軽金属
Online ISSN : 1880-8018
Print ISSN : 0451-5994
ISSN-L : 0451-5994
41 巻, 1 号
選択された号の論文の12件中1~12を表示しています
  • 大柏 英雄
    1991 年 41 巻 1 号 p. 1-2
    発行日: 1991/01/30
    公開日: 2008/10/30
    ジャーナル フリー
  • 伊藤 泰永, 難波 圭三
    1991 年 41 巻 1 号 p. 3-10
    発行日: 1991/01/30
    公開日: 2008/10/30
    ジャーナル フリー
    The object of this study is to improve poor fillet formation at the inside of vacuum brazed-joints in aluminum hollow structures such as drawn-cup type of heat-exchangers. No desirable fillets were formed at the inside of brazed-joints of test specimens which were brazed with an alloy A4004 (Al-10Si-1.2Mg). This fact has so far been ascribed to the surface oxide film. However, we noticed the existence of a certain time-lag in melt and flow of the filler metals between the inside and outside in heating sequence. At the inside the filler metals began to melt and flow above 560°C in the braze heat-cycle as Al-Si-Mg ternary eutectic, and then this molten metal effused to the outside and formed the outside fillets. On the other hand, the outside filler metals did not flow until about 577°C (Al-Si eutectic temperature). Such metal flow mechanism caused the poor fillet formation at the inside. In the test specimen using Al-10Si filler metals for one of the components in order to reduce this time-lag, large fillets were obtained both at inside and outside. In addition, amounts of magnesium vaporing from this test specimen decreased remarkably. Thus the combination of Al-Si-Mg and Al-Si alloys for component filler metals of hollow structures is expected to bring great rationalization in this vacuum brazing process.
  • 古井 光明, 松枝 恵治, 小島 陽, 松尾 守
    1991 年 41 巻 1 号 p. 11-17
    発行日: 1991/01/30
    公開日: 2008/10/30
    ジャーナル フリー
    The fundamental phenomena of Electromagnetic Casting (EMC) were investigated. The magnetic flux density, current density and meniscus shape were measured under the electromagnetic force provided to the molten aluminum by 10 turns coil. The magnetic flux density in the coil without load is directly proportional to the voltage, reaching maximum 0.09 tesla. The induced current flows mainly inside of skin in the molten metal (skin effect), and the electric power consumed in the molten aluminum is about 2kW, and the electric power efficiency is about 10%. The meniscus height is directly proportional to square of the voltage, and the surface tension due to the strong oxide film effectively supports the molten aluminum. The meniscus height decreases when the screen is inserted. It decreases to 80% (Al), 70% (Brass), 50% (cast iron) and 45% (SUS) of the height prior to insertion and it is due to electric conductivity of screen.
  • 小山 克己, 神林 幹, 稲林 芳人, 藤倉 潮三
    1991 年 41 巻 1 号 p. 18-24
    発行日: 1991/01/30
    公開日: 2008/10/30
    ジャーナル フリー
    It is revealed that the bleed-through defect occurrs in drawing and redrawing operation and not in ironing operation. The ironed and drawn sidewall surfaces of many can samples are examined by scanning electron microscopy. The dull and fissured surface with a lot of micro aluminum flakes is observed on the bleed-through defect. Lubrication conditions in drawing operation on the degree of the defects are investigated to give the results that the bleed-through defect is affected by viscosity and concentration of lubricant, and pressure between tools and the surface of materials used. The bleed-through defect on aluminum D&I cans is caused primarily by lack of lubrication on the deforming metal in drawing and redrawing process. On the basis of the above results and micrographs of sidewall of cups and redrawn samples by SEM, a model of a formation mechanism of the bleed-through defect is suggested as follows. Numerous small debris from ledges of material surface are created in the deficiency state of lubricant, and then those debris embeded into the surface of the material produce a dull and fissured surface observed optically as dark stripes. According to the model, it is assumed that the asperities of the surface of materials, in conjunction with other variables such as applied cupping lubricants, tooling and forming speed should influence the occurrence of bleed-through defects.
  • 師岡 利政, 湯浅 栄二, 石川 英治
    1991 年 41 巻 1 号 p. 25-31
    発行日: 1991/01/30
    公開日: 2008/10/30
    ジャーナル フリー
    The influence of mechanical grinding on structure of the atomized Al-2%Cr and Al-4%Cr powders was studied by using SEM, EPMA and X-Ray diffraction. Tensile properties of extrusions prepated from the mechanically ground powders were compared to those of extrusions prepared from the atomized powders. Mechanical grinding was carried out for various periods from 20 to 300min by using an attritor type ball mill. Chromium dissolves in aluminum over the solubility limit at room temperature by the atomization treatment. Very fine particles are precipitated from the matrix phase when grinding time is over 180min, but these particles can not be identified by X-Ray diffraction method. The lattice parameter of matrix phase increases with increasing grinding time. In the extrusions of the mechanically ground powders, but the precipitates are observed, but they are not observed in the extrusions of the atomized powders. No change in the lattice parameter is not observed before and after extrusion of the atomized powder, but the lattice parameter increases during extrusion of the mechanically ground powder. Tensile strength of the extrusions of the mechanically ground powders is higher than that of the atomized powders, and elongation is in the reversed relation.
  • 北原 晃, 秋山 茂, 上野 英俊
    1991 年 41 巻 1 号 p. 32-37
    発行日: 1991/01/30
    公開日: 2008/10/30
    ジャーナル フリー
    Metal coating on carbon fiber by ion-plating method was investigated in order to improve the compatibility of carbon fiber with aluminum. Eleven metals, copper (Cu), boron (B), titanium (Ti), zirconium (Zr), silicon (Si), tantalum (Ta), chromium (Cr), molybdenum (Mo), iron (Fe), nickel (Ni) and aluminum (Al) were used as coating materials. The wettability and bonding ability with aluminum were evaluated by simulating experiments with graphite plate as a substrate for carbon fiber. All metal coatings considerably improve the wettability of graphite plate with aluminum, and in particular Fe, Ni and Cu bring very excellent wetting. On the other hand, Al coating fairly improves the bonding ability of graphite with aluminum while other metal coatings bring extremely excellent bonding. The carbon fibers coated with metals except Cu are degradated considerably in strength after heating at 873K because of reaction with the coated ones. All carbon fibers coated first with one of the metals and then with aluminum are degradated extremely in strength after heating at 873K because of formation of the brittle intermetallic compound between the coated metal and aluminum.
  • 山田 茂, 能登谷 久公, 高辻 雄三, 佃 市三, 水谷 秀行
    1991 年 41 巻 1 号 p. 38-43
    発行日: 1991/01/30
    公開日: 2008/10/30
    ジャーナル フリー
    Tool wear of four different grades of high speed steel (SKH4, SKH51, SKH55, SKH57) in machining 7075 aluminum alloy given T6 treatment were examined. In order to know the wearing process, the worn rake faces were probed by EPMA after measuring the flank wear. SKH57 tool provides the best performance in the four tools. In the case of SKH4, SKH51 and SKH55 tool, the wear of the cutting edges and plateau part progress by delamination of deposits due to diffusion and adhesion between the work and tool materials at this area, while the crater wear is caused by abrasive action of chip flow containing hard metallic compounds. The wear of SKH57 tool due to diffusion and adhesion at plateau part is the smallest, therefore, the edge remains clearly. It is found that larger carbide grains containing tungsten in high speed steel resist the progress of abrasive wear induced by chip flow.
  • 北原 晃, 秋山 茂, 上野 英俊
    1991 年 41 巻 1 号 p. 44-48
    発行日: 1991/01/30
    公開日: 2008/10/30
    ジャーナル フリー
    A low density composite (Shirasu Balloons Aluminum Composites: SBAC) of volcano glass micro-balloons (Shirasu Balloons: SB) and an aluminum alloy (Al-12%Si) was investigated in terms of tensile strength. SBAC fractures abruptly at a critical tensile stress, that is a typical brittle material. The fractured surface propagates through the equatorial section of SB and the constricted parts of matrix metal where SB is in contact with together. The effective area fractions of metal and SB wall (SG) sections in the fractured surface are respectively AM=0.363-0.282 VSB and ASG=(1.28+0.556 VSB) h/R, where h and R are the wall thickness and the mean radius of SB, and VSB is the volume fraction of SB in SBAC. The tensile strength of SBAC is proportional to the summation of AM and ASG since SB wall has Young's modulus nearly equal to that of the aluminum alloy. The sphericity of SB changes the stress concentration around the cavitation in SB and affects the tensile strength of SBAC.
  • 青山 俊三, 赤瀬 誠, 坂本 勝美
    1991 年 41 巻 1 号 p. 49-54
    発行日: 1991/01/30
    公開日: 2008/10/30
    ジャーナル フリー
    It has been confirmed that the amount of water-base lubricant can be evaluated measuring the glossiness of the die surface. The relation between spraying conditions and lubricant film formation is discussed. The results show that die temperature has the greatest effect on the amount of deposited lubricant. The lubricant film is not formed when the die temperature is higher than 300°C. It is found, however, that normal lubricant film can be formed at temperature higher than 300°C by choosing proper spraying conditions, viz. spray time, spray distance, spray quantity, type of nozzle and lubricant concentration. It is also found that the measurement of die surface glossiness is one of the best ways of evaluating optimum spraying conditions.
  • 藤川 辰一郎
    1991 年 41 巻 1 号 p. 55-66
    発行日: 1991/01/30
    公開日: 2008/10/30
    ジャーナル フリー
  • 山田 徹
    1991 年 41 巻 1 号 p. 67-74
    発行日: 1991/01/30
    公開日: 2008/10/30
    ジャーナル フリー
  • 神尾 彰彦
    1991 年 41 巻 1 号 p. 75-76
    発行日: 1991/01/30
    公開日: 2008/10/30
    ジャーナル フリー
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