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49 巻, 10 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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尹 義博, 西 成基, 篠田 武雄1977 年 49 巻 10 号 p. 585-590
発行日: 1977/10/25
公開日: 2012/07/10
ジャーナル フリーThe influence of solidification conditions on microsegregation of dendritic structures was investigated with unidirectionally solidified Al-Cu alloys. In order to study the result of microsegregation, solute distribution at each different distance from the chill surface was determined as a function of the fraction of solid which was given by two dimensional solidification model. Also the mechanism of solute redistribution during the growth of dendrite was discussed.
The segregation index (S) increased by decreasing the solidification rate (R), and the S between primary dendrite arms was more remarkable than that between secondary dendrite arms. The relationship between S and R was generally obtained as follows;
S=A logR+C
where, A and C are the constants determined by concentration. Cu-isoconcentration curves around the dendrite element demonstrated Cu concentration to be minimum at the center of primary dendrite stalk. With decreasing distance from the chill surface (increasing R) the effective partition coefficient Ke (also minimum Cu concentration) increased, but Ke was little affected by concentration. The relationship between Ke and R was obtained as follows;
Ke=0.21 logR+0.2
in which, R is cm/min.
The influence of diffusion layer on the solute movement ahead of the solid-liquid interface near the dendrite tip which was not obtained by means of the prior linear analysis in Al-Cu alloys was clearly demonstrated by determining the fraction of solid from two dimensional solidification model, and it was found that the diffusion layer has a remarkable effect upon the solute redistribution. The degree of microsegregation was dependent upon the change of the effective partition coefficient with the change in the rate of solidification, and could be interpreted qualitatively by the partially mixed liquid model.抄録全体を表示PDF形式でダウンロード (670K) -
片島 三朗, 松浦 誠1977 年 49 巻 10 号 p. 591-596
発行日: 1977/10/25
公開日: 2012/07/10
ジャーナル フリーThe pressure distribution in the mold during squeezing was measured under various molding conditions. It was found that the pressure varied widely in different parts of the mold and the distribution of pressure was greatly affected by the flask or pattern dimensions and the weight of molding sand. Friction between the sand and the flask or pattern and variation in the degree of sand compression in the same mold were discussed and were shown to be significant factors governing the distribution of pressure. The average mold density in relation to the ratio of the pattern volume to the molding sand volume was also examined.抄録全体を表示PDF形式でダウンロード (648K) -
近藤 靖彦, 安江 和夫, 磯谷 三男1977 年 49 巻 10 号 p. 597-601
発行日: 1977/10/25
公開日: 2012/07/10
ジャーナル フリーThe investigation was concerned with the effect sulfur and cooling rate has on fine graphite structure and mechanical properties of annealed ferritic metal mold gray cast iron. By rapid cooling rate (19-24°C/sec) of molten iron (3.3%C, 2.7%Si), annealed ferritic metal mold gray iron has been shown to have a tensile strength of about 40kg/mm2 with about 2 percent elongation when cast as 20mm dia. bars. The graphite shape has been mainly fine D-type less than 4μm. These mechanical properties and graphite shape were found to be similar over the range of sulfur content from 0.011 to 0.016%. In slow cooling (about 8°C/sec), the reduction in sulfur content slightly increased the tensile strength. Fine D-type graphite in ferritic metal mold cast iron containing 0.011-0.016%S and which was solidified rapidly, was the same shape as the fiber-like coral graphite in Fe-C-Si alloy containing 0.002%S and rounded D-type graphite in metal mold iron containing 0.009%S. These fine graphites are more rod-like in shape than flaky. The sulfur content to obtain the needed graphite refinement depends on cooling rate at solification. More sulfur can be allowed when the cooling rate is rapid.抄録全体を表示PDF形式でダウンロード (754K) -
塩田 俊雄, 小松 真一郎1977 年 49 巻 10 号 p. 602-607
発行日: 1977/10/25
公開日: 2012/07/10
ジャーナル フリーThe low strength and the brittleness of cast iron are commonly believed to depend fully upon the notch effect of the graphite, however the graphite in cast iron can be considered also to reduce the effective sectional area of cast iron. In this paper, the authors investigated the influence of graphite-carbon content and the graphite shape on the effective sectional area and the static strength of cast iron.
The effective sectional area of flake graphite cast iron is closely correlated with its graphite-carbon content, and can be estimated by the regression equation between them. Also, it is slightly influenced by the type of graphite distribution. It is far smaller than what is estimated from the volume percentage of its graphite-carbon content, and is only between 15% and 40%. As the graphite shape changes from spheroid to semi-spheroid and to flake, the effective sectional area is influenced largely, and is approximately 80% in case of a spheroidal graphite cast iron, and decreases greatly with the decrease in the degree of graphite spheroidization.
The static strength of cast iron is determined by the product of the effective sectional area and the strength of matrix. The results of the experiment with several holed plates and others showed that the notch effect of graphite hardly influences the static strength of cast iron, and furthermore, possibly enhances the static strength because of the plasticity restriction. Brinell hardness is correlated to the effective sectional area and it increases with the increase of the effective sectional area under the condition in which the hardness of matrix is constant.抄録全体を表示PDF形式でダウンロード (713K) -
新山 英輔1977 年 49 巻 10 号 p. 608-613
発行日: 1977/10/25
公開日: 2012/07/10
ジャーナル フリーA simplified finite difference method for the estimation of solidification rate of shape castings was proposed, where numerical calculation of mold temperature was replaced by the boundary conditions to be given at the casting surfaces in a form of heat flux as expressed by a known analytical function. Owing to the elimination of the mold part of the numerical calculations, the method enables the number of element divisions to be reduced to some tenths or handredths of those needed in the usual difference method. The cumulative heat flux was tentatively assumed to be proportional to the square root of time for all mold cavity shapes, although the relation is correct only for plane mold surfaces in the strict sense. The solution of one-dimensional problems by the proposed method compared satisfactorily with those by the analytical as well as the usual finite difference solutions.
The solutions of two-dimensional problems of steel castings by the present method agreed well with the solution by the Chvorinov's method, except in the riser where the acceleration of cooling caused by the adjoining castings, which was thinner than the riser, was made evident by the present method, which, in principle, could not be detected by the Chvorinov's method. Some discrepancies were found in the solutions on the two-dimensional problems between the present and the usual finite difference methods and were attributed to the neglect in the former of the effect of mold cavity shape on the heat flux function. A future possibility of correcting this error was suggested. Three-dimensional problems were also solved in a rough fashion in order to illustrate the ease of data preparation in the present method as compared to the usual difference method.抄録全体を表示PDF形式でダウンロード (632K) -
藤井 恒弥, 尾崎 正道1977 年 49 巻 10 号 p. 614-617
発行日: 1977/10/25
公開日: 2012/07/10
ジャーナル フリーAt present, thermal treatment-scrabbing process is generally considered as the most suitable process for reclamation of foundry waste sand. But when using the CO2 processed sand for mold or core making, it is usually impossible to apply thermal treatment to the waste sand containing water glass sand, because the component of solidified water glass in waste sand is viscous at high temperatures, and causes the coagulation of heated sand to stick together. Therefore the thermal reclamation process in the fluidizing bed furnace is not applicable. We experimented with the behavior of solidified water glass in waste sand at high temperatures, and then studied the condition of flidizing bed formation for thermally treating this kind of sand. From our results, we were able to find the possibility of developing thermal systems for reclaiming this kind of waste sand.抄録全体を表示PDF形式でダウンロード (570K)
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