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53 巻, 3 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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米倉 浩司, 岩堀 弘昭, 山本 善章, 中村 元志1981 年 53 巻 3 号 p. 101-105
発行日: 1981/03/25
公開日: 2012/02/16
ジャーナル フリーIn order to elucidate how the molten metal flow behaves in a runner to affect sand and slag mark defects in castings, the metal flow pressure against the runner wall and its velocity were measured by using an open channel runner. Remarkable pressure variation of molten metal flow causes in the neighborhood of the sprue bottom, but this is considerably reduced as the distance from the sprue bottom increases. In the agitation flow region which involves sand and slag, a violent pressure variation is exerted on the mold wall, and the flow velocity is very fast and varies greatly. In contrast, in the stationary flow region which does not include sand and slag, the flow velocity is constant and is proportional to the cubic root of the pouring rate.抄録全体を表示PDF形式でダウンロード (643K) -
小池 敬一1981 年 53 巻 3 号 p. 106-111
発行日: 1981/03/25
公開日: 2012/02/16
ジャーナル フリーIn order to make the removal of plaster mold from casting, easy water soluble plaster molds containing MgSO4 were examined. The plaster containing 75∼84% CaSO4 and 16∼25% MgSO4 was easily shaped and showed considerably high transverse strength when dried. The plaster which contained some refractory fillers for foundry use, also showed increase in transverse strength by the addition of MgSO4, because of the bonding of the refractory materials with MgSO4. It was shown that molten aluminum poured into this plaster mold does not react with the mold, and castings with good surface smoothness are obtained. In the mixture of CaSO4, MgSO4 and H2O, the separation of MgSO4 takes place first and particles of CaSO4 are bonded with MgSO4⋅7H2O. Therefore this plaster is soluble in water.抄録全体を表示PDF形式でダウンロード (734K) -
斉藤 図, 田中 雄一, 戸倉 郁夫, 井川 克也1981 年 53 巻 3 号 p. 112-116
発行日: 1981/03/25
公開日: 2012/02/16
ジャーナル フリーA new method using a relatively short cylindrical bar as a test piece was proposed for measurement of thermal diffusivity of some cast irons, and the theoretical treatment and the reliability and accuracy of the method were discussed. Also, heat transfer coefficient on the surface of a test piece and the temperature difference between the initial and the final states of the test piece were found from the experiment to be small in their influence on the measured results. Furthermore, the thermal diffusivity of cast irons was measured and tabulated as a function of spheroidicity, showing that the so-called compacted-vermicular graphite cast iron was much closer to the flake graphite rather than to the spheroidal graphite cast iron in its heat transfer characteristics at around 300°C.抄録全体を表示PDF形式でダウンロード (577K) -
佐藤 敬1981 年 53 巻 3 号 p. 117-122
発行日: 1981/03/25
公開日: 2012/02/16
ジャーナル フリーThe evaluation of factors influencing the formation of spheroidal graphite in untreated cast irons was examined, which were synthetized from electrolytic iron, electrode graphite powder and metallic silicon and were desulfurized to 10 ppm of sulfur in magnesia or lime crucible under lime-fluospar flux. (1) Spheroidal graphite can be produced without a deliberate addition of any spheroidizing elements by controlling the carbon equivalent, impurities and cooling rate. In the range of composition corresponding to the maximum carbon solubility limit of austenite, the whole of the graphite can separate in spheroidal form. However, in iron with higher carbon content, the attempt to produce fully spheroidal graphite structure by desulfurization alone was not successful. (2) Rapid cooling has a favorite effect on spheroidal graphite formation especially in high carbon iron. Unidirectional freezing can bring the formation of a periodic structure consisting of alternate layers of spheroidal and flaky graphite in eutectic and hypereutectic iron of extremely low sulfur content. (3) Vacuum melting of the desulfurized iron shifted the range of composition producing fully spheroidal graphite structure to a lower level of carbon content and moreover showed no clear tendency to promote the formation of spheroidal graphite in high carbon iron.抄録全体を表示PDF形式でダウンロード (922K) -
福迫 達一, 久保 公雄, 大中 逸雄, 山本 雄三1981 年 53 巻 3 号 p. 123-129
発行日: 1981/03/25
公開日: 2012/02/16
ジャーナル フリーThe effect of various factors on pressure tightness of Cu-8%Sn alloy cylindrical castings solidified from one direction and from both directions was investigated. Darcy's law was applied to the measurement of pressure tightness, that is, a pressure of nitrogen was applied to one side of test pieces 1mm thick cut from the castings. The rate of leakage from the other side was proportional to the pressure, so pressure tightness could be represented by leakage coefficient calculated from Darcy's law. Microscopic observation showed that in the test pieces with a large leakage coefficient continuous microporosity dispersed at dendrite cell boudary, and in that with a small leakage coefficient most of porosity dispersed between secondary dendrite arms although some dispersed at the dendrite cell boundary. Leakage did not occur in the columnar grain zone, but it occcured in some of the equiaxed grain zone. There was no relation between leakage and the equiaxed grain size. Pressure tightness was related to G/Δθf where G and Δθf are temperature gradient and partial solidification time. Leakage occured when G/Δθf was below 0.019°C/cm⋅sec for the castings solidified from one direction and 0.027°C/cm⋅sec for those solidified from both directions. Leakage also occurred when porosity became more than 4%, irrespective of the solidification conditions.抄録全体を表示PDF形式でダウンロード (775K)
技術報告
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大出 卓, 大平 五郎1981 年 53 巻 3 号 p. 130-134
発行日: 1981/03/25
公開日: 2015/01/27
ジャーナル フリーPDF形式でダウンロード (2866K)
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