the process approaches more to the uniform one, it becomes possible to form cups with both of wide flange and large height. In this study, a new bulging process combined with ironing was proposed in order to form tall cups with wide flange. In this new method, as in the conventional hydraulic bulging method, hydraulic pressure was used to deform metal sheet uniformly. In this hydraulic bulging, compression around die hole by a metal ring assisted the hydraulic pressure to put material into the die-hole. In addition to that, a counter metal punch was used to prevent the material on the head of bulged portion from locally thinning. Furthermore, following ironing makes it possible to decrease thickness of sidewall. In order to clarify the effectiveness of this method, differences of the configuration and the thickness strain distribution between products formed by conventional and new methods were investigated. Finally, it was confirmed that this method make it possible to produce a cup four times as tall as conventional one.抄録全体を表示PDF形式でダウンロード (1422K) -
筆谷 秀一, 糸井 貴臣, 窪 哲雄, 河村 能人, 広橋 光治原稿種別: 研究論文
2008 年 58 巻 2 号 p. 54-57
発行日: 2008/02/29
公開日: 2008/03/30
ジャーナル フリーHot extrusion has been carried out at 623 K on machined chips of Mg96Zn2Y2 (at%) alloy. Microstructure and mechanical properties of the extruded Mg96Zn2Y2 alloy have been investigated. The extruded Mg96Zn2Y2 alloy was composed of α-Mg, Mg12ZnY and Mg3Zn3Y2 phases, and the Mg grain had a mean grain size of 450 nm. The Mg12ZnY phase was frequently observed inside the fine Mg grains. Additionally, oxidation was occurred around cavities remained after extrusion. The extruded alloy exhibited a high 0.2% proof strength of 495 MPa and elongation of failure to 3% at room temperature. Grain refinement of Mg and dispersion of Mg12ZnY and Mg3Zn3Y2 phases caused by hot extrusion lead to high strength at room temperature. Furthermore, the alloy extrusion also exhibited the superplasticity at temperatures of 623 K and 723 K with initial strain rates from 2×10−1 s−1 to 2×10−3 s−1. And also the maximum elongation was 450% at 723 K with initial strain rate of 2×10−3 s−1. The grain boundary sliding of Mg grains is dominant deformation mechanism for the alloy at high temperature ranges.抄録全体を表示PDF形式でダウンロード (1418K) -
日高 達真, 戸田 裕之, 小林 正和, 上杉 健太朗, 小林 俊郎原稿種別: 研究論文
2008 年 58 巻 2 号 p. 58-64
発行日: 2008/02/29
公開日: 2008/03/30
ジャーナル フリーSynchrotron X-ray microtomography has been utilized for the in-situ observation of ductile fracture in cast Al–7%Si alloys exposed at a high temperature for 0–106 s. A high resolution experimental configuration and deflection contrast imaging technique have enabled the reconstruction of silicon particle images with an isotropic voxel with a 0.474 μm edge. The variations in particle shape, size and spatial distribution at the high temperature are readily observed, along with the existence and growth of high-density micro-pores. Three-dimensional image analysis is applied and its feasibility is confirmed. It is clarified that in the case of an as-cast material void nucleation and growth have been observed as has been reported for the general ductile fracture of metallic materials. When it is exposure at the high temperature for a long time, however, ductile fracture is found to be attributable mainly to the growth of pre-existing micro-pores and not the nucleation of new voids at silicon particles. Since such tendency has been also confirmed for other materials, more detailed analysis might be expected in a near future in order to understand actual ductile fracture process in practical materials.抄録全体を表示PDF形式でダウンロード (2773K) -
畑中 伸夫, 飯塚 高志, 高倉 章雄, 山口 克彦, 西本 浩司原稿種別: 研究論文
2008 年 58 巻 2 号 p. 65-70
発行日: 2008/02/29
公開日: 2008/03/30
ジャーナル フリーUsing conventional deep drawing method, it is difficult to make cups or containers taller than the diameter of the cup in only one stage drawing. This is because, in case of using a blank with large diameter, the drawing resistance of the blank material is too high to draw material into die hole by punch. From simple consideration, by using the developed blank, the flange portion of which is divided into four elements just like a petal, the drawing resistance of blank material can be reduced considerably, and so this problem can be overcome. In this investigation, a deep drawing process was attempted using a developed blank instead of a conventional circular or square blank. At first, by introducing two assumptions of the parallel moving and the constant arc length, the shape of developed blank was designed. After that, the effects of the shape of developed blank on the drawn cup were investigated. Finally, it was clarified that, when developed blanks with appropriate shape was employed, very tall cups could be obtained in one stage drawing.抄録全体を表示PDF形式でダウンロード (1097K)
解説
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松木 一弘, 崔 龍範, 有田 和司, 柳沢 平, 佐々木 元原稿種別: 解説
2008 年 58 巻 2 号 p. 71-80
発行日: 2008/02/29
公開日: 2008/05/30
ジャーナル フリーPDF形式でダウンロード (3915K)
連載講座
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小山 秀夫2008 年 58 巻 2 号 p. 81-90
発行日: 2008/02/28
公開日: 2021/06/30
ジャーナル フリーPDF形式でダウンロード (1747K)
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